Lead concentrations in cortical and trabecular bones in deceased smelter workers

The aim of the study was to compare bone lead concentrations in cortical and trabecular bones in long-term exposed primary copper and lead smelter workers, and to relate the measured concentrations to the previous lead exposure of the workers. Lead concentrations in seven bones (trabecular: sternum, vertebrae, iliac crest, rib; cortical: femur, left forefinger, and temporal bone) were determined by electrothermal atomic absorption spectrometry in 32 male, long-term exposed copper and lead smelter workers, and compared with levels in 10 male occupationally unexposed reference persons. A time-integrated blood lead index (cumulative blood lead index, CBLI) was calculated for each worker. The lead levels in the seven studied bones were all significantly higher in active and retired lead workers as compared with the reference group (p相似文献   

Lung cancer in Mayak workers: interaction of smoking and plutonium exposure

Lung cancer mortality among 5058 male workers of the Mayak Production Association has been analyzed with emphasis on the interaction of smoking and radiation exposure by using the two-step clonal expansion (TSCE) model of carcinogenesis. The cohort consists of all Mayak workers with known smoking status, who were employed in the period 1948–1972, and who either had the plutonium concentration in urine measured or who worked in the reactors, where plutonium exposure was negligible. Those who died during the first two years after the first urine sampling were excluded. The follow-up extended until the end of 1998. During this time, 2176 workers died, including 244 lung cancer cases. Mayak workers were exposed to external (gamma and neutron) radiation, and in the radiochemical and plutonium plants to plutonium. In the preferred TSCE model, internal radiation and smoking act on the clonal expansion of pre-carcinogenic clones. Assuming a plutonium radiation weighting factor of 20, the excess relative risk per lung dose was estimated to be 0.11 (95% CI: 0.08; 0.17) Sv⁻¹. Most of the lung cancer deaths are found to be due to smoking. The second main factor is the interaction of smoking and internal radiation. The model is sub-multiplicative in relative risks due to smoking and radiation. In a multiplicative version of the TSCE model, internal radiation acts on initiation and transformation rates. This model version agrees with conventional epidemiological risk models, because it also suggests a higher risk estimate than the preferred TSCE model. However, it fits the data less well than the preferred model. An erratum to this article can be found at     

Liver cancers in Mayak workers

Liver cancer mortality risks were evaluated in 11,000 workers who started working at the "Mayak" Production Association in 1948-1958 and who were exposed to both internally deposited plutonium and external gamma radiation. Comparisons with Russian liver cancer incidence rates indicate excess risk, especially among those with detectable plutonium body burdens and among female workers in the plutonium plant. Comparisons within the Mayak worker cohort which evaluate the role of plutonium body burden with adjustment for cumulative external dose indicate excess risk among workers with burdens estimated to exceed 7.4 kBq (relative risk = 17; 95% CI = 8. 0-36) and among workers in the plutonium plant who did not have routine plutonium monitoring data based on urine measurements (relative risk = 2.8; 95% CI = 1.3-6.2). In addition, analyses treating the estimated plutonium body burden as a continuous variable indicate increasing risk with increasing burden (P < 0.001). Relative risks tended to be higher for females than for males, probably because of the lower baseline risk and the higher levels of plutonium measured in females. Because of limitations in current plutonium dosimetry, no attempt was made to quantify liver cancer risks from plutonium in terms of organ dose, and risk from external dose could not be reliably evaluated.     

Copper in organic proteinate or inorganic sulfate form is equally bioavailable for broiler chicks fed a conventional corn-soybean meal diet

An experiment was conducted to investigate the bioavailability of organic copper (Cu) proteinate relative to inorganic Cu sulfate for broiler chicks fed a conventional corn-soybean meal basal diet. A total of 320 day-old Arbor Acres commercial male chicks were assigned to one of five treatments in a completely randomized design involving a 2 × 2 factorial arrangement with two levels of added Cu (125 or 250 mg Cu/kg) and two Cu sources (Cu proteinate and Cu sulfate) plus a control with no added Cu for an experimental phase of 42 days. Plasma and liver tissue samples were collected at both 21 and 42 days of age, and bile samples were also obtained at 42 days of age for Cu analyses. The Cu concentrations in liver and bile increased linearly (P < 0.001) on both days 21 and 42 as dietary Cu levels increased. No significant (P > 0.17) linear regression relationships were observed between plasma Cu concentrations on days 21 and 42 or log10 liver Cu concentration on day 21 and daily analyzed Cu intake. Therefore, based on the slope ratios from multiple linear regressions of log10 liver and bile Cu concentrations with daily analyzed Cu intake on day 42, when Cu sulfate was set as 100%, the estimated relative bioavailability values of Cu proteinate were 78.8% for log10 liver Cu concentration and 79.3% for log10 bile Cu concentration, respectively. There was no significant (P > 0.08) difference in bioavailability between Cu proteinate and Cu sulfate for broilers chicks in this experiment.     

Comparative distribution of marrow CFU-e and CFU-gm progenitors in different anatomic sites in the dog

The interpretation of marrow cloning activity, particularly in serial cultures, is greatly influenced by the reproducibility of the collected marrow samples. In order to establish whether bone marrow cloning activities and precision of the cloning assays are influenced by the site of bone marrow collection in the dog, we studied the incidence of marrow erythroid (CFU-e) and granulocyte-macrophage (CFU-gm) progenitor cells in the iliac crest, sternum, vertebrae, femur, and humerus, using microplasma clot and soft agar culture systems. Marrow samples obtained from the femur and humerus revealed consistently higher cell concentrations than those from the iliac crest, vertebrae, or sternum. Those aspirated from the sternum and vertebrae had lower cell concentrations and were less reproducible. Statistical analysis revealed no significant differences in the incidence of marrow CFU-e and CFU-gm progenitor cells between the femur, humerus, iliac crest or vertebrae. With multiple sampling, the marrow cloning efficiency was consistent and reproducible within the individual dogs. We conclude that the distribution of CFU-e and CFU-gm is comparable throughout the active marrow in the dog and that these sites may be used interchangeably for multiple quantitative analysis of marrow hematopoietic progenitor cells.     

Cadmium, copper and zinc in tissues of deceased copper smelter workers

Workers at a copper and lead smelter in northern Sweden have a multifactorial exposure to a number of heavy metals. The concentrations of cadmium, copper and zinc in liver, lung, kidney and brain tissues have been determined by atomic absorption spectrometry in 32 deceased long-term exposed male lead smelter workers, and compared with those of 10 male controls. Furthermore, copper and zinc levels in hair and nails were determined by energy-dispersive X-ray fluorescence.

The highest cadmium concentrations among both workers and controls were observed in kidney, followed in order by liver, lung and brain. The levels in kidney, liver and lung were all significantly higher in the workers than in the controls (p < 0.03). Among the workers relatively strong positive correlations (p < 0.03) were observed between cadmium concentrations in liver and lung, liver and kidney, liver and brain, and lung and brain. In the exposed workers a positive correlation was observed between cadmium and zinc concentrations in the kidney (r_s = 0.38; p = 0.034). This is probably mainly due to the protein metallothionein, which is stored in the kidney, binding equimolar amounts of these two metals.

The highest concentrations of copper were found in hair and nails among both workers and controls, followed in order by liver, brain, kidney and lung. The tissue concentrations of copper in brain, lung and kidney were all significantly higher among the smelter workers than in the controls (p ≤ 0.036). Copper levels in lung and age at time of death were positively correlated among the exposed workers (r_s = 0.39; p = 0.029). In the same group, positive correlations between copper and zinc concentrations in kidney (r_s = 0.45; p = 0.009) and nails (r_s = 0.68; p < 0.001) were also observed, reflecting possible biological interactions between these two metals.

Among both workers and controls, the highest zinc concentrations were found in hair, followed in order by nails, liver, kidney, brain and lung. Significantly higher tissue concentrations among the workers as compared with the reference group were noted in kidney, liver and brain (p ≤ 0.033).

Neither copper nor zinc concentrations in hair and nails seemed to provide a useful measure of the trace element status of the smelter workers.     

Liver concentrations of copper, cobalt, and selenium in wild Norwegian red deer (Cervus elaphus)

Liver samples from 245 wild red deer (Cervus elaphus) collected during the licensed hunting season in 2001 from five different locations in western Norway were analyzed for copper (Cu), cobalt (Co), and selenium (Se). The associations between these trace elements and geographical location, age group, and sex were studied. The median (and range of) liver concentrations (microg/g wet weight) for all the examined deer were: Cu 20 (1.7-103), Co 0.08 (<0.01-0.18), and Se 0.09 (0.04-1.0). The results indicate a generally low status of Cu and Se. In total, 15 (6%) red deer had deficient Cu levels (< 4 (microg/g). For all three elements, the liver concentrations showed a significant geographic variation. The geographic difference was most distinct for Cu. The lowest median Cu concentration was found in deer from the island Hitra, where 13% of the animals had deficient Cu levels. Significant differences between age groups were found for all elements, and generally, the adults (> or =2.5 yr) had the highest levels. No significant sex differences within the various age groups were found, with three exceptions: female calves and adults had significantly higher Co levels than male deer, and adult males had significantly higher Se levels than adult females. The Cu and Se status of wild red deer in parts of Norway is low; however, the significance of this needs to be explored further.     

Vitamin E modulates radiation-induced oxidative damage in mice fed a high-lipid diet

The Vitamin E (VE) effect was examined on oxidative damage to DNA, lipids, and protein in mice that were fed various levels of lipid diets after total body irradiation (TBI) with X-rays at 2 Gy. No increase of 8-hydroxydeoxyguanosine (8OHdG) by TBI was observed in the + VE group; however, in the case of the -VE group, a significantly higher 8OHdG level was observed in the high-lipid group than in the low- or basal-lipid group. In the groups with TBI, the concentration of thiobarbituric reactive substances (TBARS) only significantly increased in the high-lipid (-VE) group. These changes in TBARS, due to TBI, were not detected in other groups. The contents of protein carbonyls only increased in the (-VE) group. The contents of protein carbonyls was significantly different between the (+VE) and the (-VE) groups, regardless of the lipid levels. The concentrations of GSH, vitamins C and E in the liver were lower, and the concentration of non-heme iron in the liver was higher in the high-lipid group than in the low- and basal-lipid groups. These concentrations in the high-lipid group were significantly different between the (+VE) and the (-VE) groups. These results strongly suggest that mice that are fed a high-lipid diet are susceptible to TBI-induced oxidative damage. Also, decreases in the GSH levels and an increase in the iron level are involved in the mechanism of this susceptibility.     

Radiation Effects on Mortality from Solid Cancers Other than Lung,Liver, and Bone Cancer in the Mayak Worker Cohort: 1948–2008

Radiation effects on mortality from solid cancers other than lung, liver, and bone cancer in the Mayak worker cohort: 1948–2008. The cohort of Mayak Production Association (PA) workers in Russia offers a unique opportunity to study the effects of prolonged low dose rate external gamma exposures and exposure to plutonium in a working age population. We examined radiation effects on the risk of mortality from solid cancers excluding sites of primary plutonium deposition (lung, liver, and bone surface) among 25,757 workers who were first employed in 1948–1982. During the period 1948–2008, there were 1,825 deaths from cancers other than lung, liver and bone. Using colon dose as a representative external dose, a linear dose response model described the data well. The excess relative risk per Gray for external gamma exposure was 0.16 (95% CI: 0.07 – 0.26) when unadjusted for plutonium exposure and 0.12 (95% CI 0.03 – 0.21) when adjusted for plutonium dose and monitoring status. There was no significant effect modification by sex or attained age. Plutonium exposure was not significantly associated with the group of cancers analyzed after adjusting for monitoring status. Site-specific risks were uncertainly estimated but positive for 13 of the 15 sites evaluated with a statistically significant estimate only for esophageal cancer. Comparison with estimates based on the acute exposures in atomic bomb survivors suggests that the excess relative risk per Gray for prolonged external exposure in Mayak workers may be lower than that for acute exposure but, given the uncertainties, the possibility of equal effects cannot be dismissed.     

大黄鱼幼鱼对饲料硒的需求量

为确定大黄鱼(Larimichthys croceus)对饲料硒的需求量, 以Na2SeO3为饲料硒源, 配制6种饲料, 硒的添加水平分别为0(对照组)、0.05、0.2、0.4、0.6和0.9 mg/kg, 实测值分别为0.08、0.16、0.27、0.44、0.66和0.96 mg/kg。在海水浮式网箱中养殖初始体重为(9.140.09) g的大黄鱼幼鱼10周, 结果表明增重率(WG)、全鱼和骨骼中的硒含量随着饲料硒含量的升高而显著升高(P0.05)。当饲料硒含量分别超过0.27、0.66、0.66 mg/kg时, 这些指标的变化趋于平稳。饲料硒含量对存活率(SR)、饲料效率(FE)、体组成、肝体比(HSI)、脏体比(VSI)和肥满度(CF)都没有显著影响(P0.05)。在血清中谷胱甘肽过氧化物酶(GPX)活性、超氧化物歧化酶(SOD)活性和总抗氧化力(T-AOC)随着饲料硒含量的升高呈现先升高后稳定的趋势(P0.05), 并分别在饲料硒含量为0.44、0.44、0.16 mg/kg时达到最大值。肝脏中GPX活性、SOD活性、T-AOC、过氧化氢酶(CAT)活性和谷胱甘肽还原酶(GR)活性与血清中相应酶的活性有相同的趋势。在肝脏中谷胱甘肽硫转移酶(GST)活性随着饲料硒含量的升高呈现先降低后升高的趋势(P0.05), 并在饲料硒含量最高(0.96 mg/kg)时其活力取得最大值。以WG为评价指标, 得出大黄鱼幼鱼对饲料中硒的需求量为0.178 mg/kg。以全鱼和骨骼中硒含量、肝脏GPX活性为评价指标, 得出大黄鱼幼鱼对饲料中硒的最小需求量分别为0.575、0.387和0.440 mg/kg。       

Cancer mortality risk among workers at the Mayak nuclear complex

At present, direct data on risk from protracted or fractionated radiation exposure at low dose rates have been limited largely to studies of populations exposed to low cumulative doses with resulting low statistical power. We evaluated the cancer risks associated with protracted exposure to external whole-body gamma radiation at high cumulative doses (the average dose is 0.8 Gy and the highest doses exceed 10 Gy) in Russian nuclear workers. Cancer deaths in a cohort of about 21,500 nuclear workers who began working at the Mayak complex between 1948 and 1972 were ascertained from death certificates and autopsy reports with follow-up through December 1997. Excess relative risk models were used to estimate solid cancer and leukemia risks associated with external gamma-radiation dose with adjustment for effects of plutonium exposures. Both solid cancer and leukemia death rates increased significantly with increasing gamma-ray dose (P < 0.001). Under a linear dose-response model, the excess relative risk for lung, liver and skeletal cancers as a group (668 deaths) adjusted for plutonium exposure is 0.30 per gray (P < 0.001) and 0.08 per gray (P < 0.001) for all other solid cancers (1062 deaths). The solid cancer dose-response functions appear to be nonlinear, with the excess risk estimates at doses of less than 3 Gy being about twice those predicted by the linear model. Plutonium exposure was associated with increased risks both for lung, liver and skeletal cancers (the sites of primary plutonium deposition) and for other solid cancers as a group. A significant dose response, with no indication of plutonium exposure effects, was found for leukemia. Excess risks for leukemia exhibited a significant dependence on the time since the dose was received. For doses received within 3 to 5 years of death the excess relative risk per gray was estimated to be about 7 (P < 0.001), but this risk was only 0.45 (P = 0.02) for doses received 5 to 45 years prior to death. External gamma-ray exposures significantly increased risks of both solid cancers and leukemia in this large cohort of men and women with occupational radiation exposures. Risks at doses of less than 1 Gy may be slightly lower than those seen for doses arising from acute exposures in the atomic bomb survivors. As dose estimates for the Mayak workers are improved, it should be possible to obtain more precise estimates of solid cancer and leukemia risks from protracted external radiation exposure in this cohort.     

Preliminary study of the distribution of the toxic elements As,Cd, and Hg in human hair and tissues by RNAA

In order to study the relationships between trace element concentrations of hair and internal body burdens, a radiochemical NAA technique has been used for determination of the elements As, Cd, and Hg in autopsy samples of liver, kidney-cortex, lung, and hair from 24 male persons who died by accident. High significant positive correlations were observed between the As concentration in hair and in kidney-cortex, and between Cd and Zn concentrations in kidney-cortex. The contents of Cd, both for lung and kidney-cortex, were related to the smoking habits of the subjects.

     

Mineral nutrition of haddock Melanogrammus aeglefinus(L.): a comparison of wild and cultured stock

The macro and trace mineral composition of vertebrae and muscle in wild and cultured haddock Melanogrammus aeglefinus was determined. Results indicated that haddock deposit c . 10% higher amounts of mineral than salmonids. Based on distribution between the analysed tissues as well as concentration differences, the minerals in wild and cultured haddock were divided into four categories: (1) As, Mn, Na, S and Zn concentration did not show any significant ( P  > 0·05) variation in both muscle and vertebrae; (2) Cr, Co, Mg, Mo and Si concentrations in wild and culture stocks muscle did not vary but vertebrae concentration showed significant differences ( P  < 0·05); (3) Ca and Cu concentration varied in muscle while remaining the same in vertebrae; (4) Al, Ba, Fe, P, K and Sr concentration showed a significant difference in both muscle and vertebrae. Vertebrae P content of cultured haddock was lower than that of wild fish whereas muscle P content was relatively high in cultured fish. Vertebrae and muscle Fe content of cultured haddock was significantly higher than in wild fish. The Mg, K, Co and Cr concentrations in vertebrae were significantly higher in wild haddock than in cultured fish, whereas Mo and Al levels were low. These differences in trace element composition of wild and cultured haddock were probably related to differences in food source and therefore the mineral composition of the diet. The nutritional significance of these findings is discussed.     

Plutonium microdistribution in the lungs of Mayak workers

The degree of nonuniform distribution of plutonium in the human lung has not been determined; thus current dosimetric models do not account for nonuniform irradiation. A better scientific basis is needed for assessing the risk of developing radiation-induced disease from inhaled alpha-particle-emitting radionuclides. We measured the distribution of plutonium activity in the lung by autoradiography and related the activity to specific compartments of the lung. The study materials were lung specimens from deceased workers employed by the Mayak Production Association. The approach to analyzing these lung samples used contemporary stereological sampling and analysis techniques together with quantitative alpha-particle autoradiography. For the first time, plutonium distribution has been quantified in the human lung. The distribution of long-term retained plutonium is nonuniform, and a significant portion of plutonium was retained in pulmonary scars. In addition, a large fraction of plutonium was present in the parenchyma, where it was retained much longer than was estimated previously. The sequestration of plutonium particles in scars would greatly reduce the radiation exposure of the critical target cells and tissues for lung cancer. Thus the prolonged retention of plutonium in lung scars may not increase the dose or risk for lung cancer.     

Glutathione S-transferase distribution and concentration in human organs

The concentration of basic, near-neutral and acid GSH S-transferase was measured in 18 organs from each of 9 male human subjects using radial immunodiffusion. Basic transferases were detectable in all tissues studied. Highest concentrations were found in liver, testis, kidney, adrenal and jejunum while low levels were found in bladder, muscle and thyroid. The concentration in liver was 230 times higher than that in thyroid. Near-neutral GSH S-transferase were absent in all tissues in 5 of the 9 individuals studied. When present they were widely distributed, highest concentrations being found in liver, testis, muscle, adrenal and brain and lowest levels in thyroid, lung, duodenum, stomach, heart and kidney. Acid GSH S-transferases were present in every individual studied although they were undetectable in the liver of a single subject. Highest concentrations were present in colon, jejunum, ileum, bladder, spleen and lung while low concentrations were found in liver. Our study provides conclusive evidence of marked inter-individual and inter-organ variation of the three groups of human GSH S-transferase.     

一氧化氮在大鼠肝肺综合征发病机制中的作用研究

目的探讨一氧化氮（NO）在大鼠肝肺综合征（HPS）发病机制中的作用。方法应用放射免疫分析法检测HIS大鼠血浆和肝组织、肺组织匀浆中NO的水平。结果（1）HIS大鼠血浆和肝组织、肺组织匀浆中NO水平动态升高。（2）各阶段血浆和肝组织、肺组织匀浆中NO水平与谷丙转氨酶（ALT）、总胆红素（TBIL）呈正相关,出现腹水者血浆和肝组织、肺组织匀浆中NO水平高于未出现腹水者。结论在HIS形成过程中,血浆和肝组织、肺组织匀浆中NO水平持续升高,与肝功能受损状态和腹水形成有关,提示扩血管物质NO可能参与HIS的发生。     

Studies on the expression of genes encoding apolipoproteins B100 and B48 and the low density lipoprotein receptor in nonhuman primates. Comparison of dietary fat and cholesterol

African green monkeys were fed diets containing low and moderate cholesterol concentrations with either polyunsaturated or unsaturated fat as 40% of calories. Plasma total cholesterol, low density lipoprotein (LDL) cholesterol, and apoB concentrations generally were higher in animals fed (a) the higher dietary cholesterol concentration and (b) saturated fat. At necropsy, liver and intestine were removed, and measurement of mRNAs for LDL receptors (liver) and for apolipoprotein B (liver and intestine) was done. Monkey small intestine mucosa made exclusively apoB48 while the liver made only apoB100, although apoB mRNA in both tissues was the same size (14 kilobases). No dietary cholesterol or fat effects were found for apoB mRNA abundance in the liver, while the animals fed the higher dietary cholesterol level had 50% lower levels of hepatic LDL receptor mRNA. In a separate group of animals, livers were perfused and the rate of apoB secretion was measured. No dietary fat effect on apoB secretion rate was found, and no relationship between plasma LDL cholesterol concentration and the rate of hepatic apoB production existed. These findings support the idea that the dietary factors that increase LDL concentrations act by reducing clearance of apoB-containing particles rather than by increasing production of these lipoproteins. Hepatic LDL receptor mRNA was similar in abundance in polyunsaturated fat and saturated fat-fed animals, suggesting that the difference in plasma cholesterol concentration between these groups is not mediated via effects on LDL receptor mRNA abundance. The level of intestinal apoB mRNA was about 30% higher in animals fed the moderate dietary cholesterol concentration. Earlier studies have shown that more cholesterol is transported in chylomicrons from the intestine when dietary cholesterol levels are higher, and the increased intestinal apoB mRNA abundance may reflect increased intestinal cholesterol transport and chylomicron apoB48 production.     

厦门海域两头中华白海豚体内铁的含量

铁是动物体的必需元素,是血红蛋白和肌红蛋白中氧的携带者。动物体内的含铁化合物主要为血红蛋白、肌红蛋白（Mb）、转铁蛋白、含铁血黄素和含铁酶（王夔,1992）。铁与水生哺乳动物的潜水能力密切相关。Wright和Davis（2006）对威德尔海豹（Leptonychotes weddellii）的研究表明,Mb是水生哺乳动物最重要的储氧部位,在胃肠吸收后状态下Mb从正常水平降低7％时,有氧潜水限度（Aerobic Dive Limit,ADL）下降39％;Mb增加两倍时,ADL则增加30％。     

Lung cancer mortality among male nuclear workers of the Mayak facilities in the former Soviet Union

An analysis of lung cancer mortality in a cohort of 1,669 Mayak workers who started their employment in the plutonium and reprocessing plants between 1948 and 1958 has been carried out in terms of a relative risk model. Particular emphasis has been given to a discrimination of the effects of external gamma-ray exposure and internal alpha-particle exposure due to incorporated plutonium. This study has also used the information from a cohort of 2,172 Mayak reactor workers who were exposed only to external gamma rays. The baseline lung cancer mortality rate has not been taken from national statistics but has been derived from the cohort itself. For both alpha particles and gamma rays, the results of the analysis are consistent with linear dose dependences. The estimated excess relative risk per unit organ dose equivalent in the lung due to the plutonium alpha particles at age 60 equals, according to the present study, 0.6/Sv, with a radiation weighting factor of 20 for alpha particles. The 95% confidence range is 0.39/Sv to 1.0/Sv. For the gamma-ray component, the present analysis suggests an excess relative risk for lung cancer mortality at age 60 of 0.20/Sv, with, however, a large 95% confidence range of-0.04/Sv to 0.69/Sv.     

Comparative study of cephalexin and cephradine distribution in the body of rats]

Distribution regularities of cephalexin and cephradine, 2 semisynthetic cephalospor in antibiotics for oral use were studied on rats. It was found that the cephalosporins had a capacity for satisfactory penetration through the histochematological barriers. The drugs were rather rapidly absorbed from the gastrointestinal tract of the rats into the blood. Their maximum blood levels were determined 1 hour after the administration. The highest cephalosporin concentrations were detected in the kidneys and liver. Still, the level of cephradine in the kidneys was lower and that in the liver was higher than the levels of cephalexin. The lowest concentrations were found in the skeletal muscles. The character of cephradine distribution in the lungs, heart and spleen differed from that of cephalexin; the maximum concentrations of cephradine in these organs were achieved 1 hour after its administration, while those of cephalexin were achieved in 30 minutes. The antibiotics were not detected in the brain tissue. No increase in the concentration gradient with time was observed.