Biomedical subjects

M T Huang

Publications and source records attributed to M T Huang.

At least 37 records · Page 2Linked to original sources

PubMed1999

Time course for early adaptive responses to ultraviolet B light in the epidermis of SKH-1 mice.

Hairless SKH-1 mice were exposed once to UVB light (180 mJ/cm2), and mechanistically important early adaptive responses in the epidermis were evaluated by immunohistochemical and morphological methods. Interrelationships in the time course for these UVB-induced responses were examined. The number of epidermal cells with DNA strand breaks (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells) or with thymine dimers increased to maximal levels within 30 min after UVB. The number of cells with DNA strand breaks located specifically in the basal layer of the epidermis was increased substantially by 3-30 min after UVB and gradually increased further over the next 5.5 hours. DNA strand breaks specifically in the basal layer of the epidermis were increased maximally at 6 h after UVB. The number of epidermal cells with DNA strand breaks or thymine dimers decreased markedly between 12 and 36 h. Pyrimidine (6-4) pyrimidone photodimers (6-4 photoproducts) in isolated epidermal DNA were increased immediately after irradiation of the mice with UVB and decreased markedly during the next 6 h. Exposure to UVB caused a rapid 8-fold increase in the number of epidermal cells with the DNA mismatch repair protein, MSH2 (within 30-60 min), and the level of MSH2-positive cells remained elevated for at least 48 h. These observations suggest a possible role of MSH2 in the repair of UVB-induced DNA damage. The number of epidermal cells with wild-type p53 protein started to increase at 1 h after UVB exposure and reached maximal levels by 8-12 h. The number of p53-positive cells fell markedly between 24 and 48 h. The time course for UVB-induced increases in the number of p53-positive cells was paralleled very closely by the time course for UVB-induced increases in the number of cells with p21(WAF1/CIP1), increases in morphologically distinct apoptotic sunburn cells, and decreases in the number of epidermal cells with bromodeoxyuridine (BrdUrd) incorporation into DNA. Although the start of UVB-induced increases in the number of p21(WAF1/CIP1)-positive cells was similar to that for the increase in p53-positive cells and very high levels of p21(WAF1/CIP1)-positive cells were observed at 8-12 h, maximal increases in p21(WAF1/CIP1)-positive cells were not achieved until 24 h after UVB irradiation (approximately 12 h after the peak value for p53). Myeloperoxidase-positive epidermal cells started to increase by 30 min after UVB exposure, and maximal numbers of myeloperoxidase-positive epidermal cells were observed at 2 h after UVB (18-fold higher than in nonirradiated control mice). An increased level of epidermal peroxidase enzyme activity in the epidermis was also observed from 1 to 24 h after exposure of the mice to UVB. Although neutrophil infiltration into the epidermis was not seen after exposure to UVB, neutrophil infiltration into the dermis (inflammatory response) was observed from 4 to 144 h after UVB exposure. In contrast to the marked inhibitory effect of UVB on BrdUrd incorporation into the DNA of epidermal cells observed at 8-12 h after UVB irradiation (>90% inhibition), BrdUrd incorporation into the DNA of epidermal cells was markedly increased (approximately 30-fold increase in the number of BrdUrd-positive cells) at 48 h after UVB exposure, and increases in epidermal cell layers and epidermal thickness (hyperplasia) were also observed. These later effects were associated with regeneration of the damaged epidermis.

Animals↗

PubMed1999

Acetophenone glycosides from thyme (Thymus vulgaris L.).

Four acetophenone glycosides were isolated from the butanol-soluble fraction of thyme extracts. Their structures were determined by spectral methods (MS, NMR, and 2D-NMR). Among them, two new compounds, 4-hydroxyacetophenone 4-O-[5-O-(3, 5-dimethoxy-4-hydroxybenzoyl)-beta-D-apiofuranosyl]-(1-->2)-beta-D -gl ucopyranoside (1) and 4-hydroxyacetophenone 4-O-[5-O-(4-hydroxybenzoyl)-beta-D-apiofuranosyl]-(1-->2)-beta-D-+ ++gluc opyranoside (2), were determined. Compound 1 showed weak cytotoxicity, inhibiting DNA synthesis of human leukemia cells.

Acetophenones↗

PubMed1999

Dose-dependent mutation profile in the c-Ha-ras proto-oncogene of skin tumors in mice initiated with benzo[a]pyrene.

Female CD-1 mice were treated topically with a low (25-50 nmol) or high (800 nmol) dose of benzo[a]pyrene (BP) or acetone vehicle, followed by 5 nmol 12-O-tetradecanoylphorbol 13-acetate (TPA) twice a week for 26 weeks. Selective UV radiation fractionation followed by PCR methods were used to analyze histologically defined subsets of cells (approximately 100-200 cells) on formalin-fixed, paraffin-embedded and H&E stained microscope sections. DNA samples from normal-appearing, hyperplastic or tumor regions from the skin of animals from each treatment group were isolated and amplified by PCR with c-Ha-ras-specific primers. Single-strand conformation polymorphism (SSCP) analyses were performed on both exon 1 and 2 products from each sample. DNA extracted from each aberrant band of SSCP analyses was amplified by PCR for further sequence analysis. The data indicate that c-Ha-ras mutations can be detected in normal-looking and hyperplastic epidermal cells as well as in tumor cells obtained from mice initiated with BP and promoted with TPA. The frequencies of c-Ha-ras mutations for normal-looking, hyperplastic and tumor samples were 3/20 (15%), 8/17 (47%) and 58/68 (85%), respectively, for the low dose group and 8/18 (44%), 10/20 (50%) and 64/86 (74%), respectively, for the high dose group. These observations indicate that there were no dose dependencies in the mutation frequencies for normal-looking, hyperplastic and tumor samples. For combined high dose and low dose samples, differences in mutation frequencies of the c-Ha-ras gene between the normal-looking, hyperplastic and tumor samples were highly significant (P < 0.0001, Fisher's exact test). All mutations detected were located at codons 12, 13 and 61 of the c-Ha-ras gene. With the numbers in parentheses indicating the nucleotide position in the coding sequence of the c-Ha-ras proto-oncogene, the distributions of mutations for G-->A (35), G-->T (35), G-->C (37), G-->T (38), C-->A (181), A-->T (182) and A-->G (182) in the low dose tumors were 5, 2, 11, 74, 0, 7 and 2%, respectively, and the distribution of mutations in tumors from animals treated with a high dose of BP were 3, 7, 13, 61, 15, 1 and 0%, respectively. Differences in the global mutation spectra (site and kind of all mutations) for the c-Ha-ras gene between the high and low dose group tumors were statistically significant (P < 0.004, Fisher's exact test) and the major difference between these two groups was C-->A (181) base substitutions. In summary, our data indicate that: (i) 79% of the BP/TPA skin tumors in CD-1 mice had c-Ha-ras mutations for the combined data for high dose and low dose tumors; (ii) the major mutations detected in BP/TPA skin tumors were G-->T transversions; (iii) the global mutation profile in the c-Ha-ras proto-oncogene in skin tumors obtained after initiation with a low dose of BP was different from that obtained after initiation with a high dose of BP.

Administration, Cutaneous↗

PubMed1999

Effects of oral administration of tea, decaffeinated tea, and caffeine on the formation and growth of tumors in high-risk SKH-1 mice previously treated with ultraviolet B light.

Treatment of SKH-1 mice with ultraviolet B light (UV-B, 30 mJ/cm2) twice a week for 22-23 weeks resulted in tumor-free animals with a high risk of developing malignant and nonmalignant tumors during the next several months in the absence of further UV-B treatment (high-risk mice). In three separate experiments, oral administration of green tea or black tea (4-6 mg tea solids/ml) as the sole source of drinking fluid for 18-23 weeks to these high-risk mice inhibited the formation and decreased the size of nonmalignant squamous cell papillomas and keratoacanthomas as well as the formation and size of malignant squamous cell carcinomas. In one experiment all these inhibitory effects of tea were statistically significant, whereas in the two other experiments many but not all of the inhibitory effects of tea were statistically significant. The decaffeinated teas were inactive or less effective inhibitors of tumor formation than the regular teas, and adding caffeine back to the decaffeinated teas restored biological activity. Oral administration of caffeine alone (0.44 mg/ml) as the sole source of drinking fluid for 18-23 weeks inhibited the formation of nonmalignant and malignant tumors, and this treatment also decreased tumor size in these high-risk mice.

Administration, Oral↗

PubMed1999

Sex differences in pediatric systemic lupus erythematosus: a retrospective analysis of 135 cases.

A retrospective review of 135 patients with systemic lupus erythematosus (SLE) (24 boys and 111 girls) under age 18 at the National Taiwan University Hospital (NTUH) from 1989 to 1998 was done. The aim of this retrospective study was to compare the differences in the age at diagnosis, clinical, laboratory features and survival among both sexes. The female to male ratio was 4.6:1. The mean age at the time of diagnosis was 13.7 years (range, 8y5m-18y) for male patients and 13.7 years (range, 6y1m-18y) for female patients. There was no significant differences in the mean age of diagnosis between the sexes. It was found that there were no significant differences in the clinical and laboratory features between male and female patients except for the prevalence of oral ulcers, alopecia and anti-SSA antibodies which were more frequent in the female group. The cumulative 5- and 10-year survival rates were 80.2% and 65%, respectively; male patients appeared to have a better survival, yet it did not reach any statistical significance. Univariate analysis showed that gender is not a significant factor on prognosis in pediatric SLE. Although abnormal creatinine was associated with poor mortality, it was not statistically significant on multivariate analysis.

Adolescent↗

PubMed1998

Adenovirus-mediated transduction of intestinal cells in vivo.

The intestinal tract has many features that make it an attractive target for therapeutic gene transfer. In this study, replication-defective adenoviral vectors were used to explore parameters that may be important in administering gene therapy vectors to the intestine. After surgically accessing the intestine, an E1-, E3-deleted adenoviral vector encoding beta-galactosidase (beta-Gal) was directly injected into various regions of the small and large intestine of rats and rabbits. Significant transduction of the tissue was observed and histochemical staining was used to identify enterocytes as the primary targets of gene transfer. Expression of beta-Gal did not differ substantially when the virus was administered to the duodenum, ileum, or colon. When the vector was directly administered to segments of the distal ileum containing a Peyer's patch, transgene expression was approximately 10-fold higher than in segments lacking a Peyer's patch. In the Peyer's patches, a high level of expression was localized to epithelial cells, potentially M cells, overlying the lymphoid follicle domes. Transduction of these cells could have application in DNA-mediated oral vaccination. Administration of an adenoviral vector encoding a secreted alkaline phosphatase to the lumen resulted in expression and secretion of this gene product into the circulation. This finding demonstrates the potential of enterocytes to serve as heterotopic sites for the synthesis of heterologous gene products that would be secreted into the lumen of the intestinal tract or into the bloodstream.

Adenoviridae↗

PubMed1998

Glycogen turnover in skeletal muscle is stimulated along with glucose uptake in vivo during contraction.

We have shown previously that glycogen synthesis in the heart can be stimulated in vivo by epinephrine. Our aim in this study was to determine whether glycogen synthesis in skeletal muscle can be similarly affected during increased energy expenditure. Left sciatic nerves of anesthetized fasted rats were electrically stimulated to allow left hindlimb muscles to contract for 5, 10, and 20 min. Glycogen contents in the contracting muscles at the end of electrical stimulation were found to be approximately 40% less than resting muscles in the right hindlimbs in all three groups of rats. Accompanying the enhanced glycogenolysis was increased incorporation of the intravenously infused [3-(3)H]-glucose into glycogen. The rate of tritium incorporation into glycogen in the contracting muscle was found to be 34-fold greater than resting muscles. Glucose utilization was determined by the phosphorylation of the intravenously injected [14C]-2-deoxyglucose in the skeletal muscle. The rate of accumulation of [14C]-2-deoxyglucose-6-phosphate in the contracting muscles was found to be 28-fold greater than resting muscles. Glycogen synthesis and glucose uptake indexes, calculated by dividing the radioactivity in [3H]-glycogen and [14C]-2-DGP by the mean specific activity of their respective precursors in the plasma, were not found to be significantly different in the contracting muscle. In conclusion, our data indicate that: (i) glycogenesis and glycogenolysis can be stimulated concurrently in the skeletal muscle; and (ii) glucose utilization in the skeletal muscle during contraction may be mediated through glycogen turnover.

Animals↗

PubMed1998

Inhibitory activity of boswellic acids from Boswellia serrata against human leukemia HL-60 cells in culture.

Four major triterpene acids including beta-boswellic acid (1), 3-O-acetyl-beta-boswellic acid (2), 11-keto-beta-boswellic acid (3), and 3-O-acetyl-11-keto-beta-boswellic acid (4) were isolated from the gum resin of Boswellia serrata and examined for their in vitro antitumor activity. They inhibited the synthesis of DNA, RNA and protein in human leukemia HL-60 cells in a dose dependent manner with IC50 values ranging from 0.6 to 7.1 microM. Among them, compound 4 induced the most pronounced inhibitory effects on DNA, RNA and protein synthesis with IC50 values of 0.6, 0.5, and 4.1 microM, respectively. The effect of 4 on DNA synthesis was found to be irreversible. Compound 4 significantly inhibited the cellular growth of HL-60 cells, but did not affect cell viability.

Antineoplastic Agents, Phytogenic↗

PubMed1998

Dietary administration of an extract from rosemary leaves enhances the liver microsomal metabolism of endogenous estrogens and decreases their uterotropic action in CD-1 mice.

We evaluated the effects of a methanol extract from the leaves of the plant Rosmarinus officinalis L. (rosemary) on the metabolism and action of estradiol and estrone. Treatment of female CD-1 mice with 2% rosemary in AIN-76A diet for 3 weeks increased the liver microsomal 2-hydroxylation of estradiol and estrone by approximately 150%, increased their 6-hydroxylation by approximately 30% and inhibited the 16alpha-hydroxylation of estradiol by approximately 50%. Treatment of female CD-1 mice with 2% rosemary diet for 3 weeks also stimulated the liver microsomal glucuronidation of estradiol and estrone by 54-67% and 37-56%, respectively. In additional studies, feeding 2% rosemary diet to ovariectomized CD-1 mice for 3 weeks inhibited the uterotropic action of estradiol and estrone by 35-50% compared with animals fed a control diet. The results of this study showed that feeding female mice a 2% rosemary diet increased the liver microsomal oxidation and glucuronidation of estradiol and estrone and inhibited their uterotropic action.

Animals↗

PubMed1998

Effect of green tea on p53 mutation distribution in ultraviolet B radiation-induced mouse skin tumors.

In the present study, administration of green tea to SKH-1 mice, via the drinking fluid, was found to significantly reduce the incidence and volume of ultraviolet B (UVB) radiation-induced skin tumors. Thirty-six skin tumors induced by UVB and 32 skin tumors induced by UVB, in mice treated with green tea in their drinking water, were collected and examined for the presence of mutations in the p53 gene. Polymerase chain reaction products from p53 exons 5-8 were screened by single-strand conformation polymorphism and direct sequence analyses. Eight of 36 UVB-induced tumors contained nine p53 mutations, with four in exon 5 and five in exon 8. In contrast, nine of 32 UVB-induced tumors in mice treated with green tea contained 11 p53 mutations, with two in exon 5, five in exon 6 and four in exon 8. All of the p53 mutations occurred at dipyrimidine sequences. These results were further corroborated by p53 immunohistochemistry. The most frequent mutations were C-->T or T-->C transitions, which are consistent with the genetic alterations caused by UVB exposure. Interestingly, mutations found in exon 6 of the p53 gene occurred only in tumors from the UVB/green tea group. Thus, the tumors observed in UVB/green-tea-treated mice have a different exon distribution of p53 mutations than tumors obtained from mice treated with UVB alone.

Animals↗

PubMed1998

Effect of dietary curcumin and dibenzoylmethane on formation of 7,12-dimethylbenz[a]anthracene-induced mammary tumors and lymphomas/leukemias in Sencar mice.

Female Sencar mice (6 weeks old) were administered 1 mg of 7,12-dimethylbenz[a]anthracene (DMBA) by oral gavage once a week for 5 weeks. At 20 weeks after the first dose of DMBA, 68% of mice developed mammary tumors (the average 1.08 tumors per mouse) and 45% had lymphomas/leukemias. Feeding 1% dibenzoylmethane (DBM) in AIN 76A diet, starting at 2 weeks before the first dose of DMBA and continuing until the end of the experiment, inhibited both the multiplicity and incidence of DMBA-induced mammary tumor by 97%. The incidence of lymphomas/leukemias was completely inhibited by 1% DBM diet. In contrast, feeding 2% curcumin diet had little or no effect on the incidence of mammary tumors, and the incidence of lymphomas/leukemias was reduced by 53%.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1998

Age-related changes in blood lymphocyte subsets of Chinese children.

BACKGROUND: Flow cytometric analysis of major lymphocyte populations and their subsets reveals age-related changes in the human cellular immune system. SUBJECTS AND METHODS: Immunophenotypic markers were evaluated in 136 healthy pediatric subjects divided into groups of newborn infants (cord blood), children aged 1 to 2 years, 2 to 5 years, and 6 to 15 years. RESULTS: The percentage of T cells increased gradually with age and the evolution of the percentage of B and NK cells was found to be variable. The percentage of CD4+ cells remains relatively unchanged from infancy to adolescence, but the percentage of CD8+ T cells was lowest at birth and reached maximal levels in the one to two year-old period. The percentage of naive T cells declined with time, but the percentage of memory T cells increased with age. Similar trends were seen in T-cell receptor alphabeta- and gammadelta-bearing T cells. The percentage of CD 11b+CD8+ T cells increased gradually from birth and reached maximal levels from 6 to 15 years old. The expression of the activation markers CD25 and HLA-DR on CD4+ T cells increased with age. The percentage of CD16+CD56- NK cells declined with age, but the evolution of the percentage of CD 16-CD56+ NK cells was variable. The fraction of B cells that expressed CD5 was high at birth (72.9%) and was highest in one to two year olds (73.1%), then declined steadily over time. The CD23 antigen was expressed on 41.9% of B cells at birth and 68.6% during the first to second year, then declined steadily with age. CONCLUSION: These data may serve as a reference range for studies of Chinese pediatric subjects.

Adolescent↗

PubMed1998

Tissue spaces in rat heart, liver, and skeletal muscle in vivo.

Tissue spaces were determined in rat heart, liver, and skeletal muscle in vivo using isotopically labeled [14C]inulin. Tracer was injected into the jugular vein of pentobarbital-anesthetized male Sprague-Dawley rats. After a 30-min equilibration period, a blood sample was taken, and heart, liver, and gastrocnemius muscle were excised and immediately freeze clamped at liquid nitrogen temperatures. The extracellular inulin space was 0.209 +/- 0.006 (n = 13), 0.203 +/- 0.080 (n = 7), and 0.124 +/- 0.006 (SE) ml/g wet wt tissue (n = 8) for heart, liver, and skeletal muscle, respectively. Total tissue water was 0.791 +/- 0.005 (n = 9), 0.732 +/- 0.002 (n = 9), and 0.755 +/- 0.005 ml/g wet wt tissue (n = 10) for heart, liver, and skeletal muscle, respectively. Expressed as a percentage of total tissue water, the intracellular space was 73.6, 72.2, and 83. 7% for heart, liver, and skeletal muscle, respectively. With use of 2,3-diphospho-D-glyceric acid as a vascular marker, the interstitial space was calculated by subtracting the counts in tissue due to whole blood from total tissue counts and dividing by plasma counts. The interstitial space was 18.8, 22.4, and 14.5% of total tissue water, with accompanying plasma spaces of 7.7, 5.3, and 1.8% for heart, liver, and gastrocnemius muscle, respectively. The tracer method used in this study provides a quantitative assessment of water distribution in tissues of nonnephrectomized rats that has applications for calculation of tissue ion and metabolite concentrations, gradients, and fluxes under normal and pathophysiological conditions.

Animals↗

PubMed1998

Curcumin is an in vivo inhibitor of angiogenesis.

BACKGROUND: Curcumin is a small-molecular-weight compound that is isolated from the commonly used spice turmeric. In animal models, curcumin and its derivatives have been shown to inhibit the progression of chemically induced colon and skin cancers. The genetic changes in carcinogenesis in these organs involve different genes, but curcumin is effective in preventing carcinogenesis in both organs. A possible explanation for this finding is that curcumin may inhibit angiogenesis. MATERIALS AND METHODS: Curcumin was tested for its ability to inhibit the proliferation of primary endothelial cells in the presence and absence of basic fibroblast growth factor (bFGF), as well as its ability to inhibit proliferation of an immortalized endothelial cell line. Curcumin and its derivatives were subsequently tested for their ability to inhibit bFGF-induced corneal neovascularization in the mouse cornea. Finally, curcumin was tested for its ability to inhibit phorbol ester-stimulated vascular endothelial growth factor (VEGF) mRNA production. RESULTS: Curcumin effectively inhibited endothelial cell proliferation in a dose-dependent manner. Curcumin and its derivatives demonstrated significant inhibition of bFGF-mediated corneal neovascularization in the mouse. Curcumin had no effect on phorbol ester-stimulated VEGF production. CONCLUSIONS: These results indicate that curcumin has direct antiangiogenic activity in vitro and in vivo. The activity of curcumin in inhibiting carcinogenesis in diverse organs such as the skin and colon may be mediated in part through angiogenesis inhibition.

Angiogenesis Inhibitors↗

PubMed1998

Predisposing factors of life-threatening deep neck infection: logistic regression analysis of 214 cases.

OBJECTIVE: In the era of antibiotics, most deep neck infections can be cured by conservative treatment, but some still result in life-threatening complications. In this study, we discuss whether or not there are predisposing factors of complicated deep neck infection. DESIGN: A retrospective chart review of patients presenting between 1988 and 1996 was conducted. METHOD: Among 214 deep neck infection patients, 18 cases resulted in lethal complications. We used the "dummy" variable with logistic regression as the statistical analysis method. RESULTS: Patients with an underlying disease, neck swelling, and delay time had a positive correlation that was statistically significance (p < .05). Patients who were older, male, with complete blood count/differential count-positive finding and fever had positive correlation, but this was not statistically significant (p > .05). CONCLUSION: Although complicated deep neck infection is a rapidly progressive disease with a high mortality, we can not thoroughly predict the prognosis or avoid it happening completely. But, if we can detect and pay more attention to the high-risk group of patients with use of aggressive therapy, the incidence of complicated deep neck infection may be reduced.

Abscess↗

PubMed1997

Effects of tea, decaffeinated tea, and caffeine on UVB light-induced complete carcinogenesis in SKH-1 mice: demonstration of caffeine as a biologically important constituent of tea.

Oral administration of green or black tea inhibited UVB light-induced complete carcinogenesis in the skin of SKH-1 mice. Green tea was a more effective inhibitor than black tea. Oral administration of decaffeinated green or black tea resulted in substantially less inhibitory activity than did administration of the regular teas, and in one experiment, administration of a high-dose level of the decaffeinated teas enhanced the tumorigenic effect of UVB. Oral administration of caffeine alone had a substantial inhibitory effect on UVB-induced carcinogenesis, and adding caffeine to the decaffeinated teas restored the inhibitory effects of these teas on UVB-induced carcinogenesis. In additional studies, topical application of a green tea polyphenol fraction after each UVB application inhibited UVB-induced tumorigenesis. The results indicate that caffeine contributes in an important way to the inhibitory effects of green and black tea on UVB-induced complete carcinogenesis.

Administration, Oral↗

PubMed1997

Enhanced skin carcinogenesis in transgenic mice with high expression of glutathione peroxidase or both glutathione peroxidase and superoxide dismutase.

Female transgenic mice (C57BL/6 x CBA/J)F1 with a 1-fold increase in expression of glutathione peroxidase (GP) or with a 1-fold increase in the expression of GP and a 3-4-fold increase in the expression of superoxide dismutase (SOD) had an enhanced carcinogenic response to initiation by 7,12-dimethylbenz[a]anthracene (DMBA) followed by promotion with 12-O-tetradecanoylphorbol-13-acetate (TPA). GP- or GP+SOD-transgenic mice that were initiated by a single topical application of 200 nmol of DMBA followed by promotion with 8 nmol of TPA twice weekly for 30 weeks developed an average of 10.9 or 11.0 skin tumors per mouse and a 100% tumor incidence in comparison with the corresponding nontransgenic mice, which had 3.9 tumors per mouse and an 83% tumor incidence. After stopping TPA application, partial skin tumor regression occurred more rapidly in nontransgenic mice than in either type of transgenic mouse. At 10 weeks after termination of TPA treatment, 9-11% of the tumor-bearing transgenic mice and 26% of the tumor-bearing nontransgenic mice had complete regression of their tumors. Histopathological examination of 96 skin papillomas revealed that the area, location, degree of tumor dysplasia, bromodeoxyuridine labeling index, and p53 protein levels were closely intercorrelated. Further analysis indicated that papillomas with the same grade of dysplasia had a higher bromodeoxyuridine labeling index and a greater p53 protein level in GP- or GP+SOD-transgenic mice than those in nontransgenic mice. The data indicated that overexpression of skin antioxidant enzymes GP or GP+SOD, which are enzymes that are believed to protect cells from oxidative damage by scavenging reactive oxygen species, lead to the increased, rather than the decreased, tumorigenesis in a DMBA/TPA two-stage skin carcinogenesis model.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1997

Steroidal saponins from Asparagus officinalis and their cytotoxic activity.

Two oligofurostanosides were isolated from the seeds of Asparagus officinalis L and their structures characterized as 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-(alpha-L-rhamnopyranosyl- (1-->4))-beta-D-glucopyranosyl]-26-O-[beta-D-glucopyranosyl]-(25R) -22 alpha-methoxyfurost-5-ene-3 beta,26-diol(methyl protodioscin) and its corresponding 22 alpha-hydroxy analogue (protodioscin). The structural identification was performed using detailed analysis of 1H- and 13C-NMR spectra including two-dimensional NMR spectroscopy (COSY, HMQC, NOESY and HMBC), and chemical conversions. These two compounds have been shown to inhibit the growth of human leukemia HL-60 cells in culture and macromolecular synthesis in a dose-dependent manner. The inhibitory effect on DNA synthesis was found to be irreversible.

Carbohydrate Conformation↗