Analgesics and cancers of the renal pelvis and ureter

To evaluate renal pelvis and ureter (RPU) cancer risk in relation to lifetime use of analgesics, a population-based case-control study was carried out in 3 areas of the United States. Among 502 cases and 496 controls diagnosed and interviewed during 1983-1986, no significant increases in risk were found for any of the non-prescription and prescription analgesics evaluated or among regular users of phenacetin, acetaminophen or aspirin. Neither cumulative lifetime ingestion nor duration of regular use of these 3 drugs, whether alone or in combination, was associated with significantly increased risk of RPU cancer, although a slight excess was observed among long-term users of acetaminophen. Risk was not increased among persons reporting highest cumulative dose and/or longest duration of phenacetin use. Although our study of RPU cancer is the largest to date, it was nonetheless limited by the small number of regular analgesic users and the relatively low response rates. Because of the relatively recent onset of widespread use of acetaminophen, its pharmacologic similarity to phenacetin, a known urothelial carcinogen, and the elevation in risk seen in long-term users, further surveillance of this analgesic is warranted.

Identification and characterization of a Bacteroides gene, csuF, which encodes an outer membrane protein that is essential for growth on chondroitin sulfate

Bacteroides thetaiotaomicron can utilize a variety of polysaccharides, including charged mucopolysaccharides such as chondroitin sulfate (CS) and hyaluronic acid (HA). Since the enzymes (chondroitin lyases I and II) that catalyze the first step in breakdown of CS and HA are located in the periplasm, we had proposed that the first step in utilization of these polysaccharides was binding to one or more outer membrane proteins followed by translocation into the periplasm, but no such outer membrane proteins had been shown to play a role in CS or HA utilization. Previously we have isolated a transposon-generated mutant, CS4, which was unable to grow on CS or HA but retained the ability to grow on disaccharide components of CS. This phenotype suggested that the mutation in CS4 either blocked the transport of the mucopolysaccharides into the periplasmic space or blocked the depolymerization of the mucopolysaccharides into disaccharides. We have mapped the CS4 mutation to a single gene, csuF, which is capable of encoding a protein of 1,065 amino acids and contains a consensus signal sequence. Although CsuF had a predicted molecular weight and pI similar to those of chondroitin lyases, it did not show significant sequence similarity to the Bacteroides chondroitin lyase II, a Proteus chondroitin ABC lyase, or two hyaluronidases from Clostridium perfringens and Streptococcus pyogenes, nor was any CS-degrading enzyme activity associated with csuF expression in Bacteroides species or Escherichia coli. The deduced amino acid sequence of CsuF exhibited features suggestive of an outer membrane protein. We obtained antibodies to CsuF and demonstrated that the protein is located in the outer membrane. This is the first evidence that a nonenzymatic outer membrane protein is essential for utilization of CS and HA.

Diet and breast cancer in Shanghai and Tianjin, China

Various aspects of adult diet have been linked to breast cancer development. These include intake of fat (risk factor), and intake of fibre, soy protein and vitamins A, C and E (protective factors). Results of previous studies have been inconsistent. We examined the possible associations between breast cancer and various indices of nutrient and food intake in two Chinese populations who are at relatively low risk for breast cancer (one-fifth the rate in US white women). Two case-control studies of breast cancer were conducted in the cities of Shanghai and Tianjin, China. In Shanghai, 534 women aged 20-69 years with histologically confirmed breast cancer were recruited, whereas in Tianjin 300 women aged 20-55 years with histologically confirmed breast cancer were interviewed. All controls were community controls who were individually matched to the cases by sex and age (case-control ratio = 1:1). All interviews were conducted in person. Findings from the two studies were similar, although the diets in Shanghai and Tianjin were different in many respects. Cases and controls were similar in their consumption of soy protein, measured either in absolute levels or as percentages of total protein. Overall, all components of dietary fat (saturated fat, monounsaturated fat, polyunsaturated fat) showed a modest, non-significant association with breast cancer after adjustment for energy intake and other non-dietary risk factors for breast cancer. Intake of crude fibre, carotene and vitamin C, on the other hand, exhibited strong, statistically significant inverse associations with breast cancer risk. The last three indices were highly correlated, rendering it impossible to disentangle their individual effects; they were closely associated with intake of green vegetables in the two study populations. Vitamin E intake was unrelated to breast cancer risk in Shanghai and Tianjin. In the multivariate logistic regression model which included all non-dietary risk factors for breast cancer and energy intake, Shanghai women in the lowest tertile of crude fibre intake and highest tertile of fat intake had a 2.9-fold increased risk for breast cancer relative to those in the highest tertile of crude fibre intake and lowest tertile of fat intake. The comparable relative risk in Tianjin women was 2.4. Our data indicate a strong protective effect against breast cancer development with intake of foods rich in fibre, vitamin C and carotene. Our results are also compatible with dietary fat having a modest, positive effect on breast cancer risk within the range of exposure experienced by women in China.(ABSTRACT TRUNCATED AT 250 WORDS)

The CAG and GGC microsatellites of the androgen receptor gene are in linkage disequilibrium in men with prostate cancer

The androgen receptor genotype was determined in the white blood cell DNA of 45 African-American, 39 non-Hispanic white, and 39 Asian (Chinese, Japanese) normal subjects and 68 patients with prostate cancer (57 whites), all of whom were residents of Los Angeles County. For each subject, we measured the number of repeats in the polymorphic CAG and GGC microsatellites of exon 1 of the androgen receptor gene. In normal subjects, the distributions of CAG and GGC microsatellites differed significantly among the races (two-sided P = 0.046 and < 0.0005, respectively). The prevalence of short CAG alleles (< 22 repeats) was highest (75%) in African-American males with the highest risk for prostate cancer, intermediate (62%) in intermediate-risk non-Hispanic whites, and lowest (49%) in Asians at very low risk for prostate cancer. High-risk African-Americans also had the lowest frequency (20%) of the GGC allele with 16 repeats; the comparable values for intermediate-risk whites and low-risk Asians were 57% and 70%, respectively. Consistent with the interracial variation in CAG and GGC distributions, there was an excess of white patients with < 22 CAG and not-16 GGC repeats relative to white controls (relative risk, 2.1; one-sided P = 0.08). We observed no association (linkage) between the two microsatellites among normal subjects. On the other hand, there was a statistically significant negative association between the numbers of CAG and GGC repeats among the prostate cancer patients studied (two-sided P = 0.008). Among the 47 subjects with short CAG alleles (< 22 repeats), 43% had long GGC alleles (> 16 repeats) whereas only 15% of the 20 subjects with long CAG alleles (> or = 22 repeats) had long GGC alleles. Overall, our data suggest a possible association between CAG and GGC microsatellites of the androgen receptor gene and prostate cancer development.

Tyrosine hydroxylase- and dopamine-beta-hydroxylase-positive neurons and fibres in the developing human cerebellum--an immunohistochemical study

Six human fetuses of gestational ages 16-28 weeks were employed. The immunocytochemical avidin-biotin-peroxidase complex method combined with the silver Bodian technique was used to evaluate the presence of tyrosine hydroxylase and dopamine-beta-hydroxylase neurons and afferent and efferent fibres in the cerebellum during development. Our results illustrated that by 16-18 weeks, immunoreactivity of the Purkinje cells and the granule cells was evident. By 23 weeks, the positive Purkinje cells were tightly packed together and the perinuclear granules began to extend into the processes. The positive cells next to Purkinje cells were the basket cells and stellate cells. By 26-28 weeks, all positive cells increased in number and size. Mossy and climbing fibres appeared early in development (16-18 weeks of gestation) and were seen synapsing with the positive granule cells. At the same time, some parallel fibres were observed. At later stages, the tyrosine hydroxylase- and dopamine-beta-hydroxylase-positive Purkinje cells were surrounded by abundant climbing fibres, while parallel fibres were also evident in the molecular layer. In the deep cerebellar nuclei, positive tyrosine hydroxylase and dopamine-beta-hydroxylase neurons were present by 16-18 weeks of development. Those in the dentate nucleus were more polymorphic but smaller in size. Some afferent fibres were also spotted around 16-18 weeks of gestation and their numbers increased later. Positive efferent fibres were present by 26 weeks. All these observations point to an early presence of tyrosine hydroxylase and dopamine-beta-hydroxylase components in cerebellar development.

Urinary excretion of 2-amino-3,8-dimethylimidazo-[4,5-f]quinoxaline in white, black, and Asian men in Los Angeles County

The heterocyclic aromatic amines produced by high temperature cooking of foods containing creatin(in)e and amino acids (such as beef, pork, poultry and fish) are a class of potent animal carcinogens and have been implicated indirectly in human colon and pancreas carcinogenesis. We studied the urinary excretion of a mutagenic heterocyclic aromatic amine compound, 2-amino-3,8-dimethylimidazo-[4,5-f]quinoxaline (MelQx), among 47 black, 41 Asian (Chinese or Japanese), and 43 non-Hispanic white (white) male residents of Los Angeles County by quantitative analysis of total free and conjugated MelQx in pooled overnight urine collections. Significant interracial differences were observed. Geometric mean level in blacks was 1.3- and 3.0-fold higher than that in Asians and whites, respectively. Urinary level of MelQx was positively associated with intake frequencies of bacon, pork/ham and sausage/luncheon meats among study subjects, consistent with the observation that in Los Angeles, blacks had the highest consumption of these three food groups among the three races. Among men in Los Angeles County, the incidence rates of pancreas and colon cancers, which have been shown to be positively related to intake of fried meats, are 50% and 20% higher in blacks relative to Asians and whites, respectively. Our results are, therefore, consistent with the hypothesis that exposure to heterocyclic aromatic amines is related to risk of pancreas and colon cancers, and may in part explain the higher incidence among blacks relative to Asians and whites in Los Angeles.

An immunohistochemical study of the c-fos protooncogene in the developing human retina

The localization and distribution of the protooncogene c-fos were studied immunohistochemically in the retina of human fetuses ranging in age from 15 to 40 weeks of gestation. The highest levels of immunoreactivity were observed in the retinae of younger fetuses, decreasing in intensity with increasing age. At 15 weeks of gestation intense immunoreactivity was observed in the inner nuclear layer while the photoreceptor cells exhibited moderate staining. At 26 weeks of gestation, immunoreactivity in the inner nuclear layer was reduced. The ganglion cells, amacrine cells and photoreceptor cells showed moderate immunopositivity throughout the 26-40 weeks period. The role of c-fos in development is discussed in the light of its other known functions.

Acetylator phenotype, aminobiphenyl-hemoglobin adduct levels, and bladder cancer risk in white, black, and Asian men in Los Angeles, California

BACKGROUND

There is a large body of epidemiologic and experimental data that have identified a number of arylamines as human bladder carcinogens. Metabolic activation is required to biotransform these arylamines into their carcinogenic forms, and N-hydroxylation, which is catalyzed by the hepatic cytochrome P4501A2 isoenzyme, is generally viewed as the first critical step. On the other hand, the N-acetylation reaction, catalyzed by the hepatic N-acetyltransferase enzyme, represents a detoxification pathway for such compounds. The N-acetyltransferase enzyme is coded by a single gene displaying two phenotypes, slow and rapid acetylators. In the United States, cigarette smoking is a major cause of bladder cancer in men, and carcinogenic arylamines present in cigarette smoke are believed to be responsible for inducing bladder cancer in smokers.

PURPOSE

Our purpose was to test the differences in three ethnic/racial groups for the prevalence of acetylator phenotypes and to ascertain whether slow acetylators actually have higher levels of activated arylamines in comparison with rapid acetylators.

METHODS

One hundred thirty-three male residents of Los Angeles County who were either white, black, or Asian (Chinese or Japanese) and over the age of 35 years were assessed for their acetylator phenotype and levels of 3- and 4-aminobiphenyl (ABP) hemoglobin adducts. Subjects were either lifetime nonsmokers (n = 72) or current cigarette smokers of varying intensity (n = 61).

RESULTS

The proportion of slow acetylators was highest among whites (54%), intermediate among blacks (34%), and lowest among Asians (14%). Similarly, geometric mean levels of both 3- and 4-ABP-hemoglobin adducts were highest in whites (1.80 and 49.2 pg/g hemoglobin [Hb], respectively), intermediate in blacks (1.54 and 38.5 pg/g Hb), and lowest in Asians (0.73 and 36.0 pg/g Hb). As expected, cigarette smokers had significantly higher mean levels of both 3- and 4-ABP-hemoglobin adducts relative to nonsmokers, and the levels increased with the number of cigarettes smoked per day (P < .0005 for both adducts). Slow acetylators consistently exhibited higher mean levels of ABP-hemoglobin adducts relative to rapid acetylators, independent of race and level of smoking.

CONCLUSION

The present cross-sectional survey supports acetylation phenotype as an important determinant of bladder cancer risk and a possible major factor in the varying bladder cancer risk among whites, blacks, and Asians.

A follow-up study of urinary markers of aflatoxin exposure and liver cancer risk in Shanghai, People's Republic of China

A cohort of 18,244 mostly middle-aged (45-64 years) men residing in four small geographically defined areas of Shanghai was accrued between January 1986 and September 1989. In addition to an in-person interview regarding dietary and other past exposures, each subject donated a single void urine sample at recruitment so that the presence of aflatoxins in urine could be assessed. In addition, a 1-year survey of market foods in Shanghai was conducted to quantitatively estimate the extent of aflatoxin exposure in the study population. After close to 70,000 person-years of follow-up, 55 incident cases of hepatocellular carcinoma (HCC) had been identified. Levels of urinary aflatoxin B1 and the oxidative metabolites, including the major aflatoxin nucleic acid adduct, aflatoxin-N7-guanine, were determined for 50 of the 55 identified cases of HCC. Two hundred sixty-seven controls were chosen randomly from the cohort; they were matched to the 50 cases by age (within 1 year), time of specimen collection (within 1 month), and residence. After integrating the high-pressure liquid chromatography chromatograms to measure aflatoxin-N7-guanine, aflatoxin M1, aflatoxin P1, and aflatoxin B1, 49, 67, 53, and 71 of the urine samples had detectable levels of these compounds, respectively. The aflatoxin metabolite detected at the highest concentration was aflatoxin P1; the range was 0.59-16.0 ng/ml. The range of aflatoxin M1 in the urine was 0.17-5.2 ng/ml. The aflatoxin-N7-guanine adduct range was 0.3-1.81 ng/ml in the 49 positive samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Histologically benign or low-grade malignant tumors adjacent to high-grade ovarian carcinomas contain molecular characteristics of high-grade carcinomas

It is presently not clear if ovarian carcinomas arise de novo or from benign precursors (cystadenomas) and if high-grade malignant tumors (carcinomas) develop from preexisting low-grade carcinomas. The presence of allelic losses on chromosome 11p15.5 distinguishes high-grade ovarian carcinomas from either low-grade carcinomas or cystadenomas. We therefore examined the distribution of such losses in different parts of heterogeneous tumors showing mixed histological grades or showing adjacent large histologically benign neoplasms. The results showed that all neoplastic areas, including those that were histologically benign or compatible with low-grade carcinomas, contained allelic losses at the above locus. This suggests that the morphologically less aggressive portions of these heterogeneous tumors were not typical cystadenomas or low-grade carcinomas and contained molecular abnormalities indicative of at least a predisposition to the high-grade carcinoma phenotype.

Enhanced IL-1 beta and tumor necrosis factor-alpha release and messenger RNA expression in macrophages from idiopathic pulmonary fibrosis or after asbestos exposure

Idiopathic pulmonary fibrosis (IPF) and asbestosis are fibrotic interstitial lung diseases characterized by alveolar wall fibrosis with accumulation of extracellular matrix, interstitial remodeling, and increased numbers of activated alveolar macrophages. Animal models and in vitro studies have shown that macrophage cytokines, namely IL-1 beta and TNF-alpha, play significant roles in the development of fibrosis. We found significant increases for TNF-alpha release in both diseases (p < 0.01) and a significant increase for IL-1 beta release in asbestosis compared to normal controls (p < 0.01). Also, the mRNA expression of these cytokines was increased in alveolar macrophages from patients with IPF or asbestosis compared with normals. The level of TNF-alpha release in macrophage supernatants correlated with the number of neutrophils per milliliter bronchoalveolar lavage fluid returned. Chrysotile, crocidolite, amosite asbestos, and silica stimulated IL-1 beta and TNF-alpha release and up-regulated their respective mRNA in macrophages or monocytes. To evaluate the role of IL-1 beta and TNF-alpha in the accumulation of extracellular matrix, we studied collagen types I and III and fibronectin gene expression in human diploid lung fibroblasts after short term (2 h) serum-free exposure to recombinant cytokines. Both cytokines up-regulated these genes 1.5- to 3.6-fold. These cytokines have the potential to influence the remodeling and fibrosis observed in the lower respiratory tract in IPF and asbestosis.

Enhanced IL-1 beta and tumor necrosis factor-alpha release and messenger RNA expression in macrophages from idiopathic pulmonary fibrosis or after asbestos exposure

Idiopathic pulmonary fibrosis (IPF) and asbestosis are fibrotic interstitial lung diseases characterized by alveolar wall fibrosis with accumulation of extracellular matrix, interstitial remodeling, and increased numbers of activated alveolar macrophages. Animal models and in vitro studies have shown that macrophage cytokines, namely IL-1 beta and TNF-alpha, play significant roles in the development of fibrosis. We found significant increases for TNF-alpha release in both diseases (p &lt; 0.01) and a significant increase for IL-1 beta release in asbestosis compared to normal controls (p &lt; 0.01). Also, the mRNA expression of these cytokines was increased in alveolar macrophages from patients with IPF or asbestosis compared with normals. The level of TNF-alpha release in macrophage supernatants correlated with the number of neutrophils per milliliter bronchoalveolar lavage fluid returned. Chrysotile, crocidolite, amosite asbestos, and silica stimulated IL-1 beta and TNF-alpha release and up-regulated their respective mRNA in macrophages or monocytes. To evaluate the role of IL-1 beta and TNF-alpha in the accumulation of extracellular matrix, we studied collagen types I and III and fibronectin gene expression in human diploid lung fibroblasts after short term (2 h) serum-free exposure to recombinant cytokines. Both cytokines up-regulated these genes 1.5- to 3.6-fold. These cytokines have the potential to influence the remodeling and fibrosis observed in the lower respiratory tract in IPF and asbestosis.

An immunohistochemical study of neuropeptide Y positive sites in the developing human hippocampal formation

Neuropeptide Y (NPY)-positive sites were evaluated by immunohistochemistry in the hippocampal formation of human fetuses aged from 15 to 41 weeks of gestation. Immunopositive cells and fibers were identified in the hippocampus as early as 15 weeks of gestation. These cells were localized in the polymorphic and pyramidal layers and their numbers increased with the age of the fetuses. NPY-positive cells were observed to be closely apposed to blood vessels and some NPY fibers, present mainly in the polymorphic layer, would infiltrate the alveus.

Effects of 60 Hz electric and magnetic fields on maturation of the rat neopallium

This study was undertaken to determine the effects of extremely low frequency (ELF; 60 Hz) electromagnetic (EM) fields on somatic growth and cortical development, as well as biochemical and morphological maturation, of the rat neopallium. On the fifth day of pregnancy, female rats were put in pairs into plastic cages that were housed in a specially constructed apparatus for irradiation under three separate sets of combination and intensity: 1) 1 kV/m and 10 gauss; 2) 100 kV/m and 1 gauss; and 3) 100 kV/m and 10 gauss. The dams were exposed for 23 h daily, from days 5 through 19 postconception, after which they were returned to cages outside the exposure apparatus until they littered. The neonates were culled to eight pups per litter. At 0 (birth), 5, 12, and 19 days postnatally, they were killed for biochemical and morphological studies. Another group of pregnant rats was sham-exposed in an identical apparatus, which was not energized, and the pups were used as controls. The irradiated rats exhibited no physical abnormalities, nor did they show brain deformities such as swelling or herniation following exposure to ELF-EM fields. There was no difference in somatic growth between control and exposed rats, but a small reduction in cortical weight was observed in rats exposed at 1 kV/m and 10 gauss, and 100 kV/m and 1 gauss, respectively. Biochemical measurements of DNA, RNA, protein, and cerebroside concentrations indicated that among the three separate exposures, only the neopallium of rats exposed at 1 kV/m and 10 gauss showed a small reduction in DNA level, as well as small reductions in RNA and protein levels. No changes were noticed in cerebroside levels in any exposed animals, and there were no differences in protein/DNA and cerebroside/DNA ratios between control and exposed rats. Morphological observations did not reveal any detectable alterations in the irradiated rats. These results indicate that exposure to ELF-EM fields caused minimal or no changes in somatic growth and cerebral development of the rat.

Effects of 60 Hz electric and magnetic fields on the development of the rat cerebellum

The effects of extremely low frequency (ELF) electromagnetic (EM) fields on the maturation of the rat cerebellum were studied. Newborn rats were exposed to 60 Hz electric and magnetic fields under three different combinations in a specially constructed apparatus. The pups were irradiated for 7-8 h daily, with a 30-min interruption for nursing. Pups were kept with their mothers for the remainder of the time. After approximately 1, 2, or 3 weeks of exposure, the pups were killed. Control pups were sham exposed. The somatic growth of the irradiated rats did not show any significant difference from sham-exposed controls. At 1 kV/m and 10 gauss exposure, there was a small but statistically significant decrease in cerebellar mass. In rats exposed at 1 kV/m and 10 gauss, DNA and RNA levels were significantly higher than those in sham-exposed controls at 6 and 13 days of age, but at 20 days, these two biochemical constituents were similar in both groups of rats. The ELF-EM treatment had no effect on protein and cerebroside concentrations. In terms of age effects, DNA and RNA exhibited increases from 6 to 13 days of age, and declined from 13 to 20 days. Protein and cerebroside levels exhibited increases during the 6-20-day periods. In rats exposed at 100 kV/m and 1 gauss, the DNA levels were initially less than those of sham-exposed controls at 8 days of age, reached approximately the same levels at 14 days, and then were higher than those of controls at 22 days. There was, therefore, a significant ELF-EM effect as well as a significant interaction between age and ELF-EM exposure. In terms of age effects, DNA levels for both control and exposed animals increased from 8 to 14 days. From 14 to 22 days, DNA levels of exposed rats continued to increase while those of the controls decreased. This age effect was significant. RNA levels in both groups of animals showed increases from 8 to 14 days of age, but the increase was less for the irradiated animals than for the controls. From days 14 to 22, RNA levels for both groups showed a reduction, but the decrease was greater in the irradiated than in control rats. ELF-EM treatment significantly reduced protein levels at 8 days of age, but at 14 to 22 days, protein levels of exposed rats were higher than those of controls.(ABSTRACT TRUNCATED AT 400 WORDS)

Absence of p53 gene mutations in primary nasopharyngeal carcinomas

Alterations in the p53 tumor suppressor gene and Epstein-Barr virus status were investigated in 15 nasopharyngeal carcinoma (NPC) biopsies, 4 xenografts, and 2 cell lines from the Cantonese region of southern China. One other established NPC cell line obtained from a northern Chinese patient was also studied. Restriction fragment length polymorphism analysis revealed a loss of heterozygosity for chromosome 17p, where the p53 gene resides, in only one of 15 NPC biopsies. Polymerase chain reaction-single-stranded conformational polymorphism analysis and direct sequencing failed to detect sequence alterations in exons 5 through 8 of the p53 gene in the 15 tumors and in the 4 NPC xenografts, all of which tested positive for Epstein-Barr virus. In contrast, the 3 NPC cell lines were all negative for Epstein-Barr virus and contained G----C transversions in the p53 gene, with cell lines CNE-1 and CNE-2 harboring identical AGA (arginine) to ACA (threonine) changes at codon 280. These results suggest that p53 inactivation is not a necessary component of nasopharyngeal carcinogenesis in Cantonese but may be important in the establishment of cell lines derived from these tumors.

A case-control study of breast cancer in Tianjin, China

In a population-based case-control study of breast cancer in Tianjin, China, involving 300 cases and 300 population controls interviewed during 1985-1986, a number of strong risk factors were identified. Although average age at menarche was late by Western standards in this developing country (14.4 years), it was clearly related to risk. Women with their first menstrual period at age 12 years or earlier had 80% greater risk than women who started at age 17 years or later. Age at first full-term pregnancy was also strongly related to risk, with women whose first birth after age 30 years having 3.2 times the risk of women whose first birth was under age 20 years. Other established breast cancer risk factors in Western populations (family history of breast cancer, a history of benign breast disease, and use of oral contraceptives late in reproductive life) were also risk factors in this population. Parity and duration of lactation were both strongly protective against breast cancer development in univariate analyses. These two variables were highly correlated with each other and with age at first full-term pregnancy. Although the effects of each variable dissipated somewhat in multivariate analysis, our data strongly suggest that both parity and lactation independently contribute to breast cancer risk.

Development of parvalbumin immunoreactive neurons in normal and intracranially transplanted retinas in the rat

Retinas from embryonic day 14 Sprague-Dawley rats were transplanted to the midbrain or cerebral cortex of newborn (P0) rats of which the right eye was enucleated at the time of transplantation. Parvalbumin immunoreactive (PV-I) neurons were studied in the developing retinal transplants, and in the remaining retina of the host, as well as in normal retinas. PV-I neurons were identifiable in retinas of normal and host rats from postnatal day 5 (P5) onward, with the PV-I somata primarily in the inner half of the inner nuclear layer and in the ganglion cell layer. An adult-like distribution of PV-I neurons was attained at P35, as judged by cell packing density, intensity of immunostaining, laminar distribution and soma size of subpopulations of PV-I cells. A similar time course of development and distribution of PV-I somata was observed in the retinal transplants, except for some minor differences such as a slight delay in PV-I cells achieving their final distribution. These findings provide evidence that PV-I neurons can survive, differentiate and mature according to predetermined programmes intrinsic to the retinal tissue following transplantation to a new and foreign environment.

Dietary beta-carotene, cigarette smoking, and lung cancer in men

A cohort of 5,080 men living in a retirement community in California (United States) and initially free from lung cancer were followed from June 1981 to December 1989. At recruitment, each study participant completed a mailed questionnaire which requested information on the subject's medical history, use of cigarettes, and usual consumption frequencies during the preceding 12 months of 44 vegetable and fruit items. Men who had never smoked had the highest mean daily intake of beta-carotene (8,505 micrograms), followed by past smokers (7,761 micrograms) and then by current smokers (6,178 micrograms). beta-Carotene intake of the subject's wife was correlated significantly with that of the husband in the 4,018 spouse pairs (r = 0.46; P = 0.0001). Among men with similar smoking habits, dietary beta-carotene intake significantly decreased with the spouse's smoking habit: never, past, and current smokers (P = 0.004; test for linear trend). During 31,477 person-years of follow-up, 125 incident cases of lung cancer were observed among the cohort of 5,080 men. Age-adjusted relative risks for lung cancer were below unity (i.e., demonstrating a reduced risk) for higher relative to lower consumption of beta-carotene, of all vegetables and fruits, and of yellow vegetables alone. However, these relative risks approached or crossed the null value when adjusted for personal smoking.

Urinary aflatoxin biomarkers and risk of hepatocellular carcinoma

Aflatoxins have long been suspected to be human hepatic carcinogens but no direct study was feasible until assays to measure individual aflatoxin exposure became available. We have used assays for urinary aflatoxin B1, its metabolites AFP1 and AFM1, and DNA-adducts (AFB1-N7-Gua) to assess the relation between aflatoxin exposure and liver cancer, as part of an ongoing prospective study of 18,244 middle-aged men in Shanghai, People's Republic of China. After 35,299 person-years of follow-up, 22 cases of liver cancer had been identified. For each case, 5 or 10 controls were randomly selected from cohort members without liver cancer on the date the disorder was diagnosed in the case and matched to within 1 year for age, within 1 month for sample collection, and for neighbourhood of residence. Subjects with liver cancer were more likely than were controls to have detectable concentrations of any of the aflatoxin metabolites (relative risk 2.4, 95% confidence interval 1.0-5.9). The highest relative risk was for aflatoxin P1 (6.2, 1.8-21.5). In an analysis adjusting for the effects of hepatitis B surface antigen seropositivity, level of education, cigarette smoking, and alcohol consumption, the relative risk for the presence of aflatoxin metabolites was 3.8 (1.2-12.2). There was a strong interaction between serological markers of chronic hepatitis B infection and aflatoxin exposure in liver-cancer risk. Reduction of aflatoxin exposure may be a useful intermediate goal in prevention of liver cancer, since the benefits of wide-scale hepatitis B vaccination will not be apparent for many years.

Cigarette smoking and cancers of the renal pelvis and ureter

A population-based case-control study of renal pelvis and ureter cancers (502 cases, 496 controls) conducted in three areas of the United States found cigarette smoking to be associated with a 3.1-fold increase in risk, with long-term (greater than 45 years) smokers having a 7.2-fold increased risk. Statistically significant dose-response associations were observed for both cancer sites and in both sexes regardless of the measure used: cigarettes per day, duration of use, or pack years. A significant decreasing trend in risk with increasing years quit smoking was also demonstrated for these cancers. Attributable risk estimates indicate that approximately 7 of 10 cancers of the renal pelvis and ureter among men and almost 4 of 10 among women are caused by smoking. The results of this study, the largest to date, confirm that cigarette smoking is the major cause of cancers of the renal pelvis and ureter, and that cessation of smoking could eliminate a large proportion of these tumors.

Nonviral risk factors for hepatocellular carcinoma in a low-risk population, the non-Asians of Los Angeles County, California

We conducted interviews on 74 patients with histologically confirmed hepatocellular carcinoma. These patients, aged 18-74 years, were black or white residents of Los Angeles County. We also interviewed 162 population control subjects who were comparable to the case patients by age, sex, and race. Cigarette smoking was a significant risk factor for hepatocellular carcinoma [relative risk (RR) = 2.1; 95% confidence limits (CL) = 1.1, 4.0]; the effects were similar in men and in women. Heavy alcohol consumption was another risk factor for hepatocellular carcinoma in men; men who consumed 80 g or more of ethanol per day had an RR of 4.7 (95% CL = 1.4, 15.4) relative to those who had never drunk alcohol on a weekly basis. The level of alcohol intake was relatively low in women, and no significant effect on risk of hepatocellular carcinoma was observed. Use of oral contraceptives was significantly related to risk of hepatocellular carcinoma in women (RR = 3.0; 95% CL = 1.0, 8.8); those who were exposed for more than 5 years exhibited a 5.5-fold increased risk (95% CL = 1.2, 24.8). The effects of these three risk factors on hepatocellular carcinoma development were independent of each other and independent of serologically determined viral hepatitis. Our data suggest that cigarette smoking, alcohol consumption, and use of oral contraceptives are major risk factors for hepatocellular carcinoma among non-Asian residents of Los Angeles County. We also observed a significant association between a history of diabetes and hepatocellular carcinoma (RR = 3.3; 95% CL = 1.5, 7.2), especially among those who had received insulin treatment (RR = 18.5; 95% CL = 2.2, 156.0). This association may have etiological significance.