Serum interleukin-4 is elevated in clinical drug-induced liver injury.

BACKGROUND: Drug-induced liver injury (DILI) remains a challenging diagnosis due to an absence of specific biomarkers. DILI due to volatile anaesthetics (VA-DILI) is characterised by trifluoroacetyl and CYP2E1 antibodies, but may not be seen for weeks after injury. Interleukin-4 (IL-4) may be involved in the production of these antibodies and may serve as a clinically useful early biomarker of VA-DILI. AIM: To prospectively compare serum IL-4 levels between patients who develop VA-DILI and controls following exposure to the volatile anaesthetic. METHODS: A nested case-control study of patients exposed to VA during surgery was conducted. Thirteen DILI cases were identified from the original cohort, and 26 controls were matched according to age, sex and VA agent. Serum samples were collected before and 48-96 h after VA exposure, and analysed for IL-4 using quantitative enzyme-linked immunosorbent assay techniques. RESULTS: There was a statistically significant difference in serum IL-4 in post-VA samples between DILI cases and controls (control: 0.030 pg/mL, IQR: 0.030 - 0.030 pg/mL vs DILI: 0.044 pg/mL, IQR: 0.030 - 0.061 pg/mL; p = 0.039). A greater proportion of DILI cases had post-VA IL-4 levels above the assay lower limit of detection compared to controls (control: 23% vs DILI: 69%; p = 0.013). CONCLUSION: IL-4 is a potential biomarker of DILI. Clinical diagnosis and understanding of DILI disease mechanisms may be improved by further investigation of novel biomarkers, and this IL-4 signal in serum is important as proof of concept for prospective study designs.

Clinical efficacy of first and second series of peptide receptor radionuclide therapy in patients with neuroendocrine neoplasm: a cohort study.

OBJECTIVES: Peptide receptor radionuclide therapy (PRRT) is an established treatment for metastatic neuroendocrine neoplasms (NEN). However, only limited data exists for the effect of multiple series of PRRT. The aim of this study was to investigate PFS and OS inNEN patients treated with multiple series of PRRT conforming to the ENETS treatment protocol. METHODS: We included all patients with gastrointestinal (GI), pancreatic and bronchopulmonary (BP) NEN treated with PRRT from 2008 to 2018. We used Kaplan-Meier estimation to evaluate PFS and OS with subgroup analysis of primary tumor, Ki67-index, type of radioisotope and number of PRRT series. RESULTS: 133 patients (female/male 61/72) were included, median age 70 (interquartile range 64-76) years. GI-NEN comprised 62%, pancreatic 23% and BP 11%. Median Ki67-index was 5%. After first PRRTG1- and G2-tumors had PFS of 25 and 22 months, compared to 11 months in G3-NENs (p < .05) and PFS was longer in G1/G2 GI-NENs than BP-NEN (30vs. 12 months, p < .05). After retreatment with a second series of PRRT, the overall PFS (G1-G3) was 19 months, with G1- and G2-tumors having the highest PFS of 19 and 22 months, respectively. Overall, the GI and BP tumors had an OS of 54 and 51 months. CONCLUSIONS: PRRT is an effective therapy with long-term PFS and OS, especially in G1 and G2 NENs, and with better prognosis in GI-NEN compared with BP-NENs. OS and PFS was shorter after the second series of PRRT compared with the first, however results were still encouraging.

Results after surgical treatment of liver metastases in patients with high-grade gastroenteropancreatic neuroendocrine carcinomas.

BACKGROUND: Gastroenteropancreatic neuroendocrine carcinomas (GEP-NEC) are generally characterized by synchronous metastases, high aggressiveness and a dismal prognosis. Current international guidelines do not recommend surgical treatment of liver metastases, however the existing data are scarce. The aim of this study was to evaluate the results of curatively intended resection/radiofrequency ablation (RFA) of liver metastases in patients with metastatic GEP-NEC. METHODS: 32 patients with a diagnosis of high-grade gastroenteropancreatic neuroendocrine neoplasm (Ki-67 > 20%) and with intended curative resection/RFA of liver metastases, were identified among 840 patients from two Nordic GEP-NEC registries. Tumor morphology (well vs poor differentiation) was reassessed. Overall survival (OS) and progression-free survival (PFS) was assessed by Kaplan-Meier analyses for the entire cohort and for subgroups. RESULTS: Median OS after resection/RFA of liver metastases was 35.9 months (95%-CI: 20.6-51.3) with a five-year OS of 43%. The median PFS was 8.4 months (95%-CI: 3.9-13). Four patients (13%) were disease-free after 5 years. Two patients had well-differentiated morphology (NET G3) and 20 patients (63%) had Ki-67 ≥ 55%. A Ki-67 < 55% and receiving adjuvant chemotherapy were statistically significant factors of improved OS after liver resection/RFA. CONCLUSION: This study shows a long median and long term survival after liver surgery/RFA for these selected metastatic GEP-NEC patients, particularly for the group with a Ki-67 in the relatively lower G3 range. Our findings indicate a possible role for surgical treatment of liver metastases in the management of this patient population.

Circulating sCD36 levels in patients with non-alcoholic fatty liver disease and controls.

BACKGROUND AND OBJECTIVE: CD36 is implicated in fatty-acid uptake in multiple tissues, including hepatocytes and adipocytes. Circulating CD36 (sCD36) is increased in non-alcoholic fatty liver disease (NAFLD). We explored this association further by investigating correlations between sCD36 levels, intrahepatic lipid content and markers of obesity in NAFLD patients and controls. METHODS: In total, 111 NAFLD patients and 33 normal/overweight controls were included. Intrahepatic lipid content was measured by magnetic resonance spectroscopy; and subgroups of participants had a dual-energy X-ray absorptiometry (n=99), magnetic resonance imaging (n=94, subcutaneous and visceral adipose tissue) and liver biopsy (n=28 NAFLD patients) performed. Plasma sCD36 was assessed by enzyme-linked immunosorbent assay. RESULTS: NAFLD patients had elevated sCD36 levels compared with controls (0.68 (0.12-2.27) versus 0.43 (0.10-1.18), P<0.01). sCD36 correlated with intrahepatic lipid (rs=0.30), alanine transaminase (ALT) (r=0.31), homeostasis model assessment index-insulin resistance (r=0.24), high-density lipoprotein (r=-0.32) and triglyceride (r=0.44, all P<0.01). Intrahepatic lipid and plasma triglyceride were independent predictors of sCD36 levels in a multiple regression analysis. Further, sCD36 and body mass index were weakly correlated (r=0.17, P=0.04); yet, we found no correlations between sCD36 and other measures of fat distribution except an inverse relation to visceral adipose tissue (rs=-0.21, P<0.05). We observed a trend for correlation between sCD36 and hepatic CD36 mRNA expression (r=0.37, P=0.07). CONCLUSIONS: sCD36 levels increased with the level of intrahepatic lipid, insulin resistance and dyslipidemia. The weak association with markers of obesity and the association with hepatic CD36 mRNA expression suggest that excess sCD36 in NAFLD patients is derived from the hepatocytes, which may support that CD36 is involved in NAFLD development. An unhealthy and unbalanced CD36 expression in adipose and hepatic tissue may shift the fatty-acid load to the liver.

Soluble CD163, a specific macrophage activation marker, is decreased by anti-TNF-α antibody treatment in active inflammatory bowel disease.

Activated macrophages shed the haemoglobin-haptoglobin scavenger receptor CD163 into the circulation as soluble(s)-CD163. We measured sCD163 as an in vivo macrophage activation marker in patients with Crohn's disease (CD) or ulcerative colitis (UC) receiving antitumour necrosis factor (TNF)-α antibody or prednisolone treatment. We also investigated the CD163 expression on circulating monocytes. 58 patients with CD, 40 patients with UC and 90 healthy controls (HC) were included. All patients had active disease at inclusion and were followed for 6 weeks of anti-TNF-α antibody or prednisolone treatment. We measured plasma sCD163 levels at baseline, 1 day, 1 week and 6 weeks after initiating treatment. CD163 expression on circulating CD14(+) monocytes was measured in 21 patients with CD receiving anti-TNF-α antibody treatment. Baseline sCD163 levels were elevated in patients with CD [1.99 (1.80-2.18) mg/l] and in patients with UC [2.07 (1.82-2.32) mg/l] compared with HC [1.51 (1.38-1.63) mg/l] (P < 0.001). Anti-TNF-α antibody treatment induced a rapid decrease in sCD163 levels in patients with CD and in patients with UC 1 day after treatment initiation (P < 0.05). One week of prednisolone treatment did not induce a reduction in sCD163 levels. Anti-TNF-α treatment normalized sCD163 levels in patients with UC, whereas patients with CD exhibited sustained increased sCD163 levels. In patients with CD, CD163 expression on CD14(+) monocytes was increased compared with HC. This study highlights that active CD and UC are associated with increased macrophage activation, as indicated by elevated sCD163 levels and monocytic CD163 expression. Anti-TNF-α antibody treatment induced a rapid decrease in sCD163 levels, suggesting a specific effect on macrophage activation in inflammatory bowel diseases.

Predictive and prognostic factors for treatment and survival in 305 patients with advanced gastrointestinal neuroendocrine carcinoma (WHO G3): the NORDIC NEC study.

BACKGROUND: As studies on gastrointestinal neuroendocrine carcinoma (WHO G3) (GI-NEC) are limited, we reviewed clinical data to identify predictive and prognostic markers for advanced GI-NEC patients. PATIENTS AND METHODS: Data from advanced GI-NEC patients diagnosed 2000-2009 were retrospectively registered at 12 Nordic hospitals. RESULTS: The median survival was 11 months in 252 patients given palliative chemotherapy and 1 month in 53 patients receiving best supportive care (BSC) only. The response rate to first-line chemotherapy was 31% and 33% had stable disease. Ki-67<55% was by receiver operating characteristic analysis the best cut-off value concerning correlation to the response rate. Patients with Ki-67<55% had a lower response rate (15% versus 42%, P<0.001), but better survival than patients with Ki-67≥55% (14 versus 10 months, P<0.001). Platinum schedule did not affect the response rate or survival. The most important negative prognostic factors for survival were poor performance status (PS), primary colorectal tumors and elevated platelets or lactate dehydrogenase (LDH) levels. CONCLUSIONS: Advanced GI-NEC patients should be considered for chemotherapy treatment without delay.PS, colorectal primary and elevated platelets and LDH levels were prognostic factors for survival. Patients with Ki-67<55% were less responsive to platinum-based chemotherapy, but had a longer survival. Our data indicate that it may not be correct to consider all GI-NEC as one single disease entity.

Cirrhosis and mortality risks of biopsy-verified alcoholic pure steatosis and steatohepatitis: a nationwide registry-based study.

BACKGROUND: Alcoholic fatty liver disease comprises alcoholic pure steatosis and alcoholic steatohepatitis. These diseases are prevalent, but their prognostic outcome is uncertain, particularly regarding the impact of hepatic inflammation. The paucity of data based on liver biopsy diagnoses contributes to this uncertainty. AIM: To examine the cirrhosis and mortality risks of Danish men and women with biopsy-verified alcoholic pure steatosis or steatohepatitis. METHODS: In this registry-based historical cohort study we combined liver biopsy diagnoses with hospital discharge diagnoses from nationwide healthcare registries to identify all Danish citizens with alcoholic pure steatosis (N = 136) or alcoholic steatohepatitis (N = 58) during 1997-2008. We enrolled a reference cohort of 100 gender- and age-matched persons from the general population for each patient and compared cirrhosis and mortality risks through 2010. RESULTS: The 5-year cirrhosis risks were 6.9% (95% CI: 3.4-12.2%) for patients with alcoholic pure steatosis and 16.0% (95% CI: 7.8-26.8%) for patients with alcoholic steatohepatitis, their 5-year mortality risks were 16.7% (95% CI: 11.3-24.2%) and 25.1% (95% CI: 15.7-38.9%), respectively. Patients with steatohepatitis had a higher liver-related mortality than patients with pure steatosis. In the reference cohort, the 5-year cirrhosis and mortality risks were 0.3% and 4.3%, respectively. CONCLUSIONS: Patients with alcoholic fatty liver disease had markedly increased cirrhosis and mortality risks compared with a matched reference cohort. The cirrhosis risk was more than twice as high for the patients with steatohepatitis than for those with pure steatosis; and was higher for women than for men.

Concentrations of IGF-I and IGFBP-3 and pancreatic cancer risk in the European Prospective Investigation into Cancer and Nutrition.

BACKGROUND: Insulin-like growth factors (IGFs) and their binding proteins (BPs) regulate cell differentiation, proliferation and apoptosis, and may have a role in the aetiology of various cancers. Information on their role in pancreatic cancer is limited and was examined here in a case-control study nested within the European Prospective Investigation into Cancer and Nutrition. METHODS: Serum concentrations of IGF-I and IGFBP-3 were measured using enzyme-linked immunosorbent assays in 422 cases and 422 controls matched on age, sex, study centre, recruitment date, and time since last meal. Conditional logistic regression was used to compute odds ratios (OR) and 95% confidence intervals (CI) adjusted for confounding variables. RESULTS: Neither circulating levels of IGF-I (OR=1.21, 95% CI 0.75-1.93 for top vs bottom quartile, P-trend 0.301), IGFBP-3 (OR=1.00, 95% CI 0.66-1.51, P-trend 0.79), nor the molar IGF-I/IGFBP-3 ratio, an indicator of free IGF-I level (OR=1.22, 95% CI 0.75-1.97, P-trend 0.27), were statistically significantly associated with the risk of pancreatic cancer. In a cross-classification, however, a high concentration of IGF-I with concurrently low levels of IGFBP-3 was related to an increased risk of pancreatic cancer (OR=1.72, 95% CI 1.05-2.83; P-interaction=0.154). CONCLUSION: On the basis of these results, circulating levels of components of the IGF axis do not appear to be the risk factors for pancreatic cancer. However, on the basis of the results of a subanalysis, it cannot be excluded that a relatively large amount of IGF-1 together with very low levels of IGFBP-3 might still be associated with an increase in pancreatic cancer risk.

Partial liver ischemia is followed by metabolic changes in the normally perfused part of the liver during reperfusion.

BACKGROUND: Temporary vascular in- and outflow occlusion is an effective technique for bleeding control during liver resection. However, occlusion can result in ischemia/reperfusion (I/R) injury to the liver. The aim of this study in a porcine model was to investigate the effect of in- and outflow occlusion of part of the liver on the metabolism of the normally perfused parenchyma of the same liver measured by microdialysis. METHODS: Eight pigs underwent laparotomy. A microdialysis catheter was inserted into in the left and right part of the liver, respectively. Microdialysis samples were collected every 30 min. Occlusion of the left part of the liver was achieved for 60 min, followed by 5 h of reperfusion. Samples were analyzed for glucose, lactate, pyruvate and glycerol. Blood samples were drawn to determine standard liver and biochemical parameters. RESULTS: Comparing the ischemic part of the liver with the normally perfused part, significant differences in the levels of lactate, pyruvate and glycerol were found. During reperfusion, similar and continuous decreases below baseline levels were observed for lactate and pyruvate in both the ischemic and normally perfused part of the liver. No significant changes in liver parameters or blood glucose levels were seen. CONCLUSIONS: Partial ischemia of the liver is without effects on metabolism in the normally perfused part. Metabolic changes in the ischemic part of the liver were reversible. However, partial liver ischemia was followed by similar continuous decreases in lactate and pyruvate levels in the whole liver, even though the ischemic insult was not detectable in transaminase levels.

Cytokine changes during warm ischemia and reperfusion of the pig liver with or without preconditioning.

BACKGROUND: Hepatic inflow occlusion results in ischemia-reperfusion injury. The aim of the present porcine study was to investigate whether the pro- and anti-inflammatory cytokine response is involved in mediating the protective effect of ischemic preconditioning (IPC) during, and after warm liver ischemia. METHODS: Fifteen randomized pigs--7 non-IPC and 8 (IPC)--underwent laparotomy followed by 60 min of total ischemia with or without IPC continued by 3 h of reperfusion. Plasma cytokines (IL-6, IL-8, IL-10, and TNF-alpha) were measured during the study period as well as liver parameters (alanine-aminotransferase, alkaline phosphatase, bilirubin, and prothrombin time). RESULTS: In the IPC group, IL-6 increased significantly during reperfusion compared to baseline and the non-IPC group. TNF-alpha increased nonsignificantly in the non-IPC group, while the levels remained stable in the IPC group. IL-8 and IL-10 increased in both groups after reperfusion. Only minor differences were observed in liver parameters. CONCLUSIONS: Warm liver ischemia with or without IPC activates inflammatory cytokines. IL-6 increased significantly in the IPC group compared to the non-IPC group, while the opposite was observed for TNF-alpha. These cytokine changes may be involved in the hepatoprotective mechanism induced by IPC.

Diet, serum insulin-like growth factor-I and IGF-binding protein-3 in European women.

OBJECTIVE: The aim of this study was to examine the relationship of diet with serum insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 in women. DESIGN: Cross-sectional study. SETTING AND SUBJECTS: The population are 2109 women who were control subjects in a case-control study of breast cancer nested in the European Prospective Investigation into Cancer and Nutrition. Control subjects were randomly chosen among risk sets consisting of female cohort members alive and free of cancer (except non-melanoma skin cancer) at the time of diagnosis of the index case. Matching criteria were age at enrolment, follow-up time, time of the day of blood collection and study centre. Diet was measured through validated questionnaires. Serum hormone concentrations were measured by enzyme-linked immunosorbent assays. The relationship between serum IGF-I, IGFBP-3, and intake of nutrients and foods was explored by linear regression in models adjusted for energy intake, age, body mass index, smoking, physical activity, centre and laboratory batch. RESULTS: Serum IGF-I levels were positively related to protein intake (P(trend)<0.001), but not related to energy, fat or carbohydrate intake. Positive relationships were observed with the intake of milk (P(trend)=0.007), calcium (P(trend)<0.001), magnesium (P(trend)=0.003), phosphorus (P(trend)<0.001), potassium (P(trend)=0.002), vitamin B6 (P(trend)=0.03), vitamin B2 (P(trend)=0.001) and inverse relationships with vegetables (P(trend)=0.02) and beta-carotene (P(trend)=0.02). IGFBP-3 was not related with most of the nutrients and foods in this study. CONCLUSIONS: In this population, circulating IGF-I is modestly related with the intake of protein and minerals, and with milk and cheese, while IGFBP-3 does not appear to be related with diet.

Omega-3 fatty acids inhibit an increase of proinflammatory cytokines in patients with active Crohn's disease compared with omega-6 fatty acids.

BACKGROUND: Crohn's disease is a chronic inflammatory condition affecting the gastrointestinal tract. Polyunsaturated omega-3 fatty acids given orally may reduce the secretion of proinflammatory cytokines and hereby downregulate the inflammatory process. AIM: To assess the effects of enteral fatty acids, in the form of Impact Powder (Novartis, Switzerland), as adjuvant therapy to corticosteroid treatment on the proinflammatory and anti-inflammatory cytokine profiles in patients with active Crohn's disease. METHODS: The proinflammatory and anti-inflammatory cytokines were measured in plasma from 31 patients with active Crohn's disease. Patients were randomized for oral intake of omega-3 fatty acid (3-Impact Powder) or omega-6 fatty acids (6-Impact Powder). Clinical and biochemical markers of inflammation were studied at baseline and after 5 and 9 weeks. RESULTS: Within the 3-Impact Powder group, no significant changes in concentrations of interleukin-6, interferon-gamma, monocyte chemoattractant protein-1, interleukin-2, interleukin-5 and interleukin-10, whereas a significant differences in concentration of interleukin-1beta and interleukin-4 were observed during therapy. Within the 6-Impact Powder group a significant changes in concentrations of interleukin-1beta, interleukin-6, interferon-gamma, monocyte chemoattractant protein-1, interleukin-2, interleukin-4, interleukin-5 and interleukin-10 were observed. CONCLUSIONS: The 3-Impact Powder showed immunomodulatory properties and might inhibit an increase of proinflammatory cytokines in contrast to the 6-Impact Powder.

The insulin-like growth factor system and markers of inflammation in adult patients with inflammatory bowel disease.

BACKGROUND AND OBJECTIVES: Catabolism and growth impairment are well-known complications of inflammatory bowel disease (IBD). Recent studies have demonstrated significant changes in the IGF system in IBD patients. The aim of the present study was to investigate correlations between the IGF system and markers of inflammation in IBD. METHODS: A cross-sectional study comprising 99 IBD patients (Crohn's disease (CD, n = 50) and ulcerative colitis (UC, n = 49)). Correlations between markers of inflammation and IGF-I, IGF-II and IGFBP-3 were examined in CD and UC patients in remission and relapse. The patients were clinically scored using Crohn's Disease Activity Index (CDAI) for CD patients and Activity Index (AI) for UC patients. RESULTS: In the UC group we found correlations between IGF-I and CRP (r(s) = Spearman's rho) (r(s) = -0.40, p < 0.01) and albumin (r(s) = 0.46, p < 0.001), IGFBP-3 and albumin (r(s) = 0.36, p < 0.01) and AI score (r(s) = -0.31, p < 0.05). IGF-II correlated with CRP (r(s) = -0.42, p < 0.01), IL-6 (r(s) = -0.65, p < 0.001), albumin (r(s) = 0.41, p < 0.01), AI score (r(s) = -0.30, p < 0.05) and orosomucoid (r(s) = -0.47, p < 0.001). In the CD group we found correlations between IGF-I and CRP (r(s) = -0.40, p < 0.05), and albumin (r(s) = -0.46, p < 0.01), IGFBP-3 and albumin (r = 0.36, p < 0.01). IGF-II correlated with IL-6 (r(s) = -0.65, p < 0.001), albumin (r(s) = 0.41, p < 0.01), CDAI score (r(s) = -0.30, p < 0.05) and orosomucoid (r(s) = -0.47, p < 0.001). CONCLUSIONS: IGF-I, IGF-II and IGFBP-3 are correlated to albumin and IGF-I and IGF-II are correlated to CRP in IBD patients. Further, IGF-II is correlated to IL-6 in IBD patients. This may suggest a correlation between inflammation and the IGF system with involvement in muscle and bone catabolism in IBD.

Markers of fetal growth and serum levels of insulin-like growth factor (IGF) I, -II and IGF binding protein 3 in adults.

Fetal growth has been linked with increased risk of cancer and cardiovascular disease later in life. The insulin-like growth factor (IGF) axis has recently been proposed as a predictor of risk of subsequent cancer and cardiovascular disease. However, only few data are available on the possible association between fetal growth and levels of IGFs later in life. We examined the association between markers of fetal growth, i.e. birth weight, birth length and Ponderal Index, from birth records and serum IGF-I, IGF-II, and IGF binding protein 3 (IGFBP-3) levels in 545 middle-aged Danish men and women. We fitted separate multivariate models including birth weight, birth length, Ponderal Index and serum IGF-I, IGF-II, and IGFBP-3, respectively. After adjustment for age, alcohol intake, smoking, diabetes mellitus, systolic and diastolic blood pressure, serum total cholesterol and current height and weight, we found negative associations between birth weight and Ponderal Index, respectively, and serum IGF-II in men, i.e. the mean regression coefficients were -49.41 (95% CI: -87.06-11.77) (microg/l)/kg and -3.49 (95% CI: -6.73-0.25) (microg/l)/(kg/m3), respectively. Furthermore, in men birth weight was negatively associated with the (IGF-I + IGF-II)/IGFBP-3 and IGF-II/IGFBP-3 ratios, which are believed to be indicators of bioavailable IGF and IGF-II, respectively. However, no other associations were found in any of the models. Between 1 and 16% of the variance in serum IGF-I, IGF-II, and IGFBP-3, respectively, could be explained by the statistical models used in the analyses. We found very little support to the hypothesis of an association between fetal growth and the IGF axis throughout life.

Soluble CD163: a marker molecule for monocyte/macrophage activity in disease.

By immunoprecipitation we have identified a soluble plasma form of CD163 (sCD163), the IL-6 inducible macrophage-receptor for clearing haptoglobin-haemoglobin complexes. A sandwich ELISA for measuring sCD163 was established and used to determine the sCD163 levels in normal subjects and patients with inflammatory and myeloproliferative diseases. In normal subjects, the concentration of sCD163 was high (median 1.9 mg/l) with low intra-individual variation. Highly increased levels were seen in patients with sepsis, myeloid leukaemia and in patients with Gaucher disease characterized by accumulation of tissue macrophages. Although the physiological role of sCD163 remains unknown, our present data suggest that sCD163 might prove to be a valuable marker molecule in infectious and myeloproliferative diseases.

Selenium complexes in the anterior pituitary of rats exposed to L-selenomethionine.

Selenium precipitates were demonstrated histochemically by silver amplification at light and electron microscopic levels in the anterior pituitary of rats exposed to L-selenomethionine (SeMeth). By electron microscopy (EM), the silver amplified selenium complexes were identified in somatotrophs, corticotrophs and gonadotrophs. Precipitates were observed mainly in the secretory granules and to a lesser extent in the lysosomes. The staining intensity increased with increasing amounts of SeMeth. Following a single injection of 3.7 mg Se/kg a substantial increase in staining was observed during the first 48 h after injection and precipitates could still be observed in the anterior pituitary after 2 weeks. During a long-term study where the rats were exposed to selenium contained in the drinking water (3.0 mg Se/l drinking water for 1, 2 or 4 weeks) an increasing amount of precipitates were observed during the first 2 weeks followed by a small decrease in staining intensity. Organic selenium, or rather a metabolite, is suggested to form bands with endogenous metal, primarily zinc, as has been suggested in the brain and anterior pituitary after exposure to sodium selenite.