SD大鼠30天喂养试验食物利用率及脏器系数正常值探讨

目的：探讨SD大鼠30d喂养试验中食物利用率及脏器系数各指标的正常值范围。方法：收集21个批次，雌雄各210只SD大鼠的体重增长，食物利用率和脏器系数等指标进行统计分析。结果：雄在鼠的增重，摄食量和食物利用率均显著高于雌大鼠，表明雄性大鼠的生长发育速度快于雌性，而同龄大鼠的脏器系数则无明的性别差异。结论：本研究所得各指标95%正常值范围与文献报道基本一致，脾脏的脏器系数变异较大，提示在用该指标评价30天喂养试验结果时应慎重。     

Role of insulin-like growth factor-1 and growth hormone in growth inhibition induced by magnesium and zinc deficiencies.

Nutritional deficiencies of magnesium or zinc lead to a progressive and often marked growth retardation. We have evaluated the effect of Mg and Zn deficiency on growth, serum insulin-like growth factor-1 (s-IGF-1), growth hormone (s-GH) and insulin (s-insulin) in young rats. In 3-week-old rats maintained on Mg-deficient fodder for 12 d the weight gain was reduced by about 34%, compared with pair-fed controls. This was accompanied by a 44% reduction in s-IGF-1, while s-insulin showed no decrease. After 3 weeks on Mg-deficient fodder, growth had ceased while serum Mg (s-Mg) and s-IGF-1 were reduced by 76 and 60% respectively. Following repletion with Mg, s-Mg was completely normalized in 1 week, and s-IGF-1 reached control level after 2 weeks. Growth rate increased, but the rats had failed to catch up fully in weight after 3.5 weeks. Absolute and relative pair-feeding were compared during a Mg repletion experiment. Absolute pair-fed animals were given the same absolute amount of fodder as the Mg-deficient rats had consumed the day before. Relative pair-fed animals were given the same amount of fodder, on a body-weight basis, consumed in the Mg-deficient group the day before. In a repletion experiment the two methods did not differ significantly from each other with respect to body-weight, muscle weight, tibia length and s-IGF-1, although there was a tendency towards higher levels in the relative pair-fed group. The peak in s-GH after growth hormone-releasing factor 40 (GRF 40) was 336 (SE 63) micrograms/l in 5-week-old rats that had been Mg depleted for 14 d, whereas age-matched control animals showed a peak of 363 (SE 54) micrograms/l (not significant). In 3-week-old rats maintained on Zn-deficient fodder for 14 d weight gain was reduced by 83% compared with pair-fed controls. Serum Zn (s-Zn) and s-IGF-1 were reduced by 80 and 69% respectively, while s-insulin was reduced by 66%. The Zn-deficient animals showed a more pronounced growth inhibition than that seen during Mg deficiency and after 17 d on Zn-deficient fodder s-IGF-1 was reduced by 83%. Following repletion with Zn, s-Zn was normalized and s-IGF-1 had increased by 194% (P less than 0.05) after 3 d. s-IGF-1, however, was not normalized until after 2.5 weeks of repletion.(ABSTRACT TRUNCATED AT 400 WORDS)     

Concurrent exposure to lead,manganese, and cadmium and their distribution to various brain regions,liver, kidney,and testis of growing rats

Growing rats were exposed to 5 mg/L Pb,ad libitum in drinking water, and administered low or high doses of Mn and Cd intraperitoneal (i.p.) for 30 days. Some groups of animals were also administered combinations of Pb + Mn and Pb + Cd in an identical manner. Analysis of Pb, Mn, and Cd in tissue samples showed the expected dose-dependent accumulation when the metal was administered singly. However, combined treatment produced different types of metal shift in different tissues. Enhanced accumulation of all three metals in the brain, Mn in liver, Pb in kidney and Cd in testis and kidney after combined exposure may make target organs vulnerable to the toxic effects of metals, even when encountered at low concentrations. Further, the decreased levels of blood Pb after combined treatment with Cd or Mn suggests that the significance of blood Pb level as a diagnostic aid for Pb toxicity in coexposed conditions may not be of much value. Changes in the metallic distribution within the tissues after coexposure may be the result of a competition between the administered metals for common binding sites.     

Evaluation of the chronic inhalation toxocity of a manganese oxide aerosol. II. Clinical observations, hematology, clinical chemistry and histopathology.

Monkeys and rats were exposed to 11.6, 112.5, or 1152 microgram Mn/m3 as an Mn3O4 aerosol twenty-four hours per day for nine months. Various serum biochemical, and hematologic evaluations were conducted on both specie. Body weight gain was accelerated in rats exposed to 1152 microgram Mn/m3. Hemoglobin concentrations were slightly elevated for both sexes and both specie exposed to 1152 microgram Mn/m3; however, the effect may not be directly related to Mn. Some evidence of hypophosphatemia was observed. No exposure related effects were demonstrated by organ weight or histopathologic observations.     

Bioavailability of zinc derived from beer and the effect of low dietary zinc intake on skeletal muscle zinc concentration

The bioavailability of zinc from freeze-dried cooked beef was determined using log total tibia zinc and body weight gain as the response criteria. Control diets consisted of different levels of zinc carbonate added to an egg-white protein source. Experimental diets were made by substituting various levels of freeze-dried beef as the zinc source. All diets were isocaloric and isonitrogenous. Zinc in the control diets was utilized as effectively as zinc in the experimental diets. The relative biological value (RBV) of zinc (ZnCO₃=100) in the experimental diet was 103 for 22-day weight gain, and 102 for total tibia zinc. These results indicate that zinc from cooked beef does not have an increased bioavailability over inorganic zinc added to an egg-white protein diet. Because a, large percentage of the total zinc in an animal is found in skeletal muscle, the content of zinc in two types of skeletal muscle was determined from animals fed different levels of dietary zinc. Animals consuming diets with zinc concentrations below their requirement had depressed growth rates; however, no significant differences were found in the zinc concentrations of either the soleus or plantaris muscle. The average zinc content of the soleus muscle (slow twitch oxidative fiber type) was 69 ppm and the plantaris muscle (fast twitch oxidative fiber type) was 15 ppm. These results indicate that the concentration of zinc in skeletal muscle is not significantly reduced in animals whose growth is restricted by low dietary zinc levels.     

Effects of prostaglandin modifiers and zinc deficiency on possibly related functions in rats

Experiments were conducted to investigate the role of prostaglandins (PG) in zinc absorption and biological functions (food intake and weight gain, alkaline phosphatase activity, T-cell-mediated immune response). PG levels were modified by administering an inhibitor of their synthesis, aspirin or indomethacin in the diet. Zinc level was modified by controlling the dietary concentration. Weanling rats were fed the assigned diets for 1 month after which they were anesthetized with ether. Samples of blood, gut contents and mucosa, liver, lung and tibia were collected for zinc, PG, lymphocyte stimulation with T-cell mitogen, and alkaline phosphatase assays. There was more than 50% inhibition of PG synthesis by indomethacin and aspirin. This inhibition of PG synthesis, however, did not affect the zinc status of the rats as measured by general appearance, food intake, weight gain, organ weight, zinc concentration in different organs, serum alkaline phosphatase activity, and cell-mediated immune response to T-cell mitogens. It is concluded that under physiological conditions inhibitors of PG synthesis do not alter these zinc metabolic functions.     

Tri- and tetrachloroguaiacol: Results of a three and six-month feeding study in rats

Male weanling rats were fed diets containing 0, 50, 500 or 5000 ppm of trior tetrachloroguaiacol for 96 days and 182 days. No effect was observed on body weight gain or on food intake. The weights of liver and kidney expressed as percent body weight were slightly increased. However, these effects were not dose-related and were not consistent at both time intervals. Asparate aminotransferase (AsAT) activity was not disturbed by the chloroguaiacols at three and six month intervals. Tetrachloroguaiacol lowered the lactic dehydrogenase activity of rats at all dose levels at the three month interval. Elevated alkaline phosphatase levels were observed in animals receiving 5000 ppm tetrachloroguaiacol after three months. Both these enzymes were unaltered after six months of exposure. All hematological parameters were found to be normal at both time intervals. Tri-and tetrachloroguaiacol caused mild lesions in the kidney of rats at the three-month but not six-month interval. Mild lesions found in the liver of rats consisted of a lobular pattern with periportal perinuclear haloes or with reduction in pericentral cytoplasmic basophilia. These results suggest that both tri-and tetrachloroguaiacol are only moderately toxic to rats.     

Maganese retention in rat brain

Manganese retention was observed in brains and in several other tissues of female Wistar rats after the intratracheal instillation of an inorganic manganese compound: manganese dioxide. Two categories of rats, younger (180 to 200g) and older (330 to 350g), were divided into a control group, in which animals received vehicle only (0.5 mL physiological saline), and an experimental group, in which rats received a dose of 0.48 mg of Mn/kg body weight (in 0.5 mL saline), twice a week for 3 months, for a total dosage of 11.80 mg of Mn/kg body weight. At the end of the exposure period, manganese retention in selected rat organs, brain, liver, kidney, and lung, was analyzed using atomic absorption spectrophotometry. At the end of the 6-wk or 12-wk manganese dioxide exposure period, analysis of variance of the manganese retention results revealed significant differences between Mn-exposed and unexposed rats in brain, kidney, and lung tissues (p<0.01) for both experimental age categories. Moreover, at the end of the 12-wk exposure period, significant results (p<0.05) between younger and older rats were obtained for both brain and kidneys. In both types of tissue, the manganese retention in the younger group was higher than that in older animals.     

Effect of palatable hyperlipidic diet on lipid metabolism of sedentary and exercised rats

OBJECTIVE: The present study was designed to examine 1) whether continuous feeding with a palatable hyperlipidic diet and cycling this diet with chow diet would affect lipid and carbohydrate metabolism in a similar way; and 2) whether the effect of chronic exercise on lipid and carbohydrate metabolism would be modified by these diet regimens. METHODS: Male 25-d-old Wistar rats were assigned to one of six groups: sedentary rats fed with chow diet; exercised (swimming 90 min/d, 5 d/wk) rats fed with chow diet; sedentary rats fed with a palatable hyperlipidic diet; exercised rats fed with the palatable hyperlipidic diet; sedentary rats fed with food cycles (four cycles alternating the chow and hyperlipidic diets weekly); and exercised rats fed with food cycles. After 8 wk of treatment, the animals were killed 24 h after the last exercise session. RESULTS: The hyperlipidic diet and food cycles schedules caused similar increases in body weight gain, carcass lipogenesis rate and adiposity, lipid content of the liver and gastrocnemius muscle, and serum total lipid, triacylglycerol, insulin, and leptin levels. The exercise attenuated body weight gain, adipose tissue mass, and serum triacylglycerol, insulin, and leptin levels similarly in the hyperlipidic and food cycles groups. Carcass lipogenesis rate was not affected by exercise in any of the three groups. CONCLUSIONS: The data showed that the continuous intake of a hyperlipidic palatable diet for 8 wk and the alternation of the high-fat intake with periods of chow intake cause obesity and affected lipid metabolism in a similar way. Chronic exercise attenuated body weight gain and adiposity and improved serum lipid concentrations in both high-fat feeding regimens.     

Splenic participation in glycemic homeostasis in obese and non-obese male rats

We evaluated the effects of splenectomy on glucose homeostasis in obese and non-obese rats. Obesity was induced by subcutaneous injections of monosodium glutamate (MSG; 4 g/kg) in neonatal rats. Control (non-obese) animals received equimolar saline. Splenectomy (SPL) was performed at 21 or 60 days of life (SPL₂₁ and SPL₆₀) in MSG obese and non-obese groups. Glucose tolerance, insulin resistance (IR), adiposity, histology of white adipose tissue (WAT) depots and glucose-induced insulin secretion (GIIS) in isolated pancreatic islets were evaluated at 90 days of life. In non-obese, despite of hyperphagia, the spleen ablation reduced body weight gain and energy efficiency, without changes in GIIS or IR. Slight reduction in glucose tolerance and augmented adipocyte size in subcutaneous WAT was noted in non-obese SPL₂₁ group. In MSG-SPL₂₁ rats was observed augmented body weight gain and energy efficiency, without alter adipocyte size. In contrast, MSG-SPL₆₀ rats had lower body weight gain, reduced energy efficiency and smaller adipocyte size in WAT visceral depot in relation to MSG non-operated. Spleen ablation reduced insulin plasma levels in the MSG-SPL₂₁ and MSG-SPL₆₀ groups. Moreover, splenectomy reduced GIIS and improved glucose tolerance in MSG-SPL₂₁ group. In MSG-SPL₆₀ rats were observed reduction in IR, without changes in GIIS, despite of elevated glucokinase expression in pancreatic islets. In conclusion, spleen ablation reduces body weight in non-obese rats and slightly modifies glucose homeostasis. In contrast, in MSG-induced obesity, absence of the spleen can ameliorate glucose tolerance and reduce insulin secretion, improving insulin sensitivity.     

Effects of intravenous nutrition on lipoprotein metabolism, body composition, weight gain and uremic state in experimental uremia in rats

The effect on serum lipids, lipoprotein fractions, body composition, weight gain and uremic state of including fat in intravenous nutrition was evaluated in rats with chronic uremia. Uremic rats were given high energy (1385 kJ.kg body weight-1.day-1), low nitrogen (0.6 g N.kg body weight-1.day-1) total parenteral nutrition (TPN) for 12 d with either glucose or glucose plus 30% lipids (Intralipid) as the energy source. Additional uremic and nonuremic groups were fed a standard diet orally. During TPN, serum triglyceride and cholesterol levels were slightly higher in rats fed lipid-based TPN compared to those administered glucose-based TPN or fed the oral diet; but there were no differences 8 h after feeding. The serum lipoprotein fractions showed accumulation of lipids in LDL resulting from the lipid-based TPN but no differences in VLDL. In orally fed uremic rats, more lipids were found in HDL than in the TPN-treated rats. The fractional clearance of the fat emulsion was normal and independent of the nutrition composition. Uremic rats administered lipid-based TPN for 21 d had the same weight gain as orally fed, nonuremic control rats (23 +/- 3 vs. 22 +/- 2%); glucose-based TPN did not support normal growth (10 +/- 1%). Uremic rats fed orally did not grow and retained significantly more body water than TPN-fed uremic rats. In uremic animals, lipid-based TPN also was associated with normal body composition despite significantly lower levels of carnitine in plasma, skeletal muscle and heart tissue.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of variable protein contents in diets containing Phaseolus vulgaris beans on performance, organ weights and blood variables in piglets, rats and chickens

A comparison was made of the effects of antinutritional factors present in Phaseolus vulgaris on piglets, rats and chickens. Also the hypothesis of whether the negative effect on weight gain due to the inclusion of raw Phaseolus vulgaris in the diet can be attributed to an insufficient supply of amino acids was tested. Test diets containing 200 g raw Phaseolus beans/kg were balanced for digestible protein and amino acids; in one diet extra casein was incorporated. The main response criteria were live-weight gain and the weight of various organs including the intestine. Live-weight gain in piglets was markedly reduced during feeding 200 g raw Phaseolus vulgaris/kg in the diet, but not in rats and chickens. Addition of casein did not improve the weight gain of the piglets, indicating that a toxic factor was responsible for the reduced weight gain and not an insufficient supply of amino acids. The weights of the spleen and thymus were markedly reduced in the piglets when the diets with raw Phaseolus beans were given, but not in the rats and chickens. Additional supply of casein did not change this effect. Indications were found that when the supply of dietary protein is adequate there is no reduction in pancreas weight with raw Phaseolus beans as was observed in previous experiments. The weight of the intestine was increased in all three species due to feeding raw Phaseolus vulgaris.     

Influence of plane of nutrition on body composition, organ size and energy utilization of Sprague-Dawley rats

Male (61) and female (53) Sprague-Dawley rats (31 d of age, 85 g) were used to evaluate the influence of plane of nutrition on body composition, internal organ size and energy utilization. Six male and nine female rats were sacrificed initially. The remaining animals were randomly assigned, within sex, and fed to gain either 105 g (H) or 40 g (M) or lose 25 g (L) during a 21-d period. Nine rats each from the H and M groups and six from the L group were then sacrificed. The remaining rats from the H (27) and M (27) groups were fed to gain at the H, M or L rate and rats from the L (12) group were fed to gain at the H or M level during a second 21-d period. All rats were sacrificed at the end of the second period. Body composition and weights of internal organs were determined and relationships between energy intake and energy gain were evaluated. Results indicated that at the end of period 2, body composition at equal age and body weight was influenced by nutritional treatment. At equal body weight, body protein weights were lower (P less than 0.05) and body fat, liver and gut weights higher (P less than 0.05) for rats on higher planes of nutrition. Feed required for maintenance of rats during period 2 tended to be lower and efficiencies of gain tended to be higher for rats fed the low level than for those fed the high level during period 1. Rats fed the medium level during period 1 had similar maintenance requirements but higher efficiencies of gain during period 2 than rats fed the high level during period 1. These results suggest that previous nutrition influenced energy utilization through adaptation of high energy expending internal organs as well as through alterations in body composition and composition of body weight gain.     

Varying levels of manganese and iron affect absorption and gut endogenous losses of manganese by rats.

The interactive effects of manganese and iron on true absorption and endogenous losses of manganese were investigated by feeding rats three levels of manganese (0.9, 48 or 188 micrograms Mn/g diet) and two levels of iron (19 or 276 micrograms Fe/g diet) for 7 wk. After 45 d, half of the rats were fed 54Mn and half were injected intraportally with 54Mn complexed to albumin. The relative distribution of 54Mn in tissues was generally similar for rats when 54Mn was administered in these two ways. Manganese-deficient animals retained more of the isotope, had both higher apparent and higher true absorption of manganese, had a greater proportion of 54Mn in their livers and had a lower proportion of 54Mn in their muscles compared with animals fed adequate or high levels of manganese. High iron intake inhibited manganese true absorption, reduced tissue manganese concentrations and inhibited heart manganese-dependent superoxide dismutase activity. However, the greatest effect of dietary iron was on mucosal cell manganese concentrations. Endogenous losses of manganese were approximately 8% of the amount of manganese actually absorbed regardless of intake. Thus, control of absorption in the gut seems to be the major way that manganese homeostasis is maintained. Furthermore, iron seems to be depressing manganese absorption by inhibiting manganese uptake into the mucosal cells.     

Effect of prednisone on growth and zinc metabolism in rats

Growth failure and increased susceptibility to infection are common complications of prednisone administration, which may be associated with reduced zinc nutriture. To test the hypothesis that prednisone administration interferes with zinc metabolism and impairs growth, 41 male, weanling Charles River rats weighing 43–60 g were randomly assigned to four groups. Three groups of 12 rats received prednisone daily for five weeks at dosages of 0.5, 2.0 and 8.0 mg/kg body weight per day, respectively. A fourth group receiving the maximum dose of prednisone. In the fifth week, all the animals received ⁶⁵Zn at 0.5 uCi/100 g body weight by stomach tube. The retention of radioactivity was measured in a small animal whole body gamma counter. The results show that the rate of weight gain decreased in the prednisone-treated animals. In addition, while there were no significant differences in food intake between the three groups of prednisone-treated rats, the food efficiency ratio of 0.10±0.03 of the maximally-treated group was significantly lower (P<.001) than that of the pair-fed controls at 0.36±0.03 as well as those at the lower levels of prednisone treatment (with values between 0.25 to 0.29). The whole body ⁶⁵Zn retention in the pair-fed control animals at 24 and 216 hours was greater than 90% and 60%, respectively, as compared with the retention of 60% and 10% at 24 and 216 hours in the rats administered the highest dose (8 mg/kg/day). Prednisone treatment depressed the capacity of the liver, kidney, muscle, bone and testes to accumulate ⁶⁵Zn. Urinary excretion of zinc and nitrogen increased in proportion to the doses of prednisone used. We conclude that using growing rats, prednisone treatment impaired body weight gain and reduced food efficiency. At a high dosage the steroid decreased whole body ⁶⁵Zn retention and increased the relative dry liver weight.     

双歧杆菌对新生鼠坏死性小肠结肠炎肠道黏膜Toll样受体表达的影响

目的:研究双歧杆菌对新生鼠坏死性小肠结肠炎模型中肠道组织Toll样受体(TLR)2、4、9表达的影响。方法:出生24 h内Sprague-Dewley新生鼠随机分为对照组、实验组、治疗组,每组12只。对照组由母鼠喂养,实验组采取人工喂养+缺氧冷刺激进行造模,治疗组采用人工喂养+缺氧冷刺激并添加喂养双歧杆菌处理(2次/日,1×108cfu/次)。每日定时称体重做记录,在实验第3天处死新生鼠。用HE染色病理切片观察新生鼠肠道病理变化,RT-PCR方法检测肠道黏膜TLR2、TLR4、TLR9的mRNA表达量。结果:3组小鼠体重比较均具有统计学意义,对照组体重增长高于实验组及治疗组,治疗组体重增长高于实验组(P<0.05);实验组病理评分高于对照组及治疗组,治疗组高于对照组(P<0.05);TLR4 mRNA相对表达量实验组高于对照组及治疗组(P<0.05),治疗组的TLR2 mRNA、TLR9 mRNA相对表达量均高于实验组,TLR4 mRNA相对表达量低于实验组,这两组的3种受体mRNA相对表达量比较均具有统计学意义(P<0.05)。结论:双歧杆菌可减轻新生鼠坏死性小肠结肠炎肠道组织病理变化,作用机制可能与双歧杆菌能降低肠道黏膜的TLR4表达及增加TLR2、TLR9表达有关。     

Delayed biochemical changes induced by mercury intoxication are prevented by zinc pre-exposure

This work evaluated the delayed effects of mercury and the effectiveness of zinc in preventing such effects. Pups were pre-treated with 1 daily dose of ZnCl₂ (27 mg/kg/day, by subcutaneous injections) from 3rd to 7th postnatal day and received 1 daily dose of 5 mg/kg of HgCl₂, for 5 subsequent days (8-12 days old). Animals were euthanized 21 days after the end of Hg-exposure. Porphobilinogen-synthase activity as well as zinc and mercury contents was determined in the liver and kidneys. Alanine aminotransferase, aspartate aminotransferase and lactic dehydrogenase activities as well as urea, creatinine and glucose levels were analyzed in plasma or serum. Some animals were considered more sensitive to mercury, since they did not recover the body weight gain and presented an increase of renal and hepatic mercury content, urea and creatinine levels; a decrease in renal porphobilinogen-synthase and alanine aminotransferase activities, as well as a decrease in the liver and an increase in kidney weights. Some animals were considered less sensitive to mercury because they recovered the body weight and presented no biochemical alterations in spite of mercury in the tissues. Zinc prevents partially or totally the alterations caused by mercury even those that persisted for a long time after the end of exposure. These findings suggest that there is difference among the animals regarding the sensitivity to mercury.     

Topiramate reduces energy and fat gains in lean (Fa/?) and obese (fa/fa) Zucker rats

OBJECTIVE: This study examined the effects of topiramate (TPM), a novel neurotherapeutic agent reported to reduce body weight in humans, on the components of energy balance in female Zucker rats. RESEARCH METHODS AND PROCEDURES: A 2 x 3 factorial experiment was performed in which two cohorts of Zucker rats differing in their phenotype (phenotype: lean, Fa/?; obese, fa/fa) were each divided into three groups defined by the dose of TPM administered (dose: TPM 0, vehicle; TPM 15, 15 mg/kg; TPM 60, 60 mg/kg). RESULTS: The reduction in body weight gain induced by TPM in both lean and obese rats reflected a decrease in total body energy gain, which was more evident in obese than in lean rats. Whereas TPM administration did not influence the intake of digestible energy in lean rats, it induced a reduction in food intake in obese animals. In lean, but not in obese rats, apparent energy expenditure (as calculated by the difference between energy intake and energy gain) was higher in rats treated with TPM than in animals administered the vehicle. The low dose of TPM decreased fat gain (with emphasis on subcutaneous fat) without affecting protein gain, whereas the high dose of the drug induced a reduction in both fat and protein gains. The effects of TPM on muscle and fat depot weights were representative of the global effects of TPM on whole body fat and protein gains. The calculated energetic efficiency (energy gain/energy intake) was decreased in both lean and obese rats after TPM treatment. TPM dose independently reduced hyperinsulinemia of obese rats, but it did not alter insulinemia of lean animals. DISCUSSION: The present results provide sound evidence for the ability of TPM to reduce fat and energy gains through reducing energetic efficiency in both lean and obese Zucker rats.     

Nutritional responses of tumor-bearing rats to oral or intravenous feeding

Two experiments were conducted with male rats weighing 170 to 190 grams. In experiment 1, some nutritional parameters were determined in tumor-bearing (TB) (Walker 256 carcinosarcoma) rats fed a 23.6% casein diet for 4 weeks after the tumor inoculation. Cumulative weight gain and food intake were less in TB rats than in nontumor-bearing (NTB) rats. At 3 and 4 weeks after the tumor inoculation, plasma histidine, alanine, and glycine levels were higher in TB rats than in NTB animals. The arginine level was lower in the plasma of TB rats at 4 weeks after the inoculation. The significance of decrease in plasma arginine with regard to tumor growth is discussed. In experiment 2, the effects of total parenteral nutrition (TPN) on TB rats were evaluated as compared with those of 5% glucose (Glc) solution. Body weights of TPN rats were maintained and their nitrogen (N) balances were positive during a 7-day experimental period, while 5% Glc animals showed severe body weight loss and apparent negative N balance. After the end of infusion, the plasma urea level of the TPN group was within normal range, whereas that of 5% Glc group showed a markedly high value. The plasma albumin level was higher in the TPN group. Liver and spleen weights were increased in TPN rats. Absolute tumor weight was somewhat greater in TPN rats than in 5% Glc rats, but the difference in tumor weight:body weight ratios became more slight. These results indicate that TPN was effective for maintaining the nutritional status of TB host without significant acceleration in tumor growth.     

Effect of carbohydrates on lead absorption and retention in weanling rats

This study was designed to determine the effect of corn starch, lactose, and sucrose on lead (Pb) absorption and retention in rat tissues and organs. Seventy weanling Wistar male rats were assigned to the following five treatment groups: Group 1, 31.2% sucrose + 29.3% starch; Group 2, 31.2% lactose + 29.3% starch; Group 3, 60% corn starch (control); Group 4, 52.1% sucrose + 8.4% starch; Group 5, 52.1% lactose + 8.4% starch. All diets were supplemented with 200 ppm lead nitrate. The animals were fed the experimental diets for 8 weeks after which they were sacrificed. Analysis of lead in whole blood, bone (tibia and femur), carcass ash, and gut (alimentary canal) was done by atomic absorption spectrophotometric (AAS) technique. Results indicated that lactose in the diet caused increased lead retention by these tissues. Pb concentration was highest in blood (500% of the control) and bone (433% of control) of animals fed the Group 5 diet with the second highest level for the tissues of rats fed the Group 2 diet. Rats fed the high lactose diet showed the lowest weight gain and those fed the low sucrose diet showed the highest weight gain. The sucrose diets caused increased Pb in bone. In rats fed the sucrose diets, the Pb content of feces was greater than the value in rats fed the corn starch diet. The results of this study show that lactose has a higher stimulatory effect on Pb retention than sucrose.