Biomedical subjects

L Möller

Publications and source records attributed to L Möller.

At least 19 recordsLinked to original sources

PubMed2005

Impairment-oriented training and adaptive motor cortex reorganisation after stroke: a fTMS study.

In a sample of 28 subacute anterior circulation ischemic stroke patients with severe arm paresis, reduced motor cortex excitability (increased motor thresholds, reduced MEP amplitudes, reduced number of active points) and a reduced conduction velocity in the corticospinal system were found in the affected hemisphere. At the same time motor cortex topology for the abductor pollicis brevis (APB) representation was comparable for the affected and non-affected hemisphere. Considerable arm motor recovery (Fugl-Meyer test) was observed when assessed four weeks later after a period of rehabilitation intervention. Motor cortex excitability and conduction velocity in the corticospinal system improved in the affected hemisphere. In addition, APB representation showed a medial shift in patients with such a representation at pre test (n=14). Multiple stepwise regression indicated that of all transcranial magnetic stimulation (TMS) parameters only the medial shift of the motor cortex map predicted motor recovery. Assessing the effect of training time (non-intensified vs. intensified therapy) and type of arm training (Bobath approach vs. Arm BASIS training) with a randomised controlled design revealed that the impairment-oriented Arm BASIS training improved motor control more than the control conditions. In addition, patients of the group receiving the Arm BASIS training with an APB representation at pre test showed a medial shift of the motor cortex map and improved conduction times. In conclusion, changes in motor cortex topology were likely to be relevant for motor recovery and might have been induced by the impairment-oriented training.

Aged↗

PubMed2003

In-line liquid-crystal microcell polarimeter for high-speed polarization analysis.

We report a type of high-speed microcell polarimeter that utilizes microelectrodes, liquid-crystal films, and ultrathin high-contrast polarizers, all integrated between the tips of two optical fibers. When combined with optimized nematic liquid-crystal materials, this compact (2.5 cm x 0.5 cm x 0.5 cm) device offers excellent optical properties and continuous, high-speed operation at > 2 kHz with moderately low operating voltages. It requires no bulk optical elements, and it shows excellent performance when implemented for the measurement of degree of polarization in 10-Gbit/s test systems. Polarimeters based on this design have promising potential applications in polarization analysis for high-speed optical communication systems.

Journal Article↗

PubMed2003

Probiotic mixture decreases DNA adduct formation in colonic epithelium induced by the food mutagen 2-amino-9H-pyrido[2,3-b]indole in a human-flora associated mouse model.

Consumption of probiotic bacteria such as bifidobacteria has been shown to reduce the risk of colon cancer in animal models. However, the composition and metabolic activities of the intestinal flora of experimental animals are significantly different from those of humans. The aim of the study was to examine whether the probiotic mixture, which consisted of Streptococcus faecalis, Clostridium butyricum and Bacillus mesentericus, could decrease DNA adduct formation induced by 2-amino-9H-pyrido[2,3-b]indole (2-amino-alpha-carboline; AAC) in the colonic epithelium of a human-flora-associated (HFA) mouse model. Ten HFA mice were divided into a control group (n=4) and a probiotic group (n=6). The control group was administered AAC for 3 days and sacrificed 24 h after the last dose. The probiotic group was administered the probiotic mixture for 2 weeks prior to the administration of AAC. Analysis of DNA adducts with the 32P-high-performance liquid chromatography method was performed on stomach, jejunum and colonic epithelium, representing direct exposure sites of AAC, and colon wall, liver and kidney, representing indirect exposure sites. The mean level of the DNA adducts in the colonic epithelium of the probiotic group was significantly lower than that of control group, while the mean levels at the other sites did not differ significantly between the groups. The results indicated that the probiotic mixture could decrease the DNA adduct formation in the colonic epithelium induced by AAC.

Animals↗

PubMed2001

[Thyroid carcinoma. Diagnosis--nonoperative therapy--after care].

Thyroid carcinomas may originate in the thyroid cells (follicular and papillary, carcinoma, so-called differentiated carcinomas, constituting roughly 80-90% of cases), and the calcitonin-producing parafollicular C cells (medullary carcinoma, roughly 10%). The suspected diagnosis is clarified with the aid of ultrasonography, scintigraphy and fine-needle aspiration cytology. Primarily, carcinomas of the thyroid are treated surgically; in the case of differentiated carcinomas, surgery is followed by radio-iodine treatment, and in the follow-up period 131I scintigraphy is performed. During this period, physical examination, ultrasonography of the neck, monitoring of the tumours markers, and treatment with levothyroxine are applied (TSH-suppressive in cases of differentiated carcinoma). In the event of a recurrence showing rapid progression, when surgical and nuclear medical treatment modalities have been exhausted, chemotherapy can be given.

Aftercare↗

PubMed2001

Formation of DNA adducts from oil-derived products analyzed by 32P-HPLC.

The aim of this study was to investigate the genotoxic potential of DNA adducts and to compare DNA adduct levels and patterns in petroleum vacuum distillates, coal tar distillate, bitumen fume condensates, and related substances that have a wide range of boiling temperatures. An in vitro assay was used for DNA adduct analysis with human and rat S-9 liver extract metabolic activation followed by 32P-postlabeling and 32P-high-performance liquid chromatography (32p-HPLC). For petroleum distillates originating from one crude oil there was a correlation between in vitro DNA adduct formation and mutagenic index, which showed an increase with a distillation temperature of 250 degrees C and a peak around a distillation point of approximately 400 degrees C. At higher temperatures, the genotoxicity (DNA adducts and mutagenicity) rapidly declined to very low levels. Different petroleum products showed a more than 100-fold range in DNA adduct formation, with severely hydrotreated base oil and bitumen fume condensates being lowest. Coal tar distillates showed ten times higher levels of DNA adduct formation than the most potent petroleum distillate. A clustered DNA adduct pattern was seen over a wide distillation range after metabolic activation with liver extracts of rat or human origin. These clusters were eluted in a region where alkylated aromatic hydrocarbons could be expected. The DNA adduct patterns were similar for base oil and bitumen fume condensates, whereas coal tar distillates had a wider retention time range of the DNA adducts formed. Reference substances were tested in the same in vitro assay. Two- and three-ringed nonalkylated aromatics were rather low in genotoxicity, but some of the three- to four-ringed alkylated aromatics were very potent inducers of DNA adducts. Compounds with an amino functional group showed a 270-fold higher level of DNA adduct formation than the same structures with a nitro functional group. The most potent DNA adduct inducers of the 16 substances tested were, in increasing order, 9,10-dimethylanthracene, 7,12-dimethylbenz[a]anthracene and 9-vinylanthracene. Metabolic activation with human and rat liver extracts gave rise to the same DNA adduct clusters. When bioactivation with material from different human individuals was used, there was a significant correlation between the CYP 1A1 activity and the capacity to form DNA adducts. This pattern was also confirmed using the CYP 1A1 inhibitor ellipticine. The 32P-HPLC method was shown to be sensitive and reproducible, and it had the capacity to separate DNA adduct-forming substances when applied to a great variety of petroleum products.

Animals↗

PubMed2000

Ring opening of benzo[a]pyrene in the germ-free rat is a novel pathway for formation of potentially genotoxic metabolites.

The metabolism of benzo[a]pyrene (BP) is known to lead to a large number of oxygenated compounds, some of which can bind covalently to DNA. We have studied the integrated metabolism of BP in vivo in germ-free rats given (14)C-labeled BP. Urinary metabolites were separated into groups according to acidity using lipophilic ion exchangers. The groups were analyzed by mass spectrometry and were further fractionated by high-performance liquid chromatography. The fraction of urinary metabolites previously shown to contain N-acetylcysteine and glucuronic acid conjugates was found to contain derivatives of 7-oxo-benz[d]anthracene-3,4-dicarboxylic acid as major components. These compounds, which were identified by mass spectrometry and NMR, accounted for about 30% of the total metabolites in urine, demonstrating that, surprisingly, ring opening is a major pathway for metabolism of BP in the germ-free rat. The dicarboxylic acid may be excreted in urine as an ester glucuronide. By using the single cell gel electrophoresis or COMET assay, we were able to demonstrate that the anhydride of 7-oxo-benz[d]anthracene-3, 4-dicarboxylic acid was an efficient inducer of DNA damage. Taken together, these results indicate that the novel ring opening metabolic pathway may provide alternative mechanisms for the toxicity of BP.

Animals↗

PubMed2000

Early oxidative DNA damages and late development of lung cancer in diesel exhaust-exposed rats.

To demonstrate DNA damages in the early stage of diesel exhaust exposure, an inhalation study of 1 through 12 months was conducted. The lung burden of diesel soot increased with increase in exposure duration. Histologically, hyperplastic foci of alveolar epithelia were found at 6-month exposure and became prominent at the 12th month, with slight nuclear atypia and positive p53 staining. The level of 8-OH-hydroxyguanosine (8-OH-dG) in the exposed rat lungs showed an increase from 1 month of exposure, followed by a gradual increase, reaching almost a plateau level at the 9th month. An in vitro experiment demonstrated significant 8-OH-dG formation when diesel particles and H(2)O(2) were added to the DNA solution. The level of bulky aromatic DNA adducts peaked at the 1st month of exposure, followed by a decrease. By the end of the observation period of 30 months, lung tumors developed even in the 6-month exposure group, and the earliest lung tumors were found only in rats that survived longer than 18 months. In conclusion, persisting oxidative stress on DNA induced in the early phase of diesel exhaust exposure, together with inflammation, seems to play an important role in carcinogenesis at advance ages after a long latent period.

Animals↗

PubMed2000

Analysis of aromatic DNA adducts in laryngeal biopsies.

Epidemiological studies have confirmed the correlation between tobacco smoking, environmental pollution and the incidence of cancers of the respiratory tract. The occurrence of laryngeal cancer in Poland is relatively high compared to other European countries. Since 1969 the mortality related to larynx cancer appears to be increasing. Tobacco smoke contains an abundance of such carcinogenic compounds as polycyclic aromatic hydrocarbons (PAH), aromatic amines and N-nitrosoamines, which can react with DNA and form adducts. We analyzed aromatic DNA adducts in laryngeal tissues from patients with primary laryngeal, which was confirmed histopathologically to be squamous cell carcinoma. The group consisted of 33 patients (5 women and 28 men). Total laryngectomy was performed in patients. A detergentphenol method was used for DNA isolation. Aromatic DNA adducts were analyzed by a 32P-postlabelling technique with butanol extraction and high performance liquid chromatography. The presence of aromatic DNA adducts was demonstrated in all tissues. Large interindividual differences of DNA adduct levels were seen in each tissue studied. There was a higher mean level of DNA adducts in interarytenoid area non-tumors (51.96/10(8) +/- 91.71 NN) than in non-tumor tissue elsewhere (46.91/10(8) +/- 46.36 NN) and tumor tissue (43.52/10(8) +/- 45.88 NN). Adduct levels were correlated with age, sex, cigarette smoking and TNM stage.

Adult↗

PubMed2000

Effects of human intestinal flora on mutagenicity of and DNA adduct formation from food and environmental mutagens.

Although the intestinal flora is believed to have a critical role in carcinogenesis, little is known about the role of the human intestinal flora on the effects of mutagens in vivo. The aim of the present study was to address a possible role of the human intestinal flora in carcinogenesis, by exploiting human-flora-associated (HFA) mice. The capacity of human faeces to activate or inactivate 2-amino-3-methyl-3H:-imidazo[4,5-f]quinoline (IQ) and 2-nitrofluorene was determined using the Ames assay. Human faecal suspensions that were active in this regard were then selected and orally inoculated into germfree NMRI mice to generate HFA mice. HFA, germfree, conventionalized and conventional mice were administered IQ, 2-amino-9H:-pyrido[2,3-b]indole (2-amino-alpha-carboline; AAC) and 2-nitrofluorene. The activity of human intestinal flora against mutagens could be transferred into the mice. In comparing germfree mice and mice harbouring an intestinal flora, the presence of a flora was essential for the activities of faeces against mutagens. After administration of IQ and 2-nitrofluorene, DNA adducts were observed in the mice with a flora, while adducts were extremely low or absent in germfree animals. DNA adducts after AAC treatment were higher in germfree mice in some tissues including colon than in mice with bacteria. Differences in DNA adduct formation were also observed between HFA mice and mice with mouse flora in many tissues. These results clearly indicate that the intestinal flora have an active role in DNA adduct formation and that the role is different for the different chemicals to which the animals are exposed. The results also demonstrate that the human intestinal flora have different effects from the mouse flora on DNA adduct formation as well as in vitro metabolic activities against mutagens. Studies using HFA mice could thus provide much-needed information on the role of the human intestinal flora on carcinogenesis in vivo.

Adult↗

PubMed1999

Protection against 12-O-tetradecanoylphorbol-13-acetate induced skin-hyperplasia and tumor promotion, in a two-stage carcinogenesis mouse model, by the 2,3-dimethyl-6(2-dimethylaminoethyl)-6H-indolo-[2,3-b]quinoxaline analogue of ellipticine.

The effects of topical applications of 2,3-dimethyl-6(2-dimethylaminoethyl)-6H-indolo-[2,3-b]quinoxaline (B-220), on 12-O-tetradecanoylphorbol-13-acetate (TPA) or benzoylperoxide (BPO) induced promotion of skin tumors and hyperplasia were studied in female SENCAR mice. Papillomas were induced by initiation with 7,12-dimethylbenz[a]anthracene (DMBA), followed by promotion biweekly with TPA or BPO. Administration of B-220 1 h before TPA promotion resulted in a prolonged latency period of tumor appearance and a significantly reduced (up to 15% of positive controls) papilloma yield at 20 weeks. Moreover, if B-220 treatment was terminated after 20 weeks and TPA treatment continued, papilloma development resumed indicating that initiated tumor cells were still present but were unable to grow with B-220 present. If B-220 pretreatment was not given during the first 10 weeks of TPA promotion, incidence at 20 weeks was not reduced but tumor multiplicity was still decreased. In addition a marked reduction of the TPA induced sustained epidermal hyperplasia was observed in the long term experiment. Neither the inflammatory response nor the increase in the number of apoptotic cells seen in short term experiment after a single TPA treatment were inhibited by B-220. B-220 administration before BPO promotion had no effect on the appearance of BPO induced papillomas or epidermal hyperplasia, suggesting that TPA and BPO promote tumor formation via at least partially different mechanisms. In experiments where B-220 was applied topically 1 h before DMBA initiation, little or no effect was seen. No morphological changes in mouse skin due to long term exposure (two times/week, 39 weeks) to B-220 were found. In conclusion, we present evidence that B-220 is a potent inhibitor of mouse skin tumor promotion by TPA, but has little effect on the initiation step or the survival of initiated cells.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1999

Activity of O(6)-methylguanine-DNA methyltransferase in relation to p53 status and therapeutic response in ovarian cancer.

The DNA-repair protein O(6)-methylguanine-DNA methyltransferase (alkyltransferase; MGMT) is a major determinant of resistance of cells to various alkylating cytostatic drugs. Its expression in tissues is highly variable, indicating complex regulatory mechanisms involved. Transfection-mediated expression of wild-type p53 has been shown to negatively regulate basal promoter activity of MGMT in vitro. To elucidate whether p53 is involved in regulation of MGMT in tumor tissue, we examined MGMT expression and the p53 status of 140 primary ovarian carcinomas and analyzed the data as to the correlation between MGMT and p53, as well as the survival response of the patients after chemotherapy. We show that MGMT expression is highly variable in ovarian carcinomas, ranging from zero level up to 2500 fmol/mg protein. MGMT activity was significantly lower in tumors with wild-type p53 (p53wt) than in tumors with mutant p53 (p53mt) (p = 0.045). As expected, the percentage of tumors with p53mt increased with increasing histologic grade of the tumors. Thus, p53mt was observed in 4, 45 and 64% of grades 1, 2 and 3 tumors, respectively (p = 0.001). Increase in p53mt was accompanied by an increase in MGMT activity, which was, on average, 460 +/- 66, 624 +/- 63 and 662 +/- 60 fmol/mg protein in grades 1, 2 and 3 tumors, respectively (p = 0.047). In addition, MGMT activity as well as p53mt were associated with the FIGO stage of the tumors. Mean MGMT activity was 472 +/- 48 fmol/mg for patients with FIGO stages I and II, as compared with 675 +/- 50 fmol/mg for patients with FIGO stages III and IV, (p = 0.0179). The percentage of p53mt was 27% and 54% in ovarian tumors with FIGO stages I/II and FIGO stages III/IV, respectively (p = 0.004). Thus, progression of ovarian tumors was clearly associated with increase of both MGMT activity and the percentage of p53mt. In tumors expressing low MGMT (<100 fmol/mg), p53mt was very rarely found. No significant association was observed between MGMT level in ovarian carcinomas and the survival of patients treated with cyclophosphamide and carboplatin. On the other hand, a clear correlation was found between histological type, grading, residual tumor mass and p53wt expression and duration of the patient's survival. The finding that p53wt expression was associated with low MGMT level in primary ovarian cancer supports the view that down-regulation of basal MGMT promoter activity by p53wt is also relevant in tumor cells in vivo. Int. J. Cancer (Pred. Oncol.) 84:388-395, 1999.

Disease-Free Survival↗

PubMed1999

Formation and persistence of DNA adducts during and after a long-term administration of 2-nitrofluorene.

2-Nitrofluorene (NF) is an environmental pollutant. Our previous studies have shown that NF is a carcinogen, primarily targeting the liver, kidney and forestomach in rats. NF-induced DNA adducts were also shown higher levels in the tumor-targeting tissues compared to non-tumor targeting organs. The present study was aimed to observe the kinetics of DNA adduct formation and persistence during the process of NF-induced tumor formation. NF was supplemented in diet at three dose levels and was fed to rats continuously for up to 11 months. DNA adduct formation in the liver, kidney, spleen and stomach of rats after different period (10 days and 11 months) of NF administration was analyzed with 32P-HPLC techniques. DNA adduct persistence in the liver was also assessed after the withdrawal of NF administration. Four major NF-DNA adducts (adducts A, B, C and D) were found in the liver and kidney. DNA adduct D showed high level in the forestomach mucosa after 10 days of NF feeding while adducts A and C were undetectable. DNA adduct C and D co-migrated with C3-(deoxyguanosin-N2-yl)-2-acetylaminofluorene (dG-N2-AAF) and N-(deoxyguanosin-8-yl)-2-aminofluorene (dG-C8-AF), respectively, by 32P-HPLC co-chromatography. DNA adducts A and B constituted the major part (>80%) of NF-DNA adducts after a long period (11 months) of NF feeding. The four NF-DNA adducts showed different recovery from different enrichment procedures, i.e., nuclease P1 or butanol treatment. Three out of the four NF-DNA adducts were still detectable in the rat liver after 11 months on the basal diet. In conclusion, four major DNA adducts are induced by NF oral administration. Among those, one is identified as dG-N2-AAF and another one as dG-C8-AF. The four NF-DNA adducts showed different kinetics of formation and persistence, which may play different roles in NF-induced tumor formation.

Air Pollutants↗

PubMed1999

The synthetic non-toxic drug 2,3-dimethyl-6(2-dimethylaminoethyl)-6H-indolo-(2,3-b)quinoxaline inhibits neutrophil production of reactive oxygen species.

The effects of the non-toxic drug 2,3-dimethyl-6(2-dimethylaminoethyl)-6H-indolo-(2,3-b)quinoxaline (B220) on the generation of reactive oxygen species froin human neutrophils were investigated. The data show that B220 inhibits neutrophil release of reactive oxygen species, as well as intracellular generation of reactive oxygen species. The inhibition is not achieved through direct oxygen radical scavenger activity of B220, and the drug has no immediate effects on the activity of the assembled oxidase. Radical production and release were inhibited by all agonists tested [i.e. the protein kinase C-activating phorbol ester phobol myristate acetate; the receptor-specific agonist N-formyl-methionyl-leucyl-phenylalanine (fMLP); and serum-opsonized yeast particles] in the presence of B220. The drug also inhibits phagocytosis and fMLP-induced mobilization of granules. However, based on the fact that the effects of B220 on phagocytosis and granule mobilization are much less significant than its effect on radical production, we suggest that the signal(s) affected by B220 is (are) located mainly downstream of the point at which the signals are generated to promote oxidase activation and phagocytosis or granule secretion, respectively.

Adult↗

PubMed1999

32P-postlabeling high-performance liquid chromatography (32P-HPLC) adapted for analysis of 8-hydroxy-2'-deoxyguanosine.

8-Hydroxy-2'-deoxyguanosine (8-OH-dG) is a promutagenic lesion in DNA caused by reactive oxygen species. It normally exists at a level of 0.1-1 per 10(5) 2'-deoxyguanosines (dG). To analyze the lesion in easily obtainable biological samples, a very sensitive analytical method is required. The method should also handle the problem with potential oxidation of dG to 8-OH-dG during workup and analysis. 32P-postlabeling high-performance liquid chromatography (32P-HPLC) is an analytical method previously used to analyze lipophilic DNA adducts at levels as low as 1 per 10(9) normal nucleotides when analyzing microgram amounts of DNA. This method was adapted for analysis of 8-OH-dG. The aim was to develop an analytical method that provided a high sensitivity and good reproducibility, prevented oxidation of dG present in samples to 8-OH-dG, was capable of analyzing DNA from very small samples and still offered high sample throughput and ease of use. In analysis of calf thymus DNA, the method had a detection limit of 0.1 8-OH-dG per 10(5) dG when 1 microgram of DNA was used. The standard deviation of repeated analyses of the same sample was +/-10% and the result corresponded well with the established analytical method using HPLC with electrochemical detection. 32P-HPLC is sensitive enough to enable analysis of low levels of 8-OH-dG in biological samples such as small volumes of blood, needle biopsies and tissue swabs. It also substantially reduces oxidation of dG to 8-OH-dG during sample workup and analysis.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1998

Reduction of oxidation during the preparation of DNA and analysis of 8-hydroxy-2'-deoxyguanosine.

The promutagenic base 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in DNA is known to be formed from oxygen radical attack on 2'-deoxyguanosine (dG) as a result of oxidative stress. Formation of 8-OH-dG from dG during workup is strongly dependent on temperature and transition metals and is mediated by oxygen radicals. The 8-OH-dG formation at temperatures between 0 and 140 degrees C for 1.5 h in an "ultrapure" solution followed a third-order equation. Fe2+ in the nM range mediated the formation of 8-OH-dG from dG without addition of H2O2. Fe3+, Cu+, and Cu2+ were shown to have weaker oxidative effects in comparison to Fe2+. The pH (5.0-9.0) had a very limited effect on 8-OH-dG formation. Acid phosphatase, which contains iron at its active site, caused the formation of 8-OH-dG, whereas alkaline phosphatase did not. Phenol was not found to be oxidative. Fe2+-catalyzed formation of 8-OH-dG was completely blocked by the nitroxide 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), whereas DMSO, mannitol, and DMPO had a significantly weaker protecting effect. Catalase cleaved the dG molecule and was not suitable for use. A simple, fast, and inexpensive method for 8-OH-dG workup and analysis was developed, and the background level seen in liver from 13-week-old male Sprague-Dawley rat was 0.23 +/- 0.020 8-OH-dG/10(5) dG, which is up to 200 times lower than reported values from some other methods and up to 26 times lower when compared to other reports using HPLC-EC methods. In summary, the TEMPO method reduces oxidation of dG to 8-OH-dG during workup by (1) using chemicals low in transition metals, (2) using a cold workup procedure, (3) limiting the incubation time, and (4) using the nitroxide TEMPO in all steps.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1998

Methodological considerations and factors affecting 8-hydroxy-2-deoxyguanosine analysis.

Oxidative stress is related to a number of diseases due to the formation of reactive oxygen species (ROS). There are also several substances found in the occupational environment or as life style related situations that generates ROS. A stable biomarker for oxidative stress on DNA is 8-hydroxy-2'-deoxyguanosine (8-OH-dG). A potential problem in the work-up and analysis of 8-OH-dG is oxidation of dG with false high levels as a result of analysis. This paper summarizes and discusses some of the critical moments in terms of auto-oxidation. The removal of transition metals, low temperatures, absence of isotopes (or 2'-deoxyguanosine) and incubation times are all important factors. Removal of oxygen is complicated while the problem is reduced if a nitroxide (TEMPO) is added during work-up. Certain reducing agents and enzymes could be critical if added during work-up. The application of the 32p-HPLC method to analyze 8-OH-dG is discussed. The 32P-HPLC method is suitable for 8-OH-dG analysis and avoids several factors that oxidizes dG by removal of dG before addition of isotopes. Factors of crucial importance (columns, eluents, gradients and detection of 32p) for the analysis of 8-OH-dG are commented upon and certain recommendations are made to make it possible to apply the 32P-HPLC methodology for this type of analysis.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1997

32P-Postlabeling high-performance liquid chromatographic improvements to characterize DNA adduct stereoisomers from benzo[a]pyrene and benzo[c]phenanthrene, and to separate DNA adducts from 7,12-dimethylbenz[a]anthracene.

Single compounds can generate complex DNA adduct patterns by reactions through different pathways, with different target nucleotides and through different configurations of the products. DNA adduct analysis by 32P-HPLC was improved by adding an isocratic plateau in an otherwise linear gradient, thereby enhancing resolution of predictable retention time intervals. This enhanced 32P-HPLC technique was used to analyze and at least partly resolve 14 out of 16 available benzo[c]phenanthrene deoxyadenosine and deoxyguanosine adduct standards, 8 out of 8 available benzo[a]pyrene deoxyadenosine and deoxyguanosine adduct standards, and 51 peaks from 7,12-dimethylbenz[a]anthracene-calf thymus DNA reaction products. The same type of gradient modifications could be used to enhance resolution in analyses of other complex DNA adduct mixtures, e.g., in vivo in humans.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1997

Social and biological predictors of early menopause: a model for premature aging.

OBJECTIVES: To investigate possible social, lifestyle-related and biological predictors of early menopause in middle-aged women, followed prospectively for 11 years. DESIGN: A prospective, population-based, cohort follow-up, observational study. SETTING: Glostrup Hospital, Copenhagen, Denmark. SUBJECTS: A total of 493 female subjects, all aged 40 years at baseline, and divided into three groups according to self-reported menopausal age (40-45, 46-51, 51+ years), after 12 months of amenorrhoea. Women having had medical or surgical interventions to influence menopausal state were excluded. MAIN OUTCOME MEASURES: Body mass index, glucose, insulin, lipids, creatinine, uric acid, thyroid-stimulating hormone (TSH), lung function tests (forced VC, FEV1, peak flow), blood pressure; a self-administered questionnaire with questions on psychosocial variables, lifestyle, and self-rated health. RESULTS: An early menopausal age correlated in an univariate way with impaired lung function, increased smoking habits and low social class (in childhood or present), as well as with a feeling of tiredness, all measured at the baseline investigation. On the contrary, a later menopausal age correlated with higher serum insulin and uric acid levels. In multiple regression analysis, with menopausal age as the dependent variable, it was found that smoking habits (number of years smoking) was inversely (P < 0.001), and insulin as well as uric acid were positively (P < 0.05) correlated with menopausal age. CONCLUSIONS: Females who smoke run an increased risk of early menopause, whereas relative hyperinsulinaemia is independently associated with later menopause. At the age of 40 years, high insulin levels in females might be just a marker for normal female sex hormone physiology, not for insulin resistance, as seen in postmenopausal female subjects. Early menopause might be useful as a potential model of premature ageing.

Adult↗