Renal and skeletal lesions in experimental cadmium poisoning: histological and biochemical approaches

The importance of cadmium as a factor in calcified upper urinary tract stone disease--a prospective 7-year study

The non-essential trace metal cadmium may cause major pathological effects on the kidneys. A group of coppersmiths who have been chronically exposed to cadmium poisoning was systematically studied over a 6-year period. The stone prevalence in the group is now just under 40% as compared with 3.5% in a general population. The blood cadmium levels have remained persistently elevated despite removal of the cadmium source. The measurement of cadmium as a means of monitoring chronic poisoning has been undertaken in terms of the prospective study in the coppersmiths and also in its relationship to other trace metals, namely serum zinc and copper. Urologists should be aware of the possibility of cadmium poisoning.

Cadmium content of human cancellous bone

The cadmium content of human cancellous bone was related to age, sex, bone loss, physical properties, and elemental composition. Bone specimens from the anterior iliac crest were collected from 889 cadavers with a normal mineral status, and from 50 cadavers which had bone loss from chronic diseases and immobilization. The element concentrations were analyzed using atomic absorption spectrophotometry. Bone fluoride levels ere determined with the ion specific electrode, the mineral density with the gamma ray attenuation method, and the compressive strength with a strain transducer. The data were analyzed using multiple linear regression analysis. The mean cadmium content of 0.22 +/- 9.16 micrograms/g dry weight (+/- SD) in the samples did not change with age and its content was slightly greater in males than in females. Furthermore, no statistically significant relation was found in cadmium content to bone loss changes or to the calcium content of bone. The cadmium content had a high statistically significant positive correlation with the strontium and nickel content.

Effect of cadmium on calcium, magnesium and phosphorus content of rat molars

Eleven groups of Wistar rats, 10 animals in each group, received graded doses of CdCl2 in the drinking water from conception until sacrifice at the age of 10 weeks. The Ca and Mg contents of whole molars as well as enamel and dentin for each group were recorded by atomic absorption spectrophotometry (AAS). The inorganic P content of the control and three experimental groups was measured by colorimetry. Four molars from each of eight additional animals, four controls and four from the 22.5 parts/10(6) Cd group were ground transversely and subjected to X-ray microanalysis. AAS analyses showed that the Ca level of whole molars increased significantly with a Cd supply above 2.5 parts/10(6). The Ca content was significantly correlated with the Cd contents of the same teeth. The increased Ca seemed to be in the enamel. The Mg content decreased significantly with Cd doses below 12.5 parts/10(6). This decrease seemed to be in dentin. The P level of the molars increased following Cd supply, but not significantly so. The X-ray spectra demonstrated that there were no significant differences between the Ca/P ratios of the two groups, either in enamel or in dentin. It is concluded that absorption of Cd alters the normal Ca, Mg and P levels in rat molars. This may reflect a disturbance of Ca, P and Mg metabolism in the organism generally.

The acute and subacute effects of cadmium an calcium homeostasis and bone trace metals in the rat

The effect of acute and subacute administration of cadmium chloride on calcium homeostasis and the trace metal content of the bone was investigated in the male rat. A single subcutaneous injection of cadmium chloride (1.5 mg Cd++/kg) produced a decreased plasma concentration of calcium and a decrease in the femur concentration of both calcium and zinc. repeated administration of cadmium chloride (1.5 mg Cd++/kg) daily, for 28 days) caused a marked hypocalciuria that persisted throughout the period of cadmium treatment. There was an accompanying increased excretion of alkaline phosphatase into the urine, and plasma inorganic phosphate was also elevated in these animals. Both of these effects are considered to be evidence of kidney damage. A possible mechanism for this cadmium-induced effect may involve a disturbance of the renal biotransformation of vitamin D, and decreased bioavailability of the essential trace metals due to metallothionein synthesis and excessive loss into the urine.

Influence of sex and age on the biological half-life of cadmium in mice

The influence of age on the whole-body biological half-life of 109Cd was studied in male mice following ip injection. The influence of sex on whole-body and organ retention was ascertained after sc injection. The whole-body biological half-life of 109Cd of the older mice was more than twice that of the younger mice, and that of the female mice was longer than that of the male. In kidneys and salivary glands the biological half-lives of 109Cd of females were also longer than those of males. These differences demonstrate a biological difference between males and females with respect to whole-body half-life of 109Cd. The effects of age and sex on the biological half-life of Cd in mice are assessed quantitatively.

Characterization of the proteinuria induced by prolonged oral administration of cadmium in female rats

Female Sprague-Dawley rats were given 200 ppm cadmium (Cd) in the drinking water for 11 months. Total proteinuria and the concentrations of Cd in blood, urine, liver and kidney cortex were determined monthly. The proteinuria was characterized by Sephadex G-75 chromatography and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. From the 8th month of treatment, the Cd concentration in the kidney cortex levels off at a value of about 250 microgram/g wet wt and this phenomenon coincides with the occurrence of proteinuria. The proteinuria was characterized by an increased urinary excretion of high molecular weight (HMW) proteins, particularly gamma-globulins. Aminoaciduria also increased which suggests the existence of a slight tubular dysfunction. The renal dysfunction induced by chronic oral administration of Cd seems different from that observed in a previous study in which Cd was administered by the i.p. route (1 mg Cd/kg, 5 times a week for 2 months). For the same level of Cd in the kidney cortex the proteinuria induced by i.p. injection of Cd was usually of mixed type and in some cases of the tubular type. The development of this proteinuria was coincident with the levelling off of Cd concentration in the kidney cortex and in the liver. The saturation of liver by Cd is very likely at the origin of he extensive tubular lesion and of the mixed type proteinuria observed in the i.p. experiment. These results demonstrate the importance of mode of Cd administration on the nature of the Cd-induced proteinuria in animal. They support also our proposal that both low and HMW proteins should be determined in urine for the early detection of renal damage occurring in man chronically exposed to cadmium.

Whole body calcium deficit in cadmium-exposed workers with hypercalciuria

Whole body elemental composition of 15 men occupationally exposed to cadmium was determined by total body in vivo neutron activation analysis and whole body counting. A significant deficit (P less than 0.01) in calcium was observed, compared with two groups of control subjects. The deficit increased with length of time exposed to cadmium.

Influence of sex and dietary calcium on intestinal cadmium absorption in rats

The influence of sex and dietary calcium on whole-body retention of orally administered 115mCdCl2 has a half-life of 43 days, distinguishing it from 115Cd of half-life 2.3 days was studied in one-year-old control and gonadectomized male and female rats. Gonadectomy was performed at the age of four months. Each of the four experimental groups was divided into three subgroups that were fed rat food with a different calcium content (2.4, 0.7, and 0.3% Ca) throughout the experiment. Regardless of sex and gonadectomy the mean percent values of 115mCd retention in the whole body decreased with increasing dietary calcium level. Male rats retained less cadmium than all other experimental groups of animals. These data clearly point out that sex and diet might influence the level of ingested cadmium in the body.

Dose-related alterations in growth and mineral disposition by chronic oral cadmium administration in the male rat

The effect of cadmium (1, 10, or 100 ppm) administered to male rats in drinking water for 13 weeks on body weight and mineral disposition (Cd, Mg, P and Zn) in several body tissues was examined. Most alterations observed in these parameters occurred only at the 100 ppm dose of Cd. Terminal body weight was decreased by 10% in rats ingesting Cd at 100 ppm resulting from decreased food intake since weight gain/food consumption ratio was the same for all treatment groups. In serum, cadmium ingestion resulted in an inhibition of alkaline phosphatase activity at all concentrations and phosphorous was elevated only in animals receiving 100 ppm Cd. No changes were observed in Ca in urea. In bone, Cd decreased zinc content, increased Ca content, but did not influence bone ash, Mg or P and roentgenographic examination revealed no bone abnormalities. In both liver and kidney, cadmium ingestion did not influence intestinal absorption of Ca, Mg, P, or Zn or the renal excretion of Ca, P, or urea. The results of this study indicate that alterations in body weight and tissue mineral disposition resulting from chronic Cd ingestion are dose-related.

Effect of chronic low-level cadmium intoxication on the Haversian remodeling system in dogs

This experiment was carried out in order to determine whether the chronic administration of low doses of cadmium resulted in an alteration of the haversian bone remodeling system in dogs. Two pairs of littermate beagles were administered 25 ppm cadmium chloride in their drinking water for 6 months. Four beagles matched for age and sex from the same colony served as controls. By means of fluorescent labeling, we measured haversian bone remodeling parameters according to the techniques described by Frost. Statistical analysis of the results showed significant changes at the 0.01 level in: activation frequency, appositional rates, and number of osteoid seams. At the 0.05 level, significant differences were found in the number of resorption spaces and the bone formation rate. In the absence of other evidence indicative of an alteration in the internal milieu of the dogs, it is concluded that a direct toxic action of cadmium on the mechanisms of activation of cells responsible for the creation and formation of new haversian systems cannot be excluded.

Cadmium effects on bone and dental tissues of rats in acute and subacute poisoning

Injection of cadmium chloride to rats fed by normal calcium diet induced distrubances of tibia and incisor hard tissues metabolism. It is suggested that there may be the possibility of direct cadmium actions on those hard tissues metabolisms.

Early signs of oral and inhalative cadmium uptake in rats

Female wistar rats, 170--190 g, were exposed for 90 days to cadmium oxide aerosols containing 25 and 50 microgram Cd/m3 and for 63 days to 100 microgram Cd/m3. Simultaneously female wistar rats, 170--190 g, were fed 25, 50, and 100 ppm cadmium in drinking water for 90 days. After inhalation and ingestion of the metal, there were comparable kidney cadmium levels, but higher liver and blood levels after oral uptake. Coincident with the higher blood cadmium concentrations, proteinuria was observed only after oral administration. Likewise, there was a significant decrease of serum iron after ingestion and no lowering of the serum iron after inhalation of the metal. The inhalation led to a marked dose dependent weight increase of the lungs, which was followed by an impairment of gas exchange. Obviously, after inhalative cadmium uptake of 90 days pulmonary changes precede renal damage.

Cadmium feeding: apparent depression of atrioventricular-his-Purkinje conduction system

Male rats were exposed to 0, 10 and 130 p.p.m. cadmium administered in 0.5% saline drinking water for 71 days. Biweekly records of ECGs, Hct, body weight and blood levels of cadmium were made. Rats exposed to 130 p.p.m. cadmium showed slower growth rates and declining Hct indicative of acute cadmium poisoning. At the end of the experimental period, carotid artery blood pressures and whole heart cadmium levels were determined. Although no significant blood pressure changes were observed in the experimental groups, the cadmium content of the hearts of the higher dose group was significantly higher than in the hearts of the lower dose group. The PR interval of the ECG was lengthened progressively and to the same extent in both experimental groups with continued cadmium feeding. These experiments offer evidence that the accumulation of even moderate amounts of cadmium will be manifested in marked changes in cardiac conduction without overt signs of cadmium poisoning.

Biomedical responses of rats to chronic exposure to dietary cadmium fed in ad libitum and equalized regimes

Forty 100 g male rats were fed, in groups of eight, either 0, 5, or 25 ppm cadmium in a purified diet for 14 wk. Three groups were fed each of the levels of cadmium on an ad libitum basis. Two other groups were fed either 0 or 5 ppm cadmium in amounts that were equalized to that consumed by the 25 ppm group fed ad libitum. Cadmium ingestion decreased daily diet consumption, weight gain, and terminal body weight. These parameters were not significantly different in rats whose diet consumption was equalized. Packed cell volume and serum iron as well as serum zinc were decreased in the rats fed 25 ppm cadmium. These effects were not related to diet intake. No major differences were observed in serum ceruloplasmin, glucose, protein, leucine aminopeptidase activity, or copper in any of the groups. Blood urea nitrogen and renal leucine aminopeptidase activity were decreased by cadmium ingestion in the rats fed ad libitum only. In contrast, serum alkaline phosphatase activity was elevated by cadmium in the equalized-intake groups only. Cadmium and zinc concentrations were elevated and the iron concentration was decreased in the kidney, liver, and intestinal mucosa of the cadmium-fed rats irrespective of level of diet consumption. The increased uptake of cadmium in these tissues was coincident with the increased content of the cadmium-binding protein, metallothionein, in the cytosol fraction. The results indicate that some parameters of chronic cadmium toxicity are associated with diet consumption whereas others are not.

Clinical and biochemical abnormalities in coppersmiths exposed to cadmium

5(18.5%) of a group 27 coppersmiths exposed to cadmium fume had stone disease. When compared with a control group of assembly workers in the same factory they had evidence of renal impairment as shown by blood biochemistry and proteinuria. A greater tendency to liver damage was found in the coppersmiths. There was evidence that restrictive airways disease was more common in the coppersmiths than in the control group. Blood-cadmium concentrations were significantly higher in the coppersmiths and in the assembly workers than in a reference population.

Metabolism of 109Cd in rats fed normal and low-calcium diets

Growing male rats were fed purified diets that contained either 0.6% or 0.1% calcium to investigate the relationship of calcium intake to the uptake, tissue distribution, and excretion of 109Cd. An equal number of rats were fed either the 0.6 or 0.1% calcium diets for 4 wk before they were used for experiments. In the first experiment 11 rats from each dietary group were administered 5 muCi 109Cd by stomach tube and were then maintained in metabolism cages for 72 hr. Animals fed the low-calcium diet took up more 109Cd, as significantly higher levels of radioactivity were found in the intestinal mucosa, serum, lungs, liver, kidneys, and urine and a significantly lower level was found in the feces. Higher levels of 109Cd, associated with low-molecular-weight proteins that may be related to the absorption process, were found in the intestinal mucosa of the low-calcium group. In the second experiment 10 rats from each dietary group were administered 5 muCi 109Cd by subcutaneous injection and then maintained in a metabolism cage for 72 hr. No significant differences were found in the distribution or excretion of 109Cd except for the lungs where radioactivity was greater in the low-calcium group. The results of the study indicate that the enhanced cadmium toxicity observed in calcium-deficient animals exposed to the heavy metal is the result of an increased uptake from the small intestine.

The ultrastructural localisation of cadmium

A modified technique for the ultrastructural localisation of heavy metals is described in this paper. The method involves precipitation of heavy metals as sulphides in the tissue by using (NH4)2 S after brief fixation in glutaraldehyde. The sulphides are, in the presence of a physical developer, then used to catalyse the reduction of silver ions into visible molecular silver. This latter step of physical development has been normally carried out after embedding and sectioning. However, when we followed this method we found that the dark metal sulphide was lost from the tissue during the embedding in epoxy resin. Hence the method was unsuitable for our proposed experiment on the ultrastructural localisation of cadmium. We subsequently modified the technique primarily by treating very thin tissue slices with the developer before dehydration and embedding, thus eliminating any problem from sulphide loss. This modified technique was used to investigate the ultrastructural localisation of cadmium in the kidneys of mice which had been exposed to 50 ppm cadmium in their drinking water for up to eight months. The molecular silver was found to be located mainly in the proximal tubule cells, either as dense clumps in apical vesicles and lysosomes or diffuse grains throughout the cytoplasm of the cells particularly in the basal region. We interpret these results as indicating that cadmium is found in the apical vesicles, lysosomes and cytoplasm of proximal tubule cells.

Antibody suppression by cadmium

Mice exposed to subclinical doses of cadmium chloride for ten weeks and inoculated with antigen six weeks after discontinuance of exposure had a remarkable decrease in antibody-forming cells, particularly IgG. These results indicate that immunosuppression produced by environmental contaminants may persist for several months after exposure to the contaminant.

Bone and kidney lesions in experimental cadmium intoxication

Young male rats were fed a diet containing cadmium (0, 10, 30, 100, and 300 ppm) so as to morphologically investigate the relationship between bone and kidney lesions caused by experimental cadmium intoxication. In the early stage of the experiment, before the occurrence of kidney lesions, ingeted cadmium caused osteoporotic changes in bone. In later stages, slight pathologic changes in the kdidney occurred in association with urinary excretion of cadmium. However, there was no evidence of osteomalacic change in bone during the 12-week experimental period. These findings suggest that cadmium may act primarily on bone, rather than secondarily through disturbances of the kidneys, which have some protective ability against cadmium intoxication in the early stage of ingestion of the metal.