Characteristics of Fecal Incontinence in Male Patients in Japan.

Objectives: Although community studies have shown no difference between the sexes in the prevalence of fecal incontinence (FI), few direct comparisons of disease characteristics between male and female patients have been reported. The aim of this study was to determine whether characteristics of FI differ between male and female patients in Japan. Methods: Included in the study were 408 (149 men, 259 women) patients with FI who visited the Matsushima Hospital Coloproctology Center between October 2016 and September 2017. We retrospectively evaluated data on age, number of bowel movements, Bristol stool form scale, number of FI, incontinence scores, anorectal manometry, comorbidities, and history of anal surgery. Results: Maximum resting pressure and maximum squeeze pressure were found to be within normal range in significantly more male than female patients (34.9% vs. 12.4%, respectively; p < 0.0001). Irritable bowel syndrome (IBS, 20.1% vs. 9.3%; p = 0.003) and a history of anal surgery (29.5% vs. 17.5%; p = 0.02) were more prevalent among male patients than among female patients. Use of mepenzolate as treatment was significantly more common among male patients than among female patients (16.8% vs. 6.6%, respectively; p = 0.005). Responses to the various treatments were good, regardless of sex. Conclusions: FI appears to be more commonly accompanied by normal anal sphincter pressures in male patients than in female patients, and IBS and previous anal surgery appear to be more common among male patients than among female patients. FI appears to be controllable in most patients, regardless of sex.

A Novel Surgical Technique for Anal Fistula Surgery Designed to Preserve the Anal Sphincter Function and Anoderm.

OBJECTIVES: We reviewed surgical outcomes after introducing a novel surgical technique for anal fistula surgery designed to preserve anal sphincter function and the anoderm. METHODS: We studied 200 male patients who underwent a functional preservative operative technique (FPOT group) for anal fistulas and 200 patients who underwent resection of trans-sphincteric anal fistulas (fistulectomy group) between February 2014 and September 2015. We compared complications, such as those affecting anal sphincter function, recurrence, and incontinence. RESULTS: Fistulas recurred in three (1.5%) patients in the FPOT group and two (1%) patients in the fistulectomy group. This difference was not significant. Other complications included gas leakage and other forms of incontinence in 1 (0.5%) and 14 (7%) patients in the FPOT and fistulectomy groups, respectively. Anal function assessment demonstrated that the FPOT was significantly better at preserving function than fistulectomy in all patients. CONCLUSIONS: There were no significant differences between the FPOT and fistulectomy in terms of recurrence or complication rates. Also, because there was no decrease in postoperative anal function, we concluded that the FPOT is an effective preservative surgical technique for treating trans-sphincteric anal fistulas.

Subcutaneous transplantation of engineered islet/adipose-derived mesenchymal stem cell sheets in diabetic pigs with total pancreatectomy.

INTRODUCTION: Intraportal islet transplantation is a promising therapeutic approach for patients with type 1 diabetes mellitus (T1DM). However, despite being minimally invasive, the method has some limitations, such as short-term graft loss, portal venous thrombosis, and difficulty in collecting adequate amounts of islets. Subcutaneous islet transplantation on adipose-derived mesenchymal stem cell (ADSC) sheets has been suggested to overcome these limitations, and in this study, we have examined its feasibility in T1DM pigs. METHODS: Inguinal subcutaneous fat was harvested from young pigs and then isolated and cultured adequate ADSCs to prepare sheets. Islets were isolated from the pancreases of mature pigs and seeded on the ADSC sheets. T1DM pigs were generated by total pancreatectomy, and ADSC sheets with transplanted islets were administered subcutaneously to the waist (n = 2). The effects of the islets on the ADSC sheets and on blood glucose levels were evaluated. Insulin secretion was measured by insulin stimulation index. RESULTS: Islet viability was higher on ADSCs compared to islets alone (91.8 ± 4.3 vs. 81.7 ± 4.1%). The insulin stimulation index revealed higher glucose sensitivity of islets on ADSC sheets compared to islets alone (2.8 ± 2.0 vs. 0.8 ± 0.3). After transplantation, the blood glucose levels of two pigs were within the normal range, and sensitive insulin secretion was confirmed by intravenous glucose tolerance tests. After graftectomy, decreased insulin secretion and hyperglycemia were observed. CONCLUSIONS: Subcutaneous islet transplantation using ADSC sheets can regulate the blood glucose levels of T1DM pigs.

Pancreaticoduodenectomy can be indicated for elderly patients: risk prediction using the estimation of physiologic ability and surgical stress (E-PASS) system.

BACKGROUND: Pancreaticobiliary malignant diseases are primarily treated by surgical resection. However, the surgical indications for elderly patients, especially for pancreaticoduodenectomy (PD), must be carefully considered due to patient compliance. Whether PD can contribute to better prognoses in elderly patients remains unclear. Therefore, we aimed to evaluate the complications, compliance, and survival of elderly and non-elderly patients who underwent PD in our department. METHODS: We retrospectively analyzed 282 patients who underwent PD from 2000 to 2017 and divided them into non-elderly (aged ≤ 79 years, n = 238) and elderly (aged ≥ 80 years, n = 44) groups. The estimation of physiologic ability and surgical stress (E-PASS) system was used to evaluate morbidity and mortality using preoperative risk score (PRS), surgical stress score (SSS), and comprehensive risk score (CRS). RESULTS: Preoperative risk score was higher in the elderly group than in the non-elderly group, although SSS and CRS were similar. No significant differences were detected in the occurrence of postoperative complications. In the elderly group, CRS was higher in patients with complications than in those without. Long-term outcomes evaluated by overall and disease-specific survival were not significantly different. CONCLUSIONS: In the elderly patients, E-PASS especially CRS can predict the occurrence of complications. The safety and prognoses of elderly patients after PD are comparable with those of non-elderly patients.

Evaluation of Mucopexy-Recto Anal Lifting (MuRAL): A New Method for Treating Hemorrhoids.

OBJECTIVES: Ligation and excision remain the commonly recognized standard surgical modality for treating hemorrhoids. Further, impediments to surgical treatment owing to social factors and the need for minimally invasive procedures and other confounders have resulted in the adoption of the mucopexy-recto anal lifting (MuRAL) method which is associated with favorable outcomes. The objective of this study was to describe the procedure and report the outcomes in patients who underwent MuRAL. METHODS: Between March 2016 and February 2018, 55 patients (26 males and 29 females) underwent MuRAL for hemorrhoids and rectal mucosal prolapse. The duration of the surgical procedure and hospitalization, postoperative complications, and satisfaction were evaluated. RESULTS: The mean age of the male patients (n = 26) was 61.5 ± 4.9 years and that of the female patients (n = 29) was 61.5 ± 3.2 years. The mean duration of surgery was 46 ± 23 minutes for males and 53 ± 28 minutes for females, and the mean observation duration was 317 ± 186 days. Intraoperative hemorrhage was low for males and females. The mean hospitalization period was 3.2 ± 1.5 days for males and 4.3 ± 2.1 days for females. Differences in several postoperative complications were observed between male and female patients. Postoperative satisfaction was rated high by the patients. CONCLUSIONS: Risks of hemorrhage and pain associated with the MuRAL method were low because the procedure does not involve incision or excision. Other than ligation and excision, recurrence is favorable compared with that of other surgical modalities for the treatment of hemorrhoids.

The long-term survival in primary retroperitoneal mucinous cystadenocarcinoma: a case report.

BACKGROUND: Primary retroperitoneal mucinous cystadenocarcinoma (PRMC) is extremely rare, and its biological behavior, pathogenesis, optimum treatments, and prognosis remain to be elucidated. We herein report a case of PRMC with an 80-month follow-up. CASE PRESENTATION: A 29-year-old woman was diagnosed with unknown retroperitoneal tumor with benign right ovarian cyst and uterine fibroids, and she underwent laparotomy. The tumor was completely resected with a subsequent histopathological diagnosis of primary retroperitoneal mucinous cystadenocarcinoma (PRMC). Eighty months after surgery, she remains recurrence-free. CONCLUSION: PRMC is an extremely rare tumor. Only around 60 cases have so far been published in the literature. The preoperative diagnosis of PRMC is difficult, and a definitive diagnosis can usually only be made based on the findings of histopathological examinations after surgery. Presently, only radical resection is useful for both diagnostic and therapeutic purposes. The optimal long-term management after surgery is still not well established. Further studies on PRMC are therefore needed to elucidate the etiology and establish effective treatments.

Gastrointestinal stromal tumor with two genetic abnormalities on different alleles: report of a case.

We report a case of a gastrointestinal stromal tumor (GIST) with strong and faint KIT protein staining, respectively, at two different sites. A single point mutation (c1727 T>C) was detected in DNA extracted from both sites, and a further deletion mutation (c1678_1680 del GTT) was detected in DNA from the site with strong KIT protein staining. Cloning analysis indicated that the point mutation and the deletion were present on different alleles.

Effects of environmentally relevant concentrations of nonylphenol on growth and 20-hydroxyecdysone levels in mysid crustacean, Americamysis bahia.

We investigated the effects of environmentally relevant concentrations of nonylphenol (NP) on survival, growth, sexual development and molting of the mysid Americamysis bahia (Crustacea: Mysidacea), including assay of 20-hydroxyecdysone (20E) levels. Seven-day-old mysids were exposed to NP concentrations of 0.3, 1, 3, 10 and 30 microg/L for 14 days. Among growth-related traits we assayed, an effect on body length was the most prominent, with the effects observed at concentrations as low as 1 microg/L NP. In addition, the total number of molting exposed to NP for 14 days was significantly decreased in the treatment groups at 10 or 30 microg/L relative to the controls. These results clearly indicate that subchronic exposure to environmentally relevant concentrations of NP affects growth of mysids. Furthermore, we investigated the effect of NP on production of 20E in female mysids during the molting period. Production of 20E in pre-molting mysids exposed to 30 microg/L of NP was lower than those in control groups, and exposure of female mysids to NP disrupted molting cycles. Taken together, the results suggest that environmentally relevant concentrations of NP can disrupt growth of A. bahia via inhibition of 20E levels and an associated delay in molting.

Factors affecting continence after fistulotomy for intersphincteric fistula-in-ano.

BACKGROUND AND AIMS: This study was undertaken to determine the incidence of and risk factors for anal incontinence after fistulotomy for intersphincteric fistula-in-ano. We also evaluated the role of anal manometry in preoperative assessment of intersphincteric fistula. MATERIALS AND METHODS: A prospective, observational study was undertaken in 148 patients who underwent fistulotomy for intersphincteric fistula between January and December 2004. Functional results were assessed by standard questionnaire and anal manometry. Possible factors predicting postoperative incontinence were examined by univariate and multivariate regression analyses. RESULTS: The mean follow-up period was 12 months. Postoperative anal incontinence occurred in 30 patients (20.3%), i.e., soiling in 6, incontinence for flatus in 27, and incontinence for liquid stool in 4. Fistulotomy significantly decreased maximum resting pressure (85.9 +/- 20.4 to 60.2 +/- 18.4 mmHg, P < 0.0001) and length of the high pressure zone (3.92 +/- 0.69 to 3.82 +/- 0.77 cm, P = 0.035), but it did not affect voluntary contraction pressure (164.7 +/- 85.2 to 160.3 +/- 84.8 mmHg, P = 0.2792). Multivariate analysis showed low voluntary contraction pressure and multiple previous drainage surgeries to be independent risk factors for postoperative incontinence. CONCLUSION: Fistulotomy produces a satisfactory outcome in terms of eradicating sepsis and preserving function in the vast majority of patients with intersphincteric fistula with intact sphincters. However, sphincter-preserving treatment may be advocated for patients with low preoperative voluntary contraction pressure or those who have undergone multiple drainage surgeries. Preoperative anal manometry is useful in determining the proper surgical procedure.

Microbiological analysis and endoanal ultrasonography for diagnosis of anal fistula in acute anorectal sepsis.

BACKGROUND AND AIMS: Treatment of anorectal sepsis requires prompt surgical drainage, but it is important to identify any associated anal fistula for preventing recurrence. We evaluated whether microbiological analysis and/or endoanal ultrasonography could be used to predict anal fistula in patients with acute anorectal sepsis. METHODS: Five hundred fourteen consecutive patients with acute anorectal sepsis were studied. Clinical data, digital examination findings, endosonographic findings, and results of microbiological analysis were compared with definitive surgical findings of the presence or absence of anal fistula. RESULTS: Anorectal abscess with anal fistula was found in 418 patients, and anorectal abscess without anal fistula was found in 96 patients. Microbiological examination showed that Escherichia coli, Bacteroides, Bacillus, and Klebsiella species were significantly more prevalent in patients with fistula (P<0.01), and coagulase-negative Staphylococci and Peptostreptococcus species were significantly more prevalent in patients without fistula (P<0.01). Results of endoanal ultrasonography were concordant with the definitive surgical diagnosis in 421 (94%) of 448 patients studied. CONCLUSION: Acute anorectal sepsis due to colonization of "gut-derived" microorganisms rather than "skin-derived" organisms is more likely to be associated with anal fistula. When the microbiological analysis yields gut-derived bacteria, but no fistula has been found in the initial drainage operation, repeat examinations during a period of quiescence, including careful digital assessment and meticulous endosonography, are warranted to identify a potentially missed anal fistula.

Reproductive effects and bioconcentration of 4-nonylphenol in medaka fish (Oryzias latipes).

The objective of this study was to investigate the reproductive success (fertility and fecundity) of medaka (Oryzias latipes) exposed to 4-nonylphenol (4-NP) in water and the viability of their F(1) offspring. In addition, we measured the bioconcentration of 4-NP in eggs. After a 21-d exposure to 100microg/l 4-NP, medaka showed reduced egg production and fertility. Hepatic vitellogenin levels were increased significantly in males treated with 10, 50 and 100microg/l of 4-NP. In the F(1) generations, the hatchability and time to hatching of embryos in the 100microg/l treatment group were adversely affected, and 2-7microg 4-NP/g egg was found in spawned eggs (the bioconcentration factor: 30-100). These results indicate that (1) 4-NP adversely affected the reproduction (fecundity and fertility) of adult medaka, (2) 4-NP accumulated in eggs through maternal transfer and (3) these levels of 4-NP were associated with adverse effects in the F(1) offspring.

Postoperative urinary retention after surgery for benign anorectal disease: potential risk factors and strategy for prevention.

PURPOSE: This study was undertaken to determine the incidence of and risk factors for urinary retention after surgery for benign anorectal disease. METHODS: We reviewed 2,011 consecutive surgeries performed under spinal anesthesia for benign anorectal disease from January through June 2003 to identify potential risk factors for postoperative urinary retention. In addition, we prospectively investigated the preventive effect of perioperative fluid restriction and pain control by prophylactic analgesics on postoperative urinary retention. RESULTS: The number of procedures and the urinary retention rates were as follows: hemorrhoidectomy, 1,243, 21.9%; fistulectomy, 349, 6.3%; incision/drainage, 177, 2.3%; and sliding skin graft/lateral subcutaneous internal sphincterotomy, 64, 17.2%. The overall urinary retention rate was 16.7%. With hemorrhoidectomy, female sex, presence of preoperative urinary symptoms, diabetes mellitus, need for postoperative analgesics, and more than three hemorrhoids resected were independent risk factors for urinary retention as assessed by multivariate analysis. With fistulectomy, female sex, diabetes mellitus, and intravenous fluids >1,000 ml were independent risk factors for urinary retention. Perioperative fluid restriction, including limiting the administration of intravenous fluids, significantly decreased the incidence of urinary retention (7.9 vs 16.7%, P<0.0001). Furthermore, prophylactic analgesic treatment significantly decreased the incidence of urinary retention (7.9 vs 25.6%, P=0.0005). CONCLUSIONS: Urinary retention is a common complication after anorectal surgery. It is linked to several risk factors, including increased intravenous fluids and postoperative pain. Perioperative fluid restriction and adequate pain relief appear to be effective in preventing urinary retention in a significant number of patients after anorectal surgery.

Effects of nonylphenol and triclosan on production of plasma vitellogenin and testosterone in male South African clawed frogs (Xenopus laevis).

We investigated the effects of nonylphenol (NP) and triclosan (TCS) on production of vitellogenin (Vg), testosterone (T), and hepatic cytochrome P450 1A and 2B activities in male South African clawed frogs (Xenopus laevis). In a 14-d waterborne exposure test, no significant differences in the level of plasma Vg synthesis in male frogs were observed among the control, 10, 50, and 100 microg/l NP and 20, 100, and 200 microg/l TCS treatment groups. Intraperitoneal injection of male frogs with 2, 20, and 200 microg/g body weight NP resulted in no significant differences in plasma Vg levels among the control and all treatment groups. However, the levels of plasma Vg in all TCS treatment groups (intraperitoneal injection of 4, 40, and 400 microg/g body weight) were lower than that in the solvent control group, and male frogs injected with high doses of NP or TCS had lower T levels than the control group. No significant differences in hepatic cytochrome P450 1A and 2B activities were observed among the all treatment groups. Male frogs injected with 20 microg/g body weight of estradiol-17beta had significantly higher plasma Vg levels than the control group. These results suggest that profiles of plasma Vg and T production in male Xenopus laevis could be useful biomarkers for detecting hormonally active agents.

Toxicity to early life stages and an estrogenic effect of a bisphenol A metabolite, 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene on the medaka (Oryzias latipes).

In a recent study, it was reported that 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), a metabolite of bisphenol A (BPA; 2,2-bis(4-hydroxyphenyl)propane), showed estrogenic activity in several in vitro assays, and the estrogenic activity of MBP was higher than that of BPA. In this study, we have investigated the early life stage toxicity and estrogenic effect of MBP on medaka (Oryzias latipes). The 96-h median lethal concentration value of MBP and BPA with 24-h-old larvae was estimated to be 1,640 and 13,900 microg/l, respectively. The hatchability of fertilized eggs exposed to MBP and BPA over 14 days was significantly decreased at doses of 2,500 microg/l and 12,500 microg/l, respectively. Moreover, to compare the potency of estrogenic activity in vivo, male medaka were exposed to various concentrations of MBP and BPA for 21 days. The lowest-observed-effect concentrations of MBP and BPA for hepatic vitellogenin induction in male medaka were estimated to be 4.1 and 1,000 microg/l, respectively. These results suggest that MBP has high toxicity for early life stages of the medaka, and that the estrogenic activity of MBP was about 250-fold higher than that of BPA to male medaka.

Effects of nonylphenol and phytoestrogen-enriched diet on plasma vitellogenin, steroid hormone, hepatic cytochrome P450 1A, and glutathione-S-transferase values in goldfish (Carassius auratus).

The effects of nonylphenol (NP) on plasma vitellogenin (VTG) and steroid hormone values, as well as hepatic cytochrome P450 1A (CYP1A) and glutathione-S-transferase (GST) activities, were measured in goldfish (Carassius auratus) fed a diet with a low (formulated diet, FD) or high (commercial diet, CD) content of phytoestrogens, including genistein and daidzein. Male goldfish with secondary sexual characteristics were exposed to nominal NP concentrations of 0.1, 1.0, 10, and 100 microg/L in the water for 28 days while being fed either the FD or CD diet at 1.0% of body weight daily. Plasma VTG concentration in male goldfish exposed to 100 microg of NP/L and fed FD was significantly higher than that in the FD-fed control fish at seven, 21, and 28 days. However, fish of the CD-fed group exposed to 100 microg of NP/ L had significantly higher plasma VTG concentration than did fish of the CD-fed control group at 28 days only. Moreover, plasma VTG concentration in fish of the CD-fed control group was about 100-fold higher than that in fish of the FD-fed control group. Although the estrogenic effects of a phytoestrogen-enriched diet caused a decrease in testosterone and/or 11-ketotestosterone values in the CD-fed fish, there was no dose-response relationship between androgen and amount of NP to which the FD-fed fish were exposed. Nonylphenol does not have appreciable effects on hepatic CYP1A and GST activities in male goldfish at concentrations as low as 100 microg/L. These results suggest that NP has estrogenic activity in male goldfish at the nominal concentration of 100 microg/L, and that phytoestrogens, such as genistein and daidzein, in the CD inhibit an aspect(s) of steroid release and/or synthesis common to testosterone and 11-ketotestosterone. However, results of in vivo screening assays for endocrine-disrupting chemicals may be seriously affected by phytoestrogens in the diet, depending on content or potency of estrogenic activity; therefore, we recommend use in research of a standardized, open-formula diet in which estrogenic substances have been reduced to amounts that do not alter the results of studies that are influenced by exogenous estrogens.

Effects of triclosan on the early life stages and reproduction of medaka Oryzias latipes and induction of hepatic vitellogenin.

Triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) is widely used as antibacterial agent in various industrial products, such as textile goods, soap, shampoo, liquid toothpaste and cosmetics, and often detected in wastewater effluent. In this study, the effects of TCS on the early life stages and reproduction of medaka (Oryzias latipes) were investigated. The 96-h median lethal concentration value of TCS for 24-h-old larvae was 602 microg/l. The hatchability and time to hatching in fertilized eggs exposed to 313 microg/l TCS for 14 days were significantly decreased and delayed, respectively. An assessment of the effects of a TCS 21-day exposure period on the reproduction of paired medaka showed no significant differences in the number of eggs produced and fertility among the control and 20, 100 and 200 microg/l TCS treatment groups. However, concentrations of hepatic vitellogenin were increased significantly in males treated with TCS at 20 and 100 microg/l. In the F(1) generations, although the hatching of embryos in the 20 microg/l treatment showed adverse effects, there was no dose-response relationship between hatchability and TCS treatment levels. These results suggest that TCS has high toxicity on the early life stages of medaka, and that the metabolite of TCS may be a weak estrogenic compound with the potential to induce vitellogenin in male medaka but with no adverse effect on reproductive success and offspring.

Effects of 17beta-estradiol on survival, growth, sexual development and molting cycles of the marine crustacean mysid shrimp, Americamysis bahia.

A 14-day partial life-cycle test was performed to assess the effects of 17beta-estradiol (E2) on the survival, growth, sexual development and molting cycles of a marine crustacean mysid shrimp (Americamysis bahia). Seven-day-old mysids were exposed to the nominal E2 concentrations of 31.3, 62.5, 125, 250 and 500 microg/l for 14 days. The total length and the body weight of mysids significantly decreased relative to the controls when exposed to 62.5, 250 and 500 microg/l E2 for 14 days. Moreover, the carapace length significantly decreased in the 500 microg/l E2 treatment groups. No significant differences were observed in sex ratio with the appearance of secondary sex characteristics in the all treatment groups including the control and solvent control groups. However, the percentage of females with eggs in the oviduct or brood sac decreased significantly in mysids treated with E2 at 62.5, 125, 250 and 500 microg/l. The cumulative total number of molting cycles when exposed to E2 for 14 days significantly decreased in the treatment groups at 500 microg/l relative to the controls. These results suggest that concentrations of E2 over 62.5 microg/l may cause growth suppression in mysid shrimp, and that the disruption of molting cycles may result in alterations in growth due to a sublethal response to toxicant exposure.

Effect of estrogenic activity, and phytoestrogen and organochlorine pesticide contents in an experimental fish diet on reproduction and hepatic vitellogenin production in medaka (Oryzias latipes).

Endocrine-disrupting chemicals (EDCs) are giving rise to serious concerns for humans and wildlife. Phytoestrogens, such as daidzein and genistein in plants, and organochlorine pesticides are suspected EDCs, because their chemical structure is similar to that of natural or synthetic estrogens and they have estrogenic activity in vitro and in vivo. We assessed estrogenic activity and dietary phytoestrogen and organochlorine pesticide contents of various fish diets made in the United Kingdom, and compared them with those features of diets made in Japan that were tested in a previous study. Genistein and daidzein were detected in all of the diets. Using an in vitro bioassay, many of these diets had higher activation of estrogen beta-receptors than estrogen alpha-receptors. Organochlorine pesticides such as hexachlorobenzene, beta-benzene hexachloride (BHC), and gamma-BHC were detected in all fish diets. On the basis of these data, we investigated the effect of differing dietary phytoestrogen content in Japanese fish diets on hepatic vitellogenin production and reproduction (fecundity and fertility) in medaka (Oryzias latipes). Assessment of the effects of a 28-day feeding period on reproduction of paired medaka did not indicate significant differences in the number of eggs produced and fertility among all feeding groups. However, hepatic vitellogenin values were significantly higher for male medaka fed diet C (genistein, 58.5 +/- 0.6 microg/g; daidzein, 37.3 +/- 0.2 microg/g) for 28 days compared with those fed diet A (genistein, < 0.8 microg/g; daidzein, < 0.8 microg/g) or diet B (genistein, 1.4 +/- 0.1 microg/g; daidzein, 2.0 +/- 0.1 microg/g). Our findings indicate that fish diets containing high amounts of phytoestrogens, such as diet C, have the potential to induce hepatic vitellogenin production in male medaka, even if reproductive parameters are unaffected. Therefore, some diets, by affecting vitellogenin production in males, may alter estrogenic activity of in vivo tests designed to determine activity of test compounds added to the diet.