The prevalence and determinants of solar keratoses at a subtropical latitude (Queensland, Australia)

We report the association between skin pigmentation and individual sun exposure, and the occurrence of solar keratoses (SKs) in an unselected population, quantified for the first time. SKs were examined in a representative sample of 197 residents of the community of Nambour in Queensland, Australia. Estimates of sun exposure were combined with a measure of ultraviolet (UV) flux to estimate actual UV exposure, both occupational and recreational, during childhood and adult life. The number of episodes of painful sunburn was used as a measure of intermittent, intense UV exposure. Eight-three participants (43%) had at least one SK, while 35 (18%) had more than 10 SKs diagnosed. The age- and sex-adjusted odds ratios (ORs) for the development of SKs were higher in individuals with fair (OR = 14.1) or medium skin (OR = 6.5), compared with olive-skinned individuals. Individuals with poor ability to develop a suntan were similarly at increased risk compared with others. High levels of occupational UV exposure during adult life were confirmed as being strongly associated with prevalent SKs (OR = 2.4 for heavy/maximal adult exposure), with an even stronger association seen in those individuals with multiple SKs (OR = 4.3 for maximal adult exposure). Although no clear association was demonstrated between SK prevalence and accumulated childhood sun exposure, a history of even one episode of sunburn in childhood was strongly associated with SK prevalence (peak OR of 5.9 for one sunburn).

Measuring exposure to S. japonicum in China. II. Activity diaries, pathways to infection and immunological correlates

In this study we examine the pathways to schistosomiasis exposure and infection among residents residing on two islands (large, Qingshan; small, Niangashan) in the Dongting Lake region (Hunan province) of China. An exposure model, based on activity diaries, was used to quantify an individual's square-metre-minute (sq.m.min) daily water contact. Subjects living on the small island had a significantly higher (P=0.0002) degree of exposure (mean+/-S.D., 13.2+/-11.0 sq.m.min) than individuals dwelling on the large island (mean+/-S.D., 5.5+/-7.1 sq.m.min). Participants identified as stool egg positive (mean+/-S.D., 8.3+/-10.4 sq.m.min) had higher exposures than for those never treated (mean+/-S.D., 2.2+/-3.4 sq.m.min) for schistosomiasis, and these high exposures rose steadily to peak at 35-49 years of age and decline after age 50. This exposure pattern differs markedly from those reported for African or South American schistosomiasis. The majority of human water contact occurs on the lake. Egg-positive subjects reported significantly higher (P < 0.05) episodes of water contact on the lake versus their egg-negative counterparts, who reported significantly higher (P < 0.01) exposure at the aquaculture ponds. The results of path analysis revealed that sex, age, island of residence and whether a fisherman or not were the most highly significant independent predictors of lake exposure. This accounted for approximately 40% (R2=0.39) of the total lake exposure. Exposure to lake water was a strong predictor (P=0.0006) of past infection and a modest predictor (P=0.05) of current infection.

Measuring exposure to S. japonicum in China. I. Activity diaries to assess water contact and comparison to other measures

We introduce a new method, activity diaries, in order to evaluate human water contact among fishing communities in an area moderately endemic for Schistosoma japonicum in the Dongting Lake region of Southern China. Two hundred and forty-nine subjects (76% male) were followed prospectively over a 9-month-period in order to verify exposure and reinfection. Exposure was determined crudely with questionnaires, direct 12-h water observations, and more precisely with activity diaries and an adjusted exposure model which took into account the time of day, the duration of contact and the percent body surface area in contact with water. Cohort subjects filled in activity diaries for an average of 85 days as compared with 2 days for the direct water observations. The typical unadjusted mean daily water contact (duration) based on the activity diaries was 53 min with 62% of this time spent in fishing. In contrast, the direct water observations revealed an average daily duration of 149 min with 53% of the time spent in fishing. Human water contact patterns (min/day) by site, activity and body part exposed were examined with the activity diaries. Individuals in the 36-49-year-old age range had the highest degree of water contact. Most of this daily contact occurred by males on the hands (mean+/-S.D.; 83.53+/-67.80 min/day) while fishing (mean+/-S.D.; 87.84+/-8.88 min/day) on the lake (mean+/-S.D.; 85.98+/-69.90 min/day). There was a strong positive log correlation (r=0.95) between the crude and adjusted (based on our derived exposure model) diary outcomes for the entire study sample, however, at higher exposure levels this relationship was differentially weaker (r=0.70). Results from this study suggest that current methods used in evaluating schistosomiasis exposure in China may overestimate and bias measures of the risk of infection. Activity diaries adjusted for the time of day, duration and the percent body surface area exposed are cost-effective and practical instruments to accurately quantify human exposure in the vast lake regions of Southern China where most of the endemic schistosomiasis japonica occurs.

The proliferation in uterine compartments of intact rats of two different strains exposed to high doses of tamoxifen or toremifene

Uterine Cell proliferation was studied in intact Sprague-Dawley (SD) and Fischer 344 (F344) rats exposed to the antiestrogens tamoxifen (TAM; 5, 10, 20, or 40 mg/kg) and toremifene (TOR: 21.2 or 42.4 mg/kg). The antiestrogens were administered to animals via gavage daily for 2 or 12 wk. Uterine proliferation was assessed using markers for the proliferating cell nuclear antigen (PCNA) and by the bromodeoxyuridine (BrdU) method. Diethylstilbestrol (DES) was used as an estrogenic reference compound. The antiestrogens either reduced or prevented changes of myometrial and stromal proliferation indices (PI). TAM and TOR caused a time-dependent reduction of endometrial glands without an associated decrease in cell proliferation. In the luminal columnar epithelium, the antiestrogens depressed PCNA PI but enhanced BrdU PI, indicating a low continuous DNA synthesis in otherwise quiescent cells. The antiestrogens induced focal hyperplastic multilayered epithelia with PCNA-positive basal cells along segments of the luminal uterine epithelium. We suggest that this hyperplastic epithelium represents remnants from the glandular epithelium. DES was less efficient in inducing these changes but induced squamous metaplasias in the F344 rats. Uterine effects of the 2 antiestrogens were comparable with the exception of I TAM-exposed (40 mg/kg) SD rat that showed squamous metaplasia. F344 rats were more sensitive to the estrogenic action of DES than were the SD rats.

Short- and intermediate-term carcinogenicity testing--a review. Part 2: available experimental models

Numerous experimental protocols for short- and intermediate-term carcinogenicity assays have been available for many years. This paper surveys various of these test systems in rodents, fish species, non-vertebrates and avian embryos in ovo. The mouse skin tumour assay and the rat liver foci assay were used to introduce the basic concepts of short- and intermediate-term carcinogenicity testing in the previous part of the review. The focus of this second part of the review is on rodent assays for carcinogenicity testing in the lung, kidney, urinary bladder, pancreas, stomach, oral cavity, small intestine, colon, and on the possibility to combine several target organs in multi-organ models. The potential use of various fish species, non-vertebrates and hatching eggs for carcinogenicity testing is outlined and the advantages and limitations are discussed. This review also presents the problem of validation of any carcinogenicity test system and proposes a strategy for contemporary safety assessment of chemicals with regard to the detection and evaluation of carcinogenicity.

Genotoxicity studies with the antiestrogen toremifene

Toremifene, a second-generation triphenylethylene antiestrogen used clinically in the chemotherapy of breast cancer and some other cancers, differs in its nonclinical toxicology from its first-generation congener tamoxifen. Tamoxifen produces DNA adducts and tumors in rat liver, whereas assays for DNA adduct formation with toremifene have been negative to weakly positive, and toremifene does not produce liver tumors in rats. To evaluate further toremifene for possible genotoxicity, it was tested in three standard, in vitro assay--reversion of bacterial point mutations, unscheduled DNA synthesis in cultured hepatocytes from two rat strains, and cytogenetics of human lymphocytes in primary culture--and in one in vivo assay, the mouse, erythrocyte micronucleus assay. The three in vitro assays were conducted with toremifene at up to the limit of cytotoxicity (100 to 250 micrograms/ml, depending on the system). The bacterial mutagenicity and lymphocyte chromosome aberration assays were performed both in the presence and absence of metabolic activation by Araclor-induced, rat liver S-9, while the hepatocyte unscheduled DNA synthesis assay provides intrinsic bioactivation. To test for chromosome damage in vivo, mice were administered up to 2g/kg toremifene once by gavage, and bone marrow was harvested daily, for three days. Normochromatic and polychromatic bone marrow erythrocytes were examined for micronuclei. Toremifene lacked genotoxicity or myelotoxicity detectable by any of the above assays. These findings, together with the reported absence of DNA binding in rat liver, provide evidence that toremifene is not genotoxic.

Short- and intermediate-term carcinogenicity testing--a review. Part 1: the prototypes mouse skin tumour assay and rat liver focus assay

Carcinogenicity testing is by far the most expensive and time-consuming study type of toxicology. For many years, the lifetime exposure with the maximum tolerated dose in two rodent species has been the gold standard of carcinogenicity testing of pharmaceuticals. Major change was introduced by the Fourth International Conference on Harmonization in July 1997; a chronic rodent bioassay in one species and a short-term carcinogenicity assay are regarded as sufficient for registration. Such requirements provide the opportunity to redirect the vast resources previously spent on the lifetime study in the second species. Numerous experimental protocols for short- and intermediate-term carcinogenicity testing in many target tissues have been available for years. The first part of this review describes the basic principles of short- and intermediate-term carcinogenicity testing using the examples of the widely used mouse skin tumour assay and the rat liver foci assay. In the context of these experimental models, the discrimination and quantification of initiating and promoting activity and the use of preneoplastic lesions as endpoints in carcinogenicity testing are described. The review includes the limitations of the models with regard to the extrapolation from effects observed in animal experiments to a potential exposure of humans.

Nonlinearities in 2-acetylaminofluorene exposure responses for genotoxic and epigenetic effects leading to initiation of carcinogenesis in rat liver

The dose responses for several effects of low-level limited exposures to 2-acetylaminofluorene (AAF) in the livers of male Fischer 344 rats were measured and a subsequent phenobarbital tumor promotion regimen was used to manifest initiation of carcinogenesis. Three doses over a 10-fold range yielding cumulative total exposures of 0.126, 0.42, and 1.26 mmol AAF/kg body weight were achieved by daily intragastric instillation for up to 12 weeks with interim terminations. This was followed by 24 weeks administration of 500 ppm phenobarbital (PB) in the diet to promote liver tumor development. At 12 weeks at the end of AAF administration, all exposures produced adducts in liver DNA, measured by 32P postlabeling, and the level of adducts increased with exposure, except that the high exposure did not produce a dose proportional increase. Measurement of arylsulfotransferase activity, a key enzyme in the metabolic activation of AAF, revealed that in livers from the high exposure animals, the enzyme was inhibited. To assess for toxicity, the centrilobular zone of glutamine synthetase-positive hepatocytes was quantified immunohistochemically at 12 weeks. The area of the zone was reduced in the high exposure group and there was a trend to reduction in relationship to exposure. The two lower exposures to AAF produced no increase in cell proliferation, whereas the high exposure resulted in a marked increase, about 8-fold over controls. Initiation was assessed by induction of hepatocellular altered foci (HAF) that expressed the placental form of glutathione S-transferase. AAF induced HAF in the high exposure group, 9-fold at 8 weeks and 170-fold at 12 weeks compared to controls. In rats maintained on PB for 24 weeks after exposure, the multiplicity of HAF increased in controls and comparably in the low and mid exposure groups, but remained at the about the same high level in the high exposure group. The high exposure produced a substantial incidence of benign neoplasms by 12 weeks, and with promotion by 36 weeks, all rats developed hepatocellular neoplasia. In the mid exposure group, only one adenoma occurred at 36 weeks in 17 rats, while in the low exposure group, no liver tumor occurred in 23 rats. Thus, these findings document nonlinearities for some of the effects of AAF, with supralinear effects at the high exposure for cell proliferation and induction of HAF, and a no-observed-effect level for induction of promotable liver neoplasms at the lowest cumulative exposure of 0.126 mmol/kg, in spite of the formation of DNA adducts. We conclude that the effects of this DNA-reactive hepatocarcinogen leading to initiation exhibit nonlinearities and possible thresholds.

Epidemiological identification of Chinese individuals putatively susceptible or insusceptible to Schistosoma japonicum: a prelude to immunogenetic study of human resistance to Asian schistosomiasis

An epidemiological method, field-tested in Hunan, China, to identify residents potentially susceptible or insusceptible to endemic schistosomiasis japonica is described, as a prelude to selection of subjects for immunogenetic studies. After an initial cross-sectional survey on two islands (Qingshan and Niangashan--population 2990) in 1995-1996, an informative cohort (N = 249) was selected for treatment and 9-month follow-up to measure exposure and re-infection. Both the population prevalence (15.8%) and the geometric mean intensity of infection (26.2 eggs/g faces) indicated that the islands were moderately endemic for schistosomiasis. Exposure measurements revealed a strong, positive, linear association (r = 0.70) between daily activity diaries and direct water-contact observation. Individuals identified as stool-positive for schistosomiasis had significantly more water contact than those who were egg-negative (P = 0.03). Almost all (93%) of the cohort had ultrasonographic evidence of periportal fibrosis before treatment but in only 1.2% was this fibrosis scored > 1 in terms of the stages identified by the World Health Organization. At the follow-up it was possible to classify the 249 subjects into three, distinct, exposure-infection epidemiological groups. The first group (N = 20) was susceptible to re-infection and constituted 8% of the cohort. The second group (N = 61) was apparently insusceptible to re-infection despite the continuing high levels of exposure and included 24% of the cohort. The other 68% of the cohort (N = 168) remained uninfected but were at most only moderately exposed, or had a status indeterminate due to non-compliance. This epidemiological identification of susceptibles and insusceptibles for schistosomiasis japonica' links field and ongoing laboratory studies aimed at characterising the genetic and immunological factors associated with resistance to re-infection and/or disease.

Five year impact of chemotherapy on morbidity attributable to Schistosoma japonicum infection in the Dongting Lake region

OBJECTIVE

To determine changes in the last 5 years of the fraction of acute and chronic symptoms attributable to schistosomiasis japonica in fishing communities with moderate endemicity in the Dongting Lake region of China.

METHOD

Complete medical histories, physical examinations, and stool samples were obtained from 1909 individuals (53% male) ranging in age from 4 to 81 years. Age, sex, occupation, frequency of water contact, number of times treated for schistosomiasis, and last year of treatment were tested as potential effect modifiers and confounders.

RESULTS

Overall, there were very few infected cases and very little variation in any prevalence ratio with infection intensity, sex, age, year of last treatment, number of times treated or frequency of water contact. The attributable fraction of liver enlargement in one village was estimated at 0.114 (11.4%), although this was not significantly > 0(95% CI; -0.008-0.237).

CONCLUSION

The chemotherapy-based schistosomiasis control programme in this locality has succeeded in reducing attributable morbidity to undetectable levels, but many uncertainties remain about sustaining control efforts in the future. Both old and new control strategies will have to be examined if the health and well-being of these people are to be maintained into the next millennium, given that periodic chemotherapy will not be accepted indefinitely.

The management of massive ultrafiltration distending the aneurysm sac after abdominal aortic aneurysm repair with a polytetrafluoroethylene aortobiiliac graft

Collections of serous fluid surrounding prosthetic grafts can be caused by infection or transudation of serum, and making the distinction is often troublesome. Bergamini and his colleagues developed a dog model of low-grade prosthetic graft contamination with Staphylococcus epidermatis. All animals developed evidence of graft infection, and 13 of 18 dogs developed a fluid-filled perigraft cyst. Signs of systemic infection, however, were present in only 1 animal, and the Staphylococcus epidermatis study strain was isolated from the tissue surrounding the graft in only 1 dog. The authors had to disrupt the biofilm to achieve positive cultures in 14 of 18 animals. This animal model seemed to conform to clinical experience and placed great emphasis on the role of indolent infections in the pathogenesis of perigraft fluid collection. It is equally clear that perigraft fluid collections may result from transudation of fluid through the prosthetic surfaces, which act similar to a dialysis membrane under certain circumstances. Noninfectious seromas are characterized generally by the accumulation of clear serous fluid with a protein and glucose content of serum and the lack of acute inflammatory cells when the sediment is examined. The need to distinguish between these 2 forms of fluid accumulation became important in the treatment of a 62-year-old man who was seen 2 1/2 years after the repair of an abdominal aortic aneurysm with an aortobiiliac stretch polytetrafluoroethylene (PTFE) prosthesis. There was no evidence of infection, and there was a 12 cm cystic mass surrounding a patent PTFE prosthesis.

Surgical repair of ruptured abdominal aortic aneurysms in the state of Maryland: factors influencing outcome among 527 recent cases

PURPOSE

Abdominal aortic aneurysm (AAA) rupture has been historically associated with high operative mortality rates. In this community-based, cross-sectional study, we examined factors influencing outcome after operations performed for ruptured AAA (rAAA).

METHODS

An analysis of a state database identified 3820 patients who underwent AAA repair between 1990 and 1995, including 527 (13.8%) who had an operation for an rAAA. Demographic variables examined included patient age, gender, race, associated comorbidity rates, operative surgeon experience with rAAA, and annual hospital rAAA and total AAA operative volumes. Outcomes measured included operative mortality rates, hospital length of stay, and charges.

RESULTS

Operative mortality rates increased significantly with advancing age (P < 0.0001) but were not related to gender (P = 0.474) or race (p = 0.598) and were significantly lower among patients with hypertension (P = 0.006) or pulmonary disease (P = 0.045). There was no relationship between hospital rAAA or total AAA volume and rAAA repair mortality rate, although high-volume surgeons (i.e., performing more than 10 rAAA repairs) had decreased mortality rates and hospital charges compared with other surgeons. Hospital lengths of stay and charges increased with age among survivors, but not nonsurvivors, of rAAA repair. Despite a stable incidence of rAAA repairs during the study interval and no significant change in the mean age of patients undergoing operation or the percentage of operations performed by high-volume surgeons, the statewide mortality rate declined from 59.3% to 43.2% (P = 0.039).

CONCLUSION

The incidence of rAAA does not appear to be declining. Although operative rAAA repair continues to be associated with substantial risk and remains an especially lethal condition among the elderly, the operative mortality rate has declined in recent years in Maryland. Lower operative mortality rates and hospital charges are associated with operations performed by high-volume surgeons.

Maternal cigarette smoking and child psychiatric morbidity: a longitudinal study

OBJECTIVE

Previous studies have linked maternal smoking during pregnancy with behavioral disturbance in children. However, additional evidence is needed to address the causality of the relationship. The present study analyses result from an Australian cohort of 5342 5-year-old children whose mothers were recruited early in pregnancy.

METHODS

Smoking history was gathered for prepregnancy, first clinic visit (FCV), late pregnancy, and when the child was 6 months and 5 years of age. Behavior problems at the age of 5 were assessed using a modified Child Behavior Check List (CBCL) shown to have high agreement with the complete CBCL. This resulted in the formation of three scales: internalizing; social, attentional and thought; and externalizing behavior problems, which were then dichotimized at the 90th percentile in each case. Logistic regression was used to model these outcomes as a function of maternal smoking at five time points during which it was assessed. A series of models explored the effect of additional adjustment for confounding. The predictors of attrition (29.5%) throughout the cohort were also identified by multivariate modeling.

RESULTS

The final analysis was carried out on a cohort of mother-child pairs for whom data and child behavior outcomes were complete. The mean age of children was 5 years, 6 months with a range from 4 to 6 years. The mean age of mothers at the time of birth of the child was 25 years, with a range from 13 to 47 years. Mothers lost to follow-up were more likely to be younger, single, and less well-educated than those who continued participation, although maternal smoking was not an independent determinant. Unadjusted analyses showed strong associations between externalizing child behavior and maternal smoking during pregnancy and at the 5-year follow-up, with relative risks (RRs) up to 2.6 for children of women smoking at least 20 cigarettes per day at the first antenatal clinic visit. A clear dose-response relationship existed in most relationships with higher levels of smoking being associated with higher rates of externalizing behavior problems. Weaker relationships occurred for internalizing behavior and social, attentional and thought behavior problems. Multivariate analysis of the timing in more detail that the association between maternal smoking and child behavior problems persisted, although the evidence for dose-response diminished. Moreover, it was primarily associated with smoking as determined by questions asked at the FCV (RR = 1.52, 2.03, 2.16) for 1 to 9, 10 to 19, and >/=20 cigarettes per day, respectively, compared with nonsmoking and secondarily by smoking determined at the 5-year follow-up (RR = 1.52, 1.87, 1.29) for 1 to 9, 10 to 19, and >/=20 cigarettes per day respectively, compared with nonsmoking. This association appeared to be independent of a wide range of possible confounders such as maternal age, education, social class, marital status and mental health, gestation at FCV, complications during pregnancy, the child's sex, gestational age at birth, and age at last follow-up. Adjustments were also made for the mother's employment since birth, family structure, and maternal mental health at the time of the CBCL assessment. Associations between externalizing behavior problems and maternal smoking at other times, and those between other behavioral problems examined and maternal smoking were not significant.

CONCLUSION

Although previous studies have found evidence for an association between maternal smoking and child behavior problems, the strength of this study lies in its size, its detailed and consistent measurement of maternal smoking, and its ability to control for many social and biological factors linked to maternal smoking and child behavior. (ABSTRACT TRUNCATED)

Faecal egg aggregation in humans infected with Schistosoma japonicum in China

In this study we examine the variation in Schistosoma japonicum egg counts caused by differences in worm loads between individuals and the variability of egg counts within individuals with a given worm load. Six villages were selected from an area moderately endemic for Asian schistosomiasis in the Dongting Lake region (Hunan province), China. From a total population of 3451 individuals (53.8% male; x = 31 years), 163 subjects were identified as consistently stool egg-positive based on three successive positive Kato-Katz (KK) smears (41.67 mg/smear) obtained from one stool specimen. The distribution of eggs among individuals was found to be strongly aggregated (k = 0.27), but the distribution within the three smears was found to be only slightly aggregated (k = 2.59), indicating only minor clustering of eggs in stools. The relatively slight clustering of eggs within stool specimens suggests that a single KK smear may be quite adequate for detecting individuals moderately to heavily infected (> 100 eggs/g stool (epg)), as needed for a strategy of morbidity control. However, for estimating the true prevalence of infection in a community, or for obtaining an accurate estimate of egg excretion for research studies, multiple KK smears are warranted.

Evaluation of possible genotoxic mechanisms for acrylonitrile tumorigenicity

Acrylonitrile (ACN) exposure is associated with tumors in rat brain, Zymbal gland, and mammary gland. Adducts affecting base pairing were formed in isolated DNA exposed in vitro to the ACN metabolite cyanoethylene oxide (CNEO). DNA from liver, which is not a cancer target organ in ACN-exposed rats, contained low levels of 7-(2-oxoethyl)guanine, and adduct believed not to interfere with base pairing. No adducts have been detected in brain DNA from ACN-exposed rats, suggesting that brain tumors may have arisen by mechanisms other than ACN-DNA reactivity. Genotoxicity assays of ACN have indicated no particular carcinogenic mechanism. Positive reverse mutagenesis in Salmonella typhimurium HisG46 base substitution tester strains by ACN is attributable to CNEO. Other in vitro genotoxicity test assays of ACN have yielded mixed results, without consistent effect of metabolic activation. Some positive genotoxicity data for ACN appear to result from artifacts or from non-DNA-reactive mechanisms. In vivo micronucleus, chromosome aberration, and autoradiographic unscheduled DNA synthesis assays were negative for ACN. The comparative genotoxicity of vinyl chloride and ACN indicates that despite other similarities, they cause rodent tumors by different mechanisms. Also, they absence of ACN-DNA adduct formation in the rat brain suggests the operation of epigenetic mechanisms.

Formation of 8-oxodeoxyguanosine in brain DNA of rats exposed to acrylonitrile

Acrylonitrile (ACN) produces tumors in rats, particularly gliomas of the brain, but tests for genotoxicity have yielded mixed results and no ACN-DNA adducts have been identified in the brain. To examine the possibility that ACN-related brain tumors were not a consequence of binding of ACN to brain DNA, experiments were conducted to investigate possible epigenetic mechanisms. Male Sprague-Dawley rats were exposed to 0, 3, 30, and 300 ppm ACN in drinking water for 21 days, a range that includes doses associated with brain tumorigenesis. In the 30 and 300 ppm ACN groups, 8-oxodeoxyguanosine (8-oxodG) levels were two fold greater than in the controls. Measures of glutathione levels, glutathione peroxidase and catalase were not significantly changed, but cyst(e)ine was somewhat increased. No changes were found in brain cytochrome oxidase activity, which indicates a lack of metabolic hypoxia. Also, no effects on thiobarbituric acid reactive substances were found, indicating a lack of lipid peroxidation. In an additional experiment, male Sprague-Dawley rats were exposed to 0 or 100 ppm ACN in drinking water for 94 days; interim sacrifices were conducted at 3, 10, and 31 days. Levels of brain nuclear DNA 8-oxodG were significantly increased in ACN-exposed rats compared with controls. Another group of animals were given weekly i.v. injections of 5 mg/kg methylnitrosurea and no increases in 8-oxodG were found. These studies suggest the possibility that ACN-induced tumors may be produced by a mode of action involving 8-oxodG. The formation of 8-oxodG is not understood, but does not appear to involve lipid peroxidation or disruption of antioxidant defenses.

Effect of rodent hepatocarcinogenic peroxisome proliferators on fatty acyl-CoA oxidase, DNA synthesis, and apoptosis in cultured human and rat hepatocytes

The effects of the rodent hepatocarcinogens clofibric acid and diprofibrate on the activity of the peroxisomal fatty acyl-CoA oxidase, DNA synthesis, and apoptosis were compared in cultured rat and human hepatocytes. Rat hepatocytes expressed a 10-fold greater level of the peroxisomal fatty acyl-CoA oxidase compared to human hepatocytes. At the highest concentration (1.0 mM), both drugs induced a two- to threefold increase in this enzyme activity in both rat and human hepatocytes. Ciprofibrate (0.1 and 0.2 mM) caused a twofold increase in DNA synthesis in rat hepatocytes, whereas clofibric acid had no effect on DNA synthesis in these cells. In contrast, increasing concentrations of both clofibric acid and ciprofibrate produced inhibition of DNA synthesis in human hepatocytes. By using the terminal transferase dUTP-biotin nick end labeling technique, it was observed that 0.1 and 0.2 mM clofibric acid and ciprofibrate suppressed transforming growth factor-beta (TGF beta)-induced apoptosis by 50% in rat hepatocytes, but they had no effect on TGF beta-induced apoptosis in human hepatocytes. Although clofibric acid and ciprofibrate diminished TGF beta-induced apoptosis, they had no effect on the basal apoptotic levels in the rat hepatocyte cultures. However, both drugs significantly increased the percent of apoptotic cells in the human hepatocyte cultures. It is concluded that primary rat and human hepatocyte cultures respond differently to peroxisome proliferators. The differences in effects on DNA synthesis and apoptosis support the hypothesis that human liver cells are refractory to peroxisome proliferator-induced hepatocarcinogenesis.

Inhibition by singlet oxygen quenchers of oxidative damage to DNA produced in cultured cells by exposure to a quinolone antibiotic and ultraviolet A irradiation

The photogenotoxicity mechanism of quinolone antibiotics was investigated by measuring oxidative DNA damage in lomefloxacin- and UVA-exposed cultured liver-derived cells. The combination of lomefloxacin and UVA irradiation produced a dose-dependent increase in 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-dG) in cell DNA. This DNA damage was substantially inhibited by co-incubation with sodium azide (NaN3) or 2,2,6,6-tetramethyl-4-piperadone (TMP), chemicals that specifically quench singlet oxygen. No significant reduction of 8-oxo-dG formation was produced by N-t-butyl-alpha-phenylnitrone (TBP) or alpha-tocopherol, which primarily scavenge hydroxyl radicals. We conclude that the photodynamic generation of 8-oxo-dG by quinolones is mediated, at least in part, by singlet oxygen.

Diagnosis of schistosomiasis japonica in Chinese schoolchildren by administration of a questionnaire

This paper describes a rapid, simple, cost-effective questionnaire for screening school-aged children at risk for Asian schistosomiasis in China. Five hundred and thirty-two children, aged 8-14 years, were selected from 3 schools in an area moderately endemic for Schistosoma japonicum in Hunan province. The questionnaire, comprising 15 multiple-choice questions, was administered by teachers in order to collect both ethnographic and epidemiological data relevant to current S. japonicum infections. This was followed by Kato-Katz thick smear stool examinations, miracidium hatching tests, and soluble egg antigen-enzyme linked immunosorbent assays in order to validate the efficacy of the questionnaire approach. The results from a combination of all 3 procedures indicated that the overall schistosomiasis prevalence in the 3 schools was 29.9% (138/472). Six risk factors (episodes of diarrhoea, frequency of water contact, school grade attained, weakness, past history of S. japonicum infection(s), and whether a subject had been previously treated for schistosomiasis) in the questionnaire were determined by logistic regression to be highly statistically significant predictors of individual current infection. The sensitivity (93.7%), specificity (91.9%) and low cost (c. US$ 0.6/true positive case) associated with the 6 variables model make the questionnaire approach a very useful diagnostic tool for screening marshland and lake communities at high risk for schistosomiasis in China before selective treatment with praziquantel or diagnostic follow-up. An even simpler 3 variables 'yes/no' model was derived from the questionnaire and found to be nearly as good at predicting individual infection (sensitivity 86.2% and specificity exceeding 97.6%) and extremely simple to use. If validated in other ecological settings in China the questionnaire, modified or as presented here, could be adopted by the national schistosomiasis control programme.

HLA class II antigens are associated with resistance or susceptibility to hepatosplenic disease in a Chinese population infected with Schistosoma japonicum

The major histocompatibility Class II alleles of 108 individuals living in an area endemic for schistosomiasis japonica in China were determined to identify possible immunogenetic associations with advanced schistosomiasis. Two alleles, HLA-DRB1*1202 (P = 0.002) and HLA-DQA*0601 (P = 0.001) were strongly associated with resistance to advanced disease. In contrast, HLA-DQB1*05031 (P = 0.02) was associated with susceptibility to advanced schistosomiasis. The remaining alleles showed no association with advanced disease. Allele DRB1*1202 co-occurred with allele DQA1*0601; therefore, their independent protective effects could not be ascertained. In contrast, alleles DQA1*0601 and DQB1*05031 never co-occurred and had opposite and significant effects on the occurrence of disease.

A study of the degradation of phenoxyacid herbicides at different sites in a limestone aquifer

The biodegradation of three phenoxyalkanoic acid herbicides, viz. MCPA, dichlorprop and mecoprop, under aerobic and anaerobic conditions was investigated using microcosm techniques. The field studies were conducted in a limestone aquifer that had suffered contamination from leaking landfill sites in which phenoxyalkanoic acid herbicides (mostly mecoprop) had undergone disposal. The results from in situ field and laboratory microcosms indicated that under microbially active aerobic conditions the biotransformation of all three herbicides was rapid and that lag phases were short. Under fully aerobic conditions the concentration of each of the three herbicides was reduced from 2,000 micrograms/l to below the detection limit (approx. 10 micrograms/l) of the HPLC system, used for their analysis, within 14 days. However, under microbially active anaerobic conditions no degradation of the herbicides could be discerned over the 100-200 day duration of the experiments. This finding has significant implications for the disposal of phenoxyalkanoic acid herbicides particularly in situations where any resulting leachate may find its way into underlying water resources.

Successful delayed bilateral renal revascularization during active phase of Takayasu's arteritis

Successful bilateral renal revascularization was performed 24 days after the development of angiotensin converting enzyme-inhibitor-induced bilateral renal artery thrombosis and anuric acute renal failure in a patient with Takayasu's arteritis. Excellent results were obtained after an unusually long ischemic time for a patient with active-phase disease. The outcome suggests that aggressive surgical revascularization can benefit patients with renal failure caused by renal arterial occlusion during the active phase of Takayasu's arteritis.