Dose-dependent increase in subjective symptoms among toluene-exposed workers

A factory survey on dose-response relationship in toluene toxicity was conducted in 1985-1989 in four cities in China. The examination items consisted of personal diffusive sampling for TWA exposure measurement, questionnaires on subjective symptoms, hematology and serum biochemistry, and clinical examination including simple neurology tests. Hippuric acid was also determined in urine samples collected at the end of the shift. With selection criteria that (1) complete results were available on all study items and (2) valid toluene exposure data (i.e., toluene shared 90% or more of the exposure) were obtained for the exposed, 452 toluene-exposed workers (206 men and 246 women; toluene exposure at 24.7 ppm as GM) and 517 nonexposed controls (246 men and 271 women) were selected. The subjective symptoms increased in close association with the intensity of exposure to toluene; the threshold concentration appeared to exist at 100 ppm in the case of symptoms during work, and it might be at 50-100 ppm when symptoms off work were evaluated. During the work with exposure at higher concentrations, various symptoms possibly related to CNS or local effects (e.g., eyes, nose, and throat) were complained, and dizziness and floating sensations were identified as typical symptoms with significant dose-response relationship. Several symptoms persisted off work, most of which were apparently related but not necessarily limited to CNS effects. Hematology and serum biochemistry were essentially negative.

Effects of smoking and drinking on excretion of hippuric acid among toluene-exposed workers

In order to investigate possible effects of smoking and drinking on the metabolism of toluene in occupational settings, 206 toluene-exposed men (mean age: 31.4 years) in shoemaking, painting, or surface-coating workshops together with 246 nonexposed control men (36.8 years) were studied for the time-weighted average intensities of exposure to toluene, hippuric acid concentration in shift-end urine samples, and the two social habits of smoking and drinking. The mean daily consumptions of cigarettes and ethanol were about 20 pieces and 10 g among smokers and drinkers, respectively. The geometric mean toluene concentration among the exposed subjects was about 20 ppm, with a maximum of 521 ppm. Regression analysis after classification of the subjects by smoking and drinking clearly demonstrated that the two social habits, when combined, markedly reduce the hippuric acid level in the urine of workers exposed to toluene. There was a significant association between smoking and drinking habits, which hindered separate evaluation of the effects of the two habits on toluene metabolism. Comparison of the present results with the findings reported in the literature, however, suggested that the observed effects may be attributable to smoking rather than to drinking habits.

Complementary deoxyribonucleic acid cloning and expression of a human liver uridine diphosphate-glucuronosyltransferase glucuronidating carboxylic acid-containing drugs

A cDNA clone, designated UGT2B7 variant, encoding a 529-amino acid human liver microsomal uridine diphosphate-glucuronosyltransferase (UGT) was isolated from a lambda gt11 human liver cDNA library. UGT2B7 variant synthesized in COS-7 cells was screened for activity toward a range of clinically used drugs and other xenobiotics. The expressed enzyme glucuronidated several carboxylic acid-containing nonsteroidal antiinflammatory agents including, in order of relative substrate activity, naproxen, ketoprofen, ibuprofen, fenoprofen, tiaprofenic acid, benoxprofen, zomepirac, diflunisal and indomethacin. Additionally, the stereoselectivity of ketoprofen, naproxen (S/R ratio approximately unity) and ibuprofen (S/R ratio 1.62) glucuronidation by the UGT2B7 variant was shown to differ. Two other carboxylic acid-containing drugs (clofibric acid and valproic acid) and a limited range of drugs containing an alcohol or phenolic functional group were also glucoronidated by expressed UGT2B7 variant. The deduced amino sequence of UGT2B7 variant was shown to differ only in one amino acid (tyrosine for histidine at position 268) from a previously published uridine diphosphate-glucuronosyltransferase cDNA, UGT2B7. Like the previously reported enzyme, this variant efficiently glucuronidated hyodeoxycholic acid, estriol, 4-hydroxyestrone and 2-hydroxyestriol. It is, therefore, apparent that UGT2B7 variant has the capacity to glucuronidate with a degree of specificity both endogenous compounds and xenobiotics. Preferred substrates for UGT2B7 variant include xenobiotic carboxylic acids, polyhydroxylated estrogens and hyodeoxycholic acid.

Biopathologic characteristics of DNA content in crypt cells of transitional mucosa adjacent to carcinomas of the rectum and rectosigmoid

The transitional mucosa (TM) adjacent to carcinomas of the large bowel shows histologic and mucin histochemical changes that may indicate premalignant change and may be of prognostic value after radical resection. In this study, 10 anterior resection specimens from patients with carcinomas of the rectum and rectosigmoid were used to compare the nuclear DNA content in TM with those in cancer tissue and with those in nontransitional mucosa (N-TM; i.e., uninvolved mucosa remote from tumors showing normal histologic and mucin histochemical features). The nuclear DNA content was assessed using DNA image cytometry on Feulgen-stained sections. As compared with N-TM, crypts in TM contained greater numbers of cells, were elongated, and were more likely to be branched with marked sialomucin secretion, accompanied by a marked reduction in the normal sulfomucin content. The mean nuclear DNA content in the upper, middle, and lower thirds of crypts was significantly higher in TM than in N-TM, and the nuclear DNA content in TM exhibited no correlation to that in tumors. The results suggest that TM adjacent to carcinomas of the rectum and rectosigmoid has higher proliferative activity, providing further evidence that TM may be an unstable premalignant change.

Effects of some natural products as components of Chinese herbal medicines on mammary gland growth and function in mice

As a possible step to evaluate the role in the mammary glands of the scales of Guanshanjia, the fruits of Lulutong and the seeds of Wangbuliouxing, which are the natural products used widely as the components of herbal medicine in China for the improvement of lactation and the therapy of breast disorders, the effects of these agents on mammary gland growth and function were studied in female mice. The chronic administration of each agent in drinking water improved several parameters; however, the mode of action differed markedly among agents. The results indicate the necessity of acquiring enough knowledge of the characteristics of each agent for the efficient prescription of herbal medicine as well as the single use of the agent.

[Affinities of PBPs of enterococci to cefepime and ampicillin]

The beta-lactam resistance of genus Streptococcus has been explained by the low binding affinity of penicillin-binding proteins (PBPs) to the drug. This study was carried out to resolve the mechanisms of resistance to beta-lactam antibiotics in the species of genus Enterococcus by means of binding affinities of PBPs. Streptococcus pyogenes, Enterococcus faecalis, Enterococcus faecium and Enterococcus avium were employed as assay microbes. Cefepime (CFPM) and ampicillin (ABPC) were used as representatives of cephems and penicillins, respectively. All the PBP fractions of S. pyogenes manifested high binding affinities to CFPM and ABPC, whereas PBPs 1 and 4 of E. faecalis showed high binding affinities to ABPC but not to CFPM. In E. faecium, PBPs of an exceptionally penicillin-susceptible strain manifested a high binding affinity to ABPC, but PBPs 5 and 6 showed low affinities to CFPM. beta-lactam resistant strains of E. faecium possessed PBPs 5 and 6 with low binding affinities to CFPM and ABPC. All the fractions of PBPs but PBP 1 in E. avium showed low binding affinities to CFPM. Although all the PBP fractions but PBPs 3 and 6 manifested high binding affinities to ABPC, PBPs 3 and 6 showed low binding affinities to ABPC. A strain of E. avium, which is susceptible to ABPC but moderately resistant to CFPM, lacked PBP 6. In conclusion, the resistance of E. avium to CFPM is based upon low binding affinities of the many fractions to this drug, and ABPC resistance is based upon PBPs 3 and 6 with low binding affinities to ABPC.

Cocaine elevates striatal dopamine efflux in spontaneously hypertensive and Wistar-Kyoto rats

The effects of acute cocaine administration on central dopaminergic systems were examined in the striata of spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats with the use of an in vivo microdialysis technique. Increased extracellular levels of dopamine were observed for 45 to 75 minutes following acute cocaine administration in both halothane-anesthetized and conscious SHR and WKY. However, no significant differences were noted between anesthetized and conscious SHR and WKY in either baseline levels or cocaine-induced changes in extracellular levels of dopamine and its metabolites. A positive, linear correlation between extracellular levels of dopamine and cocaine was demonstrated for the 60-min period following acute cocaine administration in both SHR and WKY. The slopes of the linear regression plots obtained from the data of each 15-min sample was slightly, but significantly, higher in conscious SHR than in conscious WKY. The present results suggest a transient and dose-related stimulation of striatal dopamine release following acute cocaine administration and a linear relationship between striatal extracellular levels of dopamine and cocaine in both SHR and WKY.

Comparisons of cocaine receptors in brain regions from WKY and SHR

Both high- and low-affinity sites for [3H]cocaine binding were present in the striatum, hippocampus, olfactory tubercle, and hypothalamus of WKY and SHR. In the striatum, Kd values of both sites and the Bmax value of the high-affinity site were lower in SHR than in WKY rats. In the hippocampus, only the Kd value of the high-affinity site was lower in SHR than in WKY rats. However, there were no differences in Kd or Bmax values between strains in the olfactory tubercle or hypothalamus. The differences in characteristics of [3H]cocaine binding in WKY and SHR may provide a neurochemical basis for the different responses of the two strains to cocaine administration.

[Effect of Astragalus membranaceus on erythrocyte sodium content and sodium transport in the coronary heart disease]

The purpose of this study was to investigate the effect of Astragalus membranaceus (AM) on erythrocyte sodium content and sodium transport in the coronary heart disease(CHD). 67 cases of CHD was randomly divided into treatment group (TG) and control group (CG), TG (45 cases) were treated with AM intravenous 24 g/d infused into 5% glucose 250 ml, CG (22 cases) with 5% glucose 250 ml. After a curable stage of 14 days, results showed that the erythrocyte sodium content was markedly decreased and the sodium pump activity was significantly increased (P less than 0.01 respectively) in TG; but no significant difference in membrane permeability to sodium was observed. There were no difference in erythrocyte sodium content and sodium transport in CG. It was suggested that AM had the effects to increase erythrocyte activity of sodium pump.

Prevalence of hepatitis B virus infection markers among factory workers in Beijing, China

Nearly 1,000 serum samples were obtained from apparently healthy workers of both sexes in various factories in Beijing during 1988-1989 and were examined for hepatitis B virus infection markers by radioimmunoassay. The overall prevalence (all ages and both sexes combined) of cases positive for HBsAg, anti-HBs and anti-HBc were 3.7%, 36.6% and 37.7%, respectively and the rate of those negative to any of the three markers studied was 56.1%. The infection rate was lower than the values reported early in the 1980s for Beijing populations or the values for populations in other parts of China.

Visual rehabilitation in low vision patients with age-related macular degeneration

Using optical visual aids, visual rehabilitation was performed in 14 low vision patients (25 eyes) with age-related macular degeneration. With distance aids, visual acuity improvement appeared in 24 eyes (95%) out of the 25 eyes. Twelve eyes (48%) obtained a visual acuity equal to or better than 0.4. With near visual aids, near acuity of all eyes (100%) was improved. Thirteen eyes (52%) got the near vision equal to or better than 0.5. Ten patients could read No. 5 Chinese Reading Card. The reading success rate was 71.4%. The results suggest that application of visual aids is an effective method to improve the distant and near visual acuity of low vision patients with AMD.

[Visual rehabilitation in low vision patients with aging macular degeneration]

Using optical visual aids, visual rehabilitation were performed in 14 cases (25 eye) of low vision patients with aging macular unity of all eyes (100%) was improved. Thirteen eyes (52%) got the near vision equal to or better than 0.5. Ten patients could read No. 5 Chinese Reading Card. The reading success rate was 71.4%. The results suggest that application of visual aids is an effective method to improve the distance and near visual acuity of low vision patients with AMD.

Endogenous retroviral LTR DNA sequences as markers for individual human chromosomes

The human genome carries multiple copies of sequences related to endogenous retroviral genomes that include long terminal repeat (LTR) sequences. We used the LTR of one such viral genome, called HERV-A, as a probe in Southern analysis to examine the distribution profiles of the hybridizing DNA in the genomes of twelve human x rodent hybrid cell lines carrying one or a few human chromosomes, and in the DNA samples prepared from six sorted, individual chromosomes. The HERV-A sequence was found to be widely distributed among different chromosomes and the Southern patterns for chromosomes 5, the X, and the Y, each obtained in duplicate from independently prepared cell lines or sorted chromosomes, were matched. Chromosome-specific Southern profiles can be used to monitor chromosomes in hybrid cells or to characterize chromosome aberrations, such as deletions.

[Studies on left ventricular performances pre- and post-percutaneous balloon valvuloplasty in 57 cases]

The left ventricular performances (LVP), assessed by two dimensional echocardiography (2 DE) pre- and post-percutaneous balloon mitral valvuloplasty, showed a good linear correlation with those by angiography, the correlative coefficients being 0.94 (left ventricular volume), 0.93 (ejection fraction) and 0.90 (stroke volume), respectively. The results showed that 2 DE may be used in follow-up study of left ventricular performances instead of angiography. Accordingly, it was found that the short-term (6-10 months) effect in LVP of 57 cases post-PBMV assessed by 2 DE in comparison with that pre-PBMV was statistically very significant (t = 3.73-12.92, P less than 0.001); the long-term (12-42 months) effect of 88 cases post-PBMV evaluated by 2 DE compared with that pre-PBMV was statistically very significant (t = -3.73-10.46, P less than 0.001); all these showed that both the short-term and long-term cardiac functions post-PBMV had markedly improved. However, there was a significant difference in statistics (t = 2.41-3.14, P less than 0.05-0.001) between the short-term and long-term cavity area) and radionuclide angiography both during early diastole (r = 0.94) and atrial systole (r = 0.90). The above results were better than those obtained from pulsed Doppler (E area/Total, A area/Total) and radionuclide angiography: during early diastole (r = 0.78) and atrial systole (r = 0.76). Color Doppler can be used as a new method for assessing the pattern of left ventricular filling.

Sister chromatid exchanges in peripheral lymphocytes of workers exposed to benzene, trichloroethylene, or tetrachloroethylene, with reference to smoking habits

The frequencies of sister chromatid exchanges (SCE) were studied in peripheral lymphocytes from four groups of solvent workers, i.e. 36 nonsmoking women exposed to benzene at about 50 ppm on the average, 38 men and women (male smokers and nonsmokers, and female nonsmokers) exposed to trichloroethylene (TRI) at 7 ppm, 27 men and women (both smokers and non-smokers) with tetrachloroethylene (TETRA) exposure, and 19 workers (both smokers and nonsmokers in men, and nonsmokers in women) exposed to a mixture of TRI (at 8 ppm) and TETRA (at 17 ppm) (TRI + TETRA). The results were compared with the findings in control subjects matched by age, sex, smoking habits and place of residence. No significant increase in SCE frequencies was observed in association with exposure to benzene, TRI, TETRA or TRI + TETRA. The SCE frequency was, however, significantly higher in the TRI-, TETRA- or TRI + TETRA-exposed smoking men than in the concurrent nonsmoking controls of the same sex. Possible synergism between solvent exposure and smoking is discussed.

Excretion of 1,2,4-benzenetriol in the urine of workers exposed to benzene

Urine samples were collected from 152 workers (64 men, 88 women) who had been exposed to benzene, 53 workers (men only) exposed to a mixture of benzene and toluene, and 213 non-exposed controls (113 men, 100 women). The samples were analysed for 1,2,4-benzentriol (a minor metabolite of benzene) by high performance liquid chromatography. The time weighted average solvent exposure of each worker was monitored by diffusive sampling technique. The urinary concentration of 1,2,4-benzentriol related linearly to the intensity of exposure to benzene both in men and women among workers exposed to benzene, and was suppressed by toluene co-exposure among male workers exposed to a mixture of benzene and toluene. A cross sectional balance study in men at the end of the shift of a workday showed that only 0.47% of benzene absorbed will be excreted into urine as 1,2,4-benzenetriol, in close agreement with previous results in rabbits fed benzene. The concentration of 1,2,4-benzenetriol in urine was more closely related to the concentration of quinol than that of catechol. The fact that phenol and quinol, but not catechol, are precursors of 1,2,4-benzentriol in urine was further confirmed by the intraperitoneal injection of the three phenolic compounds to rats followed by urine analysis for 1,2,4-benzenetriol.

A retrospective cohort study of leukemia and other cancers in benzene workers

A retrospective cohort study was carried out in 1982-1983 among 28,460 benzene-exposed workers (15,643 males, 12,817 females) from 233 factories and 28,257 control workers (16,621 males, 12,366 females) from 83 factories in 12 large cities in China. All-cause mortality was significantly higher among the exposed (265.46/100,000 person-years) than among the unexposed (139.06/100,000 person-years), as was mortality from all malignant neoplasms (123.21/100,000 versus 54.7/100,000, respectively). For certain cancers, increased mortality was noted among benzene-exposed males in comparison with that among unexposed males; the standardized mortality ratios (SMR) were elevated for leukemia (SMR = 5.74), lung cancer (SMR = 2.31), primary hepatocarcinoma (SMR = 1.12), and stomach cancer (SMR = 1.22). For females only leukemia occurred in excess among the exposed. Risk of leukemia rose as duration to exposure to benzene increased up to 15 years, and then declined with additional years of exposure. Leukemia occurred among some workers with as little as 6 to 10 ppm average exposure and 50 ppm-years (or possibly less) cumulative lifetime exposure (based on all available measurements for the exposed work units). Among the 30 leukemia cases identified in the exposed cohort, the proportion of subjects with acute lymphocytic leukemia was substantially lower and the proportion with acute nonlymphocytic leukemias was higher than in the general population. During 1972 to 1981, the annual incidence of leukemia ranged from 5.83 to 28.33 per 100,000 with higher rates occurring in the interval 1977 to 1981 than in the earlier years of the study period.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood cadmium levels in the populations of 3 Chinese cities

Blood samples were collected from male and female factory workers aged greater than or equal to 16 years (with no occupational exposure to metals including cadmium) in the 3 cities of Hefei (323 subjects), Shenyang (78 subjects), and Jinxi (137 subjects) in China from 1985 to 1987. The samples were analyzed for cadmium in a single laboratory by automated flameless atomic absorption spectrophotometry under strict quality control. The effect of smoking was evident in Hefei, Shenyang and Jinxi, while the effect of aging was not apparent. There were no sex or regional differences in blood cadmium levels in non-smokers in the 3 cities (e.g., 1.2, 1.3 and 1.4 micrograms/l as geometric means in non-smoking women in Hefei, Shenyang and Jinxi, respectively). There was general agreement in blood cadmium levels between the present results and the values reported in the literature, although the latter values were generally based on small study populations.