Ultrastructural changes in the liver after long-term diet of mercury-contaminated tuna

Young kittens were fed daily with contaminated tuna (containing 0.3–0.5 ppm mercury). Neurological disturbances could be observed after 7–11 mo. Electron microscopic examination revealed extensive proliferation of the smooth endoplasmic reticulum and dilatation of the rough endoplasmic reticulum suggesting active detoxification attempt of the liver. Floccular degeneration of the hepatic mitochondria was also observed. Mitochondria lost their normal matrical density, cristae, and inner limiting membrane to become single membrane-bound floccular bodies. Some of these floccular bodies were found to be extruded into the sinusoidal space and engulfed by Kupffer cells. Enlargement of the intramitochondrial granules and areas of focal cytoplasmic degradation were also observed in many hepatocytes. Vacuolar degeneration of the mitochondria in the Kupffer cells was also noted.     

Gas-liquid chromatographic determination of vitamin D in tuna liver and vitamin D resin oils.

Gas-liquid chromatographic (GLC) determination of vitamin D3 in tuna liver and vitamin D3 resin oils was investigated and a routine method slightly modified from the previously reported methods (1, 2) was established. Since both tuna liver and vitamin D3 resin oils contained large amounts of sterols, digitonin-Celite column chromatography according to SHEPPARD et al.(4) was used to remove the sterol influence from the unsaponifiable matters of the oils. After collecting the eluate and evaporating the solvent, the residue was subjected to thin-layer chromatography (TLC) using Kieselgel GF254 as an adsorbent and a mixture of n-hexane-ethyl acetate (4: 1) as a developing solvent. The scraped zones corresponding to vitamin D3 and pre-D3 were trimethylsilylated and then applied to the GLC using 1.5% OV-17 packed on Shimalite W (80-100 mesh) as a stationary phase. Trimethylsilylation of the gas chromatograms was an essential procedure, because the peaks of unknown substances in tuna liver oils and lumisterol in vitamin D3 resin oils could not be separated from the peak of pyro-D3 without trimethylsilylation. When the proposed method was applied to the samples, satisfactory results were obtained.     

Scombroid poisoning after eating tuna fish]

On two separate occasions, a total of eight subjects ate tuna fish. Three out of four persons in the first case (a father aged 54, a mother aged 51 and a daughter aged 24 years) and one out of four persons in the second case (a 28-year-old woman) experienced erythema, respiratory distress and diarrhoea shortly after eating the fish. These symptoms are indicative of scombrotoxic fish poisoning. Histamine is produced in the muscle tissue of scombroid fish, such as tuna or mackerel, if it is kept at a temperature which is too high. Since the concentration of histamine is not evenly distributed through the fish's flesh, not everyone who eats the same fish will become ill to the same extent, and some may not even become ill at all. Furthermore, since the complaints are often mild and of short duration, most patients do not seek medical help, and probably few cases are officially reported. Despite the fact that sometimes only one person from a group of people eating the same fish becomes ill, and that the clinical complaints resemble an IgE-mediated allergic reaction, the illness is a food-borne intoxication with exogenous histamine. Therefore, patients can safely eat the same type of fish again.     

Efficacy of selenium in tuna and selenite in modifying methylmercury intoxication

Efficacy of selenium naturally occurring in tuna was compared to that of selenium in selenite with respect to protection against the toxicity of methylmercury. Male weaning rats were fed diets for 70 days which contained 20 ppm methylmercury chloride (MMC) and graded concentrations of selenium originating from either tuna or sodium selenite. Regardless of its origin, selenium showed protective effect, generally corresponding to its added levels (0.5, 1.0, 1.5 ppm) in terms of survival rate, morbidity and growth rate. Efficacy of selenium in tuna, as compared to that of selenium in selenite, was roughly equivalent in growth rate but approximately half as effective in preventing neurological manifestations. Possible mechanisms were discussed as regards protection offered by selenium and the discrepancy of efficacy between tuna selenium and selenite selenium in preventing neurological signs. This study seems to warrant further investigations upon the protective activity of naturally occurring selenium against methylmercury toxicity, particularly in those fish known to contain high concentrations of both methylmercury and selenium.     

Bioavailability to rats of selenium in various tuna and wheat products

Bioavailability of selenium (Se) in tuna and wheat at various stages of processing was studied in rats. The protein source of the rat diets was torula yeast with Se supplied by either raw, precooked or canned tuna, or whole wheat flour, whole wheat bread or bran. Sodium selenite was used as the standard. Each Se source was fed at three levels: 0.05, 0.10 and 0.15 ppm. By using increase in glutathione peroxidase (GSH-Px) activity in liver, kidney and whole blood as an indicator of bioavailability, no differences were found among the three tuna products or among the three wheat products tested. However, significantly lower GSH-Px activity was found in the combined tuna groups as compared to the combined wheat groups, suggesting that selenium in wheat was more available than that in tuna. There was a significant increase in the liver Se content of rats fed all levels of Se in canned tuna and in kidney, blood and muscle Se of rats fed 0.10 and 0.15 ppm Se in canned tuna in comparison to the tissue Se content in rats fed these same levels of Se in raw or precooked tuna. Since this did not correspond with an increase in GSH-Px activity it was concluded that it did not represent increased bioavailability of canned tuna. Thus, food processing does not appear to affect Se availability, but Se appears to be more available in wheat than tuna.     

Levels of selected trace metals in canned tuna fish produced in Turkey

Trace metals (iron, zinc, copper, cadmium, tin, mercury and lead) in canned tuna, obtained from 4 different brands in Turkey, were determined using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). The trace metals were found to be in the range of 20.2-38.7 mg/kg for iron, 8.20-12.4 mg/kg for zinc, 0.48-0.58 mg/kg for copper, 0.01-0.02 mg/kg for cadmium, 0.02-0.13 mg/kg for tin, 0.06-0.30 mg/kg for mercury, and 0.09-0.45 mg/kg for lead. These results showed that there is no risk in canned tuna with respect to the concentrations of zinc, copper, cadmium and tin. However, it was determined that some of the samples may contain iron, lead and mercury above the legal limits set by health authorities. It was concluded that trace metals in canned tuna must be monitored comprehensively and periodically with respect to the consumer health.     

Scombroid fish poisoning associated with tuna steaks--Louisiana and Tennessee, 2006

Scombroid fish poisoning is an acute illness that occurs after eating fish containing high levels of histamine or other biogenic amines. Symptoms typically include facial flushing, sweating, rash, a burning or peppery taste in the mouth, diarrhea, and abdominal cramps and usually resolve within several hours without medical intervention. More severe symptoms (e.g., respiratory distress, swelling of the tongue and throat, and blurred vision) can occur and require medical treatment with antihistamines. In late 2006, two outbreaks of scombroid fish poisoning occurred, one in Louisiana and one in Tennessee. To determine the source of the outbreaks and to implement control measures, CDC and the state health departments in Louisiana and Tennessee conducted epidemiologic investigations, and the Food and Drug Administration (FDA) conducted traceback investigations of the product. This report describes the results of those investigations, which indicated that the outbreaks in Louisiana and Tennessee were associated with tuna steaks from Indonesia and Vietnam, respectively. The majority of seafood eaten in the United States is imported. FDA programs to identify and prevent seafood hazards such as scombroid fish poisoning have made substantial progress but are able to inspect only a small proportion of seafood entering the United States. The only effective method for prevention of scombroid fish poisoning is consistent temperature control of fish at 相似文献   

Microencapsulated krill and tuna oil blend raises plasma long-chain n-3 polyunsaturated fatty acid levels compared to tuna oil with similar increases in ileal contractility in rats

Long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) may be more bioavailable from krill oil compared to fish oil due to their phospholipid structure. We tested whether a microencapsulated krill and tuna oil blend (ME-TOKO) provided greater LC n-3 PUFA bioavailability, improved blood lipid profiles and increased intestinal contractility compared to microencapsulated tuna oil (ME-TO). Rats were divided into three groups to receive isocaloric diets containing ME-TO, ME-TOKO and microencapsulated olive oil (ME-OO) at 0.3 or 2?g/100?g for 4 weeks. Final body and organ weights, feed intake and waste output were similar. ME-TOKO rats had higher plasma total LC n-3 PUFA levels compared to ME-TO, but liver LC n-3 PUFA levels and plasma triglyceride and cholesterol levels were similar in non-fasted rats. Diets containing 2% ME-TO and ME-TOKO also showed similar increases in ileal contractility. In summary, ME-TO bioavailability of LC n-3 PUFA was similar to ME-TOKO.     

Mercury in canned tuna: white versus light and temporal variation

There are abundant data and advisories for mercury levels in wild fish, but far fewer for commercial fish that compose a large majority of the fish most people eat. Until recently, relatively little attention has been devoted to examining mercury in canned tuna, despite its great importance in human diets. There is substantial media coverage of the benefits and risk from fish consumption, but few peer-reviewed data on canned tuna, the most commonly consumed fish in the United States. In this paper, we examine the levels of total mercury in canned tuna obtained from a New Jersey grocery store from 1998 to 2003, looking for temporal consistency within this data set and particularly for comparison with the Food and Drug Administration's 1991 study. We analyzed 168 cans individually for total mercury. All values are reported as parts per million (= microg/g) on a wet weight basis. In a subset of samples analyzed for total and inorganic mercury, the inorganic mercury was below detection levels; hence at least 89% of the mercury can be considered methylmercury. We found that white-style tuna had significantly more total mercury (mean 0.407 ppm) than light-style tuna (mean 0.118 ppm), presumably reflecting that "white" tuna is albacore, a species relatively larger than the skipjack tuna, which is commonly available as "light" or "chunk light." The maximum mercury in a can was 0.997 ppm, but 25% of white tuna samples exceeded 0.5 ppm. Data suggest a slight increase in levels since 1991, and mercury levels were significantly higher in 2001 than in other years. The mean level of mercury in white tuna (mean 0.407 ppm) was significantly higher than the mean value of 0.17 ppm currently used by the U.S. Food and Drug Administration (FDA) in its risk assessment and public information. There were no significant differences in mercury levels in tuna packed in oil compared to water. Draining contents had no effect on mercury levels, and the fluid, both oil and water, contained little mercury. These data indicate that people who eat canned tuna frequently can choose light tuna and reduce their mercury intake. Canned mackerel had much lower levels of mercury than tuna. Since cans of white tuna frequently exceed the FDA's original action level of 0.5 ppm, it would be prudent to continue some systematic monitoring of the nation's canned fish supply, particularly as the targets of commercial fisheries inevitably change as certain stocks become depleted.