The prevalence of osteoporosis and the rate of bone loss in Korean adults: the Chungju metabolic disease cohort (CMC) study.

Because the rate of bone loss is an important risk factor for fracture, we studied longitudinal changes in bone mineral density (BMD). Although the BMD of the hip decreased over time, spine BMD remained largely stable or increased. Therefore, spine BMD may not be appropriate for assessing BMD change. INTRODUCTION: The rate of age-dependent bone loss has been shown to be an important risk factor for fracture. However, longitudinal rates of BMD loss in Korea have not yet been reported. The objective of this study was to evaluate longitudinal changes in BMD in Korea. METHODS: This cohort study was performed in a population of individuals 40 years of age or older living in the rural area of Chungju City, Korea. A second BMD examination was conducted approximately 4 years after a baseline examination. A total of 3755 of the 6007 subjects completed the follow-up visit, corresponding to a follow-up rate of 62.51%. RESULTS: The age-standardized osteoporosis prevalence was 12.81% in males and 44.35% in females. In males, the average annual BMD loss at the total hip increased from -0.25% per year in their 40s to -1.12% per year in their 80s. In females, the average annual BMD loss at the total hip increased from -0.69% per year in their 40s to -1.51% per year in their 80s. However, the average annual percentage change in spine BMD in females increased from -0.91% per year in their 40s to +1.39% per year in their 80s. CONCLUSIONS: A substantial number of subjects had osteoporosis, even though we standardized the prevalence of osteoporosis. In total hip, the mean BMD was decreased during the follow-up period; in addition, the annual percentage loss increased with age. However, spine BMD remained approximately stable or increased over time and therefore may not be appropriate for assessing BMD change.

Serum preadipocyte factor 1 concentrations and risk of developing diabetes: a nested case-control study.

AIM: To determine whether preadipocyte factor 1 could be a predictive marker for the development of diabetes in people without diabetes at baseline. METHODS: We conducted a population-based, nested case-control study of individuals who progressed to diabetes (n = 43) or prediabetes (n = 345) and control participants matched on age, sex and fasting plasma glucose concentration, who maintained normal glucose tolerance (n = 389) during a 4-year follow-up using data from the Chungju Metabolic disease Cohort Study. Circulating levels of preadipocyte factor 1 were measured using an enzyme-linked immunosorbent assay. RESULTS: Baseline serum preadipocyte factor 1 levels showed a stepwise decrease across the glucose tolerance status groups at follow-up (normal glucose tolerance: 10.02 ± 3.02 ng/ml; prediabetes: 9.48 ± 3.35 ng/ml; diabetes: 8.66 ± 3.29 ng/ml; P for trend, 0.0151). Individuals whose fasting plasma glucose level had increased or whose homeostasis model assessment of ß-cell function had decreased at follow-up showed significantly lower levels of preadipocyte factor 1 compared with their control group counterparts. After adjusting for age, BMI, fasting plasma glucose, serum insulin levels, systolic blood pressure and triglycerides, the incidence of diabetes was nearly threefold higher in the lowest vs. the upper three quartiles of circulating preadipocyte factor 1 (relative risk 2.794; 95% CI 1.188-6.571; P = 0.0185). Notably, these findings were significant in women but not in men. CONCLUSIONS: Levels of circulating preadipocyte factor 1 may be a useful biomarker for identifying women at high risk of developing diabetes.

Association between salivary amylase (AMY1) gene copy numbers and insulin resistance in asymptomatic Korean men.

AIMS: Salivary amylase gene (AMY1) copy number variations (CNVs) correlate directly with salivary amylase activity and serum amylase levels. Previously, individuals with high AMY1 CNVs exhibited low postprandial glucose levels and postprandial early insulin surge, suggesting that high AMY1 gene copy numbers may play a role in lowering the risk of insulin resistance. METHODS: We verified the relationship between AMY1 CNVs and homeostatic model assessment-insulin resistance (HOMA-IR) in a cohort of 1257 Korean men aged 20-65 years who visited two medical centres for regular health check-ups, and in subgroups of current smokers and regular alcohol drinkers. Individuals with fasting plasma glucose levels > 10.0 mmol/l, HbA1c ≥ 64 mmol/mol (8.0%) or who used oral hypoglycaemic agents or insulin were excluded. RESULTS: AMY1 CNVs correlated negatively with HOMA-IR even after adjusting for covariates (e.g. BMI, systolic blood pressure, triacylglycerol, alcohol consumption, smoking and physical activity). When the participants were divided according to current smoking and alcohol consumption habits, negative correlations between AMY1 CNVs and HOMA-IR were more evident among non-smokers and regular drinkers and were non-significant among smokers and non-regular drinkers. CONCLUSIONS: Low AMY1 CNVs correlated with high insulin resistance in asymptomatic Korean men, and such a relationship presented differently according to the status of smoking and alcohol consumption.

Cardiovascular autonomic dysfunction predicts acute ischaemic stroke in patients with Type 2 diabetes mellitus: a 7-year follow-up study.

AIMS: We investigated whether cardiovascular autonomic neuropathy (CAN) is associated with acute ischaemic stroke in patients with Type 2 diabetes. METHODS: From 1999 to 2000, cardiovascular autonomic function tests were conducted in patients with Type 2 diabetes (n = 1458). Patients were followed up between 2006 and 2007. Standard tests for CAN measured heart rate variability parameters [expiration-to-inspiration (E/I) ratio, responses to the Valsalva manoeuvre and standing]. Using the American Diabetes Association criteria, the CAN scores were determined from the results of each test as follows: 0 = normal, 1 = abnormal (total maximum score 3). We assessed the development of acute ischaemic stroke events. RESULTS: The prevalence of CAN at baseline was 55.7% (E/I 17.1%, Valsalva 39.4%, posture 27.3%) (n = 1126). During follow-up, 131 patients (11.6%) developed acute ischaemic stroke. The vascular events were more frequent in older patients (P < 0.001) and in those with diabetes of longer duration (P = 0.022), hypertension (P < 0.001) or diabetic retinopathy (P = 0.03) than in patients without vascular events. Patients with ischaemic stroke had higher creatinine levels (P = 0.045) and higher urine albumin excretion (P = 0.025) than those of patients without stroke. Cox proportional hazard regression analysis revealed that the CAN score was associated with the development of acute ischaemic stroke (total score 0 vs. 3, adjusted hazard ratio 2.7, 95% CI 1.3-5.5, P = 0.006). CONCLUSION: Cardiovascular autonomic dysfunction was significantly associated with the development of ischaemic stroke in patients with Type 2 diabetes.

Subclinical Cushing's syndrome associated with an adrenocortical oncocytoma.

Oncocytoma is a neoplasm that can arise in several organs, and it has been more commonly described in the kidney, salivary gland and thyroid. Oncocytoma arising in the adrenal gland is a rare finding. Moreover, functioning adrenocortical oncocytoma is exceptionally rare. A 47-yr-old man was incidentally discovered to have a right adrenal mass. The patient had no clinical features suggestive of increased adrenal function. However, hormonal evaluation showed a disturbed cortisol circadian rhythm, supranormal urinary cortisol excretion, a low level of ACTH, and a lack of suppressibility of cortisol secretion after dexamethasone. Right adrenalectomy was performed, and this revealed a well-circumscribed dark-brown tumor that measured 2.4x2.2 cm. The tumor consisted almost exclusively of large eosinophilic and epitheloid cells whose cytoplasm was packed with eosinophilic granulations, which corresponded to the numerous mitochondria confirmed on electron microscopy. This is a rare case of subclinical Cushing's syndrome that was caused by adrenocortical oncocytoma.

The short-term changes of bone mineral metabolism following bone marrow transplantation.

Organ transplantation is now the treatment of choice for many patients with life-threatening chronic diseases. A new set of side effects unique to these groups of patients has become recognized, and bone disease is one of these complications. However, little is known about the effects of myeloablative treatment followed by bone marrow transplantation (BMT) on bone mineral metabolism. We have prospectively investigated 31 patients undergoing BMT for hematologic diseases. Serum concentrations of calcium, phosphorus, creatinine, gonadotropins, sex hormones, and the biochemical markers of bone turnover were measured. The samples were collected before BMT and 1, 2, 3, 4, and 12 weeks, 6 months, and 1 year after BMT. Bone mineral density (BMD) was measured with dual-energy X-ray absorptiometry before BMT and 1 year after BMT. The serum carboxy-terminal cross-linked telopeptide of type I collagen increased progressively until 4 weeks after BMT. Thereafter, it began to decrease and reached basal values after 1 year. Serum osteocalcin decreased progressively until 3 weeks after BMT. After that, it increased and reached basal values after 3 months. No distinct differences were observed in the serum biochemical turnover markers between males and females, or between patients who received total body irradiation and those who did not. One year after BMT, lumbar spine BMD had decreased by 2.2%, and total proximal femoral BMD had decreased by 6.2%. Eighty-six percent of the women (12/14) went into a menopausal state immediately after BMT. This was caused by high gonadotropin levels and low estradiol levels. In contrast, gonadotropin levels and testosterone levels did not change significantly in the male patients after BMT. In conclusion, the rapid impairment of bone formation and the increase in bone resorption, as shown by the biochemical markers in this study, might play a role in post-BMT bone loss.

Clinical results of 24 pituitary macroadenomas with linac-based stereotactic radiosurgery.

PURPOSE: To determine the impact of stereotactic radiosurgery (SRS) on the clinical course, hormonal status, and follow-up CT/MRI scan of pituitary macroadenomas. METHODS AND MATERIALS: From July 1988 to March 1996, 24 pituitary macroadenomas had been treated using 6 MV linear accelerator based SRS. They consisted of 11 (45.8%) prolactinomas, 2 (8.3%) growth hormone (GH)-secreting tumors, 1 (4.2%) Cushing's disease, 8 (33.3%) nonsecreting (nonfunctioning: NF) tumors, and 2 (8.3%) mixed prolactin-growth hormone (PRL-GH)-secreting tumors (M:F = 12:12; aged 21-61 years). Postoperative irradiation was performed in all cases except for the instance of Cushing's disease. The prescribed dose to tumor center varied from 10 to 27 Gy (mean 21.1 Gy) using a collimator size of 0.5 to 2.5 cm. The follow-up duration ranged from 13 to 89 months (mean 49.2 months). Results from these patients were compared to our results using conventional radiation. RESULTS: Visual acuity and field defect were improved or became normal in 19 (79.2%) cases. Four (16.7%) remained unchanged after the treatment. One (4.1%) progressed 6 years after SRS and subsequently had repeat surgery with conventional boost irradiation. Of the 13 (46.4%) prolactinomas, including two mixed PRL-GH secreting tumors, 11 (84.1%) revealed normal hormonal levels within 1 year after SRS. In contrast, it took 2 years to become normal after conventional radiation therapy. In four GH-secreting tumors including two mixed PRL-GH secreting tumors, SRS and conventional methods showed similar responses. On follow-up imagings of the 21 patients, the mass was completely resolved in 4 (16.7%), including 3 PRLs and one NF, decreased in 11 (45.8%), and unchanged in 5 (16.7%) with central necrosis or cysts. One (4.2%) progressed and was reoperated 6 years after treatment. The complications related to SRS were comparable to those from conventional method. CONCLUSION: Radiosurgery can be used effectively in patients with pituitary adenoma. In this study, a more rapid hormonal and clinical response was achieved with radiosurgery than with conventional pituitary irradiation treatment.

Concurrent administration of fish meal and sodium nitrite does not promote renal carcinogenesis in rats after initiation with N-ethyl-N-hydroxyethylnitrosamine.

The modifying effects of concurrent administration of fish meal and sodium nitrite on the development of renal tumors after initiation with N-ethyl-N-hydroxyethylnitrosamine (EHEN) were investigated. A total of 120 male 6-week-old Wistar rats were divided into six groups. Groups 1-3 (30 animals each) were given 1000 ppm EHEN in their drinking water for 3 weeks as an initiation treatment for renal cancer induction and thereafter fed respective diets containing 64, 32, and 8% (original concentration in the basal diet) fish meal, and simultaneously given 0.12% sodium nitrite in the drinking water for 33 weeks. Groups 4-6 (ten animals each) were similarly treated without the prior application of EHEN. At the end of the 37th experimental week, all surviving animals were autopsied and examined histopathologically for the existence of renal proliferative lesions. The incidences of dysplastic lesions, adenomas or adenocarcinomas of the kidney were not significantly different among groups 1-3. No renal proliferative lesions were found in groups 4-6. Chronic nephropathy was slightly but significantly enhanced in the 64 and 32% fish meal-treated groups as compared with group 3. Our results suggest that concurrent administration of fish meal and sodium nitrite does not affect the post-initiation phase of EHEN-induced renal carcinogenesis in the rat.

Modifying effects of 4-phenylbutyl isothiocyanate on N-nitrosobis(2-oxopropyl)amine-induced tumorigenesis in hamsters.

The modifying effects of dietary 4-phenylbutyl isothiocyanate (PBITC), given during the initiation stage of carcinogenesis, were investigated in hamsters treated with N-nitrosobis(2-oxopropyl)amine (BOP). A total of 120 female 5-week-old hamsters were divided into six groups. Animals in groups 1-3, each consisting of 30 hamsters, were given BOP by two subcutaneous injections, 1 week apart, at a dose of 20 mg/kg body weight, plus 0, 10 or 100 micromol/animal of PBITC in corn oil by gavage 2 h prior to each carcinogen treatment. Ten animals in group 4 served as a vehicle control, and animals in groups 5 and 6, each consisting of ten hamsters, were given 10 and 100 micromol of PBITC alone in corn oil. Sacrifice was 52 weeks after the first BOP injection. The PBITC treatments significantly (P<0.05) inhibited the development of pancreatic ductal dysplasias and adenocarcinomas. Also, lung tumors (adenomas and adenocarcinomas) were significantly (P<0.05) reduced in a dose-dependent manner. In contrast, both hepatocellular and cholangiocellular tumors (adenomas and carcinomas) tended to be or were significantly increased by PBITC. These results, taken together with our previous findings, indicate that the natural isothiocyanate, phenethyl isothiocyanate (PEITC), has a more potent chemopreventive action against BOP-induced tumorigenesis than synthetic isothiocyanates with longer alkyl chains, such as 3-phenylpropyl isothiocyanate (PPITC) and PBITC. Thus, their lipophilicity does not necessarily reflect the chemopreventive potential because the strength of lipophilicity is PEITC

Organ-dependent modifying effects of oltipraz on N-nitrosobis(2-oxopropyl)amine (BOP)-initiation of tumorigenesis in hamsters.

5-(2-Pyrazinyl)-4-methyl-1,2-dithiole-thione (oltipraz), a substituted 1,2-dithiole-3-thione, is known to inhibit tumorigenesis induced by variety of carcinogens in several animal model systems. In the present experiment, the modifying effects of dietary oltipraz, given during N-nitrosobis(2-oxopropyl)amine (BOP) initiation of carcinogenesis, were investigated in Syrian hamsters. A total of 120 six-week-old females were divided into six groups. Groups 1-3 (30 animals each) were thrice given subcutaneous injections of BOP (10 mg/kg, body weight) at 1 week intervals and fed diets supplemented with 400 or 200 ppm of oltipraz or basal diet alone, starting 1 week prior and finishing 1 week after the carcinogen exposure. Groups 4-6 (10 animals each) were similarly treated without application of BOP. At the end of the 52nd experimental week, all surviving animals were autopsied and examined histopathologically for proliferative lesions of the major target organs for BOP tumorigenicity, including pancreas, liver, kidney, and lung. The incidences and multiplicity of adenocarcinomas of the pancreas were higher in groups 1 and 2 than in group 3 although without statistical significance. The incidence of pancreatic duct dysplasias was significantly (P<0.05) increased in group 2 (62.0%) but not in group 1 (50.0%) as compared with group 3 (46.6%). While the incidences of alveolar adenomas and carcinomas were significantly (P<0.05) decreased by the high dose, the multiplicities of hepatocellular adenomas, cholagiocellular carcinomas and gall bladder adenomas were elevated in the BOP/oltipraz groups (P<0.05). The results of the present study suggest that oltipraz exerts organ-dependent modifying effects on BOP-induced carcinogenesis in hamsters when given in the initiation stage.

Inhibition by methionine of pancreatic carcinogenesis in hamsters after initiation with N-nitrosobis(2-oxopropyl) amine.

The modifying effects of dietary L-methionine in the post-initiation phase of pancreatic carcinogenesis were investigated in hamsters treated with N-nitrosobis(2-oxopropyl)amine (BOP). Groups consisting of 20 and 30 animals, respectively, were given BOP subcutaneously, once a week five times at a dose of 10 mg/kg body wt. and then continuously fed diet supplemented with 2% (group 1) or 0% (group 2) methionine (weeks 5-32). After five subcutaneous injections of saline, group 3 animals were similarly fed diet supplemented with 2% methionine for the same period. The incidence of pancreatic ductal adenocarcinomas was significantly lower in group 1 (36.8%, P<0.05) than in group 2 (71.4%). Multiplicity of adenocarcinomas was also significantly lowered (0.52 and 1.28/hamster, P<0.05). Similarly, total numbers of combined adenocarcinomas and dysplastic lesions were significantly decreased in group 1 (2.05, P<0.05) as compared with group 2 (3.67). Methionine enhanced atrophic change of pancreatic acinar cells in hamsters given BOP, indicating that the inhibitory effects on the post-initiation stage of BOP-induced pancreatic carcinogenesis in hamsters could be generally linked to suppression of growth.

Changes in autoimmune thyroid disease following allogeneic bone marrow transplantation.

Autoimmune diseases can be transmitted and eliminated by bone marrow transplantation (BMT). There have been several cases of autoimmune thyroid disease (AITD) occurring after BMT, but AITD remission has been rarely reported. We present four cases in which the remission or transfer of AITD occurred after an allogeneic BMT. Two patients with severe aplastic anemia (SAA) showed evidence of remission of Hashimoto's thyroiditis which they had before allogeneic BMT. One patient with SAA, which developed during treatment with propylthiouracil for Graves' disease, underwent allogeneic BMT and showed evidence of Graves' disease remission following BMT. In one patient, new AITD occurred after an allogeneic BMT from an HLA-matched sibling who already had AITD. These cases support the evidence that the immune system is newly reconstituted after BMT, and severe autoimmune disease can be an indication for BMT. To fully understand the real changes in autoimmune status after BMT, long-term prospective studies are necessary.

Involvement of lipid peroxidation in spontaneous pancreatitis in WBN/Kob rats.

To cast light on the mechanisms underlying development of spontaneous pancreatitis lesions, tissues from WBN/Kob rats at various ages were histopathologically and immunohistochemically investigated with special reference to the existence of the lipid peroxidation products 4-hydroxy-2-nonenal (HNE), 4-hydroxy-2-hexenal (HHE), and malondialdehyde (MDA). Male 4-20-week-old WBN/Kob rats were killed to allow sampling of pancreatic tissues, which were fixed in cold acetone and 10% neutral-buffered formalin. and then processed for routine histopathology as well as immunohistochemistry for proteins modified by HNE, HHE, and MDA. Although no remarkable histologic changes were noted in younger animals, edema, hemorrhage, inflammatory cell infiltration, fibrosis, vacuolation of acinar cells, and ductular proliferation were observed in exocrine pancreatic tissue from animals at 10-15 weeks of age. In animals aged 20 weeks, the lesions had progressed remarkably and deposits of hemosiderin were apparent with fibrosis. Immunohistochemical examination for lipid peroxidation product-modified proteins showed HNE and MDA to be negative in all pancreatic tissues, but HHE was positive in the areas involving atrophy of acinar cells and fibrosis in the islets. The results of the present study thus provide support for the conclusion that lipid peroxidation during spontaneous pancreatitis in WBN/Kob rats may possibly be involved in the development of diabetes in this model.

Progression to overt proteinuria in microalbuminuric Koreans with non-insulin-dependent diabetes mellitus.

Long-term data concerning the progression of microalbuminuria are not available in Koreans with non-insulin-dependent diabetes mellitus (NIDDM). To elucidate potential risk factors of the development of overt proteinuria in microalbuminuric Koreans with NIDDM, we studied retrospectively 46 patients with NIDDM. Between 1989 and 1990, they were found to have persistent microalbuminuria, and then were followed up regularly. Urinary albumin excretion rates (UAEs) were measured on a 24-h urine sample. Microalbuminuria was defined as UAE between 20 and 200 microg/min, and overt proteinuria as UAE > 200 microg/min on two consecutive occasions. After a mean of 4.5 years (range 3-6), 23 patients progressed to overt proteinuria (progressors), and others remained microalbuminuric (nonprogressors). Duration of diabetes was significantly longer in progressors than in nonprogressors. Mean fasting plasma glucose and HbA1c levels during the follow-up were significantly higher in progressors compared with nonprogressors (11.5+/-3.6 vs. 8.7+/-2.5 mmol/l, P=0.006, and 8.9+/-1.5 vs. 7.5+/-1.4%, P=0.005, respectively). In addition, frequencies of overt proteinuria were significantly higher in patients with their mean HbA1c > 8% during follow-up than in patients with their mean HbA1c < or=80% during follow-up (65.2 vs. 30.4%, P=0.015). Mean systolic blood pressure and mean diastolic blood pressure during follow-up tended to be higher in progressors compared with nonprogressors. Multiple logistic regression analysis revealed that mean HbA1c levels and mean systolic blood pressure during the follow-up were the most significant predictors for the incidence of overt proteinuria at 4.5-year follow-up, when adjusted for various factors (P=0.023, P=0.038, respectively). We conclude that poor glycemic control, along with elevated systolic blood pressure, were powerful predictors for the development of overt proteinuria in microalbuminuric Koreans with NIDDM.

Dexamethasone suppresses the expansion and transdifferentiation of transplanted porcine neonatal pancreas cell clusters (NPCCs) into beta-cells in normal nude mice.

OBJECTIVES: This study was performed to investigate the effect of dexamethasone on the expansion and transdifferentiation of transplanted neonatal pancreas cell clusters (NPCCs) in vivo. METHODS: Porcine NPCCs were generated from 1 to 3-day-old neonatal pigs. After transplantation (Tx) of 4000 islet equivalents (IEqs) of NPCCs beneath the renal subcapsular space of normoglycemic nude mice, dexamethasone (Dx, 1 mg/kg) or vehicles were injected daily. Intraperitoneal glucose tolerance testing (ip-GTT) was performed at 4 weeks (n = 4) and 10 weeks (n = 7) after Tx. After harvesting the grafts, total graft and beta-cell graft mass were determined by morphometric analysis. RESULTS: Although the mean value of AUCg was elevated in the Dx-treated group at 10 weeks after Tx, the glucose levels of all the animals by ip-GTT were within the normal range. At 10 weeks after Tx, the relative volume, absolute mass of beta-cells in the graft, and total graft mass were significantly lower in the Dx-treated group (relative volume of beta-cells: 22.0% versus 35.3%, P < 0.05; beta-cells mass: 1.0 +/- 1.2 mg versus 2.2 +/- 5.6 mg, P < 0.05, total graft mass: 4.4 +/- 5.4 mg versus 6.3 +/- 1.3 mg, P < 0.05, Dx-treated versus control), but there was no difference at 4 weeks. Morphologically prominent cystic structures were observed in the Dx group at 10 weeks. CONCLUSION: Our results suggest that dexamethasone suppresses the expansion and transdifferentiation of transplanted porcine NPCCs into beta-cells in normal nude mice.

Inhibitory effects of protocatechuic acid on the post-initiation phase of hamster pancreatic carcinogenesis induced by N-nitrosobis(2-oxopropyl)amine.

The chemopreventive effects of protocatechuic acid (PCA) were investigated during the post-initiation stage of the N-nitrosobis(2-oxopropyl)amine (BOP)-initiated hamster pancreatic tumorigenesis model. Female 5-week-old hamsters were divided into 6 groups. Animals in groups 1-3, each consisting of 30 hamsters, were given two s.c. injections of 20 mg/kg body weight of BOP with a one week interval as an initiation treatment. After the BOP injection, hamsters in groups 1 and 2 were respectively fed diet supplemented with 1000 or 500 ppm of PCA for 49 weeks. The animals in group 3 were treated with BOP alone. The animals in groups 4-6, each consisting of 10 hamsters, were given 1000 or 500 ppm PCA, or basal diet alone without prior BOP injection. At the termination of experimental week 52, the incidences and multiplicities of neoplastic lesions in the pancreas were comparable among the BOP-treated groups. However, the incidence of pancreatic tumors larger than 3 cm was significantly lower in the PCA-treated high dose groups than in the control group (p < 0.05). Moreover the incidence of advanced pancreatic cancers which had directly invaded adjacent tissues such as the diaphragm, spleen and stomach was reduced by the PCA treatments, being significantly (p < 0.01) lower in group 2 than in group 3. Our results thus indicated that PCA can inhibit the late post-initiation or progression phase of BOP-induced pancreatic carcinogenesis in hamsters.

Effects of 2-bromopropane on spermatogenesis in the Sprague-Dawley rat.

In 1995, 2-bromopropane (2-BP) was associated with occupational reproductive and hematopoietic toxicity in Korea. The effect of 2-BP on spermatogenesis, or Leydig cells, has not been determined in adult rats. In the present study, 40 ten-week-old Sprague-Dawley (SD) rats were treated orally with 3.5 g/kg/d of 2-BP for 3 consecutive days. At 1, 3, 5, 7, 14, 28, 42, and 70 d after treatment, testes were perfused with Karnovsky's solution or immersed in Bouin's solution, embedded in plastic or Epon and evaluated with light and electron microscopy. DNA ploidy distributions of testicular suspensions were determined by flow cytometry, which allowed comparison of quantitative spermatogenesis with histopathologic observations. Degeneration of spermatogonia was observed during Stages I-IV in seminiferous tubules on Day 1 after treatment. Spermatocytes, spermatids, Sertoli cells, and Leydig cells appeared normal in the early stage of the study. Whereas spermatid retention in Stages IX-XI was observed on Day 7 after treatment, depletion of spermatocytes and spermatids continued over time, followed by a marked increase of germ cells on Day 42 after treatment. However, the seminiferous tubules did not completely recover by study termination. Leydig cell cellularity increased mildly without any significant morphologic modification at the end of the study. Immunohistochemistry using an antibody against proliferating cell nuclear antigen (PCNA), showed an increased number of immunoreactive Leydig cells in the interstitium. In the flow cytometry analysis, proportions of diploid and tetraploid cells gradually decreased time-dependently until Day 28 after treatment, but showed an increase on Day 42, followed by a decrease on Day 70 after treatment. These data are strengthened by qualitative descriptions of lesions observed by histopathology. These results suggest that a high dose of 2-BP can decrease spermatogenesis by adversely affecting spermatogonia followed by depletion of spermatocytes, spermatids, and spermatozoa, with subsequent testicular atrophy. The atrophied testes may not regenerate completely. The number of Leydig cells may increase mildly with 10 weeks of recovery.

Oral toxicity of a tocotrienol preparation in rats.

Tocotrienols are added as antioxidants to food. As there have been no reports of toxicological evaluation, a 13-week oral toxicity study was performed in Fischer 344 rats of both sexes at dose levels of 0 (group 1), 0.19 (group 2), 0.75 (group 3) and 3% (group 4) of a preparation in powdered diet. Suppression of body weight gain was observed in group 4 males. On hematological examination, significant decrease in mean corpuscular volume (MCV) was observed in all treated males. Platelets were significantly reduced in group 3 and 4 males. Hemoglobin concentration, MCV, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration were significantly decreased in group 3 and 4 females and hematocrit in group 4 females. On serum biochemical examination, increase in the albumin/globulin ratio (A/G) and alkaline phosphatase in all treated males, elevated alanine transaminase in group 4 of both sexes and increases in asparagine transaminase and gamma-glutamyl transaminase in group 4 females were observed. With regard to relative organ weights, liver weights in group 4 of both sexes and adrenal weights in all treated males demonstrated an increase, and ovary and uterus weights in group 4 females were reduced. Histopathologically, slight hepatocellular hypertrophy in group 3 and 4 males, and reduction of cytoplasmic vacuolation in the adrenal cortical region in group 4 males were observed. Because of pathological changes in male liver and hematological changes in females, the no-observed-adverse-effect level (NOAEL) was concluded to be 0.19% in the diet (120 mg/kg body weight/day for male rats and 130 mg/kg body weight/day for female rats). As a decrease in MCV, an increase in the A/G, elevation of alkaline phosphatase and increase in adrenal weight were observed in all treated males, a no-observed-effect level (NOEL) could not be determined in this examination.

Reporter gene transgenic mice as a tool for analyzing the molecular mechanisms underlying experimental carcinogenesis.

Carcinogenic compounds are classified into 2 categories, genotoxic and non-genotoxic, which are basically judged from in vitro genotoxicity data. However, it is well documented that genotoxicants do not necessarily exert in vivo carcinogenicity in rodents, partly because of a discrepancy between in vitro and in vivo mutagenicities. Recently, transgenic animal models with reporter genes such as lacI, lacZ and gpt have been developed as a tool for assessing in vivo mutagenicity as well as carcinogenicity. In this article, data using lacI transgenic mice and gpt delta mice are presented and their application is discussed. In lacI transgenic mice, dimethylnitrosamine (DMN) treatment significantly increased lacI mutant frequency (MF) in the liver, kidenys and lungs, but not in other non-target organs. Repeated dose ip administration of DMN was more effective than single dose treatment in the induction of lacI MF. The spectrum of mutant plaques induced by DMN was characterized by deletions as well as GC to AT base transitions. The remaining mice receiving DMN proved to have liver adenomas at a high frequency after 78 weeks. Meanwhile, dietary 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MelQx) significantly increased lacI and gpt MFs in the liver and colon. The characteristic spectrum of mutant plaques induced by MeIQx was a GC to TA base transversion in both the lacI and gpt mutations. Our results thus strongly suggest that these reporter gene transgenic animal models could offer a useful tool for analyzing molecular mechanisms underlying experimental carcinogenesis and for assessing the carcinogenic risk of environmental chemicals.

Effects of transferrin on the modulation of cytokine production on mouse spleen cells.

In order to investigate the the effects of transferrin(Tf) on the production of cytokines, mouse spleen cells were treated with various concentrations of apo- and holo-Tf, and then the production of IL-6, IFN gamma and the expression of mRNA for TNF alpha was determined. The distribution of Tf, macrophages and T cells in the mouse mammary glands was also examined. IL-6 and IFN gamma producing capabilities of the unstimulated spleen cells in the presence of apo and holo-Tf were increased in a dose dependent manner, while the cells stimulated with anti-CD3 had no significant effects on production in thd presence of graded concentrations of Tf. The relative abundance of TNF alpha mRNA was significantly affected by the concentration of TF. During early involution almost all of the secretory epithelial cells and the secretion in the alveoli showed a very strong positive reaction to transferrin antibody, and macrophages and T cells were distributed in the lumen, alveolar epithelial layer and connective tissue area. These findings suggest that the upregulated patterns of these cytokines and distribution of immune cells may play a beneficial role in the augmentation of host's defense mechanisms during involution.