Influence of dietary calcium on lead poisoning in mallard ducks (Anas platyrynchos)

Forty-five mallard ducks were allotted into 3 dietary groups. Group I was fed pelleted calcium-supplemented corn; group II was fed a pelleted commercial duck ration; and group III was fed cracked corn. Ten ducks of each group were given four No. 4 lead shot via an esophageal tube, and 5 ducks of each dietary group were kept as pair-fed controls. Anorexia and weight loss were most severe in the treated group III ducks. Group III had a maximum reduction in food consumption of 87% followed by a slight improvement in appetite; they lost 35% of their initial body weight. Group I treated ducks had a reduction in food consumption of 64% that eventually returned to the quantities consumed at the start of the experiment; group I ducks lost 18% of their initial body weight. Group II treated ducks maintained healthy appetites during the experiment and had a weight gain of 2% of their initial body weight. The number of ducks that became moribund and were euthanatized differed significantly among the treated groups with 100% of group III, 50% of group I, and 0% of group II treated ducks becoming moribund. All 3 groups of treated ducks had increased protoporphyrin IX concentrations compared with controls. Groups I and III lead-treated ducks had significant (P less than 0.05) reductions in erythrocyte counts, PCV, hemoglobin concentrations, and mean corpuscular hemoglobin concentrations as compared with controls. Group II had reduced hemoglobin concentration and mean corpuscular hemoglobin concentration compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphometric effects of exposure to lead during the preweaning period on the hippocampal formation of aging rats

Our previous morphologic studies in the rat demonstrated that exposure to lead during the preweaning period induced delays in the maturation of late-developing regions of the hippocampal formation at 15 days of age, followed by normal development or hypertrophy of the same areas in young adulthood. The present study was carried out to determine whether or not subtle or latent effects of such exposure to lead may be unmasked with the additional challenge of aging. To do this, mid-dorsal sections of the hippocampal formation from middle-aged (578-631 days old) Long-Evans control rats and from rats exposed to lead from birth until weaning via dams drinking 0.2% lead acetate were analyzed by light and electron microscopy. Exposure to lead did not alter areas of either neuropil or neuronal layers of the hippocampus or the dentate gyrus or the numbers per section or numerical densities (numbers per unit area) of neurons in hippocampal CA3 stratum pyramidale or dentate stratum granulosum. It did reduce mean size of complex invaginated mossy fiber synapses without altering their numbers in the proximal (close to dentate gyrus) mossy fiber zone, which was the zone also affected at 15 and 90 days of age in our previous studies.

Comparative effects of the sublethal poisoning of zinc, copper and lead on the gonads of the teleost Puntius conchonius ham

The histopathological impact of the sublethal concentrations of zinc, copper and lead on the gonads of Puntius conchonius was evaluated. Copper (Cu) interfered with spermatogenesis temporarily while zinc (Zn) and lead (Pb) produced dilation in the testicular blood capillaries with necrosis and disintegration of the seminiferous tubules. All three metals induced significant atresia in the ovary. The damaged mainly the younger oocytes, whereas Cu and Pb were more effective on relatively older oocytes. The studies suggest a direct action of heavy metals on the gonads.

Erythroid karyorrhexis in the peripheral blood smear in severe arsenic poisoning: a comparison with lead poisoning

Three men with severe arsenic poisoning were hospitalized with working diagnoses, respectively, of peptic ulcer, pancreatitis, and viral gastroenteritis. In the first two patients, correct diagnosis was delayed until the return of heavy-metal screening tests ordered because of painful peripheral neuropathy in one and sudden flaccid paralysis, resembling Guillain-Barré syndrome, in the other. Both patients had coarsely stippled red blood cells with markedly abnormal nuclei in their peripheral blood smears. These distinctive hematologic features led to an early diagnosis in the third patient. The author's review of past cases of lead poisoning showed that red blood cell karyorrhexis also tends to occur in patients who consume illicit whiskey ("moonshine"). Karyorrhexis or marked dyserythropoiesis in the peripheral smear, not heretofore described in arsenic or lead poisoning, may indeed be a unique hematologic clue. Scrutiny of the peripheral blood and/or buffy coat smear in patients with perplexing gastrointestinal or neurologic symptoms may enable earlier diagnosis and better therapy of arsenic poisoning.

Chronic lead administration in neonatal rats: electron microscopy of the retina

The morphologic effects on the retina resulting from chronic lead exposure were assessed in neonatal rats. Newborn rats nursed from dams were given a low (0.115%) or a high (4.5%) concentration of lead in their diet. At day 21 the pups were weaned to the mother's diet. The retinas of the pups were studied by electron microscopy at various ages up to day 60. High and low lead concentrations produced necrosis of photoreceptor cells and cells of the inner nuclear layer. The high lead concentration, in addition, was associated with swelling of endothelial cells of the retinal vessels and narrowing of the lumen. Increased permeability of the retinal vessels and pigment epithelium to horseradish peroxidase was also observed under the high-dose condition. The authors conclude that lead can produce direct neuronal damage and, at high doses, produces retinal vascular lesions and alteration of the blood-retinal barrier.

Axon membrane remodeling in the lead-induced demyelinating neuropathy of the rat

Single-teased fibers stained with the ferric ion-ferrocyanide method allowed us to study axonal remodeling in the lead-induced demyelinating neuropathy of the rat. Our findings, in agreement with recent physiological data, pointed to a transitory reorganization of the demyelinated axons to maintain impulse conduction until remyelination and formation of new cytochemically normal nodes had restored a secure saltatory conduction.

Organic lead and histological parameters of brain development

Relatively little work has been done on the structural effects of organic lead in the central nervous system (CNS), although this form of lead may be a significant fraction of total brain lead. We tested a number of easily measured light-histological parameters of neuronal development in rats for sensitivity to (a) normal growth between 18 and 28 days of life and (b) the effect of weekly injections of tetramethyl lead (TML), administered from 1 week after conception until post-natal day 6. Several of the histological parameters were found to be sensitive to normal growth, but none showed any effect of organic lead treatment. This was despite a small but significant decrease in brain weight, and a significant increase in body/brain weight ratio, with tetramethyl lead treatment. The body/brain weight ratio was the parameter most sensitive to tetramethyl lead treatment. Possible reasons for the disparity between weight and histological parameters are discussed, with reference to previous workers' findings concerning the effects of organic lead on the development of myelin in the CNS and the availability of organic lead to brain tissue.

Karyokinetic reactions in rat kidney proximal convoluted segment epithelium on long-term lead supply with drinking water

In the rat kidney proximal convoluted segment epithelium the development of intranuclear inclusion bodies was observed after long-term lead administration with the drinking water. The inclusion bodies were PAS-positive. By electron microscopy they were identified as composed of filaments and granules lacking any kind of surrounding membrane. During the experiment, the nuclear volumes increased commensurately with the duration of lead exposure. The nuclear volume increase was considered a physiological reaction since it began long before the first appearance of intranuclear inclusion bodies.

Neurobehavioral toxicology of the organoleads

Alkyl leads (R x Pb) are environmentally prevalent compounds which have been shown to produce a variety of neurological and behavioral deficits in both laboratory animals and man. Due to the increasing commercial use of these compounds, the episodes of human poisoning, and the limited understanding of their sites and mechanisms of toxicity, the organoleads, as a class, remain potentially important environmental health hazards. Recent data indicate that the constellation of behavioral effects produced by these compounds resembles the behavioral sequelae of limbic system damage. For example, alterations in sensory responsiveness and/or behavioral reactivity and task-dependent changes in avoidance learning are observed following organolead exposure and experimental disruption of the limbic system. Furthermore, neurochemical changes induced by organoleads are regionally-specific and restricted to the limbic forebrain and frontal cortex. The present review will summarize the toxic properties of organoleads, discuss their neurobehavioral effects, and suggest that these effects might be attributable to a disruption of the limbic forebrain.

[Diagnosis of peripheral neuropathy in lead workers]

Interest in subclinical lead neuropathy has recently intensified. In this paper, we aim at reviewing current methods for the diagnosis of peripheral neuropathy due to lead absorption. Neurological diagnostic methods and blood lead measurement are essential for the diagnosis of clinical lead neuropathy. However, for the diagnosis of subclinical lead neuropathy, the measurement of nerve conduction velocity is considered to be most sensitive and reliable on the group basis. But, on the individual basis, the conduction study is not sensitive enough because of small changes in the velocity often ranging around the lower limit of "normal" values.

Vulnerability to lead in protein-deprived suckling rats

Most studies on lead toxicity in the suckling rat have been performed with doses leading to growth retardation. In a previous paper ( Sundstr öm et al. 1983), the effects of different lead doses on normal suckling rats were described. The dose of 10 mg/kg body weight daily given on days 1-15 pp produced minute hemorrhagic lesions on day 15 in the cerebellum, whereas rats given 5 mg/kg body weight daily lacked microscopically discernible pathologic changes in the brain. None of these groups exhibited growth retardation. To further elucidate the association between lead encephalopathy and malnutrition, lead was administered to protein-deprived suckling rats. Protein deprivation was achieved by a diet with 50% reduction of protein content. The mothers of the pups were fed this diet from 2 weeks before conception throughout the experiment. Experimental animals were injected i.p. with 5 mg or 10 mg lead nitrate/kg b.wt. daily. Littermates, injected with vehicle without lead nitrate served as controls. Protein-deprived rats without either treatment were "external" controls. Animals were killed at 10, 15, and 20 days age for determination of lead content in blood and brain and for light-microscopic examination. The protein-deprived rats given 10 mg/kg b.wt. daily were growth-retarded as compared to unexposed protein-deprived rats. The mortality was almost 100% at 15-20 days pp. At 15 days, the cerebellum of these rats showed abundant hemorrhages, and the cerebrum was also hemorrhagically discolored. Protein-deprived rats given 5 mg/kg b.wt. daily did not differ significantly from unexposed protein-deprived rats with regard to body weight gain.(ABSTRACT TRUNCATED AT 250 WORDS)

Lead neuropathy

The still unexplained nature of the neurotropic action of lead has prompted this chronological survey of the course of development of the medical attitude towards the problems of lead neuropathy all along the centuries--from ancient times up to the present. Once a conspicuous, severe, and even frequent clinical type of plumbism, peripheral lead neuropathy has received due attention in the early classics (Tanquerel des Plances, Duchenne, Aran, Remak, Romberg, Erb, etc.) and of the pioneers in industrial medicine (Legge, Aub, Teleky, Hamilton). Even the modern era, however, has not come further than to state that lead produces different neurological effects in different animal species and even in humans--different patterns of neuromuscular involvement. With the advent of electrophysiology, conflicting and inconsistent findings have also appeared, particularly in regard to overt and latent lead neuropathies. Theories regarding the mode and site of the neurotoxic action of lead are reviewed and data which might be used as arguments both in favor and against are presented.

Development and plasticity of the hippocampal-cholinergic system in normal and early lead exposed rats

A review of previous evidence suggested the possibility of a functional association between the effects of early lead (Pb) exposure, hippocampal damage and cholinergic deficiency. To further assess this possibility, Long-Evans hooded rat pups were exposed to Pb for the first 25 postnatal days via the maternal milk. Dams were fed either 4.0% PbCO3 or a Na2CO3 control diet throughout this period. At 30 and 115 days of age, the brains of Pb and control animals were processed for acetylcholinesterase histochemistry. Morphometric evaluation of the molecular layer of the hippocampal dentate gyrus indicated that while absolute increases in the dimensions of the afferent systems to the hippocampal dentate gyrus are observed between 30 and 115 days of age, no significant rearrangement in the pattern of lamination occurs during this time. No effects of Pb were seen on the development of the cholinergic innervation of this brain region at either of these ages. Unilateral perforant path transections performed on Pb and control animals at 100 days of age indicated reduced cholinergic plasticity in the molecular layer of the hippocampal dentate gyrus of Pb exposed animals, as indicated by AChE histochemistry. These findings indicate that a decrease in neuroanatomical plasticity may be a critical brain mechanism underlying the learning deficits observed following exposure to Pb.

Lead poisoning in monkeys during pregnancy and lactation

Twenty-two female monkeys (Macaca irus) were given lead acetate by an intramuscular route during pregnancy and/or lactation. A high dose of lead (5 mg Pb2+/kg/day) can induce abortions and death in pregnant monkeys. At a lower dose (1 mg Pb2+/kg/day), the foetus can be exposed to lead via placenta and/or maternal milk. Studies using optical microscopy showed the typical renal lesions in mothers treated during pregnancy (five months) and an erythrodiapedesis in cerebral matter of the new-born at birth.

Histologic and ultrastructural lesions of mourning doves (Zenaida macroura) poisoned by lead shot

Studies were conducted in which mourning doves (Zenaida macroura) were administered lead shot, and their tissues were examined by histology and their kidneys were examined by electron microscopy. Doves that ingested four number 8 lead shot and were sacrificed 4 days later had highly elevated lead concentrations in kidney and had acid-fast intranuclear and acid-fast intracytoplasmic inclusions in the cells of the proximal convoluted tubules. Hemosiderin loading was present in the liver as was elevated concentrations of lead in liver. Doves that ingested either four or eight number 8 lead shot and were sacrificed 9 days later had elevated lead concentrations in liver, and hemosiderin loading was present. Acid-fast intranuclear inclusions were present in the proximal convoluted tubule cells. Kidney lead was highly elevated and cellular degeneration was evident with electron microscopic examination.

Intra-articular milk of calcium in saturnine gout

Radiographs of two patients with saturnine gout (lead gout) demonstrated radio-opaque material which resembled milk of calcium within several joints. A histochemical examination of knee aspirate of one of the patients revealed a combination of monosodium urate and calcium pyrophosphate dihydrate. Subsequently, the authors suspected that the findings of intra-articular milk of calcium were due to the coexistence of saturnine gout and calcium pyrophosphate dihydrate deposition disease rather than intra-articular calcified tophus.

Gentamicin nephrotoxicity in cadmium, lead and mercury pretreated rats

The effect of a previous chronic exposure to cadmium, lead or inorganic mercury on the nephrotoxic potential of gentamicin was investigated in female Sprague-Dawley rats. A daily dose of 10 mg gentamicin/kg body weight/day was administered for 21 days to rats having a renal load of 168 micrograms Cd, 35 micrograms Pb or 129 micrograms Hg/g whole kidney. Urine analysis suggests an attenuation of the nephrotoxic potential of gentamicin while a microscopical examination of kidneys indicates a superimposition of the effects of the metals and the antibiotics. The only clear interaction observed consists in a reduction of gentamicin accumulation in the cortex of cadmium-treated animals. It is concluded that none of the metal pretreatments potentiates the nephrotoxic effects of gentamicin.

Early appearance and localization of intranuclear inclusions in the segments of renal proximal tubules of rats following ingestion of lead

Intranuclear inclusions in epithelial cells lining rat renal proximal tubules were detected by electron microscopy as early as 4 days after the addition of lead (5 mg/ml as lead acetate) to the drinking water. At 9 and 12 weeks pathological changes, but very few intranuclear inclusions, were apparent in the epithelial cells lining the third segment of the proximal tubules in the outer stripe of outer zone of the medulla. On the other hand, morphological changes were less in the epithelial cells lining the first and second segments of the proximal tubules in the cortex, which contained many intranuclear inclusions. These findings suggest that lead incorporated into the epithelial cells in the proximal tubules may exist in an inert chemical form as inclusions, especially in the second segment. These bodies, therefore, may protect the cells from the toxic effect of lead.

Acid fast inclusions in tissues of dogs dosed with lead

Liver, kidney and bone from dogs with experimental lead toxicosis were examined to study the frequency of occurrence of acid fast inclusions and the results were correlated with the lead content of these tissues. Light and electron microscopic studies revealed that bone and kidney had characteristic acid fast lead inclusions in 95 and 68 per cent of cases, respectively. Liver, although it had a high lead content, did not often show inclusions. For histopathological diagnosis of lead poisoning in dogs, we suggest that Ziehl-Nielsen stained sections of the epiphyseal area of long bone be examined for the presence of acid fast inclusions in osteoclasts.

The morphological effects of lead on the developing central nervous system

The pathological changes found in the central nervous system of lead-exposed humans and laboratory animals are reviewed. Data in man relate to relatively high exposure levels. In human childhood lead encephalopathy, which occurs with blood lead levels in the range 100-800 micrograms Pb/100 ml, oedema, vacuolation, haemorrhage and reactive glial changes appear to be secondary to microvascular lesions. No primary neuronal lesions have yet been clearly identified. Neurological signs and a pathological picture closely resembling that seen in human lead encephalopathy are obtained in young lead-exposed rats with blood lead levels above 500 micrograms Pb/100 ml. Oedema and haemorrhage, cyst formation, reactive glial changes and nerve cell alterations are observed consequent to changes in capillary endothelial cells and basement membranes. High-level lead exposure in rats also produces disturbances in myelinated axons and may affect neural network formation in the central nervous system. With intermediate lead levels (200-500 microgram Pb/100 ml blood), vascular changes and their sequelae are not seen, but nutritional effects occur which may produce neuropathological changes. Data from recent studies on developing rats with low blood levels (up to 100 microgram Pb/100 ml) appear to show effects of lead on maturing and differentiated nerve cell populations. The relevance of these changes to human subclinical lead intoxication remains to be seen. However, the overall correspondence of findings in lead-poisoned man and rat would make further investigation in this area appear necessary.