Urinary ALA Research Articles

Long-term follow-up of givosiran treatment in patients with acute intermittent porphyria from a phase 1/2, 48-month open-label extension study

BackgroundAcute hepatic porphyria is a group of multisystem disorders of which acute intermittent porphyria is the most common subtype. Givosiran, a subcutaneously administered RNA interference therapeutic targeting liver ALAS mRNA, is approved for treating these disorders. This Phase 1/2 open-label extension study (NCT02949830) evaluated the long-term safety and efficacy of givosiran in adults with acute intermittent porphyria, with follow-up of up to 48 months, which is the longest follow-up of givosiran treatment to date. Participants were adults aged 18–65 years who completed part C of the Phase 1 givosiran study (NCT2452372).MethodsEnrollees received givosiran for up to 48 months. Primary and secondary endpoints included the incidence of adverse events, changes in urinary delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) levels, annualized rate of porphyria attacks, and annualized hemin use. Quality of life was assessed using the EQ-5D-5L instrument as an exploratory endpoint.ResultsSixteen patients (median age: 39.5 years) participated. Common adverse events included abdominal pain, nasopharyngitis, and nausea (50% each), with injection-site erythema (38%) and injection-site pruritus (25%) noted as frequent treatment-related reactions. Givosiran therapy reduced annualized rates of porphyria attacks and hemin use by 97% and 96%, respectively. From months > 33 to 48, all patients were free from attacks requiring significant medical intervention and did not use hemin. There were substantial reductions in median urinary ALA and PBG of 95% and 98%, respectively. Additionally, a clinically meaningful improvement in quality of life was observed.ConclusionsIn the longest follow-up of givosiran-treated patients reported to date, the therapy maintained an acceptable safety profile and demonstrated sustained improvements in clinical outcomes over 4 years in patients with acute intermittent porphyria.

In situ one-pot synthesis of chitosan@ P,N-CPDs as a ratiometric scatter up-conversion sensor for α-lipoic acid

The rapid sensitive determination of α-lipoic acid (ALA) is essential for monitoring biological functions. Nevertheless, the lack of chromophore and its occurrence in complex biological matrices renders its determination challenging and requires additional treatment steps which lengthen assay procedure and affects method sensitivity. Herein, through the coordination of frequency doubling scatter (FDS) of polysaccharide strands with up-conversion of the embedded in situ formed P, N- carbonized polymer dots (CPDs), a novel ratiometric sensing platform was constructed. One-pot synthesis of chitosan decorated P, N-CPDs (chitosan@ P,N-CPDs) was attempted through microwave-assisted crosslinking-accelerated carbonization, using phosphoric acid as crosslinker and dopant. The constructed platform responded to the presence of α-lipoic acid (ALA) in concentration dependent manner (R2 = 0.995) between 1.65–100 μg/mL, with detection limit of 0.55 μg/mL, good accuracy (%E = 0.52 %) and precision (%RSD < 2 %). Consistent results with comparison method confirmed sensor reliability for determination of ALA in urine, Thiotacid® and Thiotacid compound® tablets, with no interference from the coexisting highly absorbing water-soluble vitamins, thiamine, and cyanocobalamin, or other potential interferents. Thus, the developed high performance sensing platform could be adopted for ALA determination as it is much less prone to spectral interferences and hence more discerning than those operated in single wavelength mode.

Porphyrin precursors and risk of primary liver cancer in acute intermittent porphyria: A case-control study of 188 patients.

Acute intermittent porphyria (AIP) is a rare hereditary metabolic disease characterized by acute attacks and accumulation of the porphyrin precursors 5-aminolevulinic acid (ALA) and porphobilinogen (PBG). Patients with AIP have a high risk of primary liver cancer (PLC). We aimed to assess the association between porphyrin precursor excretion and the risk for PLC in patients with AIP. We studied 48 patients with AIP who developed PLC between 1987 - 2015 and 140 age and sex matched controls with AIP but no PLC. Data on all available urinary PBG and ALA samples collected from 1975 until one year before PLC diagnosis were analyzed and compared between cases and controls using logistic regression. Porphyrin precursor excretion was higher in patients with PLC (PBG median 7.9 (IQR 4.4-21.9) mmol/mol creatinine) than in controls (3.8 (1.2-9.8)) (adjusted odds ratio 1.07, 95% confidence interval: 1.02-1.12). None of the 28 patients with all registered samples below the upper limit of normal (ULN) developed PLC, and only one of the 45 patients with all samples <2x ULN developed PLC. Among non-PLC controls, ALA and PBG levels decreased after age 50-60 while an increasing trend was observed after age 65 among those who developed PLC. Increased urinary porphyrin precursors are associated with a high risk of developing PLC. Patients with normal levels appear to have a low risk while high or increasing ALA and PBG after age 65 indicates high risk, which should be considered in surveillance decisions. This article is protected by copyright. All rights reserved.

Occupational lead exposure health risk assessment and heme biosynthesis: A study on batik artisans in yogyakarta, Indonesia

This study aims to assess dermal and inhalation lead exposure levels among batik industry workers and evaluate noncarcinogenic and carcinogenic health risks associated with lead exposure. We investigate potential relationships between lead exposure (dermal average daily dose and inhalation exposure concentration) and the workers' blood hemoglobin levels (Hb), as well as their urinary ALA (u-ALA) concentrations. Additionally, we explore any possible associations between Hb and u-ALA levels among the workers and identify various factors influencing lead exposure levels. A total of 30 workers were recruited for the study. Interviews and exposure sampling were conducted to measure dermal and inhaled lead exposure. Sample analysis methods include XRF for exposure samples, spectrophotometry for u-ALA, and HiCN colorimetric for Hb. Carcinogenic and noncarcinogenic risk assessments, correlation analysis, as well as ANOVA for factors analysis, were performed. The average dermal exposure dose and inhalation exposure concentration of lead were 6.53 ± 3.2 ng/kg/day and 0.021 ± 0.015 μg/m3, respectively. Hazard Index (HI) values for all workers were below 1 (average: 0.372 ± 0.155), indicating no expected noncarcinogenic health effects due to lead exposure. The average Excess Lifetime Cancer Risk (ELCR) was (5.18 ± 3.84) × 10−8, significantly below acceptable limits. Correlation analysis revealed a significant negative correlation between Hb and u-ALA (r = −0.519, p = 0.058 for male workers and r = −0.531, p = 0.034 for female workers), supporting their use as lead exposure biomarkers. The factors analysis demonstrated a significant impact of working conditions on inhalation exposure (p = 0.018), with outdoor workers experiencing lower lead inhalation. This research provides crucial insights into potential dangers faced by batik workers due to lead exposure, emphasizing the importance of targeted interventions. The strong correlation between Hb and u-ALA indicates their combined effectiveness in detecting lead exposure, even at low levels. The study underscores the significance of outdoor work as a protective measure against inhaling heavy metals, such as lead, present in the air. The assessment of health risks associated with lead exposure in the batik industry lays the groundwork for informed decision-making and interventions to protect workers' well-being, particularly in informal sectors workplaces where health risks are often overlooked.

Association between Blood Lead Levels and Heme Synthesis Process in Paint Industry Workers

Lead is a heavy metal that can pose various health risks to humans. One of the effects of lead exposure is the inhibition of the delta-ALAD enzyme which plays a role in the heme synthesis process. Blood lead levels and delta-aminolevulinic acid dehydratase (ALAD) activity are considered biomarkers of lead exposure and lead toxicity respectively. The inhibition of ALAD can cause in accumulation of ALA in urine and also inhibit the heme synthesis pathway that plays a role in hemoglobin production. The present study was designed to investigate the association between the BLLs and the heme synthesis process, which is detected by the accumulation of urinary ALA (ALA-U) and decreasing hemoglobin, in paint industry workers from Indonesia. A total of 52 paint industry workers participated in this study. Blood lead was measured using ICP-MS and ALA-U was measured using spectrophotometer method. Mean blood lead was 4.213±1.6 mg/L; and 17 workers (32.7%) crossed the recommended level of 5 mg/L. Mean urinary ALA level was 3.712±2.5 mg/L; and 11 workers (11.54%) crossed the normal level of 6 mg/L but still classified as acceptable. Mean hemoglobin level was 15.273±1.03 g/L. The correlation between the BLL and ALA-U was found to be positive but not significant. Meanwhile, the correlation between the ALA-U and the hemoglobin levels was found to be negative but also not significant.

Pharmacokinetic-pharmacodynamic model of urinary δ-aminolevulinic acid reduction after givosiran treatment in patients with acute hepatic porphyria.

Givosiran, an RNA interference-based therapeutic, is a recent addition to the limited treatment armamentarium for acute hepatic porphyria (AHP). As a small interfering RNA that is selectively taken up in the liver, both the mechanism and targeted delivery create a complex relationship between givosiran pharmacokinetics (PK) and the pharmacodynamic (PD) response. Using pooled data from phase I-III clinical trials of givosiran, we developed a semimechanistic PK/PD model to describe the relationship between predicted liver and RNA-induced silencing complex concentrations of givosiran and the associated reduction in synthesis of δ-aminolevulinic acid (ALA), a toxic heme intermediate that accumulates in patients with AHP, contributing to disease pathogenesis. Model development included quantification of variability and evaluation of covariate effects. The final model was used to assess the adequacy of the recommended givosiran dosing regimen across demographic and clinical subgroups. The population PK/PD model adequately described the time course of urinary ALA reduction with various dosing regimens of givosiran, the interindividual variability across a wide range of givosiran doses (0.035-5mg/kg), and the influence of patient characteristics. None of the covariates tested had a clinically relevant effect on PD response that would necessitate dose adjustment. For patients with AHP, including adults, adolescents, and patients with mild to moderate renal impairment or mild hepatic impairment, the 2.5-mg/kg once monthly dosing regimen of givosiran results in clinically meaningful ALA lowering, reducing the risk for AHP attacks.

Estimation of urinary delta aminolevulinic acid levels in gasoline and petrol pump workers as an index of lead exposure

Lead poisoning is a phenomenon which with growing globalization is being a subject of worry.ALA i.e Amino levulinic acid is a precursor of hemoglobin, which is synthesized in mitochondria by two main components succinyl Co-A and glycine in presence of ALA-S i.e. amino levulinic acid-synthase. Urinary ALA (ALA-U) has been a recommended biomarker for lead exposure. Inhibition of Amino levulinic acid-dehydratase (ALA-D) results into activation of ALA-S which further synthesizes ALA, excess of ALA is accumulated in the blood, plasma, urine. Present manuscript is focused on the estimation of levels of ALA in the urine of gasoline and pertol pump workers, by acidifying the urine to extract out ALA and reading it colorimetrically as they are exposed to fumes released by gasoline, petrol, and petroleum products which contains lead. Awareness and safety measures such as protective masks and gears should be provided by the respective organisations to the workers.

Multibiomarker approach to assess the magnitude of occupational exposure and effects induced by a mixture of metals

Metals and metalloids including lead (Pb), arsenic (As) and manganese (Mn) can occur as mixtures in occupational contexts, such as mines. These chemicals are all known to be neurotoxic and provoke changes in heme metabolism also known to induce neurotoxicity. The objective of this work was to propose a multi-biomarker (BM) methodology to screen subjects exposed to the mixture of Pb, As and Mn and assess the severity of their exposure/effects, in an individual basis. The urinary levels of the metals, dela-aminolevulinic acid (ALA) and porphyrins were determined in Portuguese miners and in a control group. The combination of Pb and As urinary levels had the highest capability to identify subjects occupationally exposed to this mixture in mines, as evaluated through Receiver Operating Characteristic (ROC) (A = 98.2%; p < 0.05), allowing that 94.2% of 86 studied subjects were properly identified and the generation of an equation indicating the odd of a subject be considered as exposed to the metal mixture. The combination of urinary ALA and porphyrins revealed to be best one to be applied in the assessment of subjects with high, intermediate, and low magnitudes of exposure/effects, with 95.7% of 46 miners classified correctly according to their severity sub-group and allowing to generate equations, which can be applied in new subjects. The proposed methodology showed a satisfactory performance, evaluating in an integrated manner the magnitude of exposure/effects of the exposed workers, may contributing to improve the control of their health.

Erythrocyte and reticulocyte parameters during biological monitoring of lead exposure to the body

Introduction. The most susceptible to lead is the hematopoietic system of hematopoietic organs due to lead inhibition of heme and globin synthesis and cytotoxic effect on the membrane of Mature red blood cells. The aim of study was to evaluate the informative value of the study of erythrocyte and reticulocyte parameters determined on modern hematological analyzers in patients working in contact with lead during medical and biological monitoring. Materials and methods. 45 employees of the lead battery processing plant and 30 persons of control group were examined. The level of lead in the blood was determined by atomic absorption spectrometry, δ-ALA in the urine-by the reaction of pyrol formation with acetylacetone in terms of gram of creatinine, the study of hematological parameters was performed on a Sysmex HT-2000i analyzer. Statistical processing of the results was performed using the program STATISTICA 10.0. Results. Significant changes in erythrocytic (RDW) and reticulocytic (RET, IRF, LFR, MFR, HFR, RET-He) parameters, erythropoietin in workers in contact with lead compared to the control group, changes in MCV, MCH, RDW, RET indicators in the group working in dynamics after 2 years were revealed. Associations of hematological parameters with biomarkers of exposure and effect (lead level in blood and ALA in urine) were revealed. Conclusions. Assessment of erythrocyte (MCV, MCH, RDW) and reticulocyte parameters (RET% and their distribution by maturity) in dynamics during periodic medical examinations of workers in contact with lead allows us to detect the development of hematological disorders at early stages.

Normal reference ranges for urinary δ-aminolevulinic acid and porphobilinogen levels.

Acute hepatic porphyria (AHP) is a family of rare, serious, and potentially life‐threatening metabolic disorders caused by mutations in genes encoding enzymes involved in hepatic heme biosynthesis. AHP is characterized by accumulation of neurotoxic heme intermediates, δ‐aminolevulinic acid (ALA), and porphobilinogen (PBG), which are thought to be causal for the disease manifestations. Novel therapeutic treatments such as givosiran, an RNA interference therapeutic that was recently approved for treatment of adults with AHP, are focused on reducing the levels of ALA and PBG in patients toward levels observed in a healthy population. While there are two published reports on the distribution of urinary ALA and PBG levels in healthy subjects, these lacked the required details to enable the calculation of reference limits for ALA and PBG. Therefore, urinary ALA and PBG levels were quantified in 150 healthy subjects using a validated liquid chromatography tandem mass spectrometry (LC‐MS/MS) method that is highly sensitive, specific, accurate, and reproducible. These data were used to establish the upper limit of normal (ULN) values for ALA and PBG as 1.47 and 0.137 mmol/mol Cr, respectively. Relative to these ULN values, baseline urinary ALA and PBG levels in AHP patients were found to be 9.3‐ to 12‐fold, and 238‐ to 336‐fold higher, respectively. Results from this study can serve as a guide to assess the effectiveness of therapeutic interventions in lowering ALA and PBG.

Genetic polymorphism of calcium metabolism regulators in differential susceptibility to the effects of lead

Based on an examination of 102 employees of lead-acid batteries recycling plant, there have been determined associations of single nucleotide polymorphisms of calcium metabolism regulators genes VDR (rs10735810) and CALCR (rs187197) and blood lead levels, urine ALA, erythrocytic parameters, that indicates significance of these genetic markers as indicators of susceptibility to lead exposure.

Intermittently We Get Things Right: A Case of Porphyria After Esophagogastrectomy

Acute porphyrias are rare inherited metabolic disorders of heme production, intermittently presenting with abdominal pain and neurovisceral symptoms. We discuss the case of a 58-year-old African American female with a history of gastroparesis and esophageal adenocarcinoma, who presented with intractable abdominal pain, nausea and vomiting. Her symptoms were initially attributed to her previously established gastrointestinal diagnoses; however, an in-depth workup for gastric, hepatic, biliary and vascular causes was negative. Ultimately, a urine porphyria panel revealed elevated porphyrins and the patient was treated with a high carbohydrate diet and hemin infusion, with subsequent normalization of her urine porphyrins and improvement of her symptoms. Acute Porphyrias are exceedingly rare. However, the occurrence of acute porphyria after gastric surgery has been previously reported and attributed to diminished carbohydrate intake. Similarly, this patient's esophagogastrectomy reduced her caloric carbohydrate intake, perhaps resulting in the accumulation of heme precursors and the onset of a clinical crisis. The patient's dramatic normalization of urine porphyrins following hemin treatment underscores the validity of her diagnosis. Thus, we propose that acute porphyria should be considered in patients with recurrent abdominal pain, nausea and vomiting and a negative work-up for another intra-abdominal pathology. Porphyrias should also be considered in patients with persistent pain after abdominal surgery and those with reduced caloric intake. Early diagnosis of porphyria is key to effective treatment with hemin. Simple spot urine tests for urine porphinobilinogen, although not performed in this case due to low suspicion, can easily rule out the diagnosis, and should be the first step in the workup of such patients.Table 1: Urine porphyria panel results prior to hemin treatment and after hemin treatment. All values were initially elevated and were within normal levels after treatment. Urine ALA remained elevated 10 days after admission.

Acute Intermittent Porphyria—A Diagnostic Dilemma

Porphyrias are metabolic diseases resulting from a partial deficiency of an enzyme in the heme biosynthetic pathway. AIP (deficiency of hydroxymethylbilane synthase) causes acute attacks due to secondary accumulation of heme precursors. It presents with abdominal pain, tachycardia, hypertension, hyponatremia, seizures, motor neuropathy, etc. Screening is done with qualitative urinary PBG and ALA. Urinary and fecal fractionated porphyrins and DNA testing provided the confirmation. Acute attacks are treated with IV hemin and glucose. Prevention of acute attacks is with smoking cessation and avoidance of inciting agents. A 11-year-old undernourished girl, on multiple antiepileptics, for 4 years (started for refractory seizures), presented with complaints of recurrent generalized abdominal pain with weight loss since the past 1 year, with constipation and poor oral acceptance since 10 days. Examination revealed tender epigastrium, decreased air entry on left side of chest, generalized muscle wasting, and paresthesias. Investigations revealed Hb 9 g/dl; TLC 8200/cu mm (77/ 20/01/02); platelets 1,84,000/cu mm; PS-normocytic normochromic; Na 131 meq/L; K 4 meq/L; Ca 8.9 mg/dl; PO4 3.3 md/dl; ALP 255 U/L; blood urea 49 mg/dl; serum creatinine 0.9 mg/dl; bilirubin 0.5 mg/dl; SGOT 54 U/L; SGPT 21 U/L; blood culture—no growth; HIV-NR; urine examination— normal; serum amylase 112U/L; serum lipase 71U/ L; lipid profile, carbamazepine level, and CXR—normal; PPD test –NR; GA for AFB—negative; USG abdomen, CECT abdomen, and brain—normal; CECT thorax-opacities and necrotic patches on left lower zone consistent with pulmonary tuberculosis; EEGpartial epilepsy with focus at right temporal lobe; serum lead level—normal; Urine for porphobilinogen, 5-ALA, and total porphyrins—positive; and NCV— Severe axonal motor and sensory neuropathy in all four limbs. A diagnosis of AIP with pulmonary tuberculosis with partial seizure with undernutrition was made. Antiepileptics were tapered gradually and gabapentine with modified ATT was started and the child responded very well. AIP should be kept in the differentials of chronic abdominal pain and patients with psychological symptoms.

Preclinical Development of a Subcutaneous ALAS1 RNAi Therapeutic for Treatment of Hepatic Porphyrias Using Circulating RNA Quantification.

The acute hepatic porphyrias are caused by inherited enzymatic deficiencies in the heme biosynthesis pathway. Induction of the first enzyme 5-aminolevulinic acid synthase 1 (ALAS1) by triggers such as fasting or drug exposure can lead to accumulation of neurotoxic heme intermediates that cause disease symptoms. We have demonstrated that hepatic ALAS1 silencing using siRNA in a lipid nanoparticle effectively prevents and treats induced attacks in a mouse model of acute intermittent porphyria. Herein, we report the development of ALN-AS1, an investigational GalNAc-conjugated RNAi therapeutic targeting ALAS1. One challenge in advancing ALN-AS1 to patients is the inability to detect liver ALAS1 mRNA in the absence of liver biopsies. We here describe a less invasive circulating extracellular RNA detection assay to monitor RNAi drug activity in serum and urine. A striking correlation in ALAS1 mRNA was observed across liver, serum, and urine in both rodents and nonhuman primates (NHPs) following treatment with ALN-AS1. Moreover, in donor-matched human urine and serum, we demonstrate a notable correspondence in ALAS1 levels, minimal interday assay variability, low interpatient variability from serial sample collections, and the ability to distinguish between healthy volunteers and porphyria patients with induced ALAS1 levels. The collective data highlight the potential utility of this assay in the clinical development of ALN-AS1, and in broadening our understanding of acute hepatic porphyrias disease pathophysiology.

Investigation of delta-aminolevulinic acid dehydratase polymorphism affecting hematopoietic, hepatic and renal toxicity from lead in Han subjects of southwestern China

This study is to explore the effect of ALAD polymorphism on hematopoietic, hepatic and renal toxicity from lead in occupational exposure workers. We conducted a cross-sectional study on 156 workers with occupational exposure to lead between 2002 and 2007. The results of laboratory examinations were analyzed. The authors found that workers with the ALAD 1-1 genotype were associated with higher blood lead level than those with the ALADl-2 genotype. Blood and urine lead levels were much higher in storage battery workers than in cable workers. The urine ALA and blood ZPP levels in workers with the ALAD 1-1 genotype were higher than those with the ALADl-2 genotype. The serum Cr level in workers with the ALADl-1 genotype was much higher than those with the ALADl-2 genotype especially in higher lead exposure level. The ALAD-2 protein might modify the kinetics of lead in blood at a relatively higher blood lead level and protect against hematopoietic, hepatic and renal toxicity from lead. Urine ALA, blood ZPP and serum Cr levels might be considered as effective biological monitoring partners of lead induced hematopoietic and renal toxicology.

Urinary excretion of porphyrins, porphobilinogen and δ-aminolaevulinic acid following an attack of acute intermittent porphyria

Background and objectivesThe porphyrias are a group of rare, mainly inherited, diseases caused by a deficiency of one of the enzymes of the haem biosynthesis pathway. The biochemical hallmark of...

Acute Intermittent Porphyria Presented with Recurrent Abdominal Pain and Hypertension

Acute intermittent porphyria (AIP) is a rare disorder characterized biochemically by the increased excretion of porphyrins and porphyrin precursors, including delta-aminolevulinic acid (ALA) and porphobilinogen (PBG). AIP has variable clinical manifestations, such as acute abdominal pain, vomiting, nausea, constipation, peripheral neuropathy, seizures, tachycardia, and hypertension. A 16-year-old girl presented with recurrent abdominal pain, vomiting, hypertension, seizures, hypercholesterolemia, and red urine. AIP was confirmed by clinical features and increased 24-hour urine ALA and PBG. AIP should be considered in the differential diagnosis of patients who have abdominal pain, hypertension, and seizures when the results of all other tests are normal. (Korean J Pediatr Gastroenterol Nutr 2011; 14: 81∼85)

Time-dependent changes in lead and δ-aminolevulinic acid after subchronic lead exposure in rats

The time-dependent changes in lead (Pb) concentrations in major tissues, serum and urine, and the Pb biomarker delta-aminolevulinic acid (ALA) concentration in urine were studied in rats after sub-chronic Pb exposure. Female Sprague-Dawley (SD) rats were exposed to Pb in drinking water at concentrations of 100 ppm and 1000 ppm for 30 days. The Pb concentration in muscle, liver, kidney, plasma and urine, and the ALA concentration in urine were determined during exposure and every 7 days after exposure for 3 weeks. The muscle Pb concentration did not change post exposure. The liver Pb concentration increased 2.2 to 2.8 times (100 ppm group) and 3.9 to 7.4 times (1000 ppm group) during exposure, then decreased rapidly. Kidney Pb concentrations were 8.0 to 14.3 times (100 ppm group) and 13.8 to 28.5 times (1000 ppm group) higher than controls during exposure and decreased for 1 to 2 weeks post exposure. Plasma Pb concentrations were 1.2 to 3.3 times (100 ppm group) and 2.9 to 5.8 times (1000 ppm group) higher than control concentrations during exposure and decreased time-dependently in the 1000-ppm group after exposure. Urine Pb concentrations were 8.5 to 10.7 times (100 ppm group) and 30.4 to 51.1 times (1000 ppm group) higher than control concentrations during exposure and rapidly decreased after exposure, though concentrations remained up to 4 times higher than controls in the 1000 ppm exposure group. Urine ALA concentrations increased 1.7 to 2.6 and 7.1 to 32.7 times during exposure in the 100 ppm and 1000 ppm groups respectively, and remained elevated for 21 days post exposure. Our data support that urine Pb concentration is a useful marker for acute Pb exposure or post exposure. Urine ALA may be a predicator of biological response to Pb exposure.

Association between a Polymorphism of Aminolevulinate Dehydrogenase (ALAD) Gene and Blood Lead Levels in Japanese Subjects

This cross-sectional study investigated the relationship between the aminolevulinate dehydrogenase (ALAD) genotype and blood lead levels among 101 Japanese workers. Blood lead concentration measurement, biomarkers, and genotyping were performed. The minor allele frequency (MAF) for ALAD (ALAD2) was 0.08. Although the blood lead level in the subjects with heterozygous GC genotype was significantly higher than those with homozygous GG genotype, there were no significant differences for hemoglobin, hematocrit, serum and urinary ALA levels among genotypes. ALAD2 genotype was significantly associated with the blood lead concentration, even in the environmental lead exposed subjects. Further confirmation with a large sample size is needed.

The effect of haem biosynthesis inhibitors and inducers on intestinal iron absorption and liver haem biosynthetic enzyme activities

The relation between haem biosynthesis and intestinal iron absorption is not well understood, we therefore investigated the effect of compounds that alter haem metabolism on duodenal iron absorption. CD1 mice were treated with either an inhibitor (succinyl acetone (SA)) or stimulator (2-allyl-2-isopropylacetamide (AIA)) of haem biosynthesis. 5-Aminolaevulinic acid (ALA) dehydratase and urinary ALA and porphobilinogen (PBG) levels, were determined. Intestinal iron absorption was assayed with in vivo and in vitro techniques. Liver hepcidin ( Hamp1) and duodenal iron transporter mRNA levels were measured using RT-PCR. AIA caused increased hepatic ALA synthase (1.6-fold) and ALA dehydratase (1.4-fold, both p < 0.005) activities and increased urinary ALA and PBG excretion (2.1- and 1.4-fold, p < 0.005, p < 0.05, respectively). In vivo intestinal iron absorption was reduced to 49% of control ( p < 0.005). Mice treated with SA showed decreased urinary ALA and PBG levels (75 and 55% control, both p < 0.005) and reductions in both ALA synthase and ALA dehydratase activities (77 and 56% control, p < 0.05, p < 0.005, respectively) in the liver. Liver and duodenal haem and cytochrome oxidase levels were not significantly decreased. Iron absorption was enhanced (1.26-fold, p < 0.05) and hepatic Hamp1 mRNA was reduced (53% of control, p < 0.05). In vitro duodenal iron uptake after mice were injected with SA also demonstrated an increase in Fe(III) reduction and uptake (1.27- and 1.41-fold, p < 0.01 respectively). Simultaneous injections of SA and ALA blocked the enhancing effect on iron absorption seen with SA alone. We conclude that alterations in haem biosynthesis can influence iron absorption and in particular, the intermediate ALA seems to be an inhibitor of iron absorption.