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D Anderson

Publications and source records attributed to D Anderson.

At least 199 records · Page 11Linked to original sources
PubMed1997

Reactive oxygen species-induced DNA damage and its modification: a chemical investigation.

The main purpose of this study was to determine whether well-known reactive oxygen species (ROS)-generating agents can induce DNA damage in a simple chemical system with or without Fenton reaction components (iron and reducing agents), and to explore whether antioxidants which normally exist in the cellular environment can modify such damage, i.e. to determine chemical reactions of relevance to biological systems. A neutral electrophoresis technique was used to investigate DNA double stranded breaks (DSBs) caused by chemical treatments of lambda-DNA in eppendorf tubes by various ROS-generating compounds and the degree of DNA damage was categorised by analysis of enhanced digital images. Double strand breaks were induced by hydroquinone (HQ), benzoquinone (BQ), benzenetriol (BT), hydrogen peroxide (H2O2), bleomycin (BLM) and sodium ascorbate (Vit C). DNA damage was modulated by various agents including catalase (CAT), superoxide dismutase (SOD), desferoxamine mesylate (DFO), ferrous chloride (FeCl2), reduced glutathione (GSH), trolox, silymarin and myricetin. Individual chemicals (except BLM) at the concentration of 1 mM did not induce large numbers of DSBs without iron [Fe(II) or Fe(III) at 25 microM]. GSH enhanced the damaging effect of HQ, BT and Vit C, did not alter the non-damaging effect of H2O2, but had a small protective effect on BLM. When compared with the non-enzyme protein, bovine serum albumin (BSA), SOD had a protective effect against BT, H2O2 and BLM; in the presence of GSH, SOD diminished the effect of HQ, BQ and Vit C but enhanced the effect of BT, H2O2 and BLM. With both GSH and Fe and compared with BSA, SOD enhanced the effect of HQ, BQ and BLM, ameliorated the effect of H2O2, and did not affect the others. CAT showed a protective effect for almost all examined compounds, but had little effect on BLM. With GSH alone, DFO enhanced the effect of HQ, BQ, H2O2 and ameliorated the effect of BT, BLM and Vit C and trolox was largely protective. With GSH and Fe, DFO was protective for all compounds except doxorubicin (Dox), trolox was protective for all compounds except Dox and BLM, silymarin was protective except that it had little effect on BLM and Dox, but myricetin did not show any protective effect. In conclusion, the results from the present study have further highlighted the adverse potential of reducing agents and redox cycling agents, and also the need for a cautious view of antioxidants.

Antioxidants↗
PubMed1997

Somatic and germ cell effects in rats and mice after treatment with 1,3-butadiene and its metabolites, 1,2-epoxybutene and 1,2,3,4-diepoxybutane.

1,3-Butadiene is produced in large quantities for use in the manufacture of synthetic rubber. It is also an environmental pollutant. There is concern about exposure to 1,3-butadiene as it has been shown to produce tumours in rats, mice and an increased risk of leukaemia in humans. It has also been shown to produce germ cell effects in mice. Differences in responses to 1,3-butadiene have been reported in rats and mice, possibly due to different metabolic capabilities. The present study thus investigated somatic and germ cell effects of 1,3-butadiene in mice and its metabolites in both rats and mice to help determine species differences using different endpoints for genotoxic effects. These included DNA strand breakage as measured in the single cell gel electrophoresis (Comet assay) in bone marrow and testicular cells, and micronuclei in bone marrow cells using both the acridine orange and Giemsa staining methods. Unscheduled DNA synthesis (UDS) was also measured in the testes of mice. CD-1 mice were exposed to 1,3-butadiene by inhalation for 6 h/day for 4 weeks, and CD-1 mice and Sprague-Dawley rats to the metabolites after i.p. injection. 1,3-Butadiene did not affect liver, bone marrow and testicular cells in mice as measured in the Comet assay. After treatment with 1,2-epoxybutene in the Comet assay, there was a response in the testes in mice but not in rats and there was little or no effect in the bone marrow assay in mice but there was in rats. After treatment with 1,2,3,4-diepoxybutane in the Comet assay in mice, there was a response in the bone marrow cells but not in the testicular cells, and in rats there was also a response only in bone marrow cells. There was an increase in micronuclei in both rats and mice with both metabolites, but clastogenicity was stronger with 1,2,3,4-diepoxybutane, occurring at lower doses, than with 1,2-epoxybutene. In the UDS assay in the testes of mice, there was an increase in response with 1,2,3,4-diepoxybutane treatment but not with 1,2-epoxybutene. These studies would appear to confirm a species difference of CD-1 mice and Sprague-Dawley rats, where mice were sensitive at lower doses than rats.

Administration, Inhalation↗
PubMed1997

The use of the same image analysis system to detect genetic damage in human lymphocytes treated with doxorubicin in the Comet and fluoresence in situ hybridisation (FISH) assays.

Two assays, the alkaline single cell gel electrophoresis (Comet) assay and the fluorescence in situ hybridisation (FISH) of a whole chromosome or 'chromosome painting' assay have gained importance in recent years as witnessed by the increasing yield of scientific literature using these techniques. Thus, it would be useful to have one system to measure both endpoints. In the present communication, a cost-effective electronic imaging system developed by Kinetic Imaging Ltd., UK, has been used to measure, after treatment of human lymphocytes with doxorubicin, DNA damage in the Comet assay (using software package KOMET) and chromosome damage with the FISH technique (using software package KROMASCAN). The chromosome damage has been detected using chromoprobe-M for chromosome 1 and compared with chromosome damage measured using the conventional Giemsa staining technique. In all three assays, cycling cells were treated, after phytohaemagglutinin stimulation, at 48 h for about 20 h, which resulted in statistically significant dose-related responses in each assay. In non-cycling cells there was no increase in damage in the Comet assay, but there was in the chromosome assays. The FISH assay was only conducted in cycling cells, since the probe used was metaphase-specific. At the highest doses of doxorubicin used, FISH and conventional chromosome assays had similar sensitivities.

Antibiotics, Antineoplastic↗
PubMed1997

The bacteriophage phi29 packaging proteins supercoil the DNA ends.

Bacteriophage phi29 DNA with covalently bound terminal protein (DNA-gp3) and its left and right-end restriction fragments (L and R-DNA-gp3) sedimented faster in sucrose density gradients than their proteinase K-treated counterparts, and the faster sedimentation was both gp3 and Mg2+-dependent. Addition of gp16, the phi29 DNA packaging ATPase, further increased the sedimentation rates of both intact DNA-gp3 and L and R-DNA-gp3 fragments. Thus, DNAs with gp3 were more compact than gp3-free DNA, and gp16 further condensed the DNA-gp3 forms. [35S]gp16 cosedimented with the fast-sedimenting DNA-gp3 fragments, and the putative L-DNA-gp3-gp16 complexes were packaged preferentially into proheads in the defined in vitro system. Lariats of DNA-gp3 and L and R-DNA-gp3 observed by electron microscopy rationalized the sedimentation results, and lariats with multiple loops or coils increased tenfold in a preparation of L-DNA-gp3-gp16 complexes. The rapid sedimentation and the structure of the DNA-gp3-gp16 complexes were consistent with supercoiling of lariat loops, and treatment with topoisomerase I shifted fast-sedimenting complexes toward the uncoiled lariat position in sucrose density gradients. DNA-gp3 has a maturation pathway in which the packaging proteins gp3 and gp16 supercoil the DNA ends, probably as a prerequisite for efficient interaction with the prohead.

Adenosine Triphosphatases↗
PubMed1997

Simultaneous gas chromatographic-mass spectrophotometric determination of alpha-fluoro-beta-alanine and 5-fluorouracil in plasma.

A gas chromatographic-mass spectrometric (GC-MS) method is reported for simultaneous determination of alpha-fluoro-beta-alanine (FBA), the major end metabolite of 5-fluorouracil (5-FU), and 5-FU in plasma samples isolated from cancer patients. 5-Chlorouracil (5-CIU, 1 micrograms/ml) is added to samples as an internal standard. The method relies on protein precipitation of the plasma sample followed by derivatisation with pentafluorobenzyl bromide. Following sample purification with Sep-pak C18 columns the derivatives are analysed by GC-MS, with FBA, 5-FU and 5-CIU being determined at 36.96-37.03, 46.91-46.98 and 51.99-52.13 min, respectively. The ions measured in each case had m/z of 390, 490 and 506, respectively. The method showed good reproducibility with coefficients of variation between 3 and 10%, with a detection limit of < 1 ng/ml for 5-FU and < 5 ng FBA/ml plasma. The possibility of sensitive determination of FBA without the use of radioisotopes should permit routine estimation of rates of 5-FU metabolism in individual patients.

Antimetabolites, Antineoplastic↗
PubMed1997

Factors affecting various biomarkers in untreated lung cancer patients and healthy donors.

The purpose of the present communication was to determine in lung cancer patients and healthy donors if there was a possible association between cancer and biomarkers of cytogenetic damage and ras p21 oncoprotein levels, and if various exogenous confounding factors (such as smoking habit) and endogenous ones (age, sex, etc.) could affect these biomarkers. Peripheral blood and plasma were collected from 31 lung cancer patients prior to treatment and 35 healthy donors of a similar socioeconomic status and from the same region in Poland. Chromosomal aberrations (CA), sister chromatid exchanges (SCE), high frequency cells (HFC), and proliferative rate index (PRI) were examined from the blood and ras p21 oncoproteins from the plasma. These parameters were used as biomarkers of genotoxic anomalies. All the biomarkers were examined for their relationship to confounding factors of age, sex, smoking habit, and immediate family cancer history. Results were analyzed by a t-test, analysis of variance (ANOVA), and stepwise multivariate regression analysis. All types of CA (including and excluding gaps), percent aberrant cells, SCE, and ras p21 oncoproteins were statistically significantly higher in cancer patients than in the healthy donors. Although there were smaller numbers of females in the cancer patients group who were older than the males, there was a difference due to sex (gender) with statistically significant increases in females for CA, SCE, and HFC, but there was no increase for ras p21 oncoproteins. Cytogenetic damage was not related to other cancers in the immediate families of the groups. All major CA parameters differed significantly between smokers and non-smokers in the cancer patients group, and SCE and HFC differed in the healthy donors group. Such parameters also showed a significant variability with the number of cigarettes smoked and the years of smoking habit. Multivariate regression analyses showed a significant association between cytogenetic damage, ras p21 oncoproteins, and cancer. In conclusion, cytogenetic damage and ras p21 oncoproteins in this study appear to be biomarkers associated with cancer, but have not been proved causally, and confounding factors such as age, sex (gender), and smoking can have an impact on them.

Adult↗
PubMed1997

Human monitoring.

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Environmental Monitoring↗
PubMed1997

Effect of various genotoxins and reproductive toxins in human lymphocytes and sperm in the Comet assay.

There have been conflicting reports as to whether the mean sperm count in some men has diminished over the last 50 years. The downward trend has been suggested to coincide with an increase in exposure to estrogen-like compounds. These estrogenic substances are ubiquitous in the environment. We have examined the effect of such substances (diethylstilbestrol, beta-estradiol, daidzein, genestein, and nonylphenyl) in the single cell gel electrophoresis assay (Comet assay) in human sperm and compared responses with those from human peripheral lymphocytes in the same donor and in peripheral lymphocytes from a female donor. In addition, effects from the estrogens have been compared to those from known reprotoxins and genotoxins. These include lead sulfate, nitrate and acetate, dibromochloropropane, ethylene glycol monoethyl ether, 1,2-epoxybutene, and 1,2,3,4-diepoxybutane. All compounds produced positive responses, but ethylene glycol monoethyl ether only produced positive responses in sperm cells in the male and not in peripheral lymphocytes, and similarly the phytoestrogens (genistein, daidzein) were less responsive in the peripheral lymphocytes in the male than in the sperm. This may be due to greater sensitivity of sperm cells because of their lack of repair. However, since damage was generally seen over a similar dose range, a one-to-one ratio of somatic and germ cell damage was observed and has implications for man for risk assessment purposes.

Adult↗
PubMed1997

DNA integrity in human sperm.

Since the 1970s there have been conflicting reports of decreasing sperm counts in man and increasing testicular cancer. There is a hypothetical link between apparent adverse trends in several measures of human reproductive health and exposure to endocrine disrupters. Rodent bioassays are not suited for the large-scale screening of such chemicals because of their costs, complexity, and ethical concerns. Various in vitro assays have been used to examine the effects of these chemicals, but none has directly used semen as one of the target tissues in man. The present study has examined in the alkaline Comet assay in human sperm the effect of two estrogens--beta-estradiol and the phytoestrogen daidzein--and 1,2-epoxybutene, a metabolite of 1,3-butadiene, and compared them with the effects of the known reprotoxin, dibromochloropropane, in two fertile and two infertile frozen sperm samples and two fresh fertile samples. While differences were detected in the frozen fertile and infertile samples with flow cytometry, in the Comet assay both frozen and fresh samples exposed to the chemicals in vitro from fertile and infertile men produced similar altered responses by comparison with untreated samples. The integrity of DNA is necessary not only for the noncancerous state, but also for the accurate transmission of genetic material to the next generation. Thus this assay may be useful for examination of chemicals in fresh and frozen sperm samples.

DNA↗
PubMed1997

Serial measurements of body composition in obese subjects during a very-low-energy diet (VLED) comparing bioelectrical impedance with hydrodensitometry.

Bioelectrical impedance analysis (BIA) is a convenient, inexpensive, and noninvasive technique for measuring body composition. BIA has been strongly correlated with total body water (TBW) and also has been validated against hydrodensitometry (HD). The accuracy and clinical utility of BIA and HD during periods of substantial weight loss remain controversial. We measured body composition in moderately and severely obese patients serially using both methods during a very-low-energy diet (VLED). Mean initial weight in these patients was 116 (+/-30) kg (range, 74-196 kg). Mean weight loss was 24 (+/-13) kg with a decrease in fat mass (FM) by HD of kg (p < 0.001) and a decrease in fat-free mass (FFM) of 3.6 kg (p < 0.05). Loss of FFM is best predicted by the rate (kg/wk) of weight loss (r2 = 0.86, p < 0.0001). FFM, as predicted from BIA equations, was highly correlated with FFM as estimated by HD during all testing sessions (r = 0.92-0.98). Although highly correlated, BIA overestimated FFM relative to HD and this difference appeared to be more pronounced for taller patients with greater truncal obesity. Although the discrepancy was no greater during weight-loss treatment, the level of disagreement was considerable. Therefore, the two methods cannot be used interchangeably to monitor relative changes in body composition in patients with obesity during treatment with VLED. The discrepancy between BIA and HD may be caused by body mass distribution considerations and by perturbations in TBW which affect the hydration quotient for FFM (BIA) and/or which affect the density constants for FFM and FM (HD).

Adult↗
PubMed1997

A primatized MAb to human CD4 causes receptor modulation, without marked reduction in CD4+ T cells in chimpanzees: in vitro and in vivo characterization of a MAb (IDEC-CE9.1) to human CD4.

A Primatized anti-CD4 monoclonal antibody (MAb), CE9.1, with V-domain from cynomolgus macaque (showing 92% homology with human consensus sequence V-domains), and a human IgG1 constant region, was characterized in vitro and in vivo in chimpanzees. This MAb binds human CD4 with Kd of 1.0 nM and was also able to bind to human IgG Fc receptors (Fc gamma R). However, despite being of the IgG1 subclass, CE9.1 did not bind to complement component C1q, nor did it mediate complement-dependent cytotoxicity. Examination of T cells from a number of species showed restricted reactivity for CE9.1, recognizing only human and chimpanzee CD4. In both human and chimpanzee MLRs, it had an IC50 of about 10.0 ng/mL. Therefore, a chimpanzee in vivo model was used to characterize CE9.1, CE9.1 caused transient decrease in the number of lymphocytes bearing the CD4 receptor starting at doses of 0.3 mg/kg in an in vivo dose ranging study in one chimpanzee. This effect was reversed within approximately 7 days. In a multiple high-dose study in which 10.0 mg/kg of CE9.1 was administered at intervals of 1-3 months, there was a dramatic loss of CD4 marker with a reciprocal increase in the number of CD3+ CD8- CD4- cells. The CD4 receptor was totally undetectable on these lymphocytes for 1-2 weeks, with a gradual, but complete, reversal within 4 weeks. We interpret these observations as receptor modulation because, although there was apparent loss of CD4+ lymphocytes, an equivalent number of CD3+CD8- T lymphocytes were present in circulation in all four chimpanzees treated with 10.0 mg/kg CE9.1. Even at this high dose, only limited reduction of CD4+ T lymphocytes was observed in these animals. These observations are in sharp contrast to what has been reported in rodents or in human clinical studies using other IgG1 mAbs to human CD4. CD8 counts, although variable, remained unaffected by CE9.1 treatment. No adverse events were observed following administration of CE9.1 to chimpanzees, and there was no detectable host immune responses to the Primatized MAb.

Animals↗
PubMed1997

Clinical validation of cardiac output measurements using femoral artery thermodilution with direct Fick in ventilated children and infants.

OBJECTIVE: To validate clinically cardiac output (CO) measurements using femoral artery thermodilution in ventilated children and infants by comparison with CO estimated from the Fick equation via a metabolic monitor. DESIGN: Prospective, comparison study. SETTING: Paediatric intensive care unit of a university hospital. PATIENTS: 24 ventilated infants and children, aged 0.3 to 175 months (median age 19 months). INTERVENTIONS: Oxygen consumption measurements were made and averaged over a 5-min period, at the end of which arterial and mixed venous blood samples were taken and oxygen saturations measured by co-oximetry, with CO being calculated using the Fick equation. Over this 5-min period, five sets of femoral arterial thermodilution (FATD) measurements were made and averaged. One comparison of CO values was made per patient. RESULTS: Mean Fick CO was 2.55 l/min (range 0.24 to 8.71 l/min) and mean FATD CO was 2.51 l/min (range 0.28-7.96 l/min). The mean bias was 0.03 l/min (95% confidence interval -0.07 to 0.14 l/min), with limits of agreement of -0.45 to 0.52 l/min. When indexed to body surface area, the mean Fick cardiac index became 3.51 l/min per m2 (1.52-6.98 l/min per m2) and mean FATD 3.49 l/min per m2 (1.74-6.84 l/min per m2). The mean bias was 0.02 l/min per m2 (95% confidence interval -0.11 to 0.15 l/min per m2) with limits of agreement of-0.57 to 0.61 l/min per m2. The mean FATD coefficient of variation was 5.8% (SEM 0.5%). CONCLUSIONS: FATD compares favourably with Fick derived CO estimates in infants and children and may represent an advance in haemodynamic monitoring of critically ill children.

Adolescent↗
PubMed1997

The pharmacokinetics and pharmacodynamics of adinazolam: multi-ethnic comparisons.

The pharmacokinetics and pharmacodynamics of adinazolam and N-demethyladinazolam (NDMAD), its major active metabolite, were compared in 39 healthy male volunteers (13 Asian, 12 Caucasian and 14 African-American). In a four-way, double-blind crossover design, subjects were administered (1) 30 mg oral adinazolam mesylate SR tablets, (2) 10 mg parenteral (i.v.) adinazolam mesylate, (3) 30 mg i.v. NDMAD and (4) placebo. Venous blood samples were collected at specific time intervals after drug administration and assayed for adinazolam and NDMAD concentrations. Sedation was rated at the time of each blood draw according to the Nurse-Rated Sedation Scale, and the digit-symbol substitution test was administered to evaluate psychomotor performance. After i.v. administration of adinazolam, Asians manifested significantly higher Cmax, larger AUC and lower CL of both adinazolam and NDMAD than their Caucasian and African-American counterparts. Likewise, after i.v. NDMAD Asians had significantly higher NDMAD Cmax and AUC than Caucasians and African-Americans. Most of these differences remained statistically significant after controlling for body surface area. With PO adinazolam, Asians also manifested substantially higher Cmax, larger AUC and lower CL for both adinazolam and NDMAD; however, with the exception of Cmax, these differences did not reach statistical significance. These results are in accordance with previous observations for ethnic-related differences in drug pharmacokinetics. In contrast, pharmacodynamic differences were not noted among the three study groups.

Adult↗
PubMed1997

Bilateral internal mammary artery atherosclerosis: a late complication of delayed repair of coarctation of the aorta.

A 58-year old patient who had undergone repair of aortic coarctation at 19 years of age, subsequently developed coronary artery disease requiring coronary artery bypass surgery. At operation both internal mammary arteries were found to be totally occluded with calcific atherosclerosis. We therefore advise that the internal mammary arteries should be assessed carefully in patients with similar past histories.

Aortic Coarctation↗