Inhibition of rat liver transaminases by low levels of acetaldehyde and the pharmacologic effects of B6 vitamers

Pellagra and alcoholism: a biochemical perspective

Historical and clinical aspects of pellagra and its relationship to alcoholism are reviewed from a biochemical perspective. Pellagra is caused by deficiency of niacin (nicotinic acid) and/or its tryptophan (Trp) precursor and is compounded by B vitamin deficiencies. Existence on maize or sorghum diets and loss of or failure to isolate niacin from them led to pellagra incidence in India, South Africa, Southern Europe in the 18th century and the USA following the civil war. Pellagra is also induced by drugs inhibiting the conversion of Trp to niacin and by conditions of gastrointestinal dysfunction. Skin photosensitivity in pellagra may be due to decreased synthesis of the Trp metabolite picolinic acid → zinc deficiency → decreased skin levels of the histidine metabolite urocanic acid and possibly also increased levels of the haem precursor 5-aminolaevulinic acid (5-ALA) and photo-reactive porphyrins. Depression in pellagra may be due to a serotonin deficiency caused by decreased Trp availability to the brain. Anxiety and other neurological disturbances may be caused by 5-ALA and the Trp metabolite kynurenic acid. Pellagra symptoms are resolved by niacin, but aggravated mainly by vitamin B6. Alcohol dependence can induce or aggravate pellagra by inducing malnutrition, gastrointestinal disturbances and B vitamin deficiencies, inhibiting the conversion of Trp to niacin and promoting the accumulation of 5-ALA and porphyrins. Alcoholic pellagra encephalopathy should be managed with niacin, other B vitamins and adequate protein nutrition. Future studies should explore the potential role of 5-ALA and also KA in the skin and neurological disturbances in pellagra.

Fenugreek seeds, a hepatoprotector forage crop against chronic AlCl3 toxicity

Background

Having considered how bioavailable aluminium (Al) may affect ecological systems and animals living there, especially cattle, and in search for a preventive dietary treatment against Al toxicity, we aimed to test the protective role of fenugreek seeds against chronic liver injury induced by aluminum chloride (AlCl₃) in Wistar rats.

Results

Five months of AlCl₃ oral exposure (500 mg/kg bw i.g for one month then 1600 ppm via drinking water) caused liver atrophy, an inhibition of aspartate transaminase (AST), alanine transaminase (ALT) and glutamyl transpeptidase (GGT), an enhancement of both lipid peroxidation and lactate dehydrogenase (LDH) activity and an increase of total protein level in liver. Moreover, histopathological and histochemical examinations revealed moderate alterations in the hepatic parenchyma in addition to a disrupted iron metabolism. Co-administration of fenugreek seed powder (FSP) at 5% in pellet diet during two months succeeded to antagonize the harmful effects of AlCl₃ by restoring all tested parameters.

Conclusion

This study highlighted the hepatotoxicity of AlCl₃ through biochemical and histological parameters in one hand and the hepatoprotective role of fenugreek seeds on the other hand. Thus this work could be a pilot study which will encourage farmers to use fenugreek seeds as a detoxifying diet supplement for domestic animals.

Cobalamin-responsive disorders in the ambulatory care setting: unreliability of cobalamin, methylmalonic acid, and homocysteine testing

Early recognition of cobalamin (Cbl)-responsive disorders in the ambulatory care setting is essential to prevent irreversible neurologic deficits. However, diagnostic algorithms using Cbl, methylmalonic acid (MMA), and homocysteine (HCys) measurements reflect studies in academic centers, and their negative predictive values have not been established. Thus, records of 456 ambulatory patients evaluated for Cbl deficiency at a staff model HMO were reviewed. Pretherapy Cbl, MMA, and HCys values in individual patients varied by 23%, 23%, and 17%, respectively, over 2 to 6 weeks. Hematologic or neurologic responses to pharmacologic doses of Cbl occurred in 37 of the 95 evaluable patients. In these patients, pretherapy Cbl, MMA, and HCys values were normal in 54%, 23%, and 50%, respectively. If therapy had been restricted to symptomatic patients with both low or intermediate Cbl levels and increased metabolite values, 63% of responders would not have been treated. Twenty-five patients did not respond to treatment, including 5 of 11 patients (45%) with low Cbl, 22 of 49 patients (45%) with high MMA, and 13 of 30 patients (43%) with high HCys values. It is concluded that Cbl, MMA, and HCys levels fluctuate with time and neither predict nor preclude the presence of Cbl-responsive hematologic or neurologic disorders.

The formation and measurement of DNA neuroadduction in alcoholism. Case report

We present a case report of an intoxicated alcoholic driver who sustained fatal motor vehicle injuries. We subsequently quantified ethanol-derived acetaldehyde (ACE) DNA products in his brain, which may represent a major contributor to clinical alcoholic use and complications. Further, ACE DNA neuroadducts may indicate chronic exposure to alcohol, as demonstrated by 32P-prelabeled DNA and two-dimensional thin-layer chromatography. ACE and other unknown neuroadducts were evident in the histologically normal frontal, parietal, and caudate lobes. DNA neuroadduct formation was extensive and similar in three separate brain regions with normal histology. Contributing neuroadduction by chronic drug abuse is also possible, though the deceased's terminal acute blood screens for recent drug abuse were negative. The mechanism of alcohol neurotoxicity remains unknown, but biochemical nonenzymatic changes of DNA at the nucleic acid level (adduct formation) can alter gene function and stability. DNA neuroadduct detection may represent an important determinant in quantifying neurotoxicity from drug abuse or alcoholism in the absence of history, the presence of negative blood, tissue, and urine assays for recent drug and alcohol use, and the absence of neuropathology.