Study of photodynamic reactions of p-nitroacetophenone using ESR and optical techniques

The photosensitizing properties of p-nitroacetophenone (PNAP), a well-known radiosensitizer, have been studied in near UV region. The mechanism of PNAP photosensitization has been investigated by testing the efficiency of singlet oxygen production using photooxidation of 2,2,6,6-tetramethylpiperidine (TEMP) and photodegradation of guanosine. In both the cases, the enhancement effect of deuterated solvents has been observed. Results of these experiments suggest the significant role of type II mechanisms in PNAP photosensitization.

Relative efficiency of Phyllanthus emblica fruit extract and ascorbic acid in modifying lead and aluminium-induced sister-chromatid exchanges in mouse bone marrow

The identification of desmutagens and bioantimutagens in plants has prompted the search for additional plant extracts capable of modifying adverse cellular effects of environmental toxicants. The protective action of crude extracts of Phyllanthus emblica fruits (PFE) against lead (Pb) and aluminium (Al)-induced sister chromatid exchanges (SCEs) was studied in bone marrow cells of Mus musculus. The modifying effect of the crude extract was compared with that of comparable amounts of synthetic ascorbic acid (AA), a major component of the fruits. Oral administration of PFE or AA for 7 consecutive days before exposure of mice to the metals by intraperitoneal injections reduced the frequencies of SCEs induced by both metals. PFE afforded a more pronounced protective effect than AA in counteracting the genotoxicity induced by both Al and Pb: This difference was significant with Pb. The higher protection afforded by PFE may be attributed to the interaction of AA with other natural ingredients present in the crude fruit extract.

Peripartum cerebral venous thrombosis

The clinical and computed tomography (CT) features of 25 patients with peripartum CVT are described. Majority of the patients presented in postpartum period and did not receive proper antenatal care. Headache (92%), altered sensorium (80%, seizures (76%), papilloedema (80%) and hemiplegia (52%) were the common modes of presentation. CT findings included diffuse brain oedema (52%), haemorrhagic or nonhaemorrhagic infarctions on one or both sides of brain (48%), gyral enhancement (40%) and tentorial enhancement (16%). While 15 patients made good recovery, 3 cases (12%) died during acute stage of illness.

Spatio-temporal expression of estrogen sulfotransferase within the hepatic lobule of male rats: implication of in situ estrogen inactivation in androgen action

Estrogen sulfotransferase (EST) catalyzes transfer of the sulfate group from phosphoadenosine phosphosulfate to estrogenic steroids. Since estrogen sulfates do not bind to the estrogen receptor with high affinity, EST can control the intracellular level of the receptor-active estrogens. Androgen action in the rat liver, as indicated by the androgenic induction of alpha 2u-globulin, is inhibited by low levels of estrogens. Thus, in situ estrogen inactivation by EST is expected to increase hepatic androgen sensitivity. During the lifespan of the animal, rat liver undergoes three distinct phases of androgen sensitivity, i.e. prepubertal androgen insensitivity, androgen sensitivity after approximately 40 days of age, and androgen insensitivity during senescence (greater than 750 days). EST in the liver is expressed only after puberty, when the liver becomes androgen sensitive. Furthermore, localization of EST and its corresponding mRNA within the lobular unit of the liver demonstrates that only androgen-responsive hepatocytes located around the central vein contain immunoreactive EST and its corresponding mRNA. These temporal and spatial correlations of EST expression and hepatic androgen sensitivity support the concept that steroid-inactivating enzymes play important roles in sex hormone action.

Modification of metal-induced micronuclei formation in mouse bone marrow erythrocytes by Phyllanthus fruit extract and ascorbic acid

The comparative efficacy of Phyllanthus emblica fruit extract, and its main constituent, ascorbic acid, in modifying the cytotoxic action of lead and aluminium was evaluated in vivo in bone marrow cells of Mus musculus. Oral administration of Phyllanthus emblica fruit extract for 7 days before exposure to the metals through intraperitoneal injections reduced the frequency of micronuclei induced by all doses of both metals. Priming with comparable doses of synthetic ascorbic acid reduced micronuclei formation induced by both doses of aluminium and only the lower dose of lead. With the higher dose of lead (20 mg/kg body wt.) priming with ascorbic acid increased the frequency of micronuclei when compared with mice administered lead alone. The greater efficacy of Phyllanthus fruit extract in alleviating metal-induced clastogenicity may be due to the combined action of all ingredients in the crude extract, rather than to ascorbic acid alone.

Estrogen sulfotransferase of the rat liver: complementary DNA cloning and age- and sex-specific regulation of messenger RNA

Mammalian estrogen sulfotransferase (EST; EC 2.8.2.4) sulfurylates the hydroxyl group of estrogenic steroids by transferring the sulfate from a cosubstrate adenosine 3'-phosphate-5'-phosphosulfate. Sulfurylated steroids do not bind to the estrogen receptor with high affinity and, therefore, are hormonally inactive. We have purified rat liver EST and developed monoclonal antibody to this enzyme. By immunoscreening a lambda gt-11 expression library constructed from male rat liver cDNAs, the cDNA clone corresponding to EST was identified and isolated. A recombinant expression plasmid (pCMV5) containing this cDNA insert when transfected into COS-7 cells generated both immunologically and enzymatically active EST. With the help of this cDNA probe, we have explored the regulation of the EST mRNA in the liver and the possible role of this enzyme in sex hormone action. During the lifespan of male rats, only the young adult animals show hepatic androgen responsiveness. Also, estrogenic hormones strongly antagonize androgen action in the rat liver. Northern blot analysis of liver RNA derived from male rats of different ages shows that the androgen sensitivity of young adult animals is associated with a high expression of EST mRNA. During the same period, mRNA corresponding to dehydroepiandrosterone sulfotransferase is markedly (approximately 10-fold) down-regulated. Such a correlation is in concordance with the role of these enzymes in the maintenance of hepatic androgen sensitivity during young adult life by inactivating the estrogenic and sparing the androgenic steroids. Furthermore, the increase in the hepatic androgen sensitivity of androgen-treated female rats is also associated with the induction of EST.(ABSTRACT TRUNCATED AT 250 WORDS)

CD7 augments T cell proliferation via the interleukin-2 autocrine pathway

The role of CD7, a T cell differentiation antigen, in T cell function is not known at present; this study evaluates the effect of anti-CD7 mAb in PMBC cultures activated with suboptimal concentrations of lectins, antigens, and anti-CD3 mAb. We found that the inclusion of anti-CD7 resulted in increased IL-2 production and IL-2R-alpha expression in these cultures. H-7, a protein kinase C (PKC) inhibitor, and genistein, a protein tyrosine kinase (PTK) inhibitor, significantly suppressed the proliferation of T cells in comitogenic assays. This suggested that the comitogenic effect mediated by CD7 molecule involved both the PKC and the PTK pathways of T cell activation. These drugs appeared to affect the CD7-mediated effects by inhibiting the IL-2 autocrine pathway, especially the up-regulation of IL-2R-alpha since inhibition was not relieved with exogenous rIL-2. Taken together, our results suggest that CD7 augments T cell function by up-regulating IL-2R-alpha expression and IL-2 production via multiple pathways of protein phosphorylation.

Metabolism and DNA binding of 2-nitropyrene in the rat

2-Nitropyrene (2-NP), a contaminant of ambient air, is a potent bacterial mutagen in the Ames assay and induces leukemia/lymphoma in female Sprague-Dawley rats. To understand the mechanistic basis for its tumorigenic activity, it is essential to elucidate the metabolic pathways of 2-NP in vivo. Such knowledge will also assist in developing analytical methods for monitoring human exposure to nitropolynuclear aromatic hydrocarbons in ambient air. Thus, 2-nitro[U-4,5,9,10-14C]pyrene was synthesized and administered to male F344 rats by intragastric gavage at a dose of 30 mg (0.4 mCi/mM)/kg body weight. During the first 48 h, 57.5% of the dose was eliminated in the feces and 9.7% was eliminated in the urine. Correspondingly, after 168 h, 58.9 and 10.6% were excreted in feces and urine, respectively. Fecal metabolites (isolated amounts) included 6-hydroxy-2-acetylaminopyrene (19.5%), 6-hydroxy-2-aminopyrene (10.4%), 2-aminopyrene (10.0%), 2-acetylaminopyrene (0.8%), and unmetabolized 2-nitropyrene (10.0%). 6-Hydroxy-2-acetylaminopyrene, 6-hydroxy-2-aminopyrene, and 2-aminopyrene were identified as their acetyl derivatives by comparison of their chromatographic retention times, mass spectra, and UV spectra to those of synthetic standards. Urinary metabolites included 6-hydroxy-2-acetylaminopyrene (2.0%); glucuronide conjugates were tentatively identified (3.2%). The results of this study indicate that nitroreduction and ring oxidation are metabolic pathways in vivo. For DNA binding studies, rats were treated with 2-nitro[4,5,9,10-3H]pyrene [1.6 mg (598 mCi/mM)/kg body weight]. The levels of binding (pM bound/mg DNA) were as follows: 1.3, liver; 1.14, mammary tissue; 0.65, lung; 1.67, kidney; and 1.8, bladder. Upon high-performance liquid chromatographic analysis of the DNA hydrolysate (liver, mammary, and kidney), approximately 2.0% of the radioactivity coeluted with the synthetic markers derived from nitroreduction, N-(deoxyguanosin-8-yl)-2-aminopyrene and N-(deoxyadenosin-8-yl)-2-aminopyrene. Thus, simple nitroreduction of 2-NP does not significantly contribute to the total DNA binding of 2-NP metabolites in vivo. The significance of each pathway for the tumorigenic effects of 2-NP remains to be examined.

Regulation of steroid hormone action in target cells by specific hormone-inactivating enzymes

The target cell sensitivity of steroid hormones is determined by the concerted action of specific hormone receptors and steroid-inactivating enzymes. In recent years, a considerable amount of knowledge has been obtained on hormone receptor concentration-based target cell sensitivity. However, an equal understanding of the role of specific steroid-inactivating enzymes in hormone action is absent. This review highlights the importance of specific steroid-inactivating enzymes in the control of target cell sensitivity of mineralocorticoids, glucocorticoids, androgens, and estrogens. Two classes of enzymes that are actively involved in this process are hydroxysteroid dehydrogenases and hydroxysteroid sulfotransferases. Some of the target cells in which the critical roles of these enzymes have been extensively characterized are those of the kidney, endometrium, and liver. cDNA for many of these enzymes have already been cloned, and rapid progress in the elucidation of this component of steroid hormone action is anticipated.

Structural characterization of the major adducts formed by reaction of 4,5-epoxy-4,5-dihydro-1-nitropyrene with DNA

The only available marker of DNA adducts formed from 1-nitropyrene (1-NP) and DNA, N-(deoxyguanosin-8-yl)-1-aminopyrene, is derived from the nitroreduction pathway. Our studies, as well as those of others, have indicated that multiple DNA adducts are formed from 1-NP in vivo and in vitro. Thus the need for additional DNA adduct markers was apparent. Therefore, it was our goal to characterize the DNA adducts formed from 4,5-epoxy-4,5-dihydro-1-nitropyrene, a metabolite of 1-NP. The epoxide was incubated with calf thymus DNA (pH 5.4). The DNA was enzymatically hydrolyzed to deoxyribonucleosides which were analyzed by reverse phase HPLC. Three major peaks were obtained in yields less than 5%. The structural assignment of these adducts was made by comparison of their proton nuclear magnetic resonance spectra with those of cis- and trans-4,5-dihydro-4.5-dihydroxy-1-nitropyrene, and by long range coupling constants, decoupling experiments, D2O exchange, partitions and acid hydrolysis. Two adducts result from trans and one from cis addition of the N2-exocyclic amino group of deoxyguanosine to the C5-benzylic carbon of the epoxide ring. This is the first report that describes the structure of the DNA adducts formed with a ring-oxidized metabolite of 1-NP. On the basis of this finding we suggest that K-region oxides of 1-NP may be responsible for the formation of the putative 1-NP-DNA adducts in vivo.

Epilepsy as a manifestation of neurocysticercosis

Epilepsy is the commonest manifestation of neurocysticercosis. Epilepsy was observed in 127 of 150 cases (84.7%) of neurocysticercosis seen over a period of 17 years. The basis of diagnosis was clinical presentation and concomitant evidence of extraneural cysticercosis in the pre-computed tomography (CT) scan era, and typical CT findings in later years. Eighty one cases (54%) who primarily presented as epilepsy without any neurological deficit have been analysed in detail. In the pre-CT period the occurrence of epilepsy as a presenting feature in neurocysticercosis was 43.5% whereas in later years it was 61.4%. Primary generalised seizure (49 cases) was more common than partial seizure (29) and partial complex seizure (3). Status epilepticus was seen in 6 cases. Magnetic resonance imaging, done in 8 cases, proved to be more sensitive in demonstrating various stages in the development of noncalcified cysticercosis. The new larvicidal drugs offer a potential cure and cysticercosis should be entertained as a cause of epilepsy especially in endemic areas.

Age-dependent reversal of the lobular distribution of androgen-inducible alpha 2u globulin and androgen-repressible SMP-2 in rat liver

Hepatocytes situated at pericentral and periportal zones of the liver lobule show differences in the expression of several liver-specific genes, such as androgen-inducible alpha 2u globulin and androgen-repressible senescence marker protein-2 (SMP-2). A marked temporal difference in the expression of these two androgen-regulated genes has also been observed. The liver of the pre-pubertal male rat is insensitive to androgen, and during this period hepatocytes synthesize only SMP-2. During young adult life (greater than 40 days), the liver becomes androgen sensitive and concomitant synthesis of alpha 2u globulin and repression of SMP-2 occur. In the senescent male rat (greater than 750 days), the liver again becomes androgen insensitive when the decline in alpha 2u globulin is accompanied by an increase in SMP-2 synthesis. In this article we present results to show a correlation between the temporal and spatial (intralobular) changes in the expression of the androgen-inducible alpha 2u globulin and the androgen-repressible SMP-2 in rat hepatocytes. Results indicate that the temporal changes in hepatic androgen sensitivity are dictated by the intralobular location of the hepatocytes. Hepatocytes located around the central vein (pericentral/perivenous) may benefit from a paracrine advantage for the expression of a subset of genes, including the gene for the androgen receptor.

Identification of the major metabolites and DNA adducts formed from 2-nitropyrene in vitro

In contrast to 1-nitropyrene (1-NP), which is the most abundant nitropolycyclic aromatic hydrocarbon in numerous environmental sources, 2-nitropyrene (2-NP) has been detected only in the ambient air and not in direct emissions. Thus, 2-NP can be used as an indicator for monitoring human exposure to nitropolynuclear aromatic hydrocarbons in ambient air. Therefore, it is essential to determine the possible metabolic pathways of 2-NP. The metabolism of 2-NP by rat liver 9000 g supernatant was investigated. Under aerobic conditions, ring oxidation to 6-hydroxy-2-nitropyrene and nitroreduction to 2-aminopyrene (2-AP) were observed. When incubations were carried out in an atmosphere of nitrogen, 2-AP was the only metabolite detected. These results are consistent with those observed with 1-NP. In vitro metabolic activation of 2-NP to DNA adducts catalyzed by xanthine oxidase was also examined. Two adducts were characterized as N-(deoxyguanosin-8-yl)-2-aminopyrene and N-(deoxyadenosin-8-yl)-2-aminopyrene. The presence of deoxyadenosine adduct, which is derived from the nitroreduction pathway, may contribute to the powerful direct-acting mutagenicity of 2-NP.

Clinical spectrum of myasthenia gravis and problems of management

Seventeen cases of myasthenia gravis, aged 20-79 years, including one case of ocular myasthenia gravis, seen over a 3 year period, were analysed. Dysphagia was the presenting symptom in two cases. One patient had ectopic thymus gland in relation to the cardiac border, which posed difficulty in diagnosis. A majority of the patients were on medical treatment, including neostigmine, prednisolone and azathioprim. Plasmapheresis was done in 4 cases during crisis, with significant benefit. One patient was put on intermittent ventilatory support for 14-16 hours a day for over 2 years; she died during a power failure. Seven patients were subjected to thymectomy.

Androgen receptor messenger ribonucleic acid (mRNA) in the rat liver: changes in mRNA levels during maturation, aging, and calorie restriction

By means of RNAase protection assay with an antisense cRNA probe, we have shown that the liver of the young adult male rat contains androgen receptor (AR) mRNA to a level of 4% compared to the prostate. Steady state levels of AR mRNA in the liver show both sex and age specificity. Compared to that of the male, the female liver contains a markedly reduced amount of AR mRNA. AR mRNA is almost undetectable in livers of prepubertal male (less than 35 days old) and senescent male (greater than 750 days old) rats. Both prepubertal and senescent animals are relatively insensitive to the androgenic induction of alpha 2u-globulin, a hepatic secretory protein. The age-dependent decline in hepatic androgen sensitivity and AR mRNA level can be delayed considerably by a 40% reduction in the dietary calorie intake. Analysis of poly(A)-containing RNA from two liver cell populations, hepatocytes and nonhepatocytes, revealed that only the hepatocytes that express alpha 2u-globulin gene contain AR mRNA. From these results and our earlier observation of in vitro induction of alpha 2u-globulin in isolated rat liver, we conclude 1) that androgen can act directly on hepatocytes to promote alpha 2u-globulin synthesis; 2) that changes in the hepatic androgen sensitivity during maturation and aging are reflections of the age-dependent expression of the receptor gene; and 3) that retardation of the age-dependent loss of androgen sensitivity by calorie restriction is due to a concomitant delay in the decline of the hepatic AR mRNA level.

Characterization of two neuroblastoma cell lines expressing recombinant nerve growth factor receptors

In earlier studies, a 75,000-dalton glycoprotein (gp75) has been identified as a component of both low- and high-affinity nerve growth factor (NGF) receptors (NGFRs). Using an amphoteric expression vector, we have introduced the cDNA encoding the human gp75 into two neuroblastoma cell lines. SHEP is a human neuroblastoma cell line that lacks most neuronal characteristics and does not express NGFRs. The transformant line SHEP/NGFR expressed a single affinity class of NGF binding sites, did not display NGF-induced up-regulation of fos oncogene expression, and did not efficiently internalize NGF. LAN5 is a neuroblastoma cell line with neuronal characteristics, including expression of neurofilament and display of short neurites. This cell line expresses a small number of high-affinity NGFRs but no detectable low-affinity sites. The transformant line LAN5/NGFR expressed both high- and low-affinity NGFRs, displayed NGF-induced up-regulation of fos oncogene, and efficiently internalized NGF. The number of high-affinity NGF binding sites was nearly the same for LAN5 and LAN5/NGFR, a finding suggesting that there is a limiting number of some separately coded factor or subunit that is required for high-affinity NGFRs. Because NGF induction of fos oncogene expression correlated with expression of high-affinity NGFRs, the putative second factor may also limit NGF responsiveness.

Changes in hepatic androgen sensitivity and gene expression during aging

The hepatic tissue of the male rat exhibits a gradual decline and ultimate loss in androgen responsiveness during in vivo aging. Appearance of the age-associated androgen insensitivity can be delayed by dietary calorie restriction, an effective means for life-span extension. The androgen receptor mRNA is detectable in the liver only in its androgen-responsive state. Pubertal appearance of hepatic androgen sensitivity is remarkably correlated with the concomitant appearance of a cytoplasmic androgen binding (CAB) protein. Androgen resistance during senescence is associated with the loss of hepatic CAB activity as well. We are investigating the molecular basis for the temporal modulation of this hormone sensitivity through studies on the differential expression of two androgen-responsive marker genes. These are the androgen-repressible SMP-2, and the androgen-inducible alpha 2u-globulin. Androgen resistance of hepatocytes during aging results in repression of the alpha 2u-globulin gene, and derepression of the SMP-2 gene. The structural organizations for both of these genes have been characterized. The role of nuclear transcription factors (androgen receptor and any other transacting factor(s) which may be involved) in the coordinate regulation of alpha 2u-globulin and SMP-2 during aging and nutritional manipulation is being explored to establish the molecular mechanism of andropause in the liver.

Introduction of nerve growth factor (NGF) receptors into a medulloblastoma cell line results in expression of high- and low-affinity NGF receptors but not NGF-mediated differentiation

Expression of the cloned human nerve growth factor receptor (NGFR) cDNA in cell lines can generate both high- and low-affinity binding sites. Since the inability to respond appropriately to differentiation factors such as NGF may contribute to determining the malignant phenotype of neuroblastomas, we sought to determine whether the same is true of medulloblastomas. To generate a human central nervous system neuronal cell line that would respond to NGF, we infected the medulloblastoma cell line D283 MED with a defective retrovirus carrying the cDNA coding for the human NGFR. The resultant cells (MED-NGFR) expressed abundant low- and high-affinity NGFRs, and NGF treatment induced a rapid transient increase of c-fos mRNA in the NGFR-expressing cells but not in the parent line or in cells infected with virus lacking the cDNA insert. However, the MED-NGFR cells did not internalize the NGFR at high efficiency, nor did they differentiate in response to NGF. Three important conclusions emerge from this study: (i) internalization of NGFRs is not necessary for some early rapid transcriptional effects of NGF; (ii) an unknown factor(s) that cooperates with the cloned NGFR in allowing high-affinity NGF binding is found in a primitive central nervous system cell line; and (iii) NGFRs introduced into and expressed by D283 MED (i.e., MED-NGFR) cells are partially functional but are unable to induce differentiation in these primitive neuron-like tumor cells, implying that high-efficiency receptor-mediated endocytosis of NGF and its receptor may be a necessary step in the cascade of events leading to NGF-mediated differentiation.

Cysticercal meningoencephalitis

Meningoencephalitic syndrome can be caused by many infective agents. Over a period of 13 years, 15 of 170 cases of neurocysticercosis (NCC) presented as meningoencephalitis. The basis of diagnosis of NCC was positive subcutaneous nodule histopathology (4), CT scan (9) and autopsy (3) findings. The age of the patients ranged from 7-68 years (mean 32). Fever was encountered in 12, altered sensorium in 7, seizures in 10 and abnormal behaviour in 3 cases. All cases had papilloedema. Focal neurological signs included optic atrophy, lateral rectus palsy, hemiplegia, internuclear ophthalmoplegia and cerebellar ataxia. Cerebrospinal fluid was abnormal in 8 of 13 cases, leading to a suspicion of tuberculous meningitis. Twelve patients improved with therapy. Three cases ended fatally and autopsy confirmed the diagnosis.

Computed tomographic spectrum of neurocysticercosis

Computed tomography (CT) is a very sensitive modality for the diagnosis of neurocysticercosis. Fifty eight patients were evaluated by plain radiography and CT scans. The initial presentation was as seizure disorder (33), raised intracranial tension (19), meningoencephalitis (5) and psychiatric manifestation (1). Histologically confirmed subcutaneous nodules were seen in 20 cases and ocular cyst in 2 cases. CT scan showed multiple calcification in 8 cases, disc lesions in 30,ring lesions in 3, and a combination of disc and ring lesions in another 13 cases. Low attenuation lesions were seen in 4 cases in combination with disc/disc and ring lesions. All 58 cases had supratentorial lesions while 19 cases had infratentorial lesions in addition. Perifocal or generalised oedema was seen in 33 and 11 cases respectively. The ventricles were compressed in one case, large in 2 cases and normal in the rest. CT scan is valuable in the diagnosis of neurocysticercosis. Its significance is different in the various clinical and radiological groups.

Transient expression of full-length and truncated forms of the human nerve growth factor receptor

To facilitate the characterization of nerve growth factor (NGF) receptor and mutated forms of the receptor, we have set up a rapid, efficient transient expression system utilizing COS cells. The human NGF receptor is a 427 amino acid protein with a hydrophobic signal sequence, a 222 amino acid extracellular domain, a single transmembrane domain and a 155 amino acid intracellular domain. The NGF receptor and a truncated form lacking the cytoplasmic domain were expressed in a COS cell expression system. Both recombinant proteins were detected on the cell surface and at a perinuclear site. Specific binding of 125I-NGF to the recombinant proteins was detected by chemical cross-linking. The extracellular domain of the NGF receptor was also expressed in the same system and detected in the COS cell endoplasmic reticulum and in the culture supernatant. This recombinant protein also specifically binds NGF.

Modification of clastogenicity of lead and aluminium in mouse bone marrow cells by dietary ingestion of Phyllanthus emblica fruit extract

Extract of Phyllanthus emblica fruit and ascorbic acid were evaluated separately for protection against clastogenicity induced by lead (Pb) and aluminium (Al) salts on mouse bone marrow chromosomes. Oral administration of Phyllanthus fruit extract (PFE) for 7 days before exposure to both metals by intraperitoneal injection increased the frequency of cell division and reduced the frequency of chromosome breaks significantly. Comparable doses of synthetic ascorbic acid (AA) were less effective and could protect against the effects of Al and only a low dose of Pb (10 mg/kg body weight). AA administered before treatment in mice given higher doses of Pb (40 mg/kg body weight) enhanced the frequency of chromosome breaks, giving a synergistic effect. The higher protection afforded by PFE may be due to the combined action of all ingredients, rather than to AA alone.