Euglena shafiqii, Shafiq-ur-Rehman, The red-Bloom of Dal Lake of Kashmir (original) (raw)
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Neurotoxic effects and biomarkers of lead exposure: a review
Reviews on environmental health
Lead, a systemic toxicant affecting virtually every organ system, primarily affects the central nervous system, particularly the developing brain. Consequently, children are at a greater risk than adults of suffering from the neurotoxic effects of lead. To date, no safe lead-exposure threshold has been identified. The ability of lead to pass through the blood-brain barrier is due in large part to its ability to substitute for calcium ions. Within the brain, lead-induced damage in the prefrontal cerebral cortex, hippocampus, and cerebellum can lead to a variety of neurologic disorders. At the molecular level, lead interferes with the regulatory action of calcium on cell functions and disrupts many intracellular biological activities. Experimental studies have also shown that lead exposure may have genotoxic effects, especially in the brain, bone marrow, liver, and lung cells. Knowledge of the neurotoxicology of lead has advanced in recent decades due to new information on its toxic m...
NeuroToxicology, 2019
Lead is a neurotoxin that produces long-term, perhaps irreversible, effects on health and wellbeing. This article summarizes clinical and preclinical studies that have employed a variety of research techniques to examine the neurotoxic effects of low levels of lead exposure. A historical perspective is presented, followed by an overview of studies that examined behavioral and cognitive outcomes. In addition, a short summary of potential mechanisms of action is provided with a focus on calcium-dependent processes. The current level of concern, or reference level, set by the CDC is 5 μg/dL of lead in blood and a revision to 3.5 μg/dL has been suggested. However, levels of lead below 3 μg/dL have been shown to produce diminished cognitive function and maladaptive behavior in humans and animal models. Because much of the research has focused on higher concentrations of lead, work on low concentrations is needed to better understand the neurobehavioral effects and mechanisms of action of this neurotoxic metal.
Lead in Water: Neurotoxicityand Stressful Effect on Wistar Rat
The fauna and flora are severely threatened by discharges of industrial pollutants such as heav y metals (lead zinc cadmium arsenic…) which are highly dangerous. The study covers the identification of sites fixing mechanism lead to the brain, in rats Wistar according to several approaches: phenotypic, behavioural, immunohistochemical and histological. The rats are permanently acetate lead the dose of 250mg / l and 500mg/l diluted in distilled water for a period of 12 weeks compared to witnesses who receive only distilled water. On the phenotypic we found that in rats treated, lead causes exophthalmoses, a decrease in muscle tone, body weight, the intake and falling hair all over his body: anorectic effect and a decrease in water intake. The administration of the lead acetate oral causes a very significant decrease in the conduct of exploratio n (locomotors activity) and the stereotypical behaviour like (grooming, sniffing bite) compared to control group rats with rats. The experienc...
Lead neurotoxicity in children: basic mechanisms and clinical correlates
Brain, 2003
Lead has been recognized as a poison for millennia and has been the focus of public health regulation in much of the developed world for the better part of the past century. The nature of regulation has evolved in response to increasing information provided by vigorous scienti®c investigation of lead's effects. In recognition of the particular sensitivity of the developing brain to lead's pernicious effects, much of this legislation has been addressed to the prevention of childhood lead poisoning. The present review discusses the current state of knowledge concerning the effects of lead on the cognitive development of children. Addressed are the reasons for the child's exquisite sensitivity, the behavioural effects of lead, how these effects are best measured, and the long-term outlook for the poisoned child. Of particular importance are the accumulating data suggesting that there are toxicological effects with behavioural concomitants at exceedingly low levels of exposure. In addition, there is also evidence that certain genetic and environmental factors can increase the detrimental effects of lead on neural development, thereby rendering certain children more vulnerable to lead neurotoxicity. The public health implications of these ®ndings are discussed.
Cognitive Impairment Induced by Lead Exposure during Lifespan: Mechanisms of Lead Neurotoxicity
Toxics
Lead (Pb) is considered a strong environmental toxin with human health repercussions. Due to its widespread use and the number of people potentially exposed to different sources of this heavy metal, Pb intoxication is recognized as a public health problem in many countries. Exposure to Pb can occur through ingestion, inhalation, dermal, and transplacental routes. The magnitude of its effects depends on several toxicity conditions: lead speciation, doses, time, and age of exposure, among others. It has been demonstrated that Pb exposure induces stronger effects during early life. The central nervous system is especially vulnerable to Pb toxicity; Pb exposure is linked to cognitive impairment, executive function alterations, abnormal social behavior, and fine motor control perturbations. This review aims to provide a general view of the cognitive consequences associated with Pb exposure during early life as well as during adulthood. Additionally, it describes the neurotoxic mechanisms...
The effects of lead in laboratory animals and environmentally-exposed children
Toxicology, 1988
Consistent association has been found in 4 independent studies between disruption of visual-motor integration and reaction performance and markers of lead exposure (blood, teeth) in children, but not for intelligence deficit; blood-lead levels were typically below 30/~g/dl in these children. In order to demonstrate the persistent nature of Pb-induced neurobehavioral deficit experimentally rats were studied after cessation of dietary Pb-exposure in a variety of behavioral tasks. Persistent retention-deficit was found for visual discrimination-learning and for radical arm-maze performance.
Effect of lead acetate on neurobehavioral development of rats
Brazilian Journal of Medical and Biological Research, 1998
We investigated the effects of lead exposure during the pre-and postnatal period on the neurobehavioral development of female Wistar rats (70-75 days of age, 120-150 g) using a protocol of lead intoxication that does not affect weight gain. Wistar rats were submitted to lead acetate intoxication by giving their dams 1.0 mM lead acetate. Control dams received deionized water. Growth and neuromotor development were assessed by monitoring daily the following parameters in 20 litters: body weight, ear unfolding, incisor eruption, eye opening, righting, palmar grasp, negative geotaxis, cliff avoidance and startle reflex. Spontaneous alternation was assessed on postnatal day 17 using a T maze. The animals' ability to equilibrate on a beaker rim was measured on postnatal day 19. Lead intoxication was confirmed by measuring renal, hepatic and cerebral lead concentration in dams and litters. Lead treatment hastened the day of appearance of the following parameters: eye opening (control: 13.5 ± 0.6, N = 88; lead: 12.9 ± 0.6, N = 72; P<0.05), startle reflex (control: 13.0 ± 0.8, N = 88; lead: 12.0 ± 0.7, N = 72; P<0.05) and negative geotaxis. On the other hand, spontaneous alternation performance was hindered in lead-exposed animals (control: 37.6 ± 19.7; lead: 57.5 ± 28.3% of alternating animals; P<0.05). These results suggest that lead exposure without concomitant undernutrition alters rat development, affecting specific subsets of motor skills.