Modifying effects of simultaneous treatment with butylated hydroxyanisole (BHA) on rat tumor induction by 3,2'-dimethyl-4-aminobiphenyl, 2,2'-dihydroxy-di-n-propylnitrosamine and N-methylnitrosourea

The modifying effects of concurrent treatment with high or low doses of butylated hydroxyanisole (BHA) on wide-spectrum carcinogen-induced carcinogenesis were studied in male F344 rats. Groups of 20 animals were treated with 2 or 0.04% BHA for 24 weeks. Starting 2 weeks after the commencement of BHA treatment, they were given s.c. injection of 50 mg/kg body weight 3,2'-dimethyl-4-aminobiphenyl (DMAB) once a week, i.g. administrations of 200 mg/kg body weight 2,2'-dihydroxy-di-n-propylnitrosamine (DHPN) once every 2 weeks, or i.p. injection of 15 mg/kg body weight N-methylnitrosourea (MNU) once every 2 weeks for 22 weeks. Further groups of rats were treated with DMAB, DHPN, MNU, or 2 or 0.04% BHA alone. All surviving animals were killed 24 weeks after the beginning of the experiment and the target organs examined histopathologically. The BHA treatment dose-dependently decreased the incidence of DMAB-induced liver preneoplastic lesions but was associated with significant tumor induction in the forestomach (papillomas, 40%, P less than 0.01) and urinary bladder (papillomas, 53%, P less than 0.001; carcinomas, 80%, P less than 0.001), where no lesions were observed in the group given only DMAB. Concurrent administration of 2% BHA also significantly inhibited the development of alveolar hyperplasia (P less than 0.001) of the lung in DHPN-treated animals, while enhancing induction of forestomach papillomas (P less than 0.05) and simple hyperplasia in the urinary bladder. Neither MNU nor 2% BHA alone induced forestomach carcinoma or papillary or nodular hyperplasia (PN hyperplasia) in the urinary bladder. However, these lesions were observed in 100% (P less than 0.001) and 55% (P less than 0.001) of animals respectively, receiving the two compounds in combination. These results demonstrated that concurrent treatment with BHA not only inhibits but can also strongly enhance carcinogenesis depending on the organ, irrespective of whether the carcinogens act directly or require metabolism. The finding that BHA potently modified carcinogenesis at 0.04% in diet, 1/50 of the carcinogenic dose, suggests that actual dietary levels close to the human situation might play a significant role in tumor development in man.

Antagonistic effect of diethylmaleate on the promotion of forestomach carcinogenesis by butylated hydroxyanisole (BHA) in rats pretreated with N-methyl-N'-nitro-N-nitrosoguanidine

The effects of diethylmaleate (DEM), previously demonstrated to inhibit butylated hydroxyanisole (BHA)-induced forestomach hyperplasia, on BHA promotion of forestomach carcinogenesis in rats pretreated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were examined. Groups of male 6-week-old F344 animals were given a single i.g. administration of 150 mg/kg body weight MNNG and starting 1 week later administered powdered diet containing 1% BHA plus 0.2% DEM, 1% BHA, 0.2% DEM or basal diet alone for 51 weeks. Further groups of rats were treated with 1% BHA plus 0.2% DEM, 1% BHA, 0.2% DEM or basal diet alone without MNNG pretreatment. Histopathological assessment of lesions at week 52 revealed enhancement of MNNG-initiated papilloma (100 versus 50%) and squamous cell carcinoma (100 versus 0%) development by BHA as compared to controls. Additional treatment with DEM, however, significantly reduced the relative incidences of carcinoma in situ (0 versus 35.7%) and squamous cell carcinoma (35.7 versus 100%), as well as BHA-induced forestomach hyperplasia with or without prior MNNG treatment. The results thus clearly demonstrate that DEM acts as a potent antagonist to BHA-promotion of rat forestomach carcinogenesis.

[Dental caries of primary teeth and life habits in Shinshinotsu Nursery School: three years of observations]

It is well known that there is a high positive correlation between increases in caries increment and life habits such as use of nursing bottle, tooth brushing, between-meal eating, and sweet consumption. The purpose of this study was to analyze data of caries status in primary dentition and life habits observed in 373 Shinshinotsu nursery schoolchildren aged 3-5 years over three years. Dental examinations were conducted in good natural light using dental mirror and probe. Caries was diagnosed according to the Welfare Ministry criteria and life habits were examined by a questionnaire. The mean number of df was 7.1 for the whole sample for three years and 17.6 of the children were caries free, whereas 47.3 were more than 10 df. The former group showed the best score for the frequency of between-meal eating, frequency of sweet consumption, tooth brushing habits, and frequency of fluoride application. The latter group showed a tendency to lower sweet consumption during the three years. Our data also showed that the life habits at nursing (use of nursing bottle and weaning period) influenced incidence of caries.

Placental form of glutathione S-transferase in normal and diseased human uterine cervical mucosa

Expression of the human placental form of glutathione S-transferase (GST-pi), an enzyme proposed as a marker for human and experimental neoplasia, was immunohistochemically evaluated in 51 samples of 'normal' and diseased adult human uterine cervix. Five fetal uteri were also studied. GST-pi positivity was detected in 54, 92, 95 and 83% of the 'normal', non-neoplastic, cervical intra-epithelial neoplasia (CIN) and cancer cases respectively. All five fetal uteri and the positive 'normal' adult cases presented cells immunostained for GST-pi throughout the thickness of the mucosa, including the basal layer. Some non-neoplastic conditions like inflammation, repair and metaplasia and some dysplastic and neoplastic lesions showed areas of positively stained cells within an otherwise negative tissue, indicating a phenotypic heterogeneity regarding the enzyme expression. Our results confirm that GST-pi has a fetal character and indicate that it may appear in the adult cervical squamous epithelia under 'normal' or pathological conditions not necessarily linked to the process of carcinogenesis. Therefore it cannot be used as a marker for cervical epithelial neoplasia.

Modulation of diethylnitrosamine-initiated placental glutathione S-transferase positive preneoplastic and neoplastic lesions by clofibrate, a hepatic peroxisome proliferator

The effect of clofibrate (CF) on proliferation of diethylnitrosamine (DEN)-initiated glutathione S-transferase placental form (GST-P)-positive preneoplastic and neoplastic lesions as studied in male F344 rats. Animals were given a single i.p. injection of 200 mg/kg body weight of DEN, and then from 2 weeks later were given a diet containing 0.3% CF (group 1), or no supplement (group 2) until week 64. Group 3 received an injection of 0.9% NaCl instead of DEN and then a diet containing 0.3% CF, like group 1. Animals in all groups were subjected to partial hepatectomy at week 3 and killed at weeks 8, 20, 32, 49 or 64. The results showed that development of GST-P-positive lesions was significantly less in group 1 than in group 2 from week 8 (P less than 0.05). However, in group 1, morphologically distinguishable GST-P-negative preneoplastic lesions increased from week 20 (P less than 0.05), and the total number of GST-P-positive and -negative lesions was significantly greater than that in group 2 from week 32 (P less than 0.05). The induction of hepatocellular carcinoma (HCC) was greater in group 1 than in group 2 from week 49. All the HCCs induced in group 2 were GST-P-positive, whereas 38.9% (7/18) of those in group 1 were GST-P-negative. In group 3, only a few GST-P-positive and/or -negative preneoplastic lesions developed by week 64. These results suggest that CF has tumor-promoting activity, and that GST-P-positive cells induced by DEN changed to GST-P-negative cells on subsequent treatment with CF.

Amino acid residues stabilizing a Bacillus alpha-amylase against irreversible thermoinactivation

The alpha-amylase of Bacillus licheniformis (BLA) is stable and active at high temperature. More than 80% of its activity is retained after heat treatment at 90 degrees C for 30 min, and the optimum temperature for its activity is 80-85 degrees C. In contrast, the alpha-amylase of Bacillus amyloliquefaciens (BAA), the amino acid sequence of which shows 80% homology with that of BLA, is rapidly inactivated at 90 degrees C. Various chimeric genes were constructed from the structural genes for the two enzymes, and their products were analyzed for stability as to irreversible thermoinactivation. Two regions in the amino acid sequence of BLA comprising Gln178 (region I) and the 255th-270th residues (region II), respectively, were shown to determine the thermostability of BLA. Region I plays a major role in determining the thermostability. By means of site-directed mutagenesis of the BAA gene, deletion of Arg176 and Gly177 in region I and substitutions of alanine for Lys269 and aspartic acid for Asn266 in region II were shown to be responsible for the enhancement of the thermostability. Mutant BAAs containing the above deletion and substitutions showed almost the same thermostability as BLA as to irreversible thermoinactivation. Nevertheless, the mutant BAAs showed a temperature optimum as low as that of BAA (65 degrees C), indicating that they are still susceptible to reversible inactivation at temperatures higher than 65 degrees C.

The relative value of glycated albumin, hemoglobin A1c and fructosamine when screening for diabetes mellitus

We compared the usefulness of three glycated serum proteins, glycated albumin (GA), glycated hemoglobin (HBA1c) and fructosamine (FA), for diabetic screening purposes. We measured these indices in 302 adults, most of whom underwent yearly physical examinations. We measured GA and HbA1c with high precision using high-performance liquid chromatography (interassay coefficients of variation 4.9 and 4.0%, respectively) and FA using commercial reagents (interassay coefficient of variation 1.65%). All the individuals underwent a 75-g oral glucose tolerance test, which revealed significant correlations between the values of the three glycated proteins and the four plasma glucose concentrations measured as well as the sum of these glucose concentrations, sigma BS (GA, r = 0.80; HbA1c, r = 0.80; FA, r = 0.65). On the basis of the test, 130 of the subjects were classified as normal (N), 123 as borderline and 49 as having diabetes mellitus (D) according to the criteria of the Japan Diabetes Society. Of the 123 borderline cases, 26 showed impaired glucose tolerance (IGT) according to the WHO criteria. The normal group values of GA, HbA1c and FA were 17.8 +/- 0.17% (mean +/- SEM), 5.02 +/- 0.03%, and 2.55 +/- 0.02 mM/l, respectively. Borderline and IGT subjects had significantly more GA and HbA1c than normal but not more FA (P less than 0.01). We divided the subjects into 10 groups on the basis of their sigma BS values; those with values higher than 671 +/- 4.7 mg/dl had significantly more GA and HbA1c than normal, while those with values higher than 1068 +/- 40.9 mg/dl (the most extreme cases) had significantly more FA.(ABSTRACT TRUNCATED AT 250 WORDS)

Modification by catechol and resorcinol of upper digestive tract carcinogenesis in rats treated with methyl-N-amylnitrosamine

Modifying effects of the environmental contaminant catechol, and its isomers resorcinol and hydroquinone, on methyl-N-amylnitrosamine (MNAN)-induced carcinogenesis were studied in male F344 rats. Groups of 15 rats were given three i.p. injections of 25 mg/kg of body weight of MNAN within the initial 2-wk period, and commencing 1 wk thereafter they were administered 0.8% catechol, 0.8% resorcinol, or 0.8% hydroquinone in powdered basal diet or were given basal diet alone for 49 wk. Additional groups of 10 to 15 rats were similarly treated without prior carcinogen exposure. Histological examination after sacrifice at wk 52 revealed that the incidences of tongue papillomas and esophageal squamous cell carcinomas in the groups given MNAN followed by catechol (57.1% and 64.3%) or resorcinol (50% and 58.8%) were significantly higher than those in the carcinogen only controls (9.1, and 0%, respectively). Hydroquinone also enhanced the development of esophageal squamous cell carcinomas but was less active than catechol or resorcinol. The incidence of alveolar hyperplasia in the lungs of the group given MNAN followed by catechol (0%) was, in contrast, significantly reduced as compared to the control value (54.5%). Hydroquinone and resorcinol showed a similar but non-significant tendency. These results indicated that the environmental contaminant, catechol and its isomers, may play a role in the development of human upper gastrointestinal cancer, in addition to exerting modifying effects in other organs.

Transient induction of single GST-P positive hepatocytes by DEN

The single cells positive for placental glutathione S-transferase (GST-P), detectable in livers of rats soon after treatment with hepatocarcinogens, are possible 'initiated cells', the hypothesis tested in the present series of experiments. No low dose threshold was observed in male Sprague-Dawley rats at different single doses of diethylnitrosamine (DEN) although a plateau was reached between 160 and 200 mg/kg body weight. At the latter single dose approximately 12,400 positive cells/cm3 were observed immunohistochemically in rat livers after one week, the numbers then decreasing to week 8 and thereafter rising again. In the early stages single cells predominated but with time a gradual increase in mini-foci and larger lesions became evident. Application of selection pressure (feeding of diet containing 0.02% 2-AAF plus partial hepatectomy) to rats 2-24 weeks after single DEN-treatment resulted in the formation of large foci positive for GST-P, especially in the early stages, the growth response being less pronounced with time. The number of foci, on the other hand, was correlated with the number of single cells/mini-foci detected in hepatectomy tissue of the same individuals. These results suggest that the early GST-P positive populations could be the precursor for preneoplastic foci and nodules.

Strain differences in susceptibility to 2-acetylaminofluorene and phenobarbital promotion of hepatocarcinogenesis: immunohistochemical analysis of cytochrome P-450 isozyme induction by 2-acetylaminofluorene and phenobarbital

Strain differences in the expression of cytochrome P-450 isoenzymes (P-450s) during enhancement of hepatocarcinogenesis by 2-acetylaminofluorene (2-AAF) and phenobarbital (PB) were investigated immunohistochemically using monoclonal antibodies against phenobarbital (PB) (APF3) or 3-methylcholanthrene (3-MC) (APH8) inducible P-450s. LEW, SD, WBN, F344, SHR, NAR, Wistar and ODS rats were studied, the first five strains proving to be less susceptible to 2-AAF induction of APH8 while responding strongly to the promoting influence of this chemical, as reported previously. The other three strains, NAR, Wistar and ODS, demonstrated greater inducibility, this correlating with an observed resistance to promotion by 2-AAF. PB administration was not associated with any strain difference in APF3 cytochrome P-450 inducibility except in the ODS rat, in which its effects were minimal. The results provide direct evidence that differential expression of cytochrome P-450 species plays a major role in determining responsiveness to hepatocarcinogenesis-promoting agents such as 2-AAF.

Synergism between sodium chloride and sodium taurocholate and development of pepsinogen-altered pyloric glands: relevance to a medium-term bioassay system for gastric carcinogens and promoters in rats

In an approach to early detection of gastric carcinogens and promoters in an in vivo test system, promotion by sodium chloride (NaCl) and the synergistic effects of NaCl and sodium taurocholate (Na-TC) on development of pepsinogen-altered pyloric glands (PAPG) in rat glandular stomach after initiation with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were investigated. A total of 205 male WKY/NCrj rats were divided into 8 groups. Group 1 was given a single dose of MNNG of 160 mg/kg body weight by gastric intubation, and starting 2 weeks later basal diet containing Na-TC for 18 weeks. In addition, 1 ml doses of saturated NaCl solution were given by gastric intubation at weeks 4, 6, 8 and 10. Similarly, group 2 was treated with MNNG and Na-TC, while group 3 animals received MNNG and NaCl. Group 4 was given MNNG alone. Groups 5-8 served as equivalent controls without MNNG initiation. The results revealed significantly enhanced induction of immunohistochemically defined PAPG in the Na-TC + NaCl (P less than 0.001), Na-TC (P less than 0.01) and NaCl (P less than 0.01) treated animals initiated with MNNG. Sodium chloride demonstrated a clear synergistic effect with Na-TC in promoting the development of PAPG, suggesting possible advantage for its use in medium-term in vivo assays for detection of gastric carcinogens and promoters.

Strain differences in susceptibility to 2-acetylaminofluorene and phenobarbital promotion of rat hepatocarcinogenesis in a medium-term assay system: quantitation of glutathione S-transferase P-positive foci development

Strain differences in susceptibility to promotion by the liver carcinogens 2-acetylaminofluorene (2-AAF) and phenobarbital (PB) were examined in the medium-term bioassay system initially developed in our laboratory using male F344 rats as the test animal and glutathione S-transferase placental form (GST-P)-positive foci as the lesion end-point. Numbers and areas per cm2 of induced GST-P-positive hepatocellular foci were compared in LEW, F344, NAR, SD, WBN, SHR, Wistar and ODS rats initiated with diethylnitrosamine (DEN) and subjected to partial hepatectomy during subsequent administration of 2-AAF or PB. LEW, SD, WBN, and F344 rats were most susceptible to hepatopromotion by both compounds, with a hundred fold increase in lesion area being observed for 2-AAF in the LEW case. NAR and SHR strains demonstrated an intermediate response, while Wistar and, in particular, the related ODS rats demonstrated very low susceptibilities. The obvious strain differences could be expressed in terms of comparative indices of promoting effects of 2-AAF and PB as well as DEN itself regarding each of the 8 strains tested. The use of F344 rats for the bioassay model was validated by the relatively high sensitivity to both DEN and 2-AAF initiation as well as second-stage promotion stimulus exhibited.

Left ventricular pump function in right ventricular overload

To clarify how left ventricular pumping action is altered in cor pulmonale, an experimental study was performed using canine heart preparations in which the effects on left ventricular performance of right ventricular overload, with and without depressed systolic function, were investigated. For this purpose, two methods using excised perfused hearts (n = 16) and in vivo hearts (n = 6) were employed, and in the latter condition, pulmonary artery constriction (n = 7), femoral arterial-venous (A-V) shunt (n = 3) and right coronary artery occlusion (n = 6) were induced. Left ventricular systolic function was assessed by the relationship between left ventricular isovolumic developed pressure and left ventricular volume in excised heart, and by ejection fraction with 2 dimensional echocardiogram in the vivo condition, taking into account preload and afterload changes. From the excised heart preparation, it was shown that left ventricular developed pressure significantly decreases when right and left ventricular diastolic pressure increases greatly. On the other hand, in vivo right ventricular overload due to pulmonary constriction and A-V shunt, the left ventricular ejection fraction increased following afterload reduction. When we compare the left ventricular ejection fraction in pulmonary constriction with that in right coronary occlusion, in which reduction of left ventricular diastolic area from the control was similar, the latter was significantly decreased despite afterload reduction. These results suggest that right ventricular overload does not necessarily induce left ventricular systolic dysfunction unless left ventricular end-diastolic pressure, as well as that of the right ventricle, increases definitely and simultaneously.(ABSTRACT TRUNCATED AT 250 WORDS)

Synergistic effects of low-dose hepatocarcinogens in induction of glutathione S-transferase P-positive foci in the rat liver

The effects of combined administration of hepatocarcinogens at low doses on the development of glutathione S-transferase P-form (GST-P)-positive foci of rat liver were examined utilizing a bioassay model which consists of a single injection of diethylnitrosamine (DEN, 200 mg/kg, ip), two-thirds partial hepatectomy at week 3 and a 6-week administration of test compounds. The chemicals used, 2-acetylaminofluorene (2-AAF), 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB), phenobarbital (PB), thioacetamide (TAA), N-ethyl-N-hydroxyethylnitrosamine (EHEN), benzo[a]pyrene (B[a]P), carbazole, and alpha-hexachlorocyclohexane (alpha-HCH) were incorporated in the diet, except for EHEN which was dissolved in the drinking water, at levels of 1/6 of the doses usually used. The combinations were: I) 2-AAF, 3'-Me-DAB, PB, TAA, EHEN and B[a]P, II) 2-AAF, 3'-Me-DAB and PB, III) TAA, EHEN and B[a]P, IV) 2-AAF, 3'-Me-DAB, carbazole, TAA, EHEN and alpha-HCH, V) 2-AAF, 3'-Me-DAB and carbazole, and VI) TAA, EHEN and alpha-HCH. All combinations, except for II, caused an increase in the area of the foci as evaluated by the ratios of areas in the combined administration groups to the sum totals of 3 or 6 individual data: I) 1.75, II) 0.81, III) 2.01, IV) 3.62, V) 1.34 and VI) 2.91. The non-synergistic effect in combination II might be related to PB induction of hepatic microsomal enzymes leading to enhanced enzymatical detoxification of 2-AAF and 3'-Me-DAB. The present results indicate that exposure to several chemicals of similar organotropism, even at doses lower than the apparent carcinogenic levels, might be critical to the carcinogenic process.

Determination of blood volume in dogs using an enriched stable isotope 50Cr

For the measurement of canine blood volume, various experimental conditions and techniques have been investigated using a non radioactive stable isotope 50Cr. On the basis of the results in this preliminary work, erythrocytes were labeled using 50Cr. Five micrograms of 50Cr per 1 ml of blood was added and incubated for 60 min. The canine erythrocytes were tagged using 50Cr and injected into vein of the same dogs. The blood samples collected at 60 min after the injection were irradiated by thermal neutron for 20 min at the reactor of the JAERI. Activities of 51Cr (the 50Cr concentration method) and 51Cr/59Fe radioactivity ratios (the 51Cr/59Fe ratio method) in the samples were measured. There was a very high correlation (r = 0.97, P less than 0.001) between the blood volumes calculated by the 50Cr concentration method and the 51Cr/59Fe ratio method. The latter method is less complicated than the former, because measurement of the sample weight and correction of thermal neutron flux are unnecessary. The mean blood volumes calculated by the ratio method and the Evans blue method were 89.8 +/- 6.8 ml/kg B.W. (mean +/- SD) and 98.9 +/- 10.6 ml/kg, respectively, showing a significant difference between them (P less than 0.05). However, these values are almost in accord by correction of venous blood PCV values with factor 0.97. As a detection limit of 50Cr was approximately 0.1 ng per 1 ml of blood in this system, this method has been concluded to be applicable to the measurement of the blood volume of cattle.

Changes in gap junction protein (connexin 32) gene expression during rat liver carcinogenesis

A rat liver gap junction (GJ) cDNA probe that detects mRNA encoding the 32 Kd GJ-protein (connexin 32) was employed to study GJ-protein gene expression in rat liver tumors induced by a single exposure to diethylnitrosamine (DEN) followed by exposure to 2-acetylaminofluorene (AAF)/CCl4/AAF or induced by systemic administration of N-ethyl-N-hydroxyethylnitrosamine (EHEN). All carcinomas generated by these carcinogens showed markedly reduced levels of GJ-protein mRNA. This may indicate that GJ-protein levels and gap-junctional intercellular communication (GJIC) capacity are also severely compromised. Moreover, all hyperplastic nodules also showed a reduced level of GJ-protein mRNA. Taken together with our earlier finding that the liver tumor promoter phenobarbital inhibits GJ-protein gene expression, these results suggest that deranged GJIC is a relatively early event in liver multistage carcinogenesis. A range of other cDNA probes was also used to characterize gene expression in the DEN-induced tumors. Induction of expression was seen for glutathione S-transferase (placental form) (GST-P), gamma-glutamyltranspeptidase (GGT), and c-raf but not for c-Ha-ras or c-myc.

Promotion by dihydroxybenzene derivatives of N-methyl-N'-nitro-N-nitrosoguanidine-induced F344 rat forestomach and glandular stomach carcinogenesis

Modifying effects of resorcinol, hydroquinone, p-tert-butylcatechol (PTBC), p-methylcatechol (PMC), and o-methylcatechol on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced forestomach and glandular stomach carcinogenesis were investigated in F344 rats. Groups of 15 to 16 male 6-wk-old animals were given a single intragastric administration of 150 mg/kg of body weight of MNNG and starting 1 wk later were administered powdered diet containing 0.8% resorcinol, 0.8% hydroquinone, 1.5% PTBC, 1.5% o-methylcatechol, 1.5% PMC, or basal diet alone for 51 wk. Additional groups of 10 to 15 rats each were treated with the phenolic compounds or received basal diet without prior carcinogen exposure. Histological examination after sacrifice at Wk 52 revealed that squamous cell carcinoma development in the forestomachs of rats treated with MNNG followed by PTBC (75%, P less than 0.001) or MNNG followed by PMC (100%, P less than 0.001) was significantly greater than in animals receiving MNNG alone (20%). Treatment with PMC alone also resulted in a 40% yield of papilloma. In the glandular stomach, incidences of adenomatous hyperplasias in rats treated with MNNG followed by PTBC (31.3%, P less than 0.05) or PMC (100%, P less than 0.001) and the incidence of adenocarcinomas in rats treated with MNNG followed by PMC (100%, P less than 0.001) were significantly higher than in controls. In addition, PMC alone induced a 100% yield of adenomatous hyperplasias and 6.7% of adenocarcinomas. Thus, the results demonstrated that PTBC and PMC treatment significantly enhances forestomach and glandular stomach carcinogenesis and that PMC itself may possess weak carcinogenic potential in these organs. The ortho-position appears to be important for this dihydroxybenzene activity.

Lack of modifying effects of linolic acid hydroperoxides and their secondary oxidative products on combined 7,12-dimethylbenz[a]anthracene and 1,2-dimethylhydrazine-initiated mammary gland, ear duct and colon carcinogenesis in female Sprague-Dawley rats

Effects of hydroperoxides, autoxidation products of linolic acid (HPO) and secondary oxidative products of HPO (SOP) (5% each in diet) were examined in female Sprague-Dawley rats. HPO and SOP administration was carried out during or subsequent to two injections of dimethylhydrazine (DMH) (40 mg/kg body wt s.c.), and a single i.g. dose of 7,12-dimethylbenz[a]anthracene (DMBA) (50 mg/kg body wt). No significant differences in the incidences of tumors in the mammary gland, colon, ear duct and hematopoietic system associated with HPO or SOP treatment were evident, during or after carcinogen exposure. The present results therefore indicate that the environmental contaminants, HPO and SOP, lack any potential for modification of mammary gland or colon carcinogenesis under the conditions of the investigation.

Lack of carcinogenicity of magnesium chloride in a long-term feeding study in B6C3F1 mice

Groups of 50 male and 50 female B6C3F1 mice were given magnesium chloride (MgCl2.6H2O) at dose levels of 0 (control), 0.5 and 2% in the diet for 96 wk, after which all animals received the control diet for 8 wk and were then necropsied. In females of the high-dose group a decrease in body weight was observed. However, survival rates did not differ between the treatment and control groups for males or females. Furthermore, clinical signs and urinary, haematological or serum clinical chemistry parameters showed no treatment-related effects. On histological examination, tumours were mainly found in the skin/subcutis, liver and lymphatic system. However, with the exception of a significant decrease in the incidence of liver tumours among males of the high-dose group, no differences were noted in the tumour incidence between the treated and control animals. Thus, the study described here clearly shows a lack of carcinogenicity of MgCl2.6H2O given to B6C3F1 mice in the diet.

Co-carcinogenic effects of NaHCO3 on o-phenylphenol-induced rat bladder carcinogenesis

The role of urinary pH and Na+ concentration on the bladder carcinogenesis of o-phenylphenol (OPP) was examined in male F344 rats. The rats were given powdered diet containing 2% sodium o-phenylphenate (OPP-Na, group 1), 1.25% OPP plus 0.64% NaHCO3 (group 2), 1.25% OPP plus 0.32% NaHCO3 (group 3), 1.25% OPP plus 0.16% NaHCO3 (group 4), 1.25% OPP (group 5), 0.64% NaHCO3 (group 6) or no test chemical (group 7) for 104 weeks respectively. Incidences of bladder carcinoma induced were significantly higher in groups 1 (12 of 29 rats, 41.4%) and 2 (9 of 29 rats, 31.0%) than in group 7 (0 of 27 rats, 0%). Groups 3 and 4 induced bladder carcinomas in 4 of 29 rats (13.8%) and 4 of 26 rats (15.4%) respectively, whereas no tumors occurred in group 5 (0 of 27, 0%). The incidence in group 6 was 3.6% (1 of 28 rats). Groups 1 and 2 induced significant increases in urinary pH and Na+ concentrations, whereas group 5 did not. Groups 3 and 4 showed the same tendency as groups 1 and 2. Examination with a scanning electron microscope showed the appearance of pleomorphic microvilli, short, uniform microvilli, and ropy or leafy microridges on the luminal surface of the bladder in groups 1-5 of rats treated with OPP or OPP-Na for 8 weeks. The appearance and severity were the same in groups 1 and 2, followed by the groups with decreasing doses of NaHCO3. The results indicated that OPP-Na is carcinogenic for the rat bladder, but OPP is not. However, increased urinary pH and Na+ concentration play important roles in OPP-Na rat bladder carcinogenesis.

Preparation and characterization of antibodies against 3,2'-dimethyl-4-aminobiphenyl-modified DNA

Polyclonal antibodies for 3,2'-dimethyl-4-aminobiphenyl (DMAB)-DNA adducts were obtained from the sera of rabbits immunized with N-OH-DMAB-modified DNA. Using the enzyme linked immunosorbent assay (ELISA), these antibodies were shown to recognize DNA modified by N-OH-DMAB and N-hydroxy-4-aminobiphenyl, but not unmodified DNA, 2-acetylaminofluorene- or 4-nitroquinoline-1-oxide-modified DNA, free aminobiphenyl or DMAB derivatives. Using competitive ELISA with DMAB-modified denatured DNA, a 50% inhibition of antibody antigen binding was caused by 7 fmol of DMAB adducts applied to each assay well as an inhibitor. Native DNA bearing adducts was associated with 50% inhibition in the range of 22-90 fmol/asay well, depending on the levels of modification. The adducts recognized by the antibody were shown to be stable against treatment of heat or alkali denaturation. Optimal conditions for the detection of adducts in DNA from the rat organs exposed to DMAB were established by means of competitive ELISA, using alkaline-denatured DNA as an inhibitor. Thus, as little as 5 fmol adducts in 1 microgram of DNA could be detected. Indirect immunofluorescence staining indicated that anti-DMAB-DNA antibodies bound specifically to nuclear components of rat fibroblast 3Y1 cells treated with N-OH-DMAB. The intensity of the fluorescence was proportional to the dose of carcinogen administered. The antibodies should be helpful for use in studies on the formation of adducts and their removal in cells and tissues after DMAB administration.

Complete reversibility of physiological coronary vascular abnormalities in hypertrophied hearts produced by pressure overload in the rat

Using an experimental model of ascending aortic banding in the rat, we examined whether coronary circulation abnormalities in hypertrophied hearts are reversible after debanding. 4-wk banding produced significant increases in in vivo left ventricular (LV) pressure (194 +/- 13 vs. 114 +/- 9 mmHg in shamoperated controls) and LV dry wt/body wt (48 +/- 5% above controls). In isolated hearts perfused with Krebs-Henseleit buffer, coronary flow rate (CFR) was estimated under nonworking conditions. During maximal vasodilation after 1 min-ischemia, CFR at a coronary perfusion pressure (CPP) of 100 mmHg and CFR/myocardidial mass at CPPs of 100 and 150 mmHg decreased significantly (72 +/- 5%; 53 +/- 4 and 61 +/- 4% of controls). 1 or 4 wk after debanding, LV systolic pressures were similar to control values, and the degree of myocardial hypertrophy decreased to levels 23 +/- 6 (P less than 0.01) and 11 +/- 6% (P less than 0.01) above their control values, respectively. At 1 wk there was no significant increase in CFR/myocardial mass, compared to values in the banded group (67 +/- 8 vs. 53 +/- 4% of controls at 100 mmHg and 67 +/- 9 vs. 61 +/- 4% at 150 mmHg of CPP). At 4 wk, CFR and the ratio had increased toward normal. Thus, decreased coronary perfusion in hypertrophied hearts is completely reversible.

Histochemical analysis of the chemical structure of blood group-related carbohydrate chains in serous cells of human submandibular glands using lectin staining and glycosidase digestion

Using lectin staining methods in combination with exo- and endo-glycosidase digestion procedures, we analyzed the chemical structure of different types of blood group-related substances in serous cells of formalin-fixed, paraffin-embedded human submandibular glands. Serous cells produced only H antigen; A and B antigens were not present, and the expression of H antigen is dependent on the secretor status of the tissue donor. Although reactivity with Ulex europaeus agglutinin I (UEA-I) was not markedly reduced by alpha-L-fucosidase digestion, an affinity for peanut agglutinin (PNA) was seen after fucosidase digestion in the cells from secretors. In those from nonsecretors, no PNA reactivity appeared after enzyme digestion. On the other hand, sialidase digestion elicited PNA reactivity in serous cells irrespective of the donor's secretor status. PNA reactivity observed after fucosidase or sialidase digestion was susceptible to endo-alpha-N-acetylgalactosaminidase (endo-GalNAc-dase) digestion. SBA reactivity in UEA-I-negative cells from secretors, or in cells from fetuses and newborn infants, was markedly reduced by beta-galactosidase digestion. After galactosidase digestion, reactivity with Griffonia simplicifolia agglutinin II (GSA-II) appeared in the corresponding cells. This GSA-II reactivity was almost completely eliminated by subsequent beta-N-acetylhexosaminidase digestion. Whereas PNA reactivity in these cells was not reduced by beta-galactosidase treatment, it was significantly diminished by endo-GalNAc-dase digestion. These results suggest that at least two kinds of precursor disaccharides are produced in submandibular serous cells, i.e., SBA-reactive D-galactose-(beta 1-3,4)-N-acetyl-D-glucosamine and PNA-reactive D-galactose-(beta 1-3)-N-acetyl-D-galactosamine alpha 1-serine or threonine (O-glycosidically linked Type 3 chain or T antigen). Final fucosylation and synthesis of these two types of precursor chain appear to be under the control of the secretor gene.

[Two cases of adrenal cysts--the meaning of imaging in diagnosing adrenal cysts]

Two cases of adrenal cysts are reported. The first case is of a left adrenal cyst in a 19-year-old woman and was incidentally discovered by computed tomography (CT). Its margin was clear, its contents was homogeneous and its signal indicated water contents on magnetic resonance imaging (MRI). It was punctured and is now followed up by CT. The second case is of a left adrenal cyst in a 62-year-old woman, which also happened to be discovered by CT. Its contents was heterogeneous by MRI. It was removed and proved to be a lymphangiomatous cyst. The conclusion is that MRI will be useful in the differential diagnosis of adrenal cysts.