Search PubMed⌕ Search

Biomedical subjects

H Lee

Publications and source records attributed to H Lee.

At least 649 records · Page 36Linked to original sources
PubMed1993

Analysis of polycyclic aromatic hydrocarbon-DNA adducts by postlabelling with the weak beta-emitters 35S-phosphorothioate and 33P-phosphate, immobilized boronate chromatography and high-performance liquid chromatography.

The wide range of carcinogenic activities of optical isomers of bay-region diol-epoxides of polycyclic aromatic hydrocarbons (PAHs) demands analytical techniques capable of distinguishing both the diastereoisomer and enantiomers of the PAH diol-epoxide (PAH-DE) responsible for DNA adduct formation. Our laboratory recently developed postlabelling procedures using the radioisotope 35S for HPLC analysis of benzo[a]pyrene (BaP)-DNA adducts formed in BaP-treated hamster cell cultures. To allow identification and complete separation of anti-PAH-DE-DNA adducts from syn-PAH-DE-DNA adducts, an immobilized boronate chromatography procedure was developed using a high-capacity boronate column. Analysis of 7,12-dimethyl-benz[a]anthracene (DMBA)-DNA adducts formed in treated hamster embryo cells by this boronate chromatography procedure and 35S-postlabelling demonstrated that both anti- and syn-DMBA-DE were bound to DNA. These analytical techniques also provided evidence that the potent carcinogen and environmental PAH dibenzo[a,l]pyrene was metabolized in cells to a DNA-binding intermediate with structural characteristics of an anti-PAH-DE. Conditions were also developed for using 33P-labelled ATP in the postlabelling assay. The use of [33P] instead of [35S]ATP offers the advantages of ease of labelling and greater sensitivity while still using a weak beta-emitter. The development of PAH-DNA adduct analysis techniques with improved sensitivity allows more detailed studies of how PAHs interact with DNA and how this leads to cancer induction.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1993

Seroepidemiology of human T-cell lymphotropic virus type I/II in northeastern Brazil.

We investigated the prevalence of human T-lymphotropic virus I/II (HTLV-I/II) infection in Bahia, a state in Northeastern Brazil. Healthy individuals (n = 327) and patients (n = 337) with a variety of diseases were screened for antibodies to HTLV-I/II using an enzyme immunoassay and Western blot. The overall prevalence among healthy subjects was 1.8% (six of 327); among patients it was 18.4% (62 of 337). Patients with AIDS had the highest prevalence of HTLV-I/II infection, 22.7% (20/88), followed by randomly selected patients from an infectious disease hospital, 19.4% (25 of 129), and tuberculosis patients, 11.1% (10 of 90). Four of 14 patients with myelopathy and three of 16 patients with lymphoid leukemia or lymphoma were seropositive for HTLV-I/II. Sixty-three of 68 HTLV-I/II-positive specimens were then typed: 53 patients were HTLV-I positive, three patients were HTLV-II positive, and in seven patients the assay could not distinguish infection by HTLV-I or II. The finding among HIV-seropositive intravenous drug users in Bahia of coinfection with HTLV-I is contrasted with reports from other areas in which dual infection occurs with HTLV-II. Although high prevalence of HTLV-I infection was found in Bahia, the extent and clinical manifestations of HTLV-I/II infection in Brazil remains imprecisely defined, and further studies are needed.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Cognitive development of preterm low birth weight children at 5 to 8 years old.

Prematurity and low birth weight have been considered to be important risk factors for cognitive development during early childhood; however, it has been suggested that the developmental delays disappear with age. Eighty-one preterm (< 38 weeks) low birth weight (< 2500 g) children between 5 and 8 years old from the Children of the National Longitudinal Survey of Youth were compared with individually matched full-term normal birth weight children to investigate the catch-up delays in cognitive functioning including language and mathematics skills. Preterm children showed a significant delay in cognitive functioning only until 6 years old. Regression analyses showed that environmental factors accounted for more variation in cognitive development than did perinatal factors. In support of a transactional model, preterm children exhibited a self-righting tendency during their early childhood so that eventually environmental influences overshadowed biological influences.

Birth Weight↗
PubMed1993

Developing an integrated strategy to meet homeless families' health needs.

Homeless families are vulnerable to considerable health problems, yet are overlooked in the government's national strategy for health. Access to services and contact with agencies are difficult for people displaced to a new area. Helen Lee and Ann Goodburn describe the health visiting service they offer homeless families in Camden, north London, where the majority are from outside the borough and many recent immigrants to this country.

Community Health Services↗
PubMed1993

Sequence length and error analysis of Sequenase and automated Taq cycle sequencing methods.

We have examined DNA sequence error as a function of length using both a manual method of performing reactions with Sequenase and an automated Taq cycle sequencing method. DNA fragments from both methods were separated and analyzed on a sequencer. To determine the sequence of a cosmid insert (35.3 kb), 379 sequences were obtained from a manual Sequenase method, and 354 sequences were obtained from a Taq cycle sequencing method as performed on an automated robotic workstation and sequenced on an automated fluorescent sequencer. A highly redundant consensus of these sequences was obtained and aligned with the individual sequences to determine sequence error over the length of each sequence. The results of this study indicate that error is about 1% per position over the first 350 nucleotides, but increases thereafter to about 17% at 500 nucleotides. This pattern of accuracy was nearly equivalent for manual Sequenase methods and automated Taq cycle sequencing methods. The potential of these methods in large-scale DNA sequencing projects is discussed.

Cloning, Molecular↗
PubMed1992

Prevalence of antibody to human T-cell lymphotropic virus type I/II in people of Caribbean origin in Toronto.

OBJECTIVE: To estimate the prevalence of antibody to human T-cell lymphotropic virus type I/II (anti-HTLV-I/II) in people from an HTLV-I/II-endemic area (the Caribbean) living in a nonendemic region (Canada). DESIGN: Cross-sectional household survey. SETTING: Households in Toronto in 1989. PARTICIPANTS: A modified quota sampling method was used to recruit subjects of Caribbean origin as well as other Canadians. Of 2900 people invited to participate in the study 1323, 743 of Caribbean origin, were interviewed about their background and possible exposure to HTLV-I/II. MAIN OUTCOME MEASURES: Blood samples were analysed for anti-HTLV-I/II by means of an enzyme-linked immunoassay, the result being confirmed by the Western blot technique and radioimmunoprecipitation assay. The samples were also analysed for antibody to human immunodeficiency virus (anti-HIV) and hepatitis B surface antigen (HBsAg) and for surrogate markers of non-A, non-B hepatitis. RESULTS: A total of 853 blood samples (64.5%) were analysed, 483 (56.6%) from subjects of Caribbean origin. The proportion of subjects who agreed to give a blood sample was similar for the Caribbean and non-Caribbean strata. Eleven subjects, all of Caribbean origin (2.3% of the Caribbean stratum), were confirmed to be positive for anti-HTLV-I/II. There were no significant differences between the antibody-positive and antibody-negative subjects with respect to sex, age, racial origin or residence in the Caribbean for at least 22 years. All anti-HTLV-I/II-positive subjects were negative for anti-HIV and HBsAg, and four (36.4%) were positive for antibody to HBsAg and to hepatitis B core antigen. CONCLUSIONS: Except for origin, an association between antibody positivity and other factors could not be demonstrated. The findings suggest that blood donor screening might include place of origin in addition to the usual lifestyle or behavioural factors. However, the need to ensure safety of transfusion must be balanced against the need for participation of all groups in the blood transfusion program.

Adolescent↗
PubMed1992

Long range electron transfer along an alpha-helix.

The many observations of long range electron transfer in proteins raises the question of whether a protein's structure can influence the rate or path of such transfers, and if so, then how. To answer these questions requires information on which of the various structural elements composing proteins support long range electron transfer. In this report, we present evidence for long range electron transfer along the alpha-helix of a synthetic leucine zipper dimer. We also present electron transfer rate data obtained with other helical peptides.

Amino Acid Sequence↗
PubMed1992

Effect of age on human immunodeficiency virus type 1-induced changes in lymphocyte populations among persons with congenital clotting disorders. Transfusion Safety Study Group.

Children other than neonates infected with human immunodeficiency virus type 1 (HIV-1) have low rates of progression to acquired immunodeficiency syndrome (AIDS). Through 1989, 5.3% of 95 infected hemophiliacs aged 5 to 13 years developed AIDS, compared with 20.3% of 364 aged greater than or equal to 25 years. We asked whether the HIV-1 impact on peripheral blood mononuclear cell subpopulations differed with age using pairwise comparisons of uninfected and infected male children and adult hemophiliacs. Infected children had lesser reductions of total lymphocytes than adults, but proportionately lower numbers of CD2+, CD4+, CD2+CD26+, and CD4+CD29+ counts. CD4+CD45RA+ cell counts were greater than twofold higher in uninfected and infected children than adults; with infection, the CD4+CD45RA+/CD4+ proportion increased by 1.4-fold in adults, but was unchanged in children. Infected adults had highly significantly increased total CD8+ counts; both age groups had elevated CD8+HLA-DR+ counts. Infected children had significantly higher total B-cell counts than infected adults, with a disproportionately lower number of resting B cells (CD20+CD21+). During 2 years of follow-up, infected children and adults had lymphocyte changes in the same directions and these were proportionately equal. The lower rate of HIV-1 progression in children may be partly associated with differences in lymphocyte populations compared with adults; functional properties of immune cells may be equally or more important.

Acquired Immunodeficiency Syndrome↗
PubMed1992

HTLV-I infection in selected populations in Australia and the western Pacific region.

The prevalence of infection with human T lymphotropic virus type I (HTLV-I) in 19,975 blood samples from Australia and the western Pacific was determined by measuring the presence of specific antibody (anti-HTLV-I) by enzyme-linked immunosorbent assay (ELISA) with confirmation by western blot and/or radioimmunoprecipitation techniques. In Australia no evidence of HTLV-I infection was found in injecting drug users, patients with the acquired immunodeficiency syndrome (AIDS), subjects attending a sexually transmitted diseases clinic, female prostitutes, or transfusion recipients. A low prevalence of infection was detected in people with haemophilia (0.5%) and in male homosexuals (0.5%-1%). No antibody was detected in sera from Vanuatu, Kiribati, American Samoa, the Cook Islands, New Caledonia, the Federated States of Micronesia, French Polynesia and Fiji, but a low frequency of anti-HTLV-I was detected in sera from the Solomon Islands (1.2%) and Nauru (0.6%).

Acquired Immunodeficiency Syndrome↗
PubMed1992

Lipid droplets of neuroepithelial cells are a major calcium storage site during neural tube formation in chick and mouse embryos.

In situ precipitation of calcium (Ca2+) with fluoride and antimonate shows that Ca(2+)-specific precipitate is localized almost exclusively within lipid droplets of neuroepithelial cells during neural tube formation in chick and mouse embryos. The density of Ca2+ precipitate within lipid droplets is generally greater in the apical ends of cells situated in regions of the neuroepithelium that are actively engaged in bending. These findings suggest that lipid droplets, in addition to providing a source of metabolic fuel for developing neuroepithelial cells, also serve as Ca(2+)-storage and -releasing sites during neurulation.

Animals↗
PubMed1992

Imaging of human T-lymphotropic virus type I-associated chronic progressive myeloneuropathies.

We studied magnetic resonance imaging (MRI) of the head and cervical spine and CT of the head in 46 patients (14 men, 32 women) with chronic progressive myeloneuropathy. The findings were correlated with human T-lymphotropic virus type I (HTLV-I) serology, race, country of origin, and age. We found a female predominance of 2:1. Most patients were aged between 30 and 50 years, and most were Caribbean immigrants and black. There were 9 men and 17 women with blood antibody titers to HTLV-I and 7 men and 15 women with cerebrospinal fluid (CSF) titers. All patients with virus or antibodies in blood or CSF were Caribbean immigrants or black. T2-weighted cranial MRI showed scattered areas of high signal intensity in the cerebral white matter, usually in the periventricular and subcortical areas, but not in the posterior cranial fossa. Cranial CT revealed periventricular low density areas, ventricular enlargement, and atrophy MRI of the cervical spine showed atrophy of the cord. Myelography was normal in all 15 patients examined. No imaging differences were observed between the HTLV-I-positive and -negative patients. These findings, although consistent with demyelination, are not specific.

Adolescent↗
PubMed1992

Density and distribution of excitatory amino acid receptors in the developing human fetal brain: a quantitative autoradiographic study.

The binding of [alpha-3H]amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) to quisqualate receptors, [3H]kainate (KA) to KA receptors, and L-[3H]glutamate to N-methyl-D-aspartate (NMDA) receptors was determined by quantitative autoradiography in brains obtained from twelve aborted human fetuses ranging from 16.5 to 26 weeks of gestational age. Among the three receptor subtypes, specific binding to AMPA was the highest, followed by NMDA and KA, respectively, in all age groups. Receptor binding was already apparent by 16.5 weeks in the hippocampus, thalamus, and subthalamic nucleus, rose sharply by 20-21.5 weeks, and subsequently declined to their lowest levels by 24-26 weeks. Anatomically distinct binding patterns for each of the three major excitatory amino acid (EAA) receptor subtypes were well established by 20-21.5 weeks. Within the hippocampus, AMPA was localized primarily in the stratum pyramidale, NMDA in the stratum radiatum, and KA in the molecular layer of the dentate gyrus and in the stratum lucidum of the CA3 region. The cerebral cortex showed dense labeling of AMPA in the outer layers, whereas KA binding was more prominent within the inner layers. The putamen and globus pallidus also showed relatively dense receptor binding in all age groups. The sharp rise in receptor density at 20-21.5 weeks of age suggests involvement of EAA pathways in developmental plasticity, including reorganization of neuronal processes or synapses, during this period of development. Developmental changes in the density and distribution of EAA receptors, as shown in this study, may also provide insight into shifts in the localization of age-dependent selective vulnerability within the developing human fetal brain.

Autoradiography↗
PubMed1992

Production and immobilization of D-aminoacylase of Alcaligenes faecalis DA1 for optical resolution of N-acyl-DL-amino acids.

The production of D-aminoacylase by Alcaligenes faecalis DA1 was induced 5- to 50-fold by N-acetyl-D-amino acids. This strain produced about 443 units of D-aminoacylase and 52 units of L-aminoacylase per gram of cells (wet weight) when cultivated in a medium containing 1% N-acetyl-DL-leucine as the carbon source. The D-aminoacylase was partially purified by Fractogel DEAE 650 column chromatography and then immobilized on another Fractogel DEAE 650 column. The catalytic activity of the immobilized D-aminoacylase was 2,650 units per milliliter of gel. The Km values for the free and the immobilized enzymes were found to be 1.00 and 0.22 mM, respectively, using N-acetyl-D-methionine as a substrate. The optimal reaction pH and temperature for both soluble and immobilized enzyme were around 8.0 and 45 degrees C, respectively. The free enzyme was stable in the pH range from 5.0 to 11.0, whereas the immobilized enzyme tended to detach from the gel at pH values higher than 9.0. Both forms of enzyme were stable up to 40 degrees C. When used for the optical resolution of N-acetyl-DL-methionine, the immobilized enzyme maintained 90% initial activity after 17 days of continuous operation at 45 degrees C. The process of purification and immobilization of D-aminoacylase described in this report is very effective and easy to scale up.

Alcaligenes↗
PubMed1992

Germanium and silver resistance, accumulation, and toxicity in microorganisms.

Germanium is an inert metal with no known biological function in prokaryotic or eukaryotic organisms. Its toxicity is low compared to that of silver. Germanium is accumulated in certain bacterial strains by either energy-independent passive binding or an energy-dependent mechanism. Little is known about the molecular aspects of silver resistance, toxicity, and accumulation in bacterial strains. This is surprising because silver has been used as an antimicrobial agent in the medical field for centuries. It is likely that silver ions are excluded (resulting in decreased silver accumulation) from certain bacterial strains or immobilized intracellularly to prevent toxic effects from being exerted. These mechanisms of silver resistance have not been fully elucidated. This review examines the toxicity and accumulation of germanium and silver in selected microbial species. In addition, resistance mechanisms to these biologically nonessential metals is discussed, with more emphasis placed on silver-resistant bacteria due to the knowledge available.

Bacteria↗
PubMed1992

Health care worker exposure to HIV-1 and HTLV I-II in critically ill, resuscitated emergency department patients.

STUDY OBJECTIVE: Exposure to HIV-1 is of profound concern to health care workers. HTLV-I and HTLV-II, retroviruses with similar modes of transmission as HIV-1, also cause disease in human beings. Emergency department resuscitations are high-risk situations for such exposure. The purpose was to determine the seroprevalence of HIV-1 and HTLV I-II in patients undergoing ED resuscitations, the magnitude of health care worker exposure, and risk factors associated with infection. DESIGN: Prospective identity-unlinked seroepidemiologic study. SETTING: ED of a 950-bed private inner-city teaching hospital. Participants included 370 patients undergoing ED resuscitations. MEASUREMENTS: Serum was tested for antibodies to HIV-1 and HTLV I-II. Questionnaires were completed by the physician in charge of the ED resuscitations. RESULTS: Fifteen (4.1%) (95% confidence interval [CI], 2.1% to 6.1%) patients were HIV-1 seropositive, and seven (1.9%) (95% CI, 0.7% to 3.1%) were HTLV I-II positive. Eleven (5.6%) (95% CI, 2.4% to 8.8%) of 197 trauma patients and 11 (6.4%) (95% CI, 2.8% to 10.0%) of 173 medical patients were infected with one of these viruses. Health care workers had direct cutaneous contact with patient blood during 114 (31%) ED resuscitations and with infected patient blood during 11 (3%) ED resuscitations. An additional 11 ED resuscitations involved parenteral exposures, one to HIV-1-infected blood. No factors could be identified that would quickly and reliably predict infection. CONCLUSION: Health care workers must protect themselves in such high-risk situations by strict compliance to mandatory universal precautions.

Adolescent↗
PubMed1992

Transmission of human T-lymphotropic virus type I by blood components from a donor lacking anti-p24: a case report. The Transfusion Safety Study Group.

The present criteria for confirmation of human T-lymphotrophic virus types I and II (HTLV-I/II) infection in blood donors are based on seroreactivity to p24 (gag) and gp46 and/or gp61 (env) on Western blot (WB) and radioimmunoprecipitation assays (WB/RIPA). Any single band and other combinations are classified as indeterminate. This case report documents infection in a donor with a repeatedly indeterminate pattern. The blood donor was anti-HTLV-I/II positive on enzyme-linked immunoassay, and two sera taken 5 years apart were WB/RIPA-indeterminate (p19 and gp68 only). His donations in the interval were associated with transmission of HTLV-I to four of the six recipients available for study. Other recipients of blood from donors whose WB/RIPA results were indeterminate by present criteria should be examined to determine if additional patterns are at least occasionally associated with transmission. The likelihood that such donors are infected is important to those who are counseling them and making decisions concerning recipients of their bloody.

Adult↗
PubMed1992

A comparison of two supplemental procedures for confirmation of antibody to hepatitis C virus c100-3 antigen in Louisiana blood donors.

In a pilot study designed to evaluate the performance of supplemental hepatitis C virus (HCV) tests, 146 consecutive HCV enzyme immunoassay (EIA)-reactive samples (0.98% of 14,949 donors) were comparatively evaluated with two sets of supplemental tests: HCV antibody neutralization/c100-3 peptide EIA and the first-generation HCV recombinant immunoblot assay (RIBA). Of these samples, 68.5 percent were positive and 17.8 percent were negative on both supplemental assays. Nineteen samples were discordant. Eleven samples were positive on one assay (9 on neutralization/peptide, 2 on RIBA) and negative or indeterminate on the alternate supplemental test, but reacted with two additional HCV antigens outside the c100-3 region in a second-generation dot immunoblot assay. The dot immunoblot assay was used as a reference and reactive samples were considered confirmed. The remaining eight discordant samples were indeterminate or negative on either assay and did not react on the dot immunoblot assay. These data indicate a 0.74-percent prevalence of HCV exposure detected by reactivity with the c100-3 antigen in blood donors in southern Louisiana.

Adolescent↗