SummaryThis study reports age-related changes in 7 element (iron, copper, zinc, manganese, mercury, cadmium and lead) concentrations in the liver, kidney and brain of male and female Sprague-Dawley rats from 1 to 364 days of age. Atomic absorption spectrometry was used for the measurements.Copper, mercury and cadmium in the male and female kidneys increased from weaning until 127 days of age, as did iron concentrations in the female liver and kidney. After 127 days, especially, the copper concentration in the female kidney and cadmium concentration in the male and female kidney increased further. Consistent and statistically significant ( P < 0 .05) sex differences in element concentrations were found for three elements (iron, copper and zinc). Except for the zinc concentration in the liver from SO to 72 days, iron (in liver and kidney), zinc (in kidney) and copper (in liver, kidney and brain) concentrations in female rats during the adult stage, were all higher than those of male rats. Isolated differences for other elements (manganese, mercury and cadmium) were also found.The data will be helpful when setting up longterm animal investigations of the biological effect of elements. Keywords: Rat; Ageing; Sex difference; Trace element; Atomic absorption spectrometryIn animal experiments, age and sex are basic ·Present address: Tokyo University of Agriculture,

During spring 1989, thirty-three whooper swans (Cygnus cygnus) died at Lake Miyajima in Hokkaido, Japan; 15 were examined. The birds were diagnosed as having subacute lead poisoning due to ingestion of spent lead shot. The main gross findings were bile-stained liver, edematous or gelatinous bone marrow, bile-stained lining with hyperkeratosis and lead pellets in the gizzard, and proventricular impaction. Histopathologically, there was lead-hemolytic jaundice of the liver, hemosiderosis in the liver and spleen, and hypoplasia of the bone marrow with increased numbers of polychromatic erythroblasts. Acid-fast intranuclear inclusion bodies were seen in kidneys of seven swans. Under electron microscopy, inclusion bodies had frayed contours and consisted of high-electron-dense fine granules. The lead concentration of the liver ranged from 5.5 to 44.3 mg/kg wet weight. It was suggested that these changes resulted from excess breakdown of erythrocytes, inhibition of heme synthesis, and impaired erythropoiesis caused by lead shot.

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Abstrac t. Nineteen lead-p oisoned white-front ed geese (Anser a/bifrons) , includi ng nine imm ature birds, were exami ned path ologically. Subacute lead poiso ning due to ingestio n of spent lead shots was diagnosed pat hologically and confi rme d by demo nstra ting high lead conce ntra tio n in the liver. Th e liver lead conce ntration ranged from 6.9 to 67.7 mg/kg wet weight. T he most suggestive gross lesion s were mo ttled bile-stai ned liver in eight geese and provent ricular impa ction and /or the presence of lead pellets in the gizzard. Histologic lesion s of the liver consisted of Kup fTer cell hemos ideros is, large bile plugs in dilated canaliculi, bile pigment ation in hepat ocytes, and bile extravasation and assoc iated hepati c necrosis. Seven geese of the rema ining II birds also had hepat ic necrosis in the liver, the greenis h disco lora tion of which was obscure macroscopica lly. The liver discolorati on was cons idered a jau nd ice du e to both rapid ove rprod uction of bile from increase d breakdown of erythrocy tes and intrah epat ic im paired excretio n of bile. The severity of lesion s was not cor related to the liver lead concentra tions. All exa mined geese had hemosiderosis of mononuclear phagocytic system cells in the spleen and hypoplasia or ede ma of the bone marr ow with increased numbers of polychrom atic erythro blasts. Th ese prom inent changes pro bably resulted from excess breakdown of erythrocytes, hypercholia followed by intrahepat ic cholestasis, and disrupt ed erythro poiesis in bone mar row caused by lead .Key words: An ser a/bifrons; bile extravasa tion; bile infarct; cho lestasis; jaundice; lead poison ing; waterfowl; white-fro nted geese.Lead poisoning due to ingestion a nd ret en tion o f spe n t lead sho t has been recogni zed as a co mmo n disease of wild waterfowl in hea v ily hun ted a reas in th e U n ite d St ates .5,30This co nd it io n has al so been re corded in 22 co u nt ries and is st ill a serious problem in waLake Miyaj ima is a sma ll lake (area = 0.36 krn-, maximum terfowl worldwide." In Japan , mortal ity o f wh ooper dept h = 2.4 m) in Hokkaido and is the north ernmost point swa ns (Cygnu s cygnus) a ffec te d with lead poi soning in in Japan where wild water fowl arrive in spring and fall every 198 9 ha s been reported." This m ortality associa te d year. Th ey usually stay for 3 to 4 weeks at the lake during the migrat ing season. Hunt ing has been allowed at the lake with lead poisoning was th e first o f it s kind in waterfowl since the 19th century, beca use wild wat erfowl usuall y prey in Japan , a lt ho ugh it was known to ha ve occurred spo-on grains grown on the nearb y farm land. Large nu mb ers of radi call y. I I spen t lead shot have probabl y accum ulated at the bott om of Lead poison ing in geese wa s initiall y noted in 1893 the lake, and swans that frequent the lake prob abl y have in N orth Carolina." Fi ve lead-poisoned C a nad a geese ingested th is shot. (Brant a canadensis) were reported in Mich igan in Eighty white-fronted gee...

Heat resistance at 95 C, heat activation at 75 C, and germination response were determined for spores of 10 serotype strains of Clostridium perfringens type A, including five heat-resistant and five heat-sensitive strains. The D95-values ranged from 17.6 to 63.0 and from 1.3 to 2.8 for the heat-resistant and the heat-sensitive strains, respectively. The heat-activation values, the ratios between the heated and unheated viable counts of spore suspensions, ranged from 0.0035 to 0.65 and from 6.5 to 60.0 for the heat-sensitive and the heat-resistant strains, respectively. Spores of these strains were divided into two distinct germination types on the basis of their germination response; spores of the heat-resistant strains germinated in KCl medium after heat activation (K-type), and spores of the heat-sensitive strains germinated in a mixture of L-alanine, inosine, and CaCl2 in the presence of CO2 without heat activation (A-type). The strains were tested for enterotoxigenicity by a reversed. passive latex-agglutination (RPLA) test. All the heat-resistant strains were RPLApositive, whereas the heat-sensitive strains were all RPLA-negative. A total of 37 strains of the organism isolated from food-poisoning outbreaks were tested for spore germination and enterotoxin formation. All of the 20 heat-resistant strains showed K-type spore germination and, except for three strains, were RPLA-positive, whereas all of the 17 heat-sensitive strains showed A-type spore germination and, except for only one strain, were RPLA-negative.Clostridium perfringens type A is one of the most important anaerobes causing human food poisoning. The food poisoning results from the ingestion of food contaminated with a large number of viable vegetative cells of the organism. The enterotoxin produced by sporulating cells in the intestine is responsible for the food-poisoning symptoms (11,22).It has been stated that enterotoxin is a structural component of the spore coat (8) and that a direct relationship exists between enterotoxin formation and spore production in C. perfringens (4, 6). However, not all sporulating strains produce detectable amounts of enterotoxin (16,20). Among the enterotoxin-negative strains are those that sporulate almost as well as the enterotoxin-positive strains.It is well recognized that the so-called heat-resistant and heat-sensitive strains of C. perfringens are both involved in food-poisoning outbreaks (9, 23). In fact, at 31 7