Thiamin (vitamin b1) effects on lead intoxication and deposition of lead in tissues: therapeutic potential

Environmental science and pollution research role of heavy metal concentrations and vitamin intake from food in depression: a national cross-sectional study (2009-2017)

Little is known about associations between depression and serum heavy metal levels, dietary vitamin intakes. Thus, we sought to determine the nature of these associations and to predict risks of depression using marginal effects. A data set of 16,371 individuals aged ≥10 years that participated in Korea National Health and Nutrition Examination Surveys (KNHANES) conducted from 2009 to 2017 (excluding 2014 and 2015) was used to obtain information on sociodemographics, family histories, lifestyles, serum heavy metal levels, food intakes, and depression. Serum cadmium (Cd) and lead (Pb) levels were analyzed by graphite furnace atomic absorption spectrometry and mercury (Hg) levels using a mercury analyzer. Daily vitamin intakes were calculated by 24-h dietary recall. The results obtained showed that females are at higher risk of depression than males. A doubling of serum Cd was associated with a 21% increase in depression (AOR 1.21, 95% CI: 1.07-1.37, p = 0.002), whereas twofold increases in daily vitamin B1, B3 and vitamin A intakes reduced the risk of depression by 17% (0.83, 95% CI: 0.73-0.95, p = 0.005), 20% (0.80, 95% CI: 0.70-0.91, p = 0.001), and 8% (0.92, 95% CI: 0.85-0.99, p = 0.020), respectively. Interactions between heavy metals, vitamin intakes, and sex did not influence the risk of depression. The result shows that increased daily dietary vitamin intake might protect the public against depression. Further studies are needed to reduce the risks posed by heavy metals and to determine more comprehensively the effects of daily dietary vitamin intake on depression.

Dietary patterns, bone lead and incident coronary heart disease among middle-aged to elderly men

BACKGROUND

Most absorbed lead ends up in the bone, where it can be measured as a biomarker of cumulative exposure, elevations of which have been shown to predict a higher risk of coronary heart disease (CHD). Knowledge about the role of dietary patterns is critical to the development of effective interventions for the cardiovascular toxicity of cumulative lead exposure.

METHODS

594 men, free of CHD at baseline, were followed from August 1991 to June 2011 in the Normative Aging Study. Bone lead concentrations were measured by K-shell-X-ray fluorescence. Dietary patterns were identified using principal components analysis. Two dietary patterns were identified: a 'prudent' pattern characterized by high intake of fruit, vegetables, legumes, tomatoes, poultry, and seafood; and a 'Western' pattern, with high intake of red meat, processed meat, refined grains, high-fat dairy products, high-energy drinks, fries, butter and eggs. Cox proportional hazard models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for incident CHD. Effect modification on the multiplicative scale was examined through cross-product interaction terms.

RESULTS

137 men developed incident CHD events during 5071 person-years of follow-up. After adjusting for age, body mass index, total energy intake, smoking status, total cholesterol to high-density lipoprotein ratio, education and occupation, an HR of incident CHD was 1.64 (95% CI: 1.27-2.11) with each doubling in patella lead concentration in the low prudent diet group (< median prudent score); and the HR decreased to 1.07 (95% CI: 0.86-1.34) in the high prudent diet (≥ median prudent score) (p-for-interaction = 0.01), suggesting protective effects of prudent diet against lead-related CHD. By contrast, the association between tibia lead and CHD was non-significantly larger in the low Western diet group (HR = 1.43, 95% CI: 1.14-1.80) compared with the high Western diet group (HR = 1.08, 95% CI: 0.86-1.34) (p-for-interaction = 0.06). No significant effect modifications were detected by Western diet in the patella lead-CHD association and by prudent diet in the tibia lead-CHD association.

CONCLUSIONS

Prudent diet may reduce the risk of development of CHD in relation to patella lead. However, these findings need to be interpreted with caution, given the modest sample size.

The effects of 2,3-dimercapto-1-propanesulfonic acid (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA) on the nephrotoxicity in the mouse during repeated cisplatin (CDDP) treatments

Previously, we reported that specific lower dose of sodium 2,3-dimercapto-1-propanesulfonic acid (DMPS) which is an antidote to heavy metal intoxication, inversely enhanced cisplatin (CDDP)-induced antitumor activity to S-180 cell-bearing mouse. This activity was only weak with meso-2,3-dimercaptosuccinic acid (DMSA), however. This study investigated the effects of lower doses of DMPS or DMSA on the nephrotoxicity and kinetics of CDDP. Kidney and blood isolated from female mice which received CDDP with or without DMPS or DMSA once daily for 4 days were provided for measuring levels of blood urea nitrogen (BUN) and transporter proteins (OCT2: organic cation transporter; MATE1: multidrug and toxin extrusion) mRNA, and CDDP-originated platinum, and TUNEL staining of renal tubular cells. DMPS or DMSA reduced effectively CDDP-induced BUN, and caused a moderate reduction of platinum in kidney. Additionally, both dimercapto-compounds restored the CDDP-reduced mRNA levels of transporter proteins (OCT2 and MATE1), and apparently suppressed the CDDP-induced apoptosis. These results suggest that DMPS, as well as DMSA, at approximate 17-fold dose (μmol/kg) of CDDP, has an enough potential to reverse the CDDP nephrotoxicity, and concomitant use of DMPS considering both dose and timing for administration is potentially useful for preventing nephrotoxicity and enhancing antitumor activity during CDDP chemotherapy.

Dietary strategies for the treatment of cadmium and lead toxicity

Cadmium (Cd) and lead (Pb) are toxic heavy metals that cause adverse health effects in humans and animals. Chelation therapy, the conventional treatment for heavy metal toxicity, is reported to have a number of safety and efficacy issues. Recent studies have shown that dietary supplements play important roles in protecting against Cd and Pb toxicity. This paper reviews the evidence for protective effects of essential metals, vitamins, edible plants, phytochemicals, probiotics and other dietary supplements against Cd and Pb toxicity and describes the proposed possible mechanisms. Based on these findings, dietary strategies are recommended for people at risk of Cd and Pb exposure. The application of these strategies is advantageous for both the prevention and alleviation of Cd and Pb toxicity, as such supplements can be added easily and affordably to the daily diet and are expected to have very few side effects compared to the chelation therapy.

The redox status in rats treated with flaxseed oil and lead-induced hepatotoxicity

Lead is a persistent environmental pollutant, and its toxicity continues to be a major health problem due to its interference with natural environment. In the present study, we have evaluated the effect of flaxseed oil on lead acetate-mediated hepatic oxidative stress and toxicity in rats. Lead acetate enhanced lipid peroxidation and nitric oxide production in both serum and liver with concomitant reduction in glutathione, catalase, superoxide dismutase, glutathione reductase, glutathione-S-transferase, and glutathione peroxidase activities, these findings were associated with DNA fragmentation. In addition, lead acetate caused liver injury as indicated by histopathological changed of the liver with an elevation in total bilirubin, serum alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transpeptidase, and alkaline phosphatase. Treatment of rats with flaxseed oil resulted in marked improvement in most of the studied parameters as well as histopathological features. On the basis of the above results it can hypothesized that flaxseed oil is a natural product can be protect against lead acetate-mediated hepatic cytotoxicity.

Efficacy of allicin in decreasing lead (Pb) accumulation in selected tissues of lead-exposed common carp (Cyprinus carpio)

The objective of this study was to evaluate the effects of allicin, the main biologically active component of garlic clove extracts, on lead levels in different common carp tissues including liver, kidney, brain, bone, and blood following experimental lead poisoning. Fish were divided randomly into five groups depending on the combination of lead acetate and allicin treatments. Lead acetate exposure (7.0 mgL(-1), 10 days) caused a significant increase in mean Pb concentrations in all examined tissues in comparison to control unexposed fish (p < 0. 001). The results showed that allicin supplementation is effective in decreasing lead accumulation in all examined tissues of common carp. The promising ameliorative effects of allicin on tissue lead levels of common carp make it a good candidate for therapeutic intervention of lead poisoning. However, more studies are required to elucidate the pharmacokinetic effects of allicin and also molecular basis of the ameliorative properties of allicin in lead poisoning.

Paradoxical effect of 2,3-dimercapto-1-propanesulfonic acid (DMPS) on enhancing antitumor activity of cisplatin in ascites sarcoma 180 cells

We investigated the enhancing effect of two metal-chelating compounds, 2,3-dimercapto-1-propanesulfonic acid (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA), on the antitumor activity of cisplatin (CDDP). In the in vivo experiments, DMPS showed a clear synergistic effect and significantly enhanced the antitumor activity of CDDP in terms of survival and life span in mice transplanted with ascites sarcoma 180 cells (S180 cells) at a dose of <100 micromol/kg, s.c., but not at a dose of >500 micromol/kg. On the other hand, DMSA did not enhance the antitumor activity of CDDP. DMPS (50 micromol/kg, s.c.) combined with CDDP also potently suppressed [(3)H]thymidine uptake in S180 cells implanted in mice, whereas DMSA did not. In the in vitro experiments, DMPS (10(-6) to 10(-5) M) produced a time- and dose-dependent decrease in intracellular Ca(2+) concentrations ([Ca(2+)](i)) in S180 cells and, in combination with CDDP, yielded a significant increase in intracellular platinum accumulation compared to that in cells treated with CDDP alone. These results indicate that DMPS used in combination with CDDP may be of considerable benefit in enhancing the cytotoxicity of CDDP in tumor cells, especially at a low dose. The results also suggest that the enhancing effect of DMPS is closely related to a decrease in [Ca(2+)](i) and that the suitable dose and adequate administrational time of DMPS are important for its effective action.

Interactions of diorganolead(IV) with 3-(2-thienyl)-2-sulfanylpropenoic acid and/or thiamine: chemical and in vitro and in vivo toxicological results

The reactions of PbR(2)(OAc)(2) (R = Me, Ph) with 3-(2-thienyl)-2-sulfanylpropenoic acid (H(2)tspa) in methanol or ethanol afforded complexes [PbR(2)(tspa)] that electrospray ionization-mass spectrometry (ESI-MS) and IR data suggest are polymeric. X-ray studies showed that [PbPh(2)(tspa)(dmso)] x dmso, crystallized from a solution of [PbPh(2)(tspa)] in dmso, is dimeric, and that [HQ](2)[PbPh(2)(tspa)(2)] (Q = diisopropylamine), obtained after removal of [PbPh(2)(tspa)] from a reaction including Q, contains the monomeric anion [PbPh(2)(tspa)(2)](2-). In the solid state the lead atoms are O,S-chelated by the tspa(2-) ligands in all these products, and in the latter two have distorted octahedral coordination environments. NMR data suggest that tspa(2-) remains coordinated to PbR(2)(2+) in solution in dmso. Neither thiamine nor thiamine diphosphate reacted with PbMe(2)(NO(3))(2) in D(2)O. Prior addition of H(2)tspa protected LLC-PK1 renal proximal tubule cells against PbMe(2)(NO(3))(2); thiamine had no statistically significant effect by itself, but greatly potentiated the action of H(2)tspa. Administration of either H(2)tspa or thiamine to male albino Sprague-Dawley rats dosed 30 min previously with PbMe(2)(NO(3))(2) was associated with reduced inhibition of delta-ALAD by the organolead compound, and with lower lead levels in kidney and brain, but joint administration of both H(2)tspa and thiamine only lowered lead concentration in the kidney.

Thiamine reduces tissue lead levels in rats: mechanism of interaction

Lead (Pb) toxicity has been a serious concern in industrialized societies because of its association with functional deficits in nervous, haematopoietic and renal systems. Several studies have shown beneficial effects of thiamine on Pb toxicity. It is speculated that Pb chelation by thiamine may be a possible mechanism. However, the exact nature of these interactions remained elusive. In the present study we have characterized the interaction of Pb with thiamine using UV-Vis as well as fluorescence spectroscopic methods and studied the effect of thiamine treatment on blood and tissue Pb levels during simultaneous or post-exposure to Pb in rat model. The spectroscopic studies revealed that Pb interacts with the pyrimidine ring of thiamine, leading to its solubilization at physiological pH. Further, thiamine reduced the Pb levels in blood, kidney and bone during both simultaneous and post-exposure Pb treatment. Interestingly, thiamine appears to prevent the accumulation of Pb in bone during simultaneous treatment. Together these results suggest that pyrimidine ring of thiamine mediates its interaction with Pb, leading to the prevention of its accumulation and/or increased clearance from tissues.

Effect of garlic along with lead acetate administration on lead burden of some tissues in mice

Garlic ability to reduce lead burden in body tissues before and during chronic lead toxicity was studied. Eighty mice were divided into 8 groups. Group D received placebo. Groups A1, A2 and A3, respectively received 500, 250 and 125 mg kg(-1) day garlic and Groups B1, B2 and B3, respectively 1/4, 1/8 and 1/16 garlic tablet kg(-1) day in first four weeks and in second four weeks they received 5 mg kg(-1) day lead acetate plus garlic or garlic tablet. Group C received placebo in first four weeks and in second four weeks they received 5 mg kg(-1) day lead acetate and placebo. Reduction in lead burden of kidney, liver, bone and blood (except for group A3) in experimental groups was significant compared with group C (p<0.05). Results showed that fresh garlic extract and garlic tablet had almost same effects on lead reduction in tissues.

Effect of montmorillonite superfine composite on growth performance and tissue lead level in pigs

A feeding trial was conducted to study the effect of montmorillonite superfine composite (MSC) on growth performance and tissue lead levels in pigs. Sixty barrows were randomly divided into two groups. They were fed the same basal diet supplemented with 0 or 0.5% MSC, respectively, for 100 days. Serum samples were collected and analyzed to study growth hormone secretion pattern. The mean lead concentration in selected tissues was analyzed. The results showed that average daily gain, average daily feed intake, and feed conversion ratio of pigs were improved by 8.97% (p < 0.05), 3.90% (p < 0.05), and 4.76% (p < 0.05), respectively, with the supplementation of MSC compared to the control group. Serum sample analysis indicated that peak amplitude, base-line level, and mean level of growth hormone were increased by 117.14% (p < 0.01), 42.78% (p < 0.01), and 51.75% (p < 0.01), respectively. Supplementation of MSC in the diet was found to significantly reduce lead concentration of tissues in blood, brain, liver, bone, kidney and hair.

Evaluation of allicin for the treatment of experimentally induced subacute lead poisoning in sheep

Garlic (Allium sativum) is known to reduce lead toxicity in some species of animals. The objective of this study was to evaluate the efficacy of allicin, one of the most active components of garlic, in the treatment of subacute lead intoxication in sheep. Nine female sheep weighing 25-29 kg orally received a daily dose of 80 mg/kg body weight of lead acetate for 5 days. The animals were then assigned into two groups. Group 1 did not receive any further treatment and was used as the control group and group 2 was treated orally by 2.7 mg/kg body weight of allicin twice daily for 7 days. Within one day following allicin treatment, group 2 blood lead levels were significantly lower than that in group 1 (mean of 616.9 microg/l and 290.02 microg/l, respectively; P < 0.05). Also, allicin treatment significantly reduced kidney lead content and considerably reduced bone and ovary lead contents. These results suggest that allicin might have some therapeutic effects on lead poisoning.

Decreased thiamine and magnesium levels in the potentiation of the neurotoxicity of lead in occupational lead exposure

The relationship between blood lead (Pb) and serum levels of calcium and of neural nutrients such as thiamine and magnesium (Mg) has been determined in a Nigerian population that is occupationally exposed to Pb. Forty-seven male Pb workers were recruited as test subjects and 25 males unexposed to Pb served as controls. The test subjects were classified into three groups, based on severity of exposure to Pb. Blood lead (BPb) and the serum levels of Mg, thiamine, and calcium were determined in both test subjects and controls. The mean blood Pb level was not significantly higher in Pb workers. In contrast, Mg and thiamine levels were significantly decreased (p<0.05; p<0.01, respectively). However, the calcium level was not significantly lower in test subjects than in controls. Also, there was a significant negative correlation between serum thiamine and blood Pb levels (r=-0.50; p<0.01). Furthermore, there was a significant negative correlation between serum calcium and BPb levels (r=-0.41; p<0.01). This study has shown that relatively low BPb levels can enhance Pb absorption and also potentiate Pb neurotoxicity in the presence of decreased serum thiamine and Mg levels.

Effect of cysteine, methionine, ascorbic acid and thiamine on arsenic-induced oxidative stress and biochemical alterations in rats

Oxidative stress due to enhanced production of free radicals has been incriminated as one of the several mechanisms involved in arsenic-induced toxic effects in different organs. In the present study, ameliorative potential of certain amino acids like cysteine, methionine and vitamins like ascorbic acid and thiamine on some of the parameters indicative of oxidative stress in liver, kidney and blood and of hepatic and renal infliction was investigated in arsenic exposed rats. Rats were given 0 ppm (group I healthy controls) or 10 ppm arsenic in drinking water ad lib for a period of 12 weeks. During oral exposure to arsenic rats of different groups received daily oral dose of placebo, cysteine, methionine, ascorbic acid or thiamine at 25mg/kg body weight. After the end of the experimental period, animals were sacrificed under light anesthesia and blood, liver and kidney were collected. Samples were processed for estimation of arsenic, biochemical parameters indicative of oxidative stress and hepatic and renal function. Arsenic exposure resulted in significantly (P<0.05) higher accumulation of arsenic in blood, liver and kidney. It was associated with significant (P<0.05) rise in lipid peroxide level and decrease in superoxide dismutase and catalase activities in liver and kidneys. However, alterations in biochemical parameters did not reach statistical (P>0.05) significance. Treatment with vitamins and amino acids resulted in reversal of oxidative stress with significant (P<0.05) decline in tissue arsenic burden. All the treatment produced tissue specific changes in lipid peroxide level, antioxidant enzyme activities and tissue arsenic burden.

Strategies for Safe and Effective Therapeutic Measures for Chronic Arsenic and Lead Poisoning

Exposure to toxic metals remains a widespread occupational and environmental problem in world. There have been a number of reports in the recent past suggesting an incidence of childhood lead poisoning and chronic arsenic poisoning due to contaminated drinking water in many areas of West Bengal in India and Bangladesh has become a national calamity. Low level metal exposure in humans is caused by air, food and water intake. Lead and arsenic generally interferes with a number of body functions such as the central nervous system (CNS), the haematopoietic system, liver and kidneys. Over the past few decades there has been growing awareness and concern that the toxic biochemical and functional effects are occurring at a lower level of metal exposure than those that produce overt clinical and pathological signs and symptoms. Despite many years of research, we are still far from an effective treatment of chronic plumbism and arsenicosis. Medical treatment of acute and chronic lead and arsenic toxicity is furnished by chelating agents. Chelating agents are organic compounds capable of linking together metal ions to form complex ring-like structures called chelates. They have been used clinically as antidotes for acute and chronic poisoning. 2, 3-dimercaprol (BAL) has long been the mainstay of chelation therapy for lead or arsenic poisoning. Meso 2, 3, -dimercaptosuccinic acid (DMSA) has been tried successfully in animals as well as in a few cases of human lead and arsenic poisoning. DMSA could be a safe and effective method for treating lead or arsenic poisoning, but one of the major disadvantages of chelation with DMSA has been its inability to remove lead from the intracellular sites because of its lipophobic nature. Further, it does not provide protection in terms of clinical/ biochemical recovery. A new trend in chelation therapy is to use combined treatment. This includes the use of structurally different chelators or a combination of an adjuvant and a chelator to provide better clinical/biochemical recovery in addition to lead mobilization. The present review article attempts to provide update information about the current strategies being adopted for a safe, effective and specific treatment for two major toxic metals or metalloid.

Lead poisoning in Indian silver refiners

The refining of silver from old silver ornaments, articles and jeweller's waste by smelting these with lead scraps for the fabrication of new jewellery is an important small scale industry in India. The present survey and clinical investigations have shown that 31 out of 50 silver refiners with a mean blood lead level of 32.84+/-1.78 microg/dl (range 20.3-64.9), decrease in blood delta-aminolevulinic acid dehydratase (ALAD) activity and thiamine (as pyruvate) level and an enhanced urinary excretion of ALA as compared to control, were suffering from lead poisoning. Most of these workers have shown anaemia, abdominal colic, blue lining of gum and muscular wasting indicative of lead toxicity. Twenty-four workers with relatively high blood lead levels were equally divided into two groups and given either vitamin B1 (75 mg, once a day) or vitamin C (250 mg. twice a day) for 1 month. The treatment with both the vitamins significantly lowered the blood lead levels and reduced blood thiamine and copper deficiency. In addition, vitamin C was also effective in reversing the inhibition of blood ALAD activity while the effect of vitamin B1 on its activity was marginal. The daily intake of vitamin B1 and vitamin C may prevent the accumulation of lead and reduce its toxic effects particularly in those regularly exposed to lead.

Effect of garlic (Allium sativum L.) extract on tissue lead level in rats

The prophylactic efficacy of garlic (Allium sativum L.) extract to reduce tissue lead (Pb) concentration was evaluated experimentally in rats. Thirty female rats were divided into five groups, keeping group A as a healthy control. Rats of groups B, C, D and E received lead acetate orally at the rate of 5 mg per kg body weight daily for 6 weeks. The garlic extract was tried in three doses, viz. 100 (low), 200 (medium) and 400 mg (high) per kg body weight orally and given simultaneously with lead salt to the rats of group C, D and E, respectively. Mean blood lead concentrations in lead-exposed rats ranged between 0.13+/-0.02 and 0.96+/-0.06 microg/ml, whereas in garlic-treated rats, the range was between 0.16+/-0.01 and 0.80+/-0.05; 0.13+/-0.01 and 0.71+/-0.06 and 0.14+/-0.01 and 0.60+/-0.05 microg per ml in low, medium and high dose groups, respectively. The mean lead concentration in liver, kidneys, brain and bone of lead exposed rats was 2.943+/-0.206, 4.780+/-0.609, 1.019+/-0.100 and 44.075+/-2.60 microg per ml, respectively. Concomitant use of garlic extract at the three different doses was found to reduce lead concentration considerably indicating the potential therapeutic activity of garlic against lead.

Monothiols and Vitamins are Ideal Therapeutic Agents for Mercury Elimination from Nervous and Non-Nervous Tissues of Fish

Use of mercury and its compounds in various industries and agriculture is increasing its concentration in aquatic environment and affecting the organisms living therein. Among these, the fishes are commercially important for humans as an important source of protein. The fish meat transfers good amount of mercury to man, therefore, its elimination is quit essential both from fishes and the consumers. As a step in this direction, the present study has been designed to detoxify the fishes from mercury. For this purpose a freshwater fish (Channa punctatus) was treated with mercuric chloride (0.5 ppm) for 96 h and thereafter, detoxicated with vitamin B complex, glutathione and N-acetyl-DL-homocysteine thiolactone used either alone or in various combinations for another 96 h. One group of 96-h mercury treated animals were kept in tap water and sacrificed after 192 h. This group was considered as mercury washed group and it served as control to all therapeutic groups. Mercury treated fish showed a highest concentration of the metal in kidney followed by liver, gills, brain and muscles. In mercury washed group, metal was removed significantly from all the non-nervous tissues, but in brain about 52% further increase was observed. The results obtained from theraputic studies were quite exciting as 50-80% mercury was mobilized from all tissues including brain within 96 h of treatment.

Lead poisoning and toxicokinetics in a heifer and fetus treated with CaNa2 EDTA and thiamine

Lead (Pb) poisoning of a pregnant heifer was diagnosed based upon clinical signs (head pressing, blindness, muscle twitching) and a blood lead concentration of 1.73 ppm. Blood and urinary Pb half-lives with CaNa2 EDTA/thiamine therapy were determined to be 2.08 and 1.38 days, respectively. Many cations (Ca, Fe, Zn, Na, Cu), including Pb, were excreted at higher concentrations in urine during therapy. Blood (0.425 ppm) and liver (4.85 ppm) Pb concentrations in the fetus were 71.7% and 84.3% of the same tissue Pb concentrations of the dam, indicating a significant transfer of Pb in utero. Severe polioencephalomalacia was described in the adult, and hepatic lysosomes with metallic electron densities were present in the fetus.

Effects of concurrent oral administration of toxic levels of monensin and lead on concentration of different elements in the liver of broiler chicks

Monensin and lead, separately or concurrently, were orally administered to broiler chicks at different toxic levels. Monensin slightly increased the selenium and profoundly increased the lead and iron levels of liver. Lead also increased the level of iron in liver. Levels of lead and iron in liver tissue further increased when monensin and lead were administered concurrently. An increased mortality was recorded due to concurrent administration of monensin and lead during acute toxicosis but during subacute toxicosis body weights were higher in birds administered monensin and lead concurrently than those given these substances separately.

The effects of thiamine and EDTA on biliary and urinary lead excretion in sheep

Relative efficacy of thiamine (B1) and/or calcium disodium ethylinediaminetetraacetate (EDTA) administration on lead (Pb) excretion via bile and urine was studied in Pb-loaded sheep. The sheep were administered B1 s.c., 75 mg/kg body wt., EDTA i.v., 110 mg/kg body wt., and a combination of B1-EDTA at rates as above. Each treatment was followed by 69 h sampling of blood, bile, and urine. Urinary Pb excretion increased following B1-EDTA greater than EDTA greater than B1 administration. Thiamine and B1-EDTA treatments increased biliary Pb excretion. Overall, B1, EDTA and B1-EDTA administration increased Pb excretion via bile and urine by 72%, 595%, and 842% respectively over basal level (mean +/- SE: 20.1 +/- 2.9 micrograms Pb/h). It has been concluded that thiamine enhances elimination of Pb from the body and this feature may be beneficial in chelation therapy.

The effects of thiamin on lead metabolism: whole body retention of lead-203

The effects of thiamin on the whole body retention of led were evaluated in CD-1 mice treated intragastrically or intraperitoneally while exposed to a single dose of lead acetate (100 micrograms) containing 100 mu Ci lead-203. They were administered thiamin (25 or 50 mg/kg body wt.), calcium ethylenediamine tetraacetic acid (CaEDTA) (50 mg/kg body wt.) or their combination in pretreatment or posttreatment regimens for 13 days. Both pre- and posttreatment with thiamin reduced the lead retention compared to the untreated lead-exposed mice, although the different patterns of lead retention were observed. The combined pretreatment (thiamin 50 mg/kg and CaEDTA) and the CaEDTA treatment alone reduced the whole body retention of lead most effectively. Thiamin, CaEDTA and the combined treatments decreased the absorption of lead-203 and the biological half-life of retained lead-203 following oral or intraperitoneal lead exposure. The reduced absorption and enhanced excretion of lead associated with thiamin administration may have therapeutic application for the treatment of lead poisoning.

New developments in therapeutic chelating agents as antidotes for metal poisoning

An examination of the studies on therapeutic chelating agents that have been carried out during the last decade reveals that extensive efforts have been made to develop compounds superior to those previously available for the treatment of acute and chronic intoxication by many metals. These metals include primarily iron, plutonium, cadmium, lead, and arsenic, but also many other elements for which acute and chronic intoxication is less common. These studies have revealed the importance of several additional factors of importance in the design of such compounds and have led to many new compounds of considerable clinical promise. An additional development has been the introduction of previously developed chelating agents for use with certain metals on a broader scale.

Lead attenuates the antipunishment effects of ethanol

Adult male rats were exposed to a diet containing no added chemicals, or a diet containing 500 ppm added lead (as lead acetate), for 70 days. On Day 71 (training day), after 24 h of water deprivation, all animals were placed in a test apparatus and permitted to make 220 licks for a 5.5 percent (v/v) sucrose in water solution. On Day 72 (test day), all animals received conditioned punishment training where electric shock was delivered to the tongue following every 20 licks of the sucrose and water solution. Prior to commencing punishment training on Day 72, half the animals for the control diet condition (Group Control-Diet-Saline), and half the animals for the lead diet condition (Group Lead-Diet-Saline), received IP injections of saline. Conversely, the remaining half of the animals (Groups Control-Diet-Ethanol and Lead-Diet-Ethanol) received IP injections of 1.5 g/kg ethanol. The results of the conditioned punishment test revealed that animals exposed to a control diet and administered ethanol (Group Control-Diet-Ethanol) engaged in more punished licking and received more shocks than their lead-treated counterparts (Group Lead-Diet-Ethanol). Both of the groups exhibited more punished licking and received more shocks than either of the groups that received saline injections. The possibility that lead contamination may reduce the pharmacologic impact of ethanol is noted.

Influences of thiamin on lead intoxication, lead deposition in tissues and lead hematological responses of Tilapia zillii

1. Lead levels in the blood, kidney, liver, brain and muscle of fish receiving only lead were elevated markedly over the values of both controls and thiamin-treated fish. 2. No statistical difference was observed between the lead levels in bone samples of both fish receiving only lead and thiamin-treated fish. 3. In contrast to the fish receiving only lead the fish treated with thiamin appeared to be healthy and had no lead poisoning signs. 4. Over the period of study, hemoglobin content and red blood cell counts of fish receiving only lead showed significant decreases from the values of both controls and fish treated with thiamin. 5. Hematocrit values and white blood cell counts were uninfluenced by either lead exposure or thiamin treatment at all intervals. 6. The data suggest that thiamin can serve as a promising natural chelator to prevent fish mortality, not only in short term, but also in prolonged exposure.

The effects of thiamin on the tissue distribution of lead

The effects of thiamin on the tissue distribution of lead were evaluated in Sprague-Dawley rats exposed to 1000 ppm lead acetate in drinking water and treated daily with thiamin (25 or 50 mg kg-1 body weight, i.p.), calcium ethylenediamine tetraacetic acid (50 mg kg-1 body weight, i.p.) or their combination for 8 weeks. The subtoxic dose of lead did not alter weight gains, feed and water consumption during the treatment period. Thiamin decreased the blood (P less than 0.0001), liver (P less than 0.0001) and kidney (P less than 0.0001) concentrations of lead. Thiamin (50 mg kg-1 body weight) reduced the lead concentrations in tissues more effectively than thiamin (25 mg kg-1 body weight). The combined treatment was more effective than the respective individual treatments.

Thiamine and zinc in prevention or therapy of lead intoxication

Thiamine, zinc or their combination given through gastric gavage were investigated for their ability to prevent or treat experimental lead toxicity in rats. Simultaneous dietary supplementation with thiamine plus zinc was found to be the most effective way of reducing the lead-induced inhibition of delta-aminolevulinic acid dehydratase activity in blood, urinary, excretion of delta-aminolevulinic acid and accumulation of lead in blood, liver and kidney. Prevention was more effective than post-lead exposure treatment which may be due mainly to the decrease in the absorption of lead in the gastro-intestinal tract in the presence of thiamine and/or zinc.

Influence of thiamine and ascorbic acid supplementation on the antidotal efficacy of thiol chelators in experimental lead intoxication

The influence of the administration of thiamine (vitamin B1), ascorbic acid (vitamin C) or their combination on the efficacy of two thiol metal chelators, viz. alpha-mercapto-beta-(2-furyl) acrylic acid (MFA) and 2,3-dimercaptosuccinic acid (DMS), in counteracting lead (Pb) toxicity was investigated in rats. Ascorbic acid or its combination with thiamine enhanced the urinary elimination of Pb, reduced the hepatic and renal burden of Pb, and reversed the Pb-induced inhibition of the activity of blood delta-aminolevulinic acid dehydratase (delta-ALA-D). All these effects were more evident in DMS- than in MFA-treated rats. The combination of MFA and DMS treatments further improved the performance of the animals in enhancing urinary Pb excretion and in reducing Pb hepatic levels.

Chelation in metal intoxication XXVI : Influence of thiamine on the therapeutic efficacy of calcium disodium edetate in lead intoxication

The effect of pretreatment and simultaneous treatment with thiamine on therapeutic efficacy of calcium disodium edetate (CaNa2EDTA) in lead intoxication was investigated in rats. The animals exposed to Pb as Pb (CH3COO)2·3 H2O through drinking water (0.1%) for 8 wk were treated with either saline, thiamine-HCl (sc), CaNa2EDTA (ip), or thiamine-HCl plus CaNa2EDTA, for 3 d or thiamine-HCl for 3 d followed by thiamine, then HCl plus CaNa2EDTA for a further 3 d. The Pb exposure caused significant accumulation of Pb in liver, kideny, and brain, inhibition in the activity of blood δ-amino-levulinic acid dehydratase (δ-ALAD), and increase in levels of urinary δ-aminolevulinic acid, homovanillic acid (HVA), vanillyl mandelic acid (VMA), brain HVA and VMA. The brain δ-ALAD and lipomide dehydrogenase remained unaffected by Pb. Thiamine significantly enhanced the urinary excretion of Pb by CaNa2EDTA, but only marginally influenced the efficacy of CaNa2EDTA to either mobilize tissue Pb or reverse the biochemical alterations.

Effect of thiamine on the excretion of subcutaneously injected lead in rats

The effect of thiamine on the excretion of lead in feces was investigated using rats injected subcutaneously with lead acetate and thiamine pyrophosphate. The amount of lead excreted increased with the amounts of thiamine administered, while lead concentrations in blood, liver and femur also increased. The amount of lead excreted in feces decreased, however, with administration of oxythiamine and vanadium. These results suggest that excretion of lead in feces is enhanced by thiamine and that it promotes evacuation of lead from the body.

Effect of food intake on blood lead concentration in workers occupationally exposed to lead

Results from a cross-sectional study showed the concentration of lead in the blood of male workers, aged 20-55 years, occupationally exposed to lead in a steel factory, to be negatively correlated with the daily nutritional content of dietary fiber, iron and vitamin B1 (thiamine) intake. Furthermore, in experiments with rats injected subcutaneously with lead acetate, lead levels in blood and femur of animals on a vitamin-rich laboratory chow were lower than those fed a general laboratory chow. Moreover, in the group fed the vitamin-rich chow, lead excretion in feces increased, while excretion in urine did not. These results suggest that lead excretion from the body may be increased by a high intake of nutrients such as thiamine, iron and fiber, that lead excretion in feces via bile may be enhanced by a large intake of vitamins such as thiamine and that accordingly the lead concentration in the blood of the workers is reduced.

Lead poisoning in cattle

Lead poisoning is a frequent cause of poisoning in domestic animals. Signs of encephalopathy and gastroenteritis are commonly observed in cattle following lead poisoning. This article discusses the etiology, epidemiology, pathogenesis, clinical signs, diagnosis, postmortem findings, and treatment of lead poisoning in cattle.

Effects of lead treatment on intracellular iron and copper concentrations in cultured astroglia

Astroglia are implicated in the pathogenesis of lead (Pb) neurotoxicity in two capacities: as a lead sink that sequesters lead and as a target for direct cellular damage. A proposed cellular mechanism of Pb neurotoxicity is the alteration of metal concentrations, particularly the intracellular accumulation of Cu2+. We measured Pb uptake and the effects of Pb acetate on intracellular trace metal concentrations in astroglial cultures prepared from 0- to 4-day-old rat cerebral hemispheres. Mature Sprague Dawley and immature Wistar rat astroglia in culture took up lead from the medium. This finding replicates in vitro the finding reported by others that astroglia in the brain take up Pb. Intracellular Cu and Fe concentrations (micrograms per 2 x 10(6) cells) were increased fourfold or more by treatment with 100 microM Pb for 3 days in the cultures of immature astroglia. Cu levels were also increased twofold or more in mature astroglia treated for 1-3 days with 100 microM Pb. The significance of this finding is that Cu is a potent inhibitor of Na+, K+-ATPase, an enzyme by which astroglia are thought to remove K+ from the extracellular fluid in the brain. Thus, this finding supports the hypothesis that elevated [Cu], and perhaps [Fe], is a subcellular mechanism of neurotoxicity.

Chelation in metal intoxication. XXIV: Influence of various components of vitamin B complex on the therapeutic efficacy of disodium calcium versenate in lead intoxication

The supplementation of vitamin-B complex reduces lead intoxication. With a view to identify the components of vitamin-B complex responsible for such protection, riboflavin, calcium pentothenate, pyridoxine, nicotinamide, folic acid and cyanocobalamine were investigated for their ability, and their influence on the efficacy of disodium calcium versenate (Na2CaEDTA), to enhance the urinary excretion of lead, mobilize tissue lead and restore lead induced biological alterations in lead intoxicated rats. Folic acid and pyridoxine besides thiamine may be the responsible factors in prophylaxis of lead poisoning by vitamin B complex or in enhancing the antidotal properties of Na2CaEDTA.

Influence of dietary supplementation with thiamine on lead intoxication in rats

The influence of dietary supplementation with thiamine on lead (Pb) contents in blood and tissues, blood δ-aminolevulinic acid dehydratase (δ-ALAD) activity, and urinary excretion of δ-aminolevulinic acid (δ-ALA) was evaluated in male Sprague-Dawley rats. Groups of randomly selected animals were given a thiamine-deficient diet, a diet containing normal thiamine (20 mg/kg), or a thiamine-supplemented diet (50 mg/kg), along with control drinking water or water containing 100 ppm Pb, for 4 mo. Animals fed the thiamine-supplemented diet (50 mg/kg) and Pb showed decreased urinary excretion of δ-ALA and a decreased inhibition of δ-ALAD activity in blood compared to those given Pb with normal thiamine diet. The liver, kidney, and blood of rats receiving supplemental thiamine also contained significantly less Pb than the other two treatment groups given Pb-containing water. The protective effect of thiamine against Pb toxicity may be attributed to its interference with retention of the metal in body tissue, possibly resulting from the formation of excretable thiamine-lead complexes.

Preventive and therapeutic effects of thiamine, ascorbic acid and their combination in lead intoxication

Thiamine, ascorbic acid and their combination were investigated for their ability to prevent or treat the experimental lead intoxication in rats. The combination of the two vitamins was most effective in reducing the lead induced inhibition in the activity of blood delta-aminolevulinic acid dehydratase, elevation in the level of blood zinc protoporphyrin and the urinary excretion of delta-aminolevulinic acid and the uptake of lead in blood, liver and kidney. The combined treatment post lead exposure was also most effective in restoring the lead induced biochemical alterations and mobilizing lead from the tissues. The order of effectiveness was, thiamine + ascorbic acid less than ascorbic acid less than thiamine. The lead induced changes in brain biogenic amines and the brain concentration of lead remained unaffected by these vitamins.

Chelation in metal intoxication XVIII: Combined effects of thiamine and calcium disodium versenate on lead toxicity

Calcium disodium ethylenediaminetetraacetate (Ca-Na2EDTA; Versenate) was more effective than thiamine (vitamin B1) in enhancing the urinary excretion of lead, reducing tissue lead and restoring lead induced biochemical alterations in rats. However, the combination of CaNa2EDTA and vitamin B1 enhanced the beneficial effect of CaNa2EDTA in lead intoxication and was particularly effective in reducing the brain concentration of lead.

The influence of milk diet, grain diet, and method of dosing on lead toxicity in young calves

Twenty 2- to 3-week-old calves were fed a milk diet or a mixture of grain and hay. After acclimatization, all calves were dosed po with lead acetate for 7 days, either in solution via a nursing bottle or in a gelatin capsule. At the end of the treatment period, 6 of 10 calves fed milk were either dead or showed multiple signs of Pb poisoning. All calves fed grain and hay appeared normal. Tissue Pb was significantly higher in calves on a milk diet (p less than 0.05) compared to tissue from calves on a grain and hay diet. No significant differences wee found when dosing methods wee compared. These data clearly show that diet but not dosing methods greatly influenced the absorption and tissue distribution of Pb in calves. delta-Aminolevulinic acid dehydratase (ALAD) activity in blood dropped to approximately 20% of pre-Pb exposure concentrations within 24 hr after the initial dose of Pb and remained at this concentration despite continued Pb administration. Blood Pb concentrations indicate that, in this model, the Pb enters the blood rapidly and retention is prolonged. The calf model warrants further studies on absorption and metabolism.

Vitamin therapy in the absence of obvious deficiency. What is the evidence?

Vitamins are a group of organic compounds occurring naturally in food and are necessary for good health. Lack of a vitamin may lead to a specific deficiency syndrome, which may be primary (due to inadequate diet) or secondary (due to malabsorption or to increased metabolic need), and it is rational to use high-dose vitamin supplementation in situations where these clinical conditions exist. However, pharmacological doses of vitamins are claimed to be of value in a wide variety of conditions which have no, or only a superficial, resemblance to the classic vitamin deficiency syndromes. The enormous literature on which these claims are based consists mainly of uncontrolled clinical trials or anecdotal reports. Only a few studies have made use of the techniques of randomisation and double-blinding. Evidence from such studies reveals a beneficial therapeutic effect of vitamin E in intermittent claudication and fibrocystic breast disease and of vitamin C in pressure sores, but the use of vitamin A in acne vulgaris, vitamin E in angina pectoris, hyperlipidaemia and enhancement of athletic capacity, of vitamin C in advanced cancer, and niacin in schizophrenia has been rejected. Evidence is conflicting or inconclusive as to the use of vitamin C in the common cold, asthma and enhancement of athletic capacity, of pantothenic acid in osteoarthritis, and folic acid (folacin) in neural tube defects. Most of the vitamins have been reported to cause adverse effects when ingested in excessive doses. It is therefore worthwhile to consider the risk-benefit ratio before embarking upon the use of high-dose vitamin supplementation for disorders were proof of efficacy is lacking.