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Biomedical subjects

D Anderson

Publications and source records attributed to D Anderson.

At least 271 records · Page 15Linked to original sources
PubMed1995

Determination of quercetin in human plasma using reversed-phase high-performance liquid chromatography.

A method is reported for the measurement of quercetin in human plasma using reversed-phase high-performance liquid chromatography (HPLC). Quercetin and kaempferol (as internal standard) were spiked into plasma samples and extracted using C18 Sep-Pak Light cartridges (efficiency > 85%). Flavonoids were eluted with aqueous acetone (50% v/v, pH 3.5), dried down and redissolved in aqueous acetone (45% v/v, pH 3.5). The increased osmolarity promoted a phase separation and the water-saturated acetone layer, containing the flavonoids, was analysed by HPLC with aqueous acetone mobile phase (45% v/v acetone in 250 mM sodium dihydrogen sulphate. The mixture was adjusted to pH 3.5 with phosphoric acid and used at a flow-rate of 1.0 ml/min) and mu Bondapak C18 column (150 x 3.9 mm I.D., 10 microns particle size). The detection limit (A375 nm) for quercetin in plasma was 0.1 microgram/ml (300 nM). The method also detects metabolites of quercetin, although these are not yet identified.

Chromatography, High Pressure Liquid↗
PubMed1995

Comparison of lithium ratio between African-American and Caucasian bipolar patients.

Lithium RBC/plasma ratio (LR) was studied in 34 bipolar subjects on therapeutic doses of lithium carbonate. The sample was divided into 22 Caucasians and 12 African-Americans to observe possible ethnic differences in LR as previously reported. The latter group demonstrated a higher LR as well as increased reports of side effects (p < .05), even after controlling previous confounding factors. Our findings suggest that African-Americans may be more susceptible to the side effects associated with lithium treatment, and consequently, lower dosages may be necessary for this group.

Adult↗
PubMed1995

Interleukin 15 and its receptor.

Interleukin 15 (IL-15) is a member of the four-helix bundle cytokine family that shares many in vitro biological activities with IL-2. Previous work demonstrated that IL-15 utilizes the beta and gamma chains of the IL-2 receptor (IL-2R), and that these are essential for IL-15-mediated signal transduction. However, several lines of evidence indicated the existence of an additional, IL-15-specific receptor component. An IL-15 binding chain was identified on a murine T cell clone, and direct expression cloning was used to isolate the corresponding cDNA. The predicted structure of this protein shows sequence similarity to the IL-2R alpha chain. Transfection of this cDNA into a murine, IL-3-dependent myeloid cell line, 32D-01, conferred IL-15 binding and, together with transfection of the IL-2R beta chain, rendered the cells responsive to IL-15 stimulation. This experiment confirmed that the IL-15 binding chain is part of the IL-15 receptor, and it is designated as the IL-15R alpha subunit. The expression pattern of the IL-15R alpha mRNA is distinct from that of IL-2R alpha mRNA. Recombinant expression of a soluble form of IL-15R alpha demonstrated that it is a potent inhibitor of IL-15 biological activity.

Animals↗
PubMed1995

Reconstitution of a functional interleukin (IL)-7 receptor demonstrates that the IL-2 receptor gamma chain is required for IL-7 signal transduction.

The interleukin (IL)-2 receptor gamma chain has recently been shown to be a component of the IL-7 and IL-4 receptors. Using a transient transfection assay and the trans-activation of reporter gene constructs which are under the control of cytokine-responsive promoter elements, we have studied signal transduction through the IL-7 receptor (IL-7R). The reporter gene expression was not stimulated by receptors that contained the cytoplasmic domain of the IL-7R, either as intact IL-7R or as part of a chimeric receptor. However, co-expression of the IL-7R with the IL-2 receptor gamma chain was able to stimulate gene activation. For maximal stimulation the intact cytoplasmic domains of each chain was required.

Amino Acid Sequence↗
PubMed1995

Induction of polyploidy in human lymphocytes in vitro by excess adenine, but not by adenosine.

It is known that high levels of DNA precursors can be both clastogenic and mutagenic in cultured cell lines and in vivo. The purpose of the present study was to examine at an observational level the cytogenetic effects of adenine and adenosine in primary human cell cultures. Human peripheral blood lymphocytes from four donors were cultured and treated with a range of concentrations of adenine and adenosine. Although no increase in sister chromatid exchange (SCE) frequency was observed with either compound, there was a statistically significant, dose-related increase in the proportion of polyploid cells in cultures treated with adenine, but not in those treated with adenosine. Some of the polyploid metaphases found after adenine treatment contained diplochromosomes, suggesting that endoreduplication might have been involved in polyploid formation in these cells. It is concluded that a high level of adenine can cause genetic changes in human lymphocytes by interfering with mitosis, perhaps by disturbing the balance of DNA precursor pools.

Adenine↗
PubMed1995

Genotoxicity of m-phenylenediamine and 2-aminofluorene in Salmonella typhimurium and human lymphocytes with and without plant activation.

The promutagenic arylamines, m-phenylenediamine (mPDA) and 2-aminofluorene (2-AF), were evaluated for their genotoxicity in Salmonella typhimurium strain YG1024 and in human lymphocytes. These agents were assayed with and without TX1MX plant activation mix. Both arylamines without activation were refractory in S. typhimurium, demonstrating that plant activation was required for the generation of their ultimate mutagenic metabolites. However, using the alkaline single-cell gel/Comet assay, both mPDA and 2-AF directly induced DNA damage in human lymphocytes. This effect was reduced when the human cells were treated with the arylamine plus TX1MX. mPDA with or without plant activation was not toxic to the exposed cells. However, at concentrations over 80 microM, 2-AF was toxic to lymphocytes. This toxic response was eliminated by incubation with TX1MX. mPDA and 2-AF were plant-activated into mutagens for S. typhimurium. However, these plant-activated products had a reduced genotoxic potency in human lymphocytes.

Adult↗
PubMed1995

An investigation of the DNA-damaging ability of benzene and its metabolites in human lymphocytes, using the comet assay.

Benzene and five of its known metabolites--muconic acid, hydroquinone, catechol, p-benzoquinone, and benzentriol--were examined for DNA damage in human lymphocytes using the alkaline Comet assay, and conditions were optimised to determine responses. Metabolic activation (S-9 mix) was included in the assay for varying times to try to enhance effects. In addition, the effects of catalase were investigated as it is known to be present in S-9 mix reducing oxidative damage, and some benzene metabolites are known to react through oxygen radical mechanisms. Effects were also examined in cycling cells to determine whether they were more sensitive to damage then noncycling cells. Comets were measured either by eye or by image analysis. Data have been presented according to length of treatments. When Comets were measured by eye after treatment with hydrogen peroxide (H2O2), the positive control, and each compound for 0.5 hr, only H2O2 and benzenetriol induced pronounced DNA damage without metabolic activation. The effect of catechol was moderate compared with that of benzenetriol. There was a very weak effect of benzene in the absence of rat liver S-9 mix. In the presence of S-9 mix, benzene was not activated. The effect of benzenetriol was greatly reduced by the external metabolising system, but p-benzoquinone became activated to some extent. Catalase abolished the effect of benzenetriol, suggesting that H2O2 formed during autoxidation may be responsible for the DNA-damaging ability of this metabolite. The presence of catalase in S-9 mix may explain the detoxification of benzenetriol and the failure to detect consistent benzene responses. Mitogen-stimulated cycling cells were less sensitive to H2O2 and benzenetriol than unstimulated G0 lymphocytes. When comets were measured by image analysis, a 0.5-hr treatment with H2O2 and benzenetriol and catechol confirmed results analysed by eye, with S-9 mix greatly reducing responses. When treatments were increased to 1 hr in the presence and absence of S-9 mix, benzene at a 5-fold increased dose produced a significant positive response but not at the lower dose. When treatment times were increased to 2 and 4 hr, doses were also increased, and muconic acid, hydroquinone, catechol, and benzoquinone in the presence of S-9 mix showed positive time and dose-related responses, and at the highest dose of benzoquinone the morphology of the nucleus was affected. Effects tended to become more pronounced at high doses and after longer exposures, although this was not always consistent from experiment to experiment. In conclusion, benzene and all metabolites investigated gave positive responses. Where altered responses were observed, they were significantly different from the corresponding controls.

Adult↗
PubMed1995

Serial quantitation of HPV-16 in the smears of women with mild and moderate dyskaryosis.

The aim of this study was to examine the efficacy of semi-quantitative polymerase chain reaction (PCR) testing in cervical smears as an adjunct to cytological surveillance in a cohort of women with mild or moderate dyskaryosis. The study population comprised a group of 62 women who underwent twelve months of cytological and colposcopic surveillance as part of a larger randomised prospective study of women with mild and moderate dyskaryosis. Semi-quantitative PCR for HPV-16 DNA was carried out on the initial and twelve month study smears before a large loop excision of the transformation zone (LLETZ) was carried out. Smears from a control population which comprised 167 women without a history of abnormal cervical cytology who were attending family planning and general practitioner clinics for routine cervical smears were tested similarly. The presence of high or intermediate levels of HPV-16 DNA on both the initial and twelve month study smear was positively associated with the identification of cervical intraepithelial neoplasia (CIN) grades II or III in the LLETZ specimen (P = 0.01). While the combination of HPV-16 DNA testing with cytology on a repeat cervical smear improved the selection of women with underlying CIN II/III, there was still a false negative rate of 53%. Twenty-nine women had 'low risk' levels of HPV-16 DNA and mild dyskaryosis or less on both repeat smears indicating suitability for surveillance, but in fact 34% of them had CIN II/III. This study supports the finding reported previously of an association between high and intermediate levels of HPV-16 DNA and CIN II/III.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Developmental and symptom specificity of hopelessness, cognitive errors, and attributional bias among clinic-referred youth.

The present study examined the unique and interactive relationships between age and indices of psychopathology (i.e., anxiety, aggression, and depression), with three types of maladaptive cognitions: hopelessness, negative cognitive errors, and attributional bias. Some negative cognitions were not unique to depression and were associated with broader psychopathology. Developmental considerations also influenced some negative cognitions or qualified the association between negative cognitions and depression.

Adolescent↗
PubMed1995

The effect of antioxidants on bleomycin treatment in in vitro and in vivo genotoxicity assays.

Antioxidants are thought to be important in protecting against damage from active oxygen species. The effects of the antioxidant nutrients vitamins C and E have been investigated after bleomycin treatment in the Salmonella typhimurium bacterial mutation assay, in the human peripheral lymphocyte chromosome aberration assay, and in the mouse micronucleus assay in peripheral blood and bone marrow cells. There were no protective effects from vitamins C and E in the bacterial mutation assay, but vitamin C and not vitamin E abolished chromosome damaging responses in human peripheral lymphocytes, and both vitamins reduced responses in micronuclei from peripheral blood cells in mice. This would suggest that in human cells in vitro and mouse cells in vivo these vitamins could have a protective role.

Analysis of Variance↗
PubMed1995

Cyclophosphamide: review of its mutagenicity for an assessment of potential germ cell risks.

Cyclophosphamide (CP) is used to treat a wide range of neoplastic diseases as well as some non-malignant ones such as rheumatoid arthritis. It is also used as an immunosuppressive agent prior to organ transplantation. CP is, however, a known carcinogen in humans and produces secondary tumors. There is little absorption either orally or intravenously and 10% of the drug is excreted unchanged. CP is activated by hepatic mixed function oxidases and metabolites are delivered to neoplastic cells via the bloodstream. Phosphoramide mustard is thought to be the major anti-neoplastic metabolite of CP while acrolein, which is highly toxic and is produced in equimolar amounts, is thought to be responsible for most of the toxic side effects. DNA adducts have been formed after CP treatment in a variety of in vitro systems as well as in rats and mice using 3H-labeled CP. 32P-postlabeling techniques have also been used in mice. However, monitoring of adducts in humans has not yet been carried out. CP has also been shown to induce unscheduled DNA synthesis in a human cell line. CP has produced mutations in base-pair substituting strains of Salmonella tryphimurium in the presence of metabolic activation, but it has been shown to be negative in the E. coli chromotest. It has also been shown to be positive in Saccharomyces cerevisiae in D7 strain for many endpoints but negative in D62.M for aneuploidy/malsegregation. It has produced positive responses in Drosophila melanogaster for various endpoints and in Anopheles stephensi. In somatic cells, CP has been shown to produce gene mutations, chromosome aberrations, micronuclei and sister chromatid exchanges in a variety of cultured cells in the presence of metabolic activation as well as sister chromatid exchanges without metabolic activation. It has also produced chromosome damage and micronuclei in rats, mice and Chinese hamsters, and gene mutations in the mouse spot test and in the transgenic lacZ construct of Muta Mouse. Increases in chromosome damage and gene mutations have been found in the peripheral blood lymphocytes of nurses, pharmacists and female workers occupationally exposured to CP during its production or distribution. Chromosome aberrations, sister chromatid exchanges and gene mutations have been observed in somatic cells of patients treated therapeutically with CP. In general, there is a maximum dose and an optimum time for the detection of genetic effects because the toxicity associated with high doses of CP will affect cell division. In germ cells, CP has been shown to induce genetic damage in mice, rats and hamsters although the vast majority of such studies have used male mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Rarefied white matter in patients with Alzheimer disease.

Magnetic resonance head scans of 94 patients with probable Alzheimer disease (AD) and 45 patients with possible AD were examined prospectively to determine the prevalence and significance of rarefied cerebral white matter (leukoaraiosis) in patients with AD. Only 8.7% of patients with probable AD and 11.1% of patients with possible AD exhibited large confluent areas of subcortical leukoaraiosis. The remaining patients had variable degrees of leukoaraiosis surrounding the lateral ventricles. The magnitude of leukoaraiosis correlated with the patient's age but not with the Hachinski Ischemic and Mini Mental Status scores. Postmortem studies of two Alzheimer patients showed that their large confluent areas of subcortical leukoaraiosis consisted of rarefied white matter, gliosis, and arteriosclerotic small arteries. Eight additional Alzheimer patients who underwent autopsy had similar but less pronounced white matter changes limited to the periventricular regions of the cerebral hemispheres. Large confluent areas of rarefied subcortical white matter occur in a small minority of Alzheimer patients and are probably not caused by AD.

Aged↗
PubMed1995

Childhood injuries and the importance of documentation in the emergency department.

The purpose of this study is 1) to evaluate the extent to which documentation of the medical record is completed for dependent children who present for evaluation of an acute injury, and 2) to examine the factors that favorably or adversely influence completion of the medical record. The emergency department (ED) ledgers of 669 children less than nine years of age were reviewed, including 172 (25.7%) who presented for evaluation of an acute injury. Each of the latter charts was examined for basic demographic data, as well as information about injury type and mechanism, ED provider, and involvement of social services personnel. The ledgers were further examined to determine completeness of chart documentation in several relevant areas, including the circumstances and characteristics of the acute injury, pertinent past medical history, and course of management and referral while in the ED. Each of 15 individual documentation variables was assigned a score of either zero (incompletely/not addressed or documented) or one (completely addressed or documented). The 15 individual scores were equally weighted and summed, resulting in a total documentation score ranging from zero (failure to address or document any of the 15 variables) to 15 (all variables completely addressed/documented). The mechanisms of injury included falls from height (48.3%), direct blunt impact other than falls (26.7%), penetrating injury (6.4%), burn (5.2%), and ingestion (8.1%). Seventeen patients (9.9%) were admitted for primarily medical, and one (0.6%) for primarily social, indications; one patient died as a result of his injuries.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1995

Evaluation of biomarkers in plasma, blood, and urine samples from coke oven workers: significance of exposure to polycyclic aromatic hydrocarbons.

OBJECTIVE: The aim was to assess the significance of two biomarkers; antibody to benzo(a)pyrene DNA adducts and concentration of hydroxyethylvaline haemoglobin adducts in samples from a well studied group of coke oven workers. As a measure of exposure we have used 1-hydroxypyrene in urine. METHODS: Urine and blood samples were collected from coke oven workers and a control group. Samples from coke oven plant workers were collected in January and June. 1-Hydroxypyrene was measured in urine by high performance liquid chromatography (HPLC), antibodies to benzo(a)pyrene DNA adducts were measured by ELISA and hydroxyethylvaline haemoglobin adducts were measured by gas chromatography-mass spectrometry (GC-MS). RESULTS: Mean urinary 1-hydroxypyrene in samples from coke oven workers varied from 1.11 to 5.53 umol/mol creatinine and 0.14 umol/mol creatinine in the control group. Workers at the top side had the highest values of urinary 1-hydroxypyrene. Antibody to benzo(a)pyrene DNA adducts did not correlate with either 1-hydroxypyrene nor length of work at the coke oven plant. But antibody concentration in samples collected in January was predictive of the concentration in samples collected in June. A small non-significant increase in hydroxyethylvaline haemoglobin adducts was found in samples from coke oven workers relative to the control group when comparing smokers and nonsmokers separately. CONCLUSION: 1-Hydroxypyrene correlates well with exposure groups based on job description. Antibodies to benzo(a)-pyrene DNA adducts was related to people and not exposure. Work at a coke oven plant might lead to increased hydroxyethylvaline haemoglobin adducts.

Adult↗
PubMed1995

Effects of fixation and paraffin embedding on the immunohistological detection of cell-associated HIV-1 by different monoclonal antibodies.

This study evaluates a panel of monoclonal antibodies (MAbs) to HIV-1 antigens (DuPont anti-gp120, gp41, p24; Olympus anti-gp120/160, gp41, p24A, p24B, p55, p18A, p18B, reverse transcriptase) for their ability to detect the virus in tissues after exposure to various fixatives (100% acetone, 10% formaldehyde, 2.5% glutaraldehyde, 4% paraformaldehyde/1% glutaraldehyde, Bouin's fluid) and after paraffin embedding. Acetone, 10% formaldehyde, and Bouin's fluid all preserved a wide range of viral epitopes compared with other fixatives. The most robust MAbs were DuPont p24 and Olympus p55, which produced excellent staining regardless of the fixative used. Embedding in paraffin variability influenced the capacity of MAbs to detect HIV-1 epitopes on fixed cells. Certain antibodies (e.g., DuPont gp24, Olympus p24B) produced good staining, whereas other epitopes (e.g., DuPont gp120, formaldehyde) were destroyed. In some cases, paraffin embedding revealed antigenic sites that had been formerly masked (e.g., Olympus gp120 and p24A; formaldehyde and glutaraldehyde fixation). These results indicate that HIV-1 antigens can be detected by immunohistology on cells exposed to most common fixatives. Therefore, retrospective analysis of pathological material is possible, provided that the antibodies are matched to the fixative used to preserve the tissue.

Acetates↗