Enhancement of mitochondrial oxidative stress and up-regulation of antioxidant protein peroxiredoxin III/SP-22 in the mitochondria of human pre-eclamptic placentae

A growing body of evidence indicates that the pathogenesis of pre-eclampsia is closely associated with oxidative stress occurring in mitochondria. In the present study, we evaluated the degree of mitochondrial lipid peroxidation by assessing the accumulation of 4-hydroxy-2-nonenal (HNE)-modified proteins and examined the expression of mitochondrial antioxidant protein peroxiredoxin III/SP-22 in normal and pre-eclamptic human placentae. The accumulation of HNE-modified proteins increased to a greater extent in both the mitochondria and cytosol of pre-eclamptic placentae than in those of normal placentae. Moreover, the accumulation of HNE-modified proteins was much more evident in the mitochondria than in the cytosol, indicating that lipid peroxidation occurred mainly in the mitochondria of pre-eclamptic placentae. The mRNA expression of peroxiredoxin III/SP-22 was increased about 2-fold in pre-eclamptic placentae compared to normal placentae. The protein levels of peroxiredoxin III/SP-22 were approximately 4-fold higher in pre-eclamptic placentae than in normal placentae. Immunohistochemistry of placental tissues showed that the levels of peroxiredoxin III/SP-22 protein were increased in the trophoblasts of floating villi, stromal cells of stem villi, and decidual cells in pre-eclamptic placentae. These results indicate that peroxiredoxin III/SP-22 plays a crucial role in the protection of placental function from oxidative stress occurring in mitochondria of pre-eclamptic placentae.

Monocarboxylates and glucose utilization as energy substrates in rat brain slices under selective glial poisoning--a 31P NMR study

We have investigated effects of various energy substrates including glucose, lactate and pyruvate on the recovery of the high energy phosphate levels after high-K+ stimulation in rat brain slices by using 31P NMR. It was found that lactate, pyruvate and glucose almost equally supported the recovery of phosphocreatine (PCr) levels after high-K+ stimulation (60 mM, 8 min) in artificial cerebrospinal fluid (ACSF). In iodoacetic acid (IAA) and fluorocitrate (FC)-pretreated slices, whereas glucose was unable to be utilized, the recovery of the PCr level after high-K+ stimulation in ACSF containing lactate was completely abolished, the recovery of the PCr in ACSF containing pyruvate was unaffected. These results indicate that neurons themselves can utilize pyruvate as an exogenous energy substrate, but not lactate, without glial support. In intact brain, glucose may be metabolized to pyruvate in glial cells and then transported to neurons as an energy substrate. These suggest an astrocyte-neuron pyruvate shuttle mechanism of the brain energy metabolism in vivo. We also investigated the effect of ischemic-preconditioning in FC-pretreated slices, which showed that the PCr levels recovered substantially in ACSF containing lactate after high-K+ stimulation. This indicates that after the preconditioning, such as ischemia, neurons themselves acquired the ability to utilize lactate as an energy substrate.

Lactate utilization as an energy substrate in ischemic preconditioned rat brain slices

We examined the utilization of lactate as an energy substrate in ischemic preconditioned slices obtained from the rat brain left hemisphere, of which the contralateral middle cerebral artery was occluded 48 h before the slice preparation. The levels of high-energy phosphates in the brain slices were measured using 31P NMR with a time resolution of 4 min at 25 degrees C. When iodoacetic acid-pretreated brain slices were further treated with fluorocitrate, a glial toxin, for 2 h (neuron-rich slices), the recovery of the phosphocreatine (PCr) level in artificial cerebrospinal fluid (ACSF) containing lactate after high-K+ stimulation was completely abolished in intact slices, whereas the PCr level in ischemic preconditioned slices well recovered in otherwise similar conditions. These results indicated that neurons, when preconditioned with ischemia, acquire the ability to utilize lactate as an energy substrate. In parallel experiments, we recorded population excitatory postsynaptic potentials and spikes from granule cells in hippocampal slices. Population spikes of intact slices in ACSF containing lactate were completely abolished in 30 min, but those of the ischemic preconditioned slices were maintained well over 50%. These results show that ischemic preconditioning may induce certain systematic changes in neurons, such as the expression of lactate transporters and/or the activation of lactate dehydrogenase.

Mortality among Japanese construction workers in Mie Prefecture

AIMS

A historical cohort mortality study was conducted among 17 668 members of the Construction Workers' Health Insurance Society of Mie Prefecture in Japan, in order to verify the relation between occupations and mortality status.

METHODS

The cohort was followed from 2 April 1973 to 1 April 1998. Standardised mortality ratios (SMR) were calculated for all members and each job classification.

RESULTS

98.7% of the members were traced successfully until the date when the follow up terminated. When all members were considered together, significant excess mortality was observed for "accidents and adverse effects". Significant excess mortalities were also observed for lung cancers among scaffold men and ironworkers, for cancer of the oesophagus among plumbers, and for "chronic liver disease and cirrhosis" among scaffold men and painters.

CONCLUSION

Results suggest that more detailed investigations, which would include some minor job classifications should be undertaken. This is an updated cohort study which was partially completed in 1997.

Differential effect of phosphodiesterase inhibitors on IL-13 release from peripheral blood mononuclear cells

Increased cyclic AMP (cAMP)-phosphodiesterase (PDE) activity in peripheral blood leucocytes is associated with the immunological inflammation that characterizes allergic diseases, such as atopic dermatitis and allergic rhinitis. Recently, it has been found that IL-13 has similar biological functions to IL-4. The aim of this study was to investigate the possible involvement of cAMP-PDE activity on IL-13 release from peripheral blood mononuclears cells (PBMC) from atopic asthma patients. Phytohaemagglutinin (PHA)-induced IL-13 release from PBMC was concentration-dependently inhibited by rolipram, a type 4 PDE inhibitor, as well as by dibutyryl cAMP, a membrane-permeant cAMP analogue. However, theophylline, a non-specific PDE inhibitor, and cilostazol, a type 3 PDE inhibitor, failed to inhibit IL-13 release. The inhibitory effect of rolipram was enhanced by the addition of forskolin (10(-4) m), an adenylyl cyclase stimulator. PHA itself did not alter the intracellular cAMP level. Rolipram concentration-dependently increased cAMP level in PHA-stimulated PBMC, and this increase was synergistically facilitated by the addition of forskolin (10(-4) m). These results suggest that type 4 PDE inhibitors, alone or synergistically in combination with forskolin, inhibit PHA-induced IL-13 release from PBMC of atopic asthma patients by elevating intracellular cAMP concentrations. These inhibitors have the potential to exert an anti-inflammatory effect by inhibiting IL-13 production in allergic diseases such as atopic asthma.

Induction of histamine release from rat peritoneal mast cells by histatins

Human salivary histatins (Hsts), which belong to a salivary polypeptide family, have potent antifungal activity against Candida albicans and Cryptococcus neoformans, and are expected to be useful as therapeutic reagents against Candida species. However, little is known about the effect of Hsts on host immune systems. Thus we conducted a series of in vitro experiments with rat mast cells to determine whether histatin 5 (Hst 5) or histatin 8 (Hst 8) has a histamine-releasing effect on mast cells. Both Hst 5 and Hst 8 induced histamine release from rat peritoneal mast cells in a dose-dependent manner (10(-9) to 10(-5) M). Hst 5 had a stronger releasing effect than Hst 8. The histamine release induced by Hst 5 (10(-6) M) was increased by the presence of 0.5 mM Ca2+, but decreased by 2mM Ca2+. Alternatively, the histamine release induced by Hst 8 (10(-6) M) was inhibited by the presence of Ca2+ (0.5 to 2 mM). These results suggest that Hsts have limited usefulness as therapeutic agents due to induction of histamine release from mast cells.

2-difluoromethylornithine and dehydroepiandrosterone inhibit mammary tumor progression but not mammary or prostate tumor initiation in C3(1)/SV40 T/t-antigen transgenic mice

Female transgenic mice that express SV40 T/t antigens under the regulatory control of the rat C3(1) gene spontaneously develop multifocal mammary lesions that predictably evolve into invasive, hormone-independent carcinomas, whereas male mice are prone to develop prostate cancer. Chemopreventive agents were administered to female C3(1)/SV40 large T-antigen mice from 7 to 19 weeks of age, during which time the mammary lesions developed and progressed to invasive carcinomas. No significant differences in the numbers of preinvasive mammary intraepithelial neoplasia lesions (histologically similar to human ductal carcinoma in situ) were observed after 2 or 8 weeks of treatment between mice receiving either vehicle alone, dehydroepiandrosterone (DHEA), or 2-difluoromethylornithine (DFMO). However, a dose-response reduction in invasive carcinoma growth was observed for both DFMO, an inhibitor of ornithine decarboxylase, and DHEA, the primary steroid precursor to both androgens and estrogens in primates. Despite unaltered expression of the transgene, tumor incidence was reduced approximately 20% by DFMO (8000 mg/kg) and 30% by DHEA (4000 mg/kg; P < 0.05). Tumor multiplicity was reduced by approximately 50% by both DFMO and DHEA (P < 0.05). DFMO had a dose-dependent effect on total tumor burden, which was reduced by 25% at low doses (4000 mg/kg) and 70% at high doses (8000 mg/kg). DHEA reduced tumor burden by 50% and 66% at low (2000 mg/kg) and high (4000 mg/kg) doses, respectively. Interestingly, despite its inhibitory effects on tumor development, DHEA caused a dose-dependent increase of serum estradiol levels that we have previously shown to increase mammary tumor formation in this model. No effect on the development of the prostate cancer precursor lesions (prostate intraepithelial neoplasia) was observed when mice were treated with DHEA, DFMO, tocopherol acetate, selenomethionine, or 9-cis-retinoic acid, although the effects on late-stage prostate cancer development were not determined. These results demonstrate that despite the expression of the highly transforming C3(1)/SV40 large T-antigen transgene, this transgenic model can be used to study the effects of chemopreventive agents on mammary cancer progression. The tumor-inhibitory effects of DHEA and DFMO on mammary cancer growth appear to occur after the development of preinvasive lesions, suggesting that these agents inhibit tumor progression but not initiation.

Adrenomedullin and proadrenomedullin N-terminal 20 peptide induce histamine release from rat peritoneal mast cell

Adrenomedullin (ADM)-induced histamine release from rat peritoneal mast cells was investigated. We compared the ability of full-length ADM to induce histamine release to the fragments ADM-(1-25) and ADM-(22-52), as well as proadrenomedullin N-terminal 20 peptide (PAMP). ADM (10(-8) to 10(-5) M) and PAMP (10(-8) to 10(-5) M) dose-dependently increased histamine release from peritoneal mast cell preparations. The effect of ADM-(1-25) was similar to ADM, whereas ADM-(22-52) did not show any effects. These data suggest the relative importance of the ADM C-terminal fragment, which contains a six-membered ring structure. Histamine release, induced by ADM, was significantly and dose-dependently inhibited by the addition of ADM-(22-52) (10(-5) M), Ca(2+) (0.5 to 2.0 mM), and benzalkonium chloride (3 to 7 microM), a selective inhibitor of Gi type G proteins. In contrast, PAMP (10(-5) M)-induced histamine release was not inhibited by Ca(2+). These results suggest that ADM induce histamine release via a putative ADM receptor in a manner sensitive to Gi-protein function and extracellular Ca(2+) concentration, and that PAMP might produce its effect by a different mechanism than ADM.

Enhanced protein levels of protein thiol/disulphide oxidoreductases in placentae from pre-eclamptic subjects

Recent studies have indicated that pre-eclampsia is closely associated with oxidative stress both in maternal circulation and in the placenta. Protein thiol/disulphide oxidoreductases, such as thioredoxin, glutaredoxin, and protein disulphide isomerase have recently been found to eliminate reactive oxygen species (ROS) and regenerate oxidatively damaged proteins. Protein thiol/disulphide oxidoreductases may also play a role in combating pre-eclampsia. In this study, we examined the accumulation of 4-hydroxy-2-nonenal (HNE)-modified proteins, which are markers of lipid peroxidation, in human placentae of normal and pre-eclamptic subjects. We also examined the protein levels of thioredoxin, glutaredoxin, and protein disulphide isomerase in placentae. Immunoblotting and immunohistochemistry showed that HNE-modified proteins accumulated to a greater extent in pre-eclamptic placentae than in normal placentae. In both normal and pre-eclamptic placentae, thioredoxin, glutaredoxin, and protein disulphide isomerase were detected in the trophoblasts of the floating villi. The levels of these proteins were increased approximately 2- to 3-fold in the pre-eclamptic placentae compared to the normal placentae. These results indicated that the pre-eclamptic placentae were exposed to oxidative stress and that the protein thiol/disulphide oxidoreductases were adaptively induced in pre-eclamptic placentae, suggesting possible roles for thioredoxin, glutaredoxin, and protein disulphide isomerase in protecting placental functions against oxidative stress caused by pre-eclampsia.

Airborne fiber concentration and size distribution of mineral fibers in area with serpentinite outcrops in Aichi prefecture, Japan

Airborne fiber concentrations and size distributions of both asbestos and nonasbestos fibers were determined at property boundaries of 4 serpentinite quarries producing crushed stone (quarry property boundary), 10 sites within 10 km of the area with serpentinite outcrops (serpentinite area), and 2 sites in a reference area. The asbestos was identified in 7 rock and 3 soil samples collected in the serpentinite area. The geometric means of airborne concentrations of asbestos and nonasbestos fibers longer than 0.2 microm in length were: 384 and 447 fibers/liter (f/L) in the quarry property boundary (in operation), 12 and 124 f/L in the quarry property boundary (in closed), 5 and 103 fibers/liter in the serpentinite area, and less than 2 and 59 fibers/liter in the reference area, respectively. There was a significant difference in airborne concentrations of both asbestos and nonasbestos fibers among the areas. Ttremolite/actinolite were found with chrysotile in the stones. Airborne concentrations of tremolite/actinolite were higher than those of chrysotile at the quarry property boundary and in the serpentinite area. Tremolite/actinolite were also found in the soils. There was no significant difference among the areas in the arithmetic means of fiber size distribution of both asbestos and nonasbestos fibers.

Urinary 8-oxo-7, 8-dihydro-2'-deoxyguanosine and biopyrrins levels among construction workers with asbestos exposure history

It has been suggested that oxidative stress is associated with the cancers caused by asbestos. Since construction workers are sometimes exposed to low levels of asbestos, we investigated whether oxidative stress was elevated in construction workers who had been exposed to low levels of asbestos. The subjects were 48 Japanese construction workers. The defined asbestos-exposed group consisted of subjects who had the history of suspected exposure to asbestos and were diagnosed to have irregular opacities or pleural plaques. We measured the amount of 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) and biopyyrins in the urine of the subjects. The results showed that 8-oxodG and biopyyrins levels in the defined asbestos-exposed group were higher, although they were not statistically significant, than those in the control group. In addition, the urinary 8-oxodG levels tended to correlate positively with the duration of suspected exposure to asbestos. These results suggest that even low-level asbestos exposure may induce oxidative stress and that the resulting's the oxidative stress might be related to lung cancer in construction workers.

[Positive skin test and age]

OBJECTIVE: To evaluate positive responses to skin tests for immediate hypersensitivity to allergens in children with asthma and rhinitis at different ages. METHOD: We observed positive skin test reactivity in prick tests using fifteen allergens of same origin (total dust and Dermatophagoides sp.; Dermatophagoides pteronyssinus; Dermatophagoides farinae; Blomia tropicalis; Penicillium sp; Alternaria alternata; Cladosporium herbarium; Aspergillus fumigatus; Bermuda grass; forage grass; dog and cat epithelia; feathers; Blatella germanica and wool). We placed 713 selected patients into different age groups - Group I: 6 to 11 months; Group II: 1 to 3 years and 11 months; Group III: 4 to 8 years and 11 months; and Group IV: 9 to 15 years. We used the chi-square test for statistical analysis. RESULTS: The total significant differences between these groups were: I to II = 5; II to III = 5; II to IV = 5; III to IV = 6; I to III = 10; and I to IV = 10. CONCLUSION: Skin test reactivity is acquired progressively with age, and can be observed as early as at 12 months. Reactivity is significantly more positive from the age of 4 on.

Suppression of mammary carcinoma growth in vitro and in vivo by inducible expression of the Cdk inhibitor p21

Mammary carcinomas that develop in C3 (1)/SV40 T- antigen (TAg) transgenic mice have lost the p53-mediated induction of p21, leading to increased cellular proliferation and significant elevations of cyclins and Cdks. To test whether p21 could serve as a target for anticancer therapy for this mammary cancer model, a retroviral delivery system for the inducible expression of p21 was developed. We demonstrate that overexpression of p21 in C3(1)/TAg mammary tumor cells using the retroviral inducible p21 expression system results in increased apoptosis, reduced cell proliferation in vitro and reduced tumor growth in vivo associated with reduced expression of cyclins D1 and E, and Cdks 2, 4, and 6. Reciprocal changes in the expression of p21 and p27(Kip1), another cell-cycle regulator, were also observed. Because reduced p21 expression occurs frequently in human breast cancer, restoration of the Cdk inhibitor p21 by gene therapy approaches may provide a method for inhibiting mammary tumor progression.

Neurotoxicity of 2-bromopropane and 1-bromopropane, alternative solvents for chlorofluorocarbons

To clarify the neurotoxicity of 2-bromopropane (2-BP) in comparison with 1-bromopropane (1-BP), 36 Wistar strain male rats were divided into 4 groups of 9 and exposed daily to 100-ppm 2-BP, 1000-ppm 2-BP, 1000-ppm 1-BP, or fresh air for 8 h a day. Exposure to 1000 ppm of 1-BP was discontinued after 5 or 7 weeks' exposure because of the unexpected appearance of incomplete hindlimb paralysis followed by serious emaciation. The other groups were sacrificed at the end of 12 weeks' exposure. Exposure to 1000 ppm of 2-BP resulted in significant decreases in body weight and motor nerve conduction velocity (MCV) and elongation in distal latency (DL). A ball-like enlargement of myelin sheaths was observed. Significant reductions in the number of erythrocytes, platelets, and leukocytes, testicular germ cell loss, and seminiferous atrophy were also observed in this group, but not in 100-ppm 2-BP group. Exposure to 1000 ppm of 1-BP for 5 or 7 weeks caused a significant decrease in body weight and MCV and elongation in DL. Linearly arranged ovoid- or bubble-like debris of the axons and myelin sheaths in the teased tibial nerves and axonal swelling in gracilis nucleus were found in this group. No significant changes in hematological indices or histopathological findings of the testis were found in this group. In conclusion, 2-BP is neurotoxic to the peripheral nerves in addition to its toxic effects on the reproductive and hematopoietic systems at 1000 ppm. No noticeable changes were found in the rats exposed to 100 ppm of 2-BP. 1-BP is a potent neurotoxicant at 1000 ppm for 5 or 7 weeks, while testicular and hematopoietic toxicity was not found.

Effects of box weight, vertical location and symmetry on lifting capacities and ratings on category scale in Japanese female workers

The aim was to clarify the effects of box weight, vertical location and symmetry on the lifting capacities and subjective burden in Japanese female workers with manual material handling tasks. Sixteen healthy females were tested. They performed 12 different lifting tasks (three heights * two weights * two symmetries). It is difficult for Japanese women to exert dynamic force in lifting a 15-kg weight from the elbow to the shoulder level. A remarkable increase was observed in heart rate and category scale with ratio properties (CR-10) on large muscle group in lifting a 15-kg weight as compared with lifting a 10-kg one. Judging from calculation of the Recommended Weight Limit using the application manual by the National Institute for Occupational Safe and Health, it was also suggested that lifting the 15-kg weight from the elbow to the shoulder level was difficult for female workers. Not only peak force, but also the average upward acceleration and peak velocity were lower in asymmetric liftings than those in symmetric liftings. CR-10 for the left back and right thigh were also higher in 90 degrees right lateral plane lifting than in the mid-sagittal plane. Thus, asymmetric lifting was supposed to impose higher stress on the back contralaterally and thigh ipsilaterally to the location of the weight.

Expression of mitochondrial thioredoxin-dependent antioxidant protein, SP-22, in normal human and inflammatory mouse placentae

The aim of this study was to elucidate whether a novel mitochondrial antioxidant protein, SP-22, is localized in placenta and whether its expression is induced in placenta of lipopolysaccharide (LPS)-exposed mouse. Western blot analysis of normal human placenta indicated that the SP-22 protein was located in the mitochondrial fraction. Immunohistochemical analysis of SP-22 in normal placenta showed that immunoreactive SP-22 was distributed mostly in cytotrophoblastic cells but with almost no signal in syncytiotrophoblasts. The positive signals were also detected in the decidual cells and stromal cells in stem villi of normal placenta. We also examined LPS-mediated inflammatory placenta on day 13 of pregnancy at various time points after LPS injection (50 microg/kg, intraperitoneally). Western blot analysis indicated that LPS approximately quadrupled the expression of SP-22 in placenta of LPS-exposed mouse. When the SP-22 protein was localized immunohistochemically, the decidua and the diploid trophoblasts in the basal zone were intensively stained in placenta of LPS-exposed mouse compared to the control. The localization and inducible expression of SP-22 protein in placenta suggest a possible role in antioxidant system in mitochondria of normal and inflammatory placentae.

1-Bromopropane, an alternative to ozone layer depleting solvents, is dose-dependently neurotoxic to rats in long-term inhalation exposure

1-Bromopropane has been newly introduced as an alternative to ozone layer-depleting solvents. We aimed to clarify the dose-dependent effects of 1-bromopropane on the nervous system. Forty-four Wistar male rats were randomly divided into 4 groups of 11 each. The groups were exposed to 200, 400, or 800 ppm of 1-bromopropane or only fresh air 8 h per day for 12 weeks. Grip strength of forelimbs and hind limbs, maximum motor nerve conduction velocity (MCV), and distal latency (DL) of the tail nerve were measured in 9 rats of each group every 4 weeks. The other 2 rats of each group were perfused at the end of the experiment for morphological examinations. The rats of the 800-ppm group showed poor kicking and were not able to stand still on the slope. After a 12-week exposure, forelimb grip strength decreased significantly at 800 ppm and hind limb grip strength decreased significantly at both 400 and 800 ppm or after a 12-week exposure. MCV and DL of the tail nerve deteriorated significantly at 800 ppm. Ovoid or bubble-like debris of myelin sheaths was prominent in the unraveled muscular branch of the posterior tibial nerve in the 800-ppm group. Swelling of preterminal axons in the gracile nucleus increased in a dose-dependent manner. Plasma creatine phosphokinase (CPK) decreased dose-dependently with significant changes at 400 and 800 ppm. 1-Bromopropane induced weakness in the muscle strength of rat limbs and deterioration of MCV and DL in a dose-dependent manner, with morphological changes in peripheral nerve and preterminal axon in the gracile nucleus. 1-Bromopropane may be seriously neurotoxic to humans and should thus be used carefully in the workplace.

Reproductive toxicity of 1-bromopropane, a newly introduced alternative to ozone layer depleting solvents, in male rats

1-Bromopropane has been newly introduced as an alternative to ozone-depleting solvents. We aimed to clarify its dose-dependent reproductive toxicity in male rats. Thirty-six Wistar male rats were randomly divided into 4 groups of 9. The groups were exposed to 200, 400, or 800 ppm 1-bromopropane or only fresh air, 8 h per day for 12 weeks. Epididymal sperm indices were evaluated after a 12-week exposure. The testes, epididymides, seminal vesicle, prostate, and other organs were weighed and examined histopathologically. Spermatogenic cells, in stage VII seminiferous tubules, and retained spermatids, at the basal region of stages IX-XI seminiferous epithelium, were counted. Plasma testosterone levels were measured by radioimmunoassay. The testicular weight did not significantly change, but the weight of epididymides, seminal vesicle, and prostate dose-dependently decreased. The weight of seminal vesicle decreased significantly at the lowest concentration of 200-ppm and over. 1-Bromopropane induced a dose-dependent decrease in the epididymal sperm count and in motility, as well as an increase in tailless sperm and sperm with an immature head shape. The spermatogonia, preleptotene spermatocytes, pachytene spermatocytes, and round spermatids did not decrease significantly at stage VII. Retained, elongated spermatids near the basement membrane at the postspermiation stages IX-XI increased dose-dependently. Plasma testosterone levels significantly decreased at the 800-ppm dosage. 1-Bromopropane caused failure of spermiation. Its reproductive toxicity is different from that of 2-bromopropane, which specifically impairs spermatogonia. Thus, this solvent may have serious reproductive toxic effects in men, and should be used very cautiously in the workplace.

The C3(1)/SV40 T-antigen transgenic mouse model of mammary cancer: ductal epithelial cell targeting with multistage progression to carcinoma

The 5' flanking region of the C3(1) component of the rat prostate steroid binding protein (PSBP) has been used to successfully target the expression of the SV40 large T-antigen (Tag) to the epithelium of both the mammary and prostate glands resulting in models of mammary and prostate cancers which histologically resemble the human diseases. Atypia of the mammary ductal epithelium develops at about 8 weeks of age, progressing to mammary intraepithelial neoplasia (resembling human ductal carcinoma in situ [DCIS]) at about 12 weeks of age with the development of invasive carcinomas at about 16 weeks of age in 100% of female mice. The carcinomas share features to what has been classified in human breast cancer as infiltrating ductal carcinomas. All FVB/N female mice carrying the transgene develop mammary cancer with about a 15% incidence of lung metastases. Approximately 10% of older male mice develop anaplastic mammary carcinomas. Unlike many other transgenic models in which hormones and pregnancy are used to induce a mammary phenotype, C3(1)/Tag mice develop mammary tumors in the mammary epithelium of virgin animals without hormone supplementation or pregnancy. Although mammary tumor development appears hormone-responsive at early stages, invasive carcinomas are hormone-independent, which corresponds to the loss of estrogen receptor-alpha expression during tumor progression. Molecular and biologic factors related to mammary tumor progression can be studied in this model since lesions evolve over a predictable time course. Genomic alterations have been identified during tumor progression, including an amplification of the distal portion of chromosome 6 containing ki-ras and loss of heterozygosity (LOH) in other chromosomal regions. We have demonstrated that stage specific alterations in the expression of genes which are critical regulators of the cell cycle and apoptosis are functionally important in vivo. C3(1)/Tag mice appear useful for testing particular therapies since growth of the mammary tumors can be reduced using chemopreventive agents, cytokines, and an anti-angiogenesis agent.

Decreased antipyrine clearance following endotoxin administration: in vivo evidence of the role of nitric oxide

Klebsiella pneumoniae endotoxin has been found to decrease hepatic P450-mediated drug-metabolizing enzyme activity in a time-dependent manner. In this study, we investigated the role of nitric oxide (NO) in the decrease in hepatic drug-metabolizing enzyme activity caused by endotoxin in vivo. We measured in vivo pharmacokinetic parameters of antipyrine in rats treated with endotoxin and/or a selective inhibitor of inducible NO synthase (iNOS), S-methylisothiourea. Intraperitoneal injection of endotoxin (1 mg/kg of body weight) dramatically decreased the systemic clearance of antipyrine, reflecting reduced hepatic drug-metabolizing enzyme activity, and significantly increased the level of nitrite and nitrate (NOx) in the plasma. S-Methylisothiourea (10 mg/kg) reversed this decreasing antipyrine clearance and reduced the level of NOx in plasma. Repeated injections of an NO donor, (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (FK-409; 10 mg/kg), at a dose which maintained plasma NOx at the same levels as those caused by endotoxin injection, also decreased the systemic clearance of antipyrine. These findings suggest that the overproduction of NO observed in this animal model is at least partially responsible for the significant reduction in the hepatic drug-metabolizing enzyme activity that may happen in a gram-negative bacterial infection.

Association between musculoskeletal pain in Japanese construction workers and job, age, alcohol consumption, and smoking

A cross-sectional epidemiologic study was conducted to determine the prevalence of self-reported musculoskeletal pain (MSP) in construction workers and identify associations between MSP and individual factors (i.e., job, age, alcohol consumption, and smoking). The prevalence of total hand/arm pain (T-HAP), total shoulder pain (T-SP), and total low-back pain (T-LBP) was 28.4%, 28.7%, and 53.2%, respectively. Risk factors for total pain and for relatively severe pain in the hand/arm (RS-HAP), shoulder (RS-SP), and low-back (RS-LBP) were estimated by multiple logistic regression analysis. The results showed that musculoskeletal pain was significantly associated with age, and that the odds ratios (ORs) for relatively severe musculoskeletal pain increased almost linearly with age. Regarding job, compared with architects whose work is presumed to be sedentary, almost all ORs for T-HAP, T-SP, and T-LBP for non-sedentary construction jobs were significantly high. Current smokers of 20 cigarettes a day or more had significantly higher ORs for RS-HAP and RS-LBP than "never smokers". We suppose that 1) total and relatively severe pain were associated with age, 2) non-sedentary work was at higher risk of total MSP than sedentary work, and 3) heavy smoking contributed to RS-LBP.

2-Bromopropane causes ovarian dysfunction by damaging primordial follicles and their oocytes in female rats

Ovarian dysfunction induced by 2-bromopropane (2-BP) has been described in female factory workers and experimental animals. However, the underlying mechanism is still unclear. To establish the reproductive target site and define mechanisms of 2-BP toxicity in adult female rats, we examined the effects of different doses and duration of exposure to 2-BP in female rats. In the dose-dependent experiments, female rats were exposed to 2-BP at 100, 300, or 1000 ppm or fresh air (n = 9 each) in exposure chambers for 8 h/day for 9 weeks. In the time-course experiments, female rats were exposed to 2-BP at 3000 ppm for 8 h (n = 7 each). The rats were then euthanized 1, 3, 5, and 17 days after exposure. Differential follicle counts and in situ terminal deoxynucleotidyl transferase assay were used to evaluate 2-BP effect on primordial, growing, and antral follicles. Exposure to 2-BP at 300 and 1000 ppm produced a significant reduction in the percentage of primordial, growing, and antral follicles in a dose-dependent manner. Significant reduction in the percentage of primordial follicles at 17 days after exposure was observed in time-course experiments. Exposure to 2-BP at 3000 ppm for 8 h resulted in histological changes in primordial follicles complex at 5 and 17 days after exposure. These changes consisted of distortion of the symmetry of oocytes and their nuclei at Day 5 after exposure and appearance of eccentric pyknotic cells and shrinkage of oocyte nuclei at Day 17 after exposure. In situ end labeling showed increased numbers of apoptotic oocytes and granulosa cells in primordial follicles at Days 5 and 17 after exposure. Our results suggested that ovarian dysfunction induced by 2-BP was caused by the destruction of primordial follicle and its oocyte due to the induction of apoptosis. Our studies also show that the follicle differential count is a more sensitive method than the vaginal smear in monitoring the female reproductive disorders induced by 2-BP.