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Biomedical subjects

Z R Guo

Publications and source records attributed to Z R Guo.

At least 55 records · Page 3Linked to original sources
PubMed1987

[Chemoprevention of cancer of the uterine cervix--preliminary study on the intervention of the cervical precancerous lesion by retinamide RII].

Twenty seven women with mild, moderate or severe cervical dysplasia proven by pathology were treated by retinamide RII suppository. Retinamide RII suppository, 10 mg QD, was given intravaginally for six months (three months as a course). Clinical examination, Papanicolaou cytology and tissue biopsy under colposcope were carried out before and after treatment. The results indicated that after the second course, 26 out of 27 patients responded; of them, precancerous lesions disappeared in 24 and even normal squamous epithelium was observed in 3. The overall response rate was 96.29% and the marked response rate was 88.89%. The general side effects were mild. There was little cervical and vaginal irritation which was well tolerated. The results of this clinical trial make available a practical base for chemoprevention of cervical cancer.

Antineoplastic Agents↗
PubMed1984

Examination of the interrelationship between aliphatic group dipole moment and polar substituent constants.

The relationships between 210 aliphatic group dipole moments (mu) and Taft polar constants (sigma *) are explored, and they are shown to be correlated by a general equation: mu = -a X sigma * -b X n' -c, where a, b, and c are constants. The value n' is a parameter reflecting the attenuating factor due to the number and electronic nature of the interval atoms between the most electronegative atom and the first atom connected to the acetate in the measurement of sigma *. The mu and sigma * values of over 214 aliphatic substituents are compiled for future correlation studies. Comparative examples using sigma * and mu in quantitative structure-activity relationships are presented.

Anticonvulsants↗
PubMed1984

Crystallography, quantitative structure-activity relationships, and molecular graphics in a comparative analysis of the inhibition of dihydrofolate reductase from chicken liver and Lactobacillus casei by 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazine s.

The inhibition of dihydrofolate reductase from chicken liver and from Lactobacillus casei has been studied with 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazines. It was found that for the chicken enzyme, inhibitor potency for 101 triazines was correlated by the following equation: log 1/Kiapp = 0.85 sigma tau' - 1.04 log (beta X 10 sigma tau' + 1) + 0.57 sigma + 6.36. The parameter tau' indicates that for certain substituents, tau = 0. In the case of the L. casei DHFR results, meta and para derivatives could not be included in the same equation. For 38 meta-substituted compounds, it was found that log 1/Kiapp = 0.38 tau'3-0.91 log (beta X 10 tau'3 + 1) + 0.71I + 4.60 and for 32 para-substituted phenyltriazines log 1/Kiapp = 0.44 tau'4-0.65 log (beta tau'4 + 1') - 0.90 upsilon + 0.69I + 4.67. In the L. casei equation, I is an indicator variable for substituents of the type CH2ZC6H4-Y and ZCH2C6H4-Y, where Z = O, NH, S, or Se. The parameter upsilon is Charton's steric parameter, which is similar to Taft's Es. The mathematical models obtained from correlation analysis are compared with stereo color graphics models.

Animals↗
PubMed1984

Inhibition of human dihydrofolate reductase by 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazine s. A quantitative structure-activity relationship analysis.

The inhibitory activity of 101 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazines against purified dihydrofolate reductase from human lymphoblastoid cell (WIL 2) has been studied. From the obtained Kiapp values, quantitative structure-activity relationships (QSAR) have been derived. The QSAR from human dihydrofolate reductase are compared with QSAR for triazines inhibiting bovine and murine tumor DHFR, as well with QSAR for their inhibitory action on murine tumor cell culture.

Animals↗
PubMed1981

Comparison of the inhibition of methotrexate-sensitive and -resistant Lactobacillus casei cell cultures with purified Lactobacillus casei dihydrofolate reductase by 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(3-substituted-phenyl)-s-triazines. Use of quantitative structure-activity relationships in making inferences about the mechanism of resistance and the structure of the enzyme is situ compared with the enzyme in vitro.

The inhibitory action of a set of 4,5-diamino-1,2-dihydro-2,2-dimethyl-1-(3-substituted-phenyl)-s-triazines on Lactobacillus casei dihydrofolate reductase is compared with their action on methotrexate-resistant and methotrexate-sensitive cell cultures by means of quantitative structure-selectivity analysis. The analysis uncovers major differences in the steric and hydrophobic interactions of the substituents X with the three different systems. Correlation analysis is used to define the hydrophobic binding site for 3-X in the isolated enzyme. This is shown to be similar to that of the sensitive cells but different from that in the resistant cells, which have a larger hydrophobic binding site. When X has the general structure 3-CH2ZC6H4-Y (Z = O or NH), it is shown that Y does not interact with the isolated enzyme, but in the living cells, Y interacts with a molecular barrier in a way that can be quantitatively related to the molar refractivity of X. The methotrexate-resistant cells are resistant to highly hydrophilic inhibitors such as methotrexate but are not able to resist hydrophobic inhibitors. The results with the inhibition of L. casei dihydrofolate reductase are compared with the inhibition of enzyme from bovine liver.

Drug Resistance↗