Biomedical subjects

S G Kim

Publications and source records attributed to S G Kim.

At least 109 records · Page 6Linked to original sources

PubMed2000

Early temporal characteristics of cerebral blood flow and deoxyhemoglobin changes during somatosensory stimulation.

The close correspondence between neural activity in the brain and cerebral blood flow (CBF) forms the basis for modern functional neuroimaging methods. Yet, the temporal characteristics of hemodynamic changes induced by neuronal activity are not well understood. Recent optical imaging observations of the time course of deoxyhemoglobin (HbR) and oxyhemoglobin have suggested that increases in oxygen consumption after neuronal activation occur earlier and are more spatially localized than the delayed and more diffuse CBF response. Deoxyhemoglobin can be detected by blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI). In the present study, the temporal characteristics of CBF and BOLD changes elicited by somatosensory stimulation in rat were investigated by high-field (9.4 T) MRI. With use of high-temporal-resolution fMRI, it was found that the onset time of the CBF response in the somatosensory cortex was 0.6 +/- 0.4 seconds (n = 10). The CBF changes occurred significantly earlier than changes in HbR concentration, which responded after 1.1 +/- 0.3 seconds. Furthermore, no early increases in HbR (early negative BOLD signal changes) were observed. These findings argue against the occurrence of an early loss of hemoglobin oxygenation that precedes the rise in CBF and suggest that CBF and oxygen consumption increases may be dynamically coupled in this animal model of neural activation.

Animals↗

PubMed2000

Implant-related damage to an adjacent tooth: a case report.

Implant-related damage to an adjacent tooth is shown to be an iatrogenic complication. The affected tooth may require apical curettage, root canal therapy, apicoectomy, or even extraction. A case is presented of a patient who complained of damage to an adjacent root after implant placement.

Apicoectomy↗

PubMed2000

The essential role of phosphatidylinositol 3-kinase and of p38 mitogen-activated protein kinase activation in the antioxidant response element-mediated rGSTA2 induction by decreased glutathione in H4IIE hepatoma cells.

The protective adaptive response to electrophiles and reactive oxygen species is mediated by the enhanced expression of the phase II detoxifying genes through antioxidant response elements (AREs). The current study was designed to identify the signaling pathways responsible for the expression of rGSTA2 in response to cellular oxidative stress and to establish the molecular mechanistic basis. Deprivation of cystine and methionine caused oxidative stress in H4IIE hepatoma cells as evidenced by a marked decrease in the reduced glutathione (first order rate constant = 0.056 h(-1); t(1/2) = 12.6 h) and an increase in pro-oxidant production. Electrophoretic mobility shift assay revealed that the ARE complex, consisting of Nrf-1/2 and Maf proteins, was activated 12 to 48 h after sulfur amino acid deprivation (SAAD). The rGSTA2 mRNA level was elevated by SAAD beginning at 24 h, whereas the rGSTA2 subunit was maximally induced at 48 h. Nuclear ARE activation and rGSTA2 mRNA increase were both completely inhibited by wortmannin or LY294002, the phosphatidylinositol 3-kinase (PI3-kinase) inhibitors. The p38 mitogen-activated protein (MAP) kinase was activated at 0.5 to 3 h after SAAD, followed by sustained diminished activation up to 12 h. Inhibition of p38 MAP kinase by SB203580 prevented the ARE-mediated rGSTA2 induction. The activation of p38 MAP kinase, however, failed to be inhibited by wortmannin or LY294002, showing that PI3-kinase is not involved in the activation of p38 MAP kinase. Data showed that PI3-kinase plays an essential role in the ARE-mediated rGSTA2 induction by oxidative stress after SAAD, which activates the p38 MAP kinase and leads to rGSTA2 induction.

Amino Acids, Sulfur↗

PubMed2000

Magnetic resonance studies of brain function and neurochemistry.

In the short time since its introduction, magnetic resonance imaging (MRI) has rapidly evolved to become an indispensable tool for clinical diagnosis and biomedical research. Recently, this methodology has been successfully used for the acquisition of functional, physiological, and biochemical information in intact systems, particularly in the human body. The ability to map areas of altered neuronal activity in the brain, often referred to as functional magnetic resonance imaging (fMRI), is probably one of the most significant recent achievements that rely on this methodology. This development has permitted the examination of functional specialization in human and animal brains with unprecedented spatial resolution, as demonstrated by mapping at the level of orientation and ocular dominance columns in the visual cortex. These functional imaging studies are complemented by the ability to study neurochemistry using magnetic resonance spectroscopy, allowing the determination of metabolic processes that support neurotransmission and neurotransmission rates themselves.

Animals↗

PubMed2000

Motor area activity during mental rotation studied by time-resolved single-trial fMRI.

The functional equivalence of overt movements and dynamic imagery is of fundamental importance in neuroscience. Here, we investigated the participation of the neocortical motor areas in a classic task of dynamic imagery, Shepard and Metzler's mental rotation task, by time-resolved single-trial functional Magnetic Resonance Imaging (fMRI). The subjects performed the mental-rotation task 16 times, each time with different object pairs. Functional images were acquired for each pair separately, and the onset times and widths of the activation peaks in each area of interest were compared to the response times. We found a bilateral involvement of the superior parietal lobule, lateral premotor area, and supplementary motor area in all subjects; we found, furthermore, that those areas likely participate in the very act of mental rotation. We also found an activation in the left primary motor cortex, which seemed to be associated with the right-hand button press at the end of the task period.

Brain↗

PubMed2000

Decreased RR interval complexity and loss of circadian rhythm in patients with congestive heart failure.

The present study investigated how the RR interval complexity and variability and their circadian rhythms alter for patients with congestive heart failure (CHF). Sixteen patients aged between 41 and 72 years with CHF and 20 control subjects were included. 24-h ambulatory electrocardiographic recordings were analyzed, and digitized data was partitioned into sections of 30-min duration. For each section, time- and frequency-domain indices, and complexity indices of heart rate variability were calculated. For CHF patients, 24-h average values of all indices were significantly decreased. The circadian rhythms of mean RR intervals were preserved and resembled the abnormal circadian rhythms of the low-frequency power. The circadian rhythms of high-frequency power and all complexity indices shown in the normal control were lost. Conclusively, the patients with CHF showed decreased RR interval complexity and loss of its circadian rhythm, in addition to decreased frequency-domain RR interval variability and its abnormal circadian rhythm.

Adult↗

PubMed2000

Incidence of presbycusis of Korean populations in Seoul, Kyunggi and Kangwon provinces.

Presbycusis, a bilateral sensorineural hearing loss caused by changes in the inner ear, is related to multiple factors such as noise exposure and otologic disease. In institute-based studies, we tried to determine the incidence of presbycusis in Korean populations living in Seoul, Kyunggi and Kangwon provinces by gender and age groups. The subjects were people who had visited health promotion centers. Pure tone audiometry was done over 20 years on 6,028 subjects. In a community-based study, the subjects were elderly residents of Kanghwa-do area. There were no obvious factors that could cause hearing impairment in the subjects. For the pure tone audiometry, hearing threshold was obtained by using the six-dimension method. The incidence of presbycusis for subjects aged 65 years and older was 37.8% and 8.3% for > or = 27 dB HL criterion and > or = 41 dB HL criterion, respectively. The incidence increased with age. A statistically significant difference in the hearing threshold was found between men and women aged 65 years or older. No differences were found between the community-based study and the institute- based studies. There was a high incidence (about 40%) of presbycusis among Koreans aged 65 years or older (for > or = 27 dB HL criterion). With an aging population, we anticipate that this report could be used to provide a basic data for the study of presbycusis.

Adult↗

PubMed2000

Primary stenting for acute myocardial infarction via the transradial approach: a safe and useful alternative to the transfemoral approach.

BACKGROUND: Primary stenting in acute myocardial infarction (AMI) has been demonstrated to reduce recurrent ischemic events. However, transradial stenting in AMI has not been well established. Therefore, we sought to investigate the feasibility and utility of transradial coronary stenting in patients with AMI. METHODS: From April 1998 to April 1999, 56 patients (43 male; mean age of 57 years) who arrived within 6 hours of pain onset with culprit vessel size > 2.5 mm constituted this study. The transradial approach (Group 1) was used in 30 patients with hemodynamically stable and palpable right radial pulse. The transfemoral approach (Group 2) was used for vascular access in the remainder of patients (26) who might have required a second vascular access site for intraaortic balloon pumping (in cardiogenic shock) and/or a transvenous temporary pacemaker. RESULTS: Overall success rate was achieved in 54 of 56 patients (96%). The success rate was 90% (27/30) in Group 1 and 96% (25/26) in Group 2. The cannulation time (from patient arrival at the catheterization room to the time of arterial cannulation) and the total procedure time (from patient arrival at the catheterization room to the completion of the procedure) were not significantly different between Group 1 and Group 2 (9.2+/-5.3 versus 8.9+/-5. 8 minutes, p>0.05; 53.7+/-19.4 versus 57.5 +/-26.8 minutes, p>0.05, respectively). In the Group 1 patients, there was no forearm ischemia or loss of radial pulse during the 30-day follow-up period. CONCLUSION: Primary coronary stenting for acute myocardial infarction via the transradial approach is a safe and feasible alternative to the conventional transfemoral approach, and is especially useful for hemodynamically stable patients who do not require a second vascular access site.

Adult↗

PubMed2000

Enhanced expression of microsomal epoxide hydrolase and glutathione S-transferase by imidazole correlates with the radioprotective effect.

Previous studies have shown that induction of microsomal epoxide hydrolase (mEH) and glutathione S-transferase (GST) by oltipraz correlated with the radioprotective effect. The present study was designed to investigate the expression of the antioxidant enzymes and the radioprotective effect by imidazole (IM). Northern blot analysis revealed that IM increased the mEH and GST mRNA levels in the rat liver in a dose-dependent manner. Rats irradiated with 3 Gy of gamma-rays in combination with IM showed enhanced increases in mEH and rGSTA2 mRNAs, as compared to either IM or irradiation alone. IM prevented elevations in the hepatic GSH content by gamma-irradiation. In contrast to IM, cysteine blocked radiation-inducible increases in the mRNAs with no suppression of the GSH content. The radioprotective effect by IM was greater than that by cysteine, as assessed by the 30-day survival rate of mice (i.e. 80% and 69%, respectively, vs. 48% in control). These results demonstrated that IM enhanced radiation-inducible mEH and GST expression with prevention of the increase in GSH content, which correlated with the radioprotective effect, and that the mechanistic basis of radioprotection by IM differed from that by cysteine.

Animals↗

PubMed1999

Suppression of rat hepatic cytochrome P450s by protein-calorie malnutrition: complete or partial restoration by cysteine or methionine supplementation.

Pharmacokinetic profiles of therapeutic agents are altered by protein-calorie malnutrition (PCM). The current study was designed to determine the expression of hepatic cytochrome P450s in rats after protein restriction and to investigate its molecular basis. Western blot analysis revealed that rats with protein restriction for 4 weeks exhibited marked suppression in the hepatic P450 1A2, 2C11, 2E1, and 3A1/2 levels. Northern blot analysis showed that hepatic P450 1A2, 2C11, and 3A1/2 mRNAs were significantly decreased in the state of PCM. The P450 2E1 mRNA level was slightly decreased in PCM rats, suggesting the possibility that expression of P450 2E1 affected by PCM might result from the transcriptional and/or posttranscriptional regulation. PCM-induced changes in most P450 expression completely or partially returned to control levels by a week of cysteine supplementation. Cysteine also prevented decreases in P450 1A2, 2C11, 2E1, and 3A1/2 mRNA levels by PCM. Methionine was minimally active in restoring the P450 expression. A metabolic change in hepatic ethoxyresorufin dealkylase activity in PCM rats was consistent with the P450 apoprotein and mRNA levels. Although the plasma concentrations of azosemide, a loop diuretic, primarily metabolized by cytochrome P450 1A, increased in protein-deprived rats, cysteine supplementation significantly reduced the increased plasma concentrations of the drug. The altered pharmacokinetic parameters of azosemide in PCM rats returned to those of control after cysteine supplementation, corroborating the conclusion that cysteine was effective in restoring cytochrome P450 expression and metabolic activities.

Animals↗

PubMed1999

Effects of brazilin on GLUT4 recruitment in isolated rat epididymal adipocytes.

The effects of brazilin on glucose transport into isolated rat epididymal adipocytes were investigated. Brazilin increased [3H]2-deoxy-D-glucose uptake, which was characterized by an increase in Vmax with no effect on the Km value. Phenylarsine oxide, which inhibits the translocation of glucose transporters, decreased brazilin-stimulated glucose transport to the basal level. The inhibition of phosphatidylinositol 3-kinase (PI3-kinase) with wortmannin also blocked brazilin-stimulated glucose transport. Western blot analysis with an anti-GLUT4 antibody revealed that brazilin increased the translocation of GLUT4 from intracellular pools to the plasma membrane. Brazilin, in combination with phorbol ester, showed an additive effect on glucose transport. The stimulating effect of phorbol ester on glucose transport was inhibited by staurosporine, but the effect of brazilin remained unchanged. Protein kinase C activity was not influenced by brazilin treatment. The inhibition of protein synthesis showed no effect on brazilin-stimulated glucose transport, and GLUT4 content in the total membrane fraction was not altered as a result of treatment with brazilin for 4 hr. Metabolic labeling of GLUT4 with [35S]methionine showed that de novo synthesis of GLUT4 was not induced by brazilin. These data suggest that brazilin may increase glucose transport by recruitment of GLUT4 from intracellular pools to the plasma membrane of adipocytes via the activation of PI3-kinase. However, the effect of brazilin may not be mediated by GLUT4 synthesis and protein kinase C activation.

Adipocytes↗

PubMed1999

Functional mapping in the human brain using high magnetic fields.

An avidly pursued new dimension in magnetic resonance imaging (MRI) research is the acquisition of physiological and biochemical information non-invasively using the nuclear spins of the water molecules in the human body. In this trial, a recent and unique accomplishment was the introduction of the ability to map human brain function non-invasively. Today, functional images with subcentimetre resolution of the entire human brain can be generated in single subjects and in data acquisition times of several minutes using 1.5 tesla (T) MRI scanners that are often used in hospitals for clinical purposes. However, there have been accomplishments beyond this type of imaging using significantly higher magnetic fields such as 4 T. Efforts for developing high magnetic field human brain imaging and functional mapping using MRI (fMRI) were undertaken at about the same time. It has been demonstrated that high magnetic fields result in improved contrast and, more importantly, in elevated sensitivity to capillary level changes coupled to neuronal activity in the blood oxygenation level dependent (BOLD) contrast mechanism used in fMRI. These advantages have been used to generate, for example, high resolution functional maps of ocular dominance columns, retinotopy within the small lateral geniculate nucleus, true single-trial fMRI and early negative signal changes in the temporal evolution of the BOLD signal. So far these have not been duplicated or have been observed as significantly weaker effects at much lower field strengths. Some of these high-field advantages and accomplishments are reviewed in this paper.

Brain↗

PubMed1999

Enhancement of biliary excretion of aflatoxin B(1) and suppression of hepatic ornithine decarboxylase activity by 2-(allylthio)pyrazine in rats.

2-(Allylthio)pyrazine (2-AP), a synthetic pyrazine derivative with an allylsulfur moiety, has protective effects against chemically-induced hepatic toxicity. Previous studies have shown that 2-AP significantly reduces the formation of preneoplastic foci in rats exposed to aflatoxin B(1) (AFB(1)). The present study was designed to determine whether 2-AP could increase the biliary excretion of metabolites of AFB(1) in rats treated with this carcinogen and whether the agent could alter the activity of ornithine decarboxylase (ODC), which is considered to be associated with tumor promotion. Rats were pretreated with 2-AP (p.o.) at a daily dose of 50 mg/kg for 5 consecutive days. AFB(1) (5 mg/kg) was administered intraperitoneally 2 h after the last dose of 2-AP. Amounts of principal AFB(1) metabolites, AFB(1)-glutathione and a glucuronide conjugate secreted in bile juice was increased by 56 and 50%, respectively, after the 2-AP treatment. Levels of radiolabelled AFB(1) covalently bound to calf thymus DNA catalyzed by microsomes obtained from 2-AP-treated rats (10 and 50 mg/kg, for 5 days) were reduced by 47 to 66%. ODC activity in AFB(1)-treated rats was determined by the three-step medium-term hepatocarcinogenesis assay. Rats were treated with 2-AP at the daily doses of 10, 25 and 50 mg/kg for 16 consecutive days. During this period, four repeated doses of AFB(1) (1.0 mg/kg) were given to the animals. Rats were then subjected to two-third partial hepatectomy, followed by administration of phenobarbital. 2-AP inhibited AFB(1)-induced ODC activity by 40 to 66%, as determined at the 44th day. Inhibition of AFB(1)-induced ODC activity by 2-AP in conjunction with acceleration of AFB(1) elimination through metabolic conjugation may contribute to its chemopreventive effects against this carcinogen.

Aflatoxin B1↗

PubMed1999

2-(Allylthio)pyrazine inhibition of aflatoxin B1-induced hepatocarcinogenesis in rats.

2-(Allylthio)pyrazine (2-AP), a synthetic pyrazine derivative with an allylsulfur moiety, has hepatoprotective effects against toxicants. Effect of 2-AP on hepatic tumorigenesis in association with glutathione S-transferase (GST) induction was examined in rats exposed to aflatoxin B1 (AFB1). Both AFB1-DNA adduct formation in the liver and urinary elimination of 8,9-dihydro-8-(N7-guanyl)-9-hydroxy-aflatoxin B1 (AFB1-N7-guanine) adduct were also determined. Male Sprague Dawley rats were treated with 2-AP at the daily oral doses of 10, 25 and 50 mg/kg for 16 consecutive days, during which four repeated doses of AFB1 (1.0 mg/kg) were given to the animals. Rats were then subjected to two-thirds of hepatectomy, followed by administration of phenobarbital (PB). Focal areas of hepatocellular alteration were identified after 44 days and preneoplastic foci expressing the placental form of glutathione S-transferase P (GST-P) were quantified by immunostaining of liver sections. 2-AP reduced the volume of liver occupied by GST-P foci by 65-96%. Under these experimental conditions, 2-AP treatment resulted in significant elevations in GST activity in the liver. Levels of radiolabeled AFB1 covalently bound to hepatic DNA, RNA and proteins were significantly reduced in rats treated with 2-AP for 5 days. 2-AP pretreatment also caused a 45% reduction in the urinary elimination of AFB1-N7-guanine adduct over the 24-h postdosing period. The present findings demonstrated that 2-AP exhibited protective effects against AFB1-induced hepatocarcinogenesis in rats with a marked decrease in the level of AFB1-DNA adduct. Reduction of hepatic DNA adducts might result from elevations of activity of GST, which catalyzes detoxification of the carcinogen.

Aflatoxin B1↗

PubMed1999

Analysis of cDNAs expressed during first cell division of petunia petal protoplast cultures using expressed sequence tags.

A large-scale sequence analysis of randomly selected cDNA clones was performed to isolate numerous genes in petunia petal protoplast cultures. We have partially sequenced 1158 randomly selected genes of the cDNA library constructed from 2-6 d cultured petal protoplasts. Three hundred and sixty-five different genes were identified, 25% of which showed significant similarity to existing sequences in the petunia, and an array of other organisms. In this report, 90 independent genes are analyzed in detail. A functional categorization of the database-matched expressed sequence tags (ESTs) showed that defense- or stress-related genes, as well as genes involved in the primary metabolic pathways and in the transcriptional or translational apparatus are abundantly represented. In particular, ESTs were identified with apparent homologies to the cyclin-dependent kinase, histone, actin-depolymerizing factor, proteasome, and ubiquitin which are expected to be related to cell division or to cell cycle control.

Cell Division↗

PubMed1999

Description of hydration free energy density as a function of molecular physical properties.

A method to calculate the solvation free energy density (SFED) at any point in the cavity surface or solvent volume surrounding a solute is proposed. In the special case in which the solvent is water, the SFED is referred to as the hydration free energy density (HFED). The HFED is described as a function of some physical properties of the molecules. These properties are represented by simple basis functions. The hydration free energy of a solute was obtained by integrating the HFED over the solvent volume surrounding the solute, using a grid model. Of 34 basis functions that were introduced to describe the HFED, only six contribute significantly to the HFED. These functions are representations of the surface area and volume of the solute, of the polarization and dispersion of the solute, and of two types of electrostatic interactions between the solute and its environment. The HFED is described as a linear combination of these basis functions, evaluated by summing the interaction energy between each atom of the solute with a grid point in the solvent, where each grid point is a representation of a finite volume of the solvent. The linear combination coefficients were determined by minimizing the error between the calculated and experimental hydration free energies of 81 neutral organic molecules that have a variety of functional groups. The calculated hydration free energies agree well with the experimental results. The hydration free energy of any other solute molecule can then be calculated by summing the product of the linear combination coefficients and the basis functions for the solute.

Journal Article↗

PubMed1999

Thioureas differentially induce rat hepatic microsomal epoxide hydrolase and rGSTA2 irrespective of their oxygen radical scavenging effect: effects on toxicant-induced liver injury.

Thioureas have been employed as potent hydroxyl radical scavengers and also inhibit production of oxygen free radicals. The in vitro oxygen radical scavenging effect by N,N'-substituted thioureas including dimethylthiourea (DMT), diethylthiourea (DET), tetramethylthiourea (TMT) and diphenylthiourea (DPT) was assessed by the conversion of phi x-174 DNA from supercoiled DNA to the open circular form or to fragmented DNA. Addition of the N,N'-substituted thioureas to the incubation mixture significantly prevented a single strand breakage of phi x-174 DNA induced by autooxidation of benzenetriol. These thioureas were also effective in preventing degradation of phi x-174 DNA induced by autooxidation of benzenetriol in the presence of ferrous iron. In view of the in vitro radical scavenging effect by the thioureas and the role of reactive oxygen species in the induction of phase II detoxifying enzymes, expression of microsomal epoxide hydrolase (mEH) and rGSTA2 in response to these agents was investigated in the rat liver. Rats treated with each of the alkylthioureas exhibited marked increases of mEH and rGSTA2 mRNA levels with TMT being the most effective. DPT an arylthiourea, however, was minimally active in increasing the mRNAs. Time-course studies revealed that DMT, DET and TMT increased the mRNA levels to the greatest extent at 24 h after a single dose of treatment. The levels of mEH and rGSTA2 mRNA were elevated in a dose-dependent manner by the alkylthioureas. Immunoblot analysis showed that the alkylthioureas induced mEH and rGSTA2 proteins in the liver (0.6 mmol/kg per day, 3 days), which was consistent with the increases in the mRNA levels. DMT, DET or TMT enhanced CCl4-induced liver toxicity, as monitored by plasma aminotransferase activity, although each of the agents alone caused only slight increase in the alanine aminotransferase activity. In contrast to the effects of the alkylthioureas, DPT protected the liver against the toxicant-induced injury. All of the thioureas prevented decreases in the hepatic glutathione level by CCl4. Expression of cytochrome P450 2E1 and P450 2B1/2, which are implicated with metabolic activation of CCl4, was assessed after treatment with the thioureas. P450 2E1 and P450 2B1/2 were differentially induced by the alkylthioureas with the expression of P450 2E1 being inversely related with that of P450 2B1/2. These results showed that N,N'-substituted alkylthioureas were capable of inducing mEH and rGSTA2 in the liver with elevation of the mRNAs, that induction of mEH and rGSTA2 by these alkylthioureas might be mediated by production of the reactive oxygens derived from metabolic activation of the agents irrespective of their radical scavenging effect and that the agents rather enhanced toxicant-induced liver injury with the induction of P450 2E1 or P450 2B1/2.

Alanine Transaminase↗

PubMed1999

Inhibitory effects of isopropyl-2-(1,3-dithietane-2-ylidene)-2- [N-(4-methylthiazol-2-yl)carbamoyl]acetate (YH439) on benzo[a]pyrene-induced skin carcinogenesis and micronucleated reticulocyte formation in mice.

Recently, a great deal of attention has been devoted to organosulfur compounds with potential cancer chemopreventive properties. Many sulfur-containing substances present in Brassica plants have been reported to possess striking anticarcinogenic and antimutagenic activities. Besides naturally occurring organosulfur compounds, certain synthetic sulfur-containing pharmaceuticals, such as oltipraz and sulindac, are known to exert substantial chemopreventive or chemoprotective effects. Isopropyl-2-(1, 3-dithietane-2-ylidene)-2-[N-(4-methylthiazol-2-yl)carbamoyl ]acetate (YH439) was initially developed for its possible use as a hepatoprotectant. The compound has been found to up-regulate the expression of cytochrome P-450 IA1 [I.J. Lee, K.S. Jeong, B.J. Roberts, A.T. Kallarakal, P. Fernandez-Salguero, F.J. Gonzalez, B.J. Song, Transcriptional induction of the cytochrome P-450 1A1 gene by a thiazolium compound YH439, Mol. Pharmacol. 49 (1996) 980-988.] which plays a pivotal role in metabolism of the majority of polycyclic aromatic carcinogens and mutagens, such as benzo[a]pyrene (B[a]P). In the present study, we found that oral administration of YH439 to CD-1 mice significantly suppressed B[a]P-initiated skin tumorigenesis. B[a]P-induced formation of micronuclei in mouse peripheral reticulocytes was also attenuated by YH439 pretreatment. Likewise, diallyl sulfide, a major volatile thioether present in garlic, also protected against B[a]P-induced skin tumorigenesis and micronucleated reticulocyte formation in mice.

Animals↗