Differentiation of mesenchymal stem cells into dopaminergic neuron-like cells in vitro

OBJECTIVE

To explore the way to induce mesenchymal stem cells (MSCs) to differentiate into dopaminergic neurons in vitro.

METHODS

MSCs were obtained from rat bone marrow, cultured and passaged. MSCs used in this experiment had multipotency, which was indirectly proved by being induced to differentiate into chondrocytes and adipocytes. MSCs were cultured in medium containing 0.5 mmol/L IBMX for 2 days. Then the medium was replaced with induction medium, which contained GDNF, IL-1beta, mesencephalic glial-cell-conditioned medium and flash-frozen mesencephalic membrane fragments. The surface markers of the differentiated neurons, such as NSE, nestin, MAP-2a, b and TH were detected by immunocytochemistry and Western blot after MSCs were cultured in induction medium for 7 days and 15 days.

RESULTS

MSCs differentiated into neural progenitors and expressed nestin after MSCs were incubated with medium containing IBMX for 2 d. After the medium was replaced with induction medium containing many inducing agents, MSCs differentiated into neuron-like cells and dopaminergic neuron-like cells and expressed NSE, MAP-2a, b and TH. The percentage of NSE-positive cells, MAP-2a, b-positive cells and TH-positive cells was 30.032 +/- 2.489%, 41.580 +/- 5.101% and 34.958 +/- 5.534%, respectively after MSCs were induced in medium containing GDNF, IL-1beta, mesencephalic glial-cell-conditioned medium and flash-frozen mesencephalic membrane fragments for 15 days.

CONCLUSION

MSCs can differentiate into dopaminergic neuron-like cells and are a new cell source for the treatment of neurodegeneration diseases and have a great potential for wide application.

Nardostachys chinensis Glycoside Induces Characteristics of Neuronal Differentiation in Rat Pheochromocytoma PC12 Cells

Rat pheochromocytoma PC12 cells undergo neuronal differentiation in response to nerve growth factor. We show here that exposure of PC12 cells to Nardostachys chinensis glycoside induces the outgrowth of neurites, increases the activity of AChE, triggers cell cycle arrest in G1 and enhances the expression of growth associated protein 43 (GAP-43). Both the outgrowth of neurites and the increase in AChE activity are prevented partly by PD98059, a specific inhibitor of MEK1. These results suggest that N. chinensis glycoside induces the characteristics of neuronal differentiation in PC12 cells via the mitogen-activated protein kinase (MAPK)-related signal cascade.

Triethylene tetraamine: a novel telomerase inhibitor

Telomerase inhibition can be achieved by stabilization of G-quadruplex structure. Triethylene tetraamine, a small linear molecule, has been identified as a potent telomerase inhibitor. It stabilizes both intra- and inter-molecular G-quadruplexes and shows a good differential between potent telomerase inhibition and acute cytotoxicity.

[Study on repairing injured middle brain by Schwann cells transplantation]

OBJECTIVE

To explore the ability of grafted Schwann cells to promote restore of injured neurons in rat.

METHODS

Schwann cells labeled by BrdU in vitro transplanted into rat middle brain area prior to injure with electric needle stimulus. Immunohistochemistry and image analyzer were used to investigate the expression of BrdU and GAP-43 as well as quantitative analysis respectively.

RESULTS

BrdU positive cells could be identified for up to 8 months and the number increased about 15%, which mainly migrated toward injured ipsilateral cortex. The GAP-43 expression reached its peak one month after transplantation and was significant compared with control group (P < 0.05).

CONCLUSION

The transplantation of Schwann cells could promote the restoration of injured neurons.

[Effects of a comprehensive health education program on reproductive tract infections/sexually transmitted diseases intervention among reproductive age population in the rural areas of China]

OBJECTIVE

To evaluate the effectiveness on comprehensive health education intervention program regarding reproductive tract infections/sexually transmitted diseases (RTIs/STDs) among reproductive age population in the rural areas of China.

METHODS

Data were generated from the Reproductive Health/Family Planning Project implemented by the State Family Planning Committee and the Ministry of Health from 1998 to 2002, which covered 32 counties in 22 provinces. A quasi-experimental design was used. Six counties were selected from 32 project counties as intervention group, while 6 non-project counties were taken as controls which were similar in number of population and economic level to the counties as selected. Subjects of the study were mothers with children under 3 years and men under 35 years of age. A total number of 675 mothers and men were interviewed using a structured questionnaire by strictly trained investigators. Logistic model was used to compare the difference of knowledge on RTIs/STDs between intervention group and control group. OR value was used to describe the degree of the difference.

RESULTS

Over the 18 month intervention period, persons in the intervention group had more knowledge of RTIs/STDs than those in control group. Logistic regression analysis indicated that intervention was significantly associated with better knowledge on factors as transmission, risks, symptoms, management and prevention of RTIs/STDs with 95% CI of OR as 2.4 - 6.4, 2.0 - 4.8, 3.0 - 6.4, 1.9 - 5.7 and 1.8 - 6.8 respectively, after controlling the demographic factors. Level of education was an important factor influencing the subjects to receive knowledge on RTIs/STDs.

CONCLUSION

Comprehensive health education intervention programs had significant impact on knowledge about RTIs/STDs among the target population, indicating that the Reproductive Health/Family Planning Project implemented in the rural areas of China had been successful.

Definitive experimental evidence for two-band superconductivity in MgB2

The superconducting-gap of MgB2 has been studied by high-resolution angle-resolved photoemission spectroscopy. The results show that superconducting gaps with values of 5.5 and 2.2 meV open on the sigma band and the pi band, respectively, but both the gaps close at the bulk transition temperature, providing a definitive experimental evidence for the two-band superconductivity with strong interband pairing interaction in MgB2. The experiments validate the role of k-dependent electron-phonon coupling as the origin of multiple-gap superconductivity as well as the high transition temperature of MgB2.

[Effect of pertussis bacilli on the release of excitatory amino acids in brain slice of rats]

OBJECTIVE

To investigate the effect of pertussis bacilli on the release of excitatory amino acids (EAAs) in rat-brain slice and to know whether MK-801(dizocipine) protects brain tissue from excitotoxicity.

METHODS

SD rats were randomly divided into 3 groups: 1. Normal slice cultured group(NC); 2. 10% pertussis bacilli(PB) slice cultured group(PBC); 3. 10% PB slice cultured group after pretreatment with MK-801. The release of EAAs from brain slices was measured by high performance liquid chromatography.

RESULTS

The concentrations of glutamate(Glu 29.53 +/- 8.00), aspartate(Asp 23.74 +/- 5.79) and LDH(38.03 +/- 8.45) were significantly higher in PBC group than those(Glu 16.46 +/- 4.00, Asp 15.27 +/- 5.31, LDH 23.10 +/- 5.11) in MPBC group and (Glu 16.09 +/- 3.74, Asp 11.47 +/- 2.51, LDH 25.82 +/- 4.50) NC group.

CONCLUSION

Pertussis bacilli may elicit a large increase of extracellular EAAs and LDH in vitro, while MK-801 protects brain tissue from excitotoxicity.

[Study of protective effect and mechanism for baicalin on bacillus pertussis infected brain tissue and its dose-effect relationship]

OBJECTIVE

To study the possible mechanism of protective effect for Baicalin on Bacillus pertussis (BP) infected brain tissue and the dose-effect relationship.

METHODS

Brain tissues slices were divided into 7 groups: (1) the normal group; (2) the model group: infected by 10% BP; (3) the baicalin group, which was pretreated with baicalin, infected by BP and subdivided into 5 sub-groups according to different doses of baicalin used; (4) the glutamic acid group: cultured with glutamic acid; (5) the baicalin plus glutamic acid group; (6) the peroxide group: cultured with hydrogen peroxide; and (7) the baicalin plus peroxide group. The lactate dehydrogenase (LDH) content in the supernatant of culture was determined and quantitative protein determination was conducted.

RESULTS

The LDH releasing was higher in the model group, glutamic acid group and peroxide group as compared with that in the normal group, 15.10 +/- 4.89 u/g. protein (the same unit below), 15.49 +/- 5.66 and 16.54 +/- 5.47 vs 6.10 +/- 2.87 respectively (P < 0.01). After being pretreated with 0.25 mmol/L baicalin, LDH level decreased significantly to 8.65 +/- 2.43, which was significantly different from that in the model group (P < 0.01), LDH was also decreased in the baicalin plus glutamic acid group (9.93 +/- 2.89) and baicalin plus peroxide group (9.54 +/- 2.82), which was significantly lower than that in the glutamic acid group and the peroxide group respectively (P < 0.01).

CONCLUSION

Pretreatment of baicalin has protective effect on BP caused nerve cell injury in rat brain slices, the protection is possibly related with the reduction of glutamic acid and hydrogen peroxide induced damage on nerve cells in vitro.

Peroxisome proliferator-activated receptor gamma ligands inhibit mitogenic induction of p21(Cip1) by modulating the protein kinase Cdelta pathway in vascular smooth muscle cells

The cyclin-dependent kinase inhibitor p21(Cip1) is up-regulated in response to mitogenic stimulation in various cells. PPARgamma ligands troglitazone (TRO, 10 microm) and rosiglitazone (RSG, 10 microm) attenuated the induction of p21(Cip1) protein by platelet-derived growth factor (PDGF) and insulin without affecting cognate mRNA levels in rat aortic smooth muscle cells (RASMC). The protein kinase Cdelta (PKCdelta) inhibitor rottlerin also blocked the induction of p21(Cip1) protein, whereas the conventional PKC isotype inhibitor Gö 6976 had no effect. Kinetic studies using the protein synthesis inhibitor cycloheximide showed that TRO, RSG, and rottlerin shortened the half-life of p21(Cip1) protein. TRO, RSG, and rottlerin inhibited PDGF-induced expression of p21(Cip1), but they did not affect insulin-induced expression of p21(Cip1). Both ligands inhibited PKCdelta enzymatic activity in PDGF-stimulated RASMC but not in insulin-stimulated cells. Adenovirus-mediated overexpression of PKCdelta rescued the down-regulation of p21(Cip1) expression both by TRO and RSG in PDGF-treated RASMC. These data suggested that the PKCdelta pathway plays a critical role in PDGF-induced expression of p21(Cip1) in RASMC and may be the potential target for PPARgamma ligand effects. Src kinase-dependent tyrosine phosphorylation of PKCdelta was decreased substantially by TRO and RSG. Tyrosine phosphorylation and activation of c-Src in response to PDGF were unaffected by either PPARgamma ligand. Protein-tyrosine-phosphatase inhibitors sodium orthovanadate and dephostatin prevented PPARgamma ligand effects on PKCdelta tyrosine phosphorylation and enzymatic activity. Both inhibitors also reversed PPARgamma ligand effects on p21(Cip1) expression in PDGF-treated RASMC. PPARgamma ligands enhanced protein-tyrosine-phosphatase activity in RASMC, which may be the mechanism for decreased PKCdelta tyrosine phosphorylation and activity. PPARgamma ligands regulate p21(Cip1) at a post-translational level by blocking PKCdelta signaling and accelerating p21(Cip1) turnover.

Troglitazone inhibits growth of MCF-7 breast carcinoma cells by targeting G1 cell cycle regulators

Peroxisome proliferator activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily. Ligand activation of PPARgamma has been shown to cause growth arrest in several human tumor cell types, but the underlying molecular mechanism has not been elucidated. We report here that the PPARgamma ligand troglitazone (TRO) inhibited MCF-7 cell proliferation by blocking events critical for G1 --> S progression. Flow cytometry demonstrated that TRO at 20 microM increased the percentage of cells in G1 from 51 to 69% after 24 h. Accumulation of cells in G1 was accompanied by an attenuation of Rb protein phosphorylation associated with decreased CDK4 and CDK2 activities. Inhibition of CDK activity by TRO correlates with decreased protein levels for several G1 regulators of Rb phosphorylation (cyclin D1, and CDKs 2, 4, and 6). Overexpression of cyclin D1 partially rescued MCF-7 cells from TRO-mediated G1 arrest. Targeting of G1 regulatory proteins, particularly cyclin D1, and the resulting induction of G1 arrest by TRO may provide a novel antiproliferative therapy for human breast cancer.

Retinoids inhibit proliferation of human coronary smooth muscle cells by modulating cell cycle regulators

Retinoids inhibit rat vascular smooth muscle cell (VSMC) proliferation in vitro and intimal hyperplasia in vivo. We examined the mechanism of the antiproliferative effect of retinoids on human coronary artery smooth muscle cells (human CASMCs). The RAR ligands all-trans-retinoic acid (atRA) and ethyl-p-[(E)-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)-l-propenyl]-benzoic acid (TTNPB); a pan-RXR/RAR agonist, 9-cis-retinoic acid (9cRA); and the RXR-selective ligand AGN4204 all inhibited DNA synthesis stimulated with platelet-derived growth factor and insulin (IC(50): TTNPB 63 nmol/L, atRA 120 nmol/L, AGN4204 460 nmol/L, 9cRA 1.5 micromol/L). All retinoids blocked cell cycle progression as determined by flow cytometry and inhibited retinoblastoma protein (Rb) phosphorylation. TTNPB, atRA, and AGN4204 inhibited the mitogenic induction of cyclin D1, whereas 9cRA had no effect. None of the retinoids affected the expression of CDK 2, 4, or 6 or cyclin E. All retinoids attenuated mitogen-induced downregulation of CDKI p27(Kip1), a major negative regulator of Rb phosphorylation, partly through stabilizing p27(Kip1) turnover. These data demonstrate that retinoids have antiproliferative activity by modulating G(1) --> S cell cycle regulators in human CASMCs through inhibition of Rb phosphorylation and elevation of p27(Kip1) levels.

Extracranial radiosurgery: immobilizing liver motion in dogs using high-frequency jet ventilation and total intravenous anesthesia

PURPOSE

Extracranial radiosurgery requires control of organ motion. The purpose of this study is to quantitatively determine the extent of liver motion in anesthetized dogs with continuous i.v. propofol infusion with or without muscle relaxants and high-frequency jet ventilation.

METHODS AND MATERIALS

Five dogs were used in the experiment. Each dog was restrained while anesthetized in the supine position using an alpha cradle. Surgical metal clips were implanted around the liver periphery so that its motion could be visualized using a fluoroscopic imaging device in a conventional simulator. Initially, two orthogonal simulation films were taken to correlate locations of implanted clips. Two orthogonal views of fluoroscopic images for each anesthetized dog were recorded on a magnetic tape and analyzed from the post-imaging data. Liver motion was documented under the following three conditions: 1) ventilated with a conventional mechanical ventilator, 2) ventilated with a high-frequency jet ventilator, and 3) ventilated with a high-frequency jet ventilator and total muscle paralysis (with vecuronium injection). The maximum liver motion for each dog was analyzed in three orthogonal directions: the inferior-to-superior direction, the anterior-to-posterior direction, and the right-to-left direction.

RESULTS

When the anesthetized dogs were ventilated with a conventional mechanical ventilator, the average liver motions were 1.2 cm in the inferior-to-superior direction, 0.4 cm in the anterior-to-posterior direction, and 0.2 cm in the right-to-left direction, respectively. After the introduction of high-frequency jet ventilation, the average liver motions were reduced to 0.2 cm in the inferior-to-superior direction, 0.2 cm in the anterior-to-posterior direction, and 0.1 cm in the right-to-left direction. The maximum liver motion was dependent on ventilator settings. There was no additional measurable motion reduction with the addition of the muscle relaxant.

CONCLUSION

The liver motion in each anesthetized dog was controlled under 3.0 mm in all directions with the use of high-frequency jet ventilation. No detectable advantage was identified by the injection of muscle relaxant in terms of further reducing the liver motion. The preclinical animal study indicated that the use of high-frequency jet ventilation (HFJV) would be able to limit the liver motion to an extent acceptable for the application of extracranial radiosurgery in humans. Radiosurgery for localized liver tumors warrants further investigation.

Apigenin inhibits growth and induces G2/M arrest by modulating cyclin-CDK regulators and ERK MAP kinase activation in breast carcinoma cells

We have previously reported that apigenin inhibits the growth of thyroid cancer cells by attenuating epidermal growth factor receptor (EGF-R) tyrosine phosphorylation and phosphorylation of ERK mitogen-activated protein (MAP) kinase. In this study, we assessed the growth inhibitory effect of apigenin on MCF-7 breast carcinoma cells that express two key cell cycle regulators, wild-type p53 and the retinoblastoma tumor suppressor protein (Rb), and MDA-MB-468 breast carcinoma cells that are mutant for p53 and Rb negative. We found that apigenin potently inhibited growth of both MCF-7 and MDA-MB-468 breast carcinoma cells. The approximate IC50 values determined after 3 days incubation, were 7.8 micrograms/ml for MCF-7 cells, and 8.9 micrograms/ml for MDA-MB-468 cells, respectively. Because the cell cycle studies using FACS showed that both MCF-7 and MDA-MB-468 cells were arrested in G2/M phase after apigenin treatment, we studied the effects of apigenin on cell cycle regulatory molecules. We observed that G2/M arrest by apigenin involved a significant decrease in cyclin B1 and CDK1 protein levels, resulting in a marked inhibition of CDK1 kinase activity. Apigenin reduced the protein levels of CDK4, cyclins D1 and A, but did not affect cyclin E, CDK2 and CDK6 protein expression. In MCF-7 cells, apigenin markedly reduced Rb phosphorylation after 12 h. We also found that apigenin treatment resulted in a dose- and time-dependent inhibition of ERK MAP kinase phosphorylation and activation in MDA-MB-468 cells. These results suggest that apigenin is a promising antibreast cancer agent and its growth inhibitory effects are mediated by targeting different signal transduction pathways in MCF-7 and MDA-MB-468 breast carcinoma cells.

[Comparison of infectious brain edema models induced by different kinds of pertussis bacilli in rats]

OBJECTIVE

To understand the difference of infectious brain edema models induced by varied kinds of pertussis bacilli in rats and to look for a new infectious brain edema model.

METHODS

Sprague-Dawley rats were randomly divided into 3 groups: normal saline group(NS); rude pertussis bacilli(PBR); purified pertussis bacilli(PBP). After infectious brain edema model was induced by rude pertussis bacilli or purified pertussis bacilli, the water content(WC), Evan's blue content(EB), Na+ and K+ content in brain tissues were measured.

RESULTS

The WC, EB and Na+ contents in brain tissues in PBR and PBP groups were significantly increased than those in NS group; K+ content was significantly decreased in PBR and PBP groups than that in NS group(P < 0.01). Evan's blue discoloration was demonstrated in all rats of PBR group, but 6 rats of PBP group showed bluish discoloration. EB content in brain tissues was significantly increased in PBR group than that in PBP group.

CONCLUSIONS

The infectious brain edema model can be induced by rude pertussis bacilli or purified pertussis bacilli in rats, the former gives priority to mixed brain edema, and the latter mainly avails cytotoxin brain edema.

Peroxisome proliferator-activated receptor gamma ligands inhibit retinoblastoma phosphorylation and G1--> S transition in vascular smooth muscle cells

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily that is activated by binding certain fatty acids, eicosanoids, and insulin-sensitizing thiazolidinediones (TZD). The TZD troglitazone (TRO) inhibits vascular smooth muscle cell proliferation and migration both in vitro and in vivo. The precise mechanism of its antiproliferative activity, however, has not been elucidated. We report here that PPARgamma ligands inhibit rat aortic vascular smooth muscle cell proliferation by blocking the events critical for G(1) --> S progression. Flow cytometry demonstrated that both TRO and another TZD, rosiglitazone, prevented G(1) --> S progression induced by platelet-derived growth factor and insulin. Movement of cells from G(1) --> S was also inhibited by the non-TZD, natural PPARgamma ligand 15-deoxy-(12,14)Delta prostaglandin J(2) (15d-PGJ(2)), and the mitogen-activated protein kinase pathway inhibitor PD98059. Inhibition of G(1) --> S exit by these compounds was accompanied by a substantial blockade of retinoblastoma protein phosphorylation. TRO and rosiglitazone attenuated both the mitogen-induced degradation of p27(kip1) and the mitogenic induction of p21(cip1). 15d-PGJ(2) and PD98059 inhibited both the degradation of p27(kip1) and the induction of cyclin D1 in response to mitogens. These effects resulted in the inhibition of mitogenic stimulation of cyclin-dependent kinases activated by cyclins D1 and E. These data demonstrate that PPARgamma ligands are antiproliferative drugs that act by modulating cyclin-dependent kinase inhibitors; they may provide a new therapeutic approach for proliferative vascular diseases.

[Changes of glutamate and gamma-aminobutyric acid contents in brain tissue of brain edema and effects of baicalin on them in rats]

OBJECTIVE

To observe the changes of glutamates (Glu) and gamma-aminobutyric acid (GABA) contents in brain tissue of infectious brain edema, and effects of baicalin on them in rats.

METHODS

The high performance liquid chromatography (HPLC) was used to determine the Glu and GABA contents in homogenized brain tissue after baicalin was injected intraperitoneally on infectious brain edema induced by pertussis bacilli in rats.

RESULTS

Glu contents of homogenized brain tissue in blank control group (C), normal saline group (NS), pertussis bacilli group (PB) and baicalin group (BC) had no significant difference (P > 0.05). The concentration of GABA was more significantly increased in the BC group (4.06 +/- 0.52) than that in the PB group (2.71 +/- 0.29) (P < 0.05). Water content of brain was reduced in the BC group (79.8 +/- 0.4) as compared with the PB group (82.2 +/- 0.3)(P < 0.01).

CONCLUSION

Baicalin has a protective effect against the pertussis bacilli-induced brain edema in rats, and protective effect was correlated to the increased content of GABA in the brain tissue in rats.

Environmental and genetic determinants of aflatoxin-albumin adducts in the Gambia

Aflatoxins together with chronic hepatitis B virus (HBV) infection contribute to the high incidence of hepatocellular carcinoma in developing countries. An understanding of the mechanism of interaction between these factors would provide a strong rationale for developing effective prevention strategies. In this study in The Gambia we examined the effect of environmental (place of residence and timing of sample collection) and host factors (age, sex, HBV status and interindividual variations in carcinogen metabolising enzymes) in determining blood aflatoxin-albumin adduct levels in 357 individuals of whom 181 were chronic HBV carriers. Samples were analysed for aflatoxin-albumin adducts, HBV status and genotypes of glutathione S-transferase (GST) M1, GSTT1, GSTP1 and epoxide hydrolase (EPXH). Urine samples were analysed for 6beta-hydroxycortisol:cortisol ratio as a marker of cytochrome P450 (CYP) 3A4 activity. Adduct levels were significantly higher in subjects resident in rural [geometric mean adduct level 34.9 pg aflatoxin B1-lysine equivalent (28.5-42.8; 95%CI)/mg albumin] than in periurban areas [22.2 pg (14.9-33.4)/mg] and were approximately twice as high in the dry season [mid-February to March; 83.2 pg (53.3-130.8)/mg] than the wet [July to August; 34.9 pg (28.5-42.8)/mg]. In contrast, HBV status, CYP3A4 phenotype, GSTT1, GSTP1 and EPXH genotypes were not associated with aflatoxin-albumin adduct level. However, mean adduct levels were significantly higher in non-HBV infected subjects with GSTM1 null genotype. The main factors which affect aflatoxin-albumin adduct levels in this population are environmental, notably place of residence and timing of sample collection. This study further emphasises the priority to reduce aflatoxin exposure in these communities by primary prevention measures.

Environmental and genetic determinants of aflatoxin-albumin adducts in the Gambia

Aflatoxins together with chronic hepatitis B virus (HBV) infection contribute to the high incidence of hepatocellular carcinoma in developing countries. An understanding of the mechanism of interaction between these factors would provide a strong rationale for developing effective prevention strategies. In this study in The Gambia we examined the effect of environmental (place of residence and timing of sample collection) and host factors (age, sex, HBV status and interindividual variations in carcinogen metabolising enzymes) in determining blood aflatoxin-albumin adduct levels in 357 individuals of whom 181 were chronic HBV carriers. Samples were analysed for aflatoxin-albumin adducts, HBV status and genotypes of glutathione S-transferase (GST) M1, GSTT1, GSTP1 and epoxide hydrolase (EPXH). Urine samples were analysed for 6beta-hydroxycortisol:cortisol ratio as a marker of cytochrome P450 (CYP) 3A4 activity. Adduct levels were significantly higher in subjects resident in rural [geometric mean adduct level 34.9 pg aflatoxin B1-lysine equivalent (28.5-42.8; 95%CI)/mg albumin] than in periurban areas [22.2 pg (14.9-33.4)/mg] and were approximately twice as high in the dry season [mid-February to March; 83.2 pg (53.3-130.8)/mg] than the wet [July to August; 34.9 pg (28.5-42.8)/mg]. In contrast, HBV status, CYP3A4 phenotype, GSTT1, GSTP1 and EPXH genotypes were not associated with aflatoxin-albumin adduct level. However, mean adduct levels were significantly higher in non-HBV infected subjects with GSTM1 null genotype. The main factors which affect aflatoxin-albumin adduct levels in this population are environmental, notably place of residence and timing of sample collection. This study further emphasises the priority to reduce aflatoxin exposure in these communities by primary prevention measures.