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Biomedical subjects

G F Huang

Publications and source records attributed to G F Huang.

45 records · Page 3Linked to original sources
PubMed1977

Biologic activities of poly (2-azaadenylic acid) and poly (2-azainosinic acid).

Poly (2-azaadenylic acid) [(aza2A)n] and poly(2-azainosinic acid [(aza2I)n], two newly synthesized analogues of (A)n and (I)n, in which CH-2 of the purine ring is replaced by a nitrogen atom, have been evaluated in various biological assay systems. (Aza2A) n formed a complex with (U)n and (br5U)n, and (aza2I)n formed a complex with (C)n and (br5C)n, but these complexes were markedly destabilized relative to the corresponding (A)n or (I)n complexes. The (aza2A)n-and (aza2I)n-derived complexes failed to stimulate the production of interferon in primary rabbit kidney cells and human diploid fibroblasts, under conditions (A)n. (U)n, (I)n. (C)n and (I)n. (br5C)n induced high amounts of interferon. both (aza2A)n and (aza2I)n exerted a marked inhibitory effect on the endogenous RNA directed DNA polymerase (reverse transcriptase) activity associated with murine leukemia virus. They caused a relatively mild inhibition of complement activity in an hemolytic assay system.

Aza Compounds↗
PubMed1976

Mutagenicity of K-region epoxides of polycyclic aromatic compounds: structure-activity relationship.

The mutagenicity of several K-region arene oxides was tested in histidine-dependent mutants of Salmonella typhimurium. Benzo(a)pyrene-4,5-oxide and pyrene-4,5-oxide as well as some substituted phenanthrene oxides were mutagenic in strains TA 1538 and TA 98 which detect frame-shift mutagens. Structure-activity relationships are discussed from the standpoint of chemical reactivity. The absence of direct correlation between electrophilic reactivity and mutagenicity may suggest that primilarily physical properties, such as relative position of the epoxide group and molecular shape of arene oxides, are important for the emergence of mutagenicity of arene oxides.

Benzopyrenes↗
PubMedDate not supplied

An in vitro study on restoring bond strength of a GIC to saliva contaminated enamel under unrinse condition.

OBJECTIVES: This study attempted to find a method of restoring the tensile bond strength of glass ionomer cement (GIC) to saliva contaminated enamel under unrinse condition. METHODS: One hundred and thirty human non-carious permanent teeth were divided into two major groups. Either treatment with air drying, acetone, polyacrylic acid, maleic acid, tartaric acid, Scotchbond primer or no treatment at all was applied to both clean and saliva contaminated enamel surfaces prior to GIC placement. Samples were debonded in tension after 7 days of storage in water using a universal testing machine. Statistical analysis was performed using one-way ANOVA, Tukey's studentized range test and Wilcoxon's rank sums test to determine the significance of the difference of tensile bond strengths within and between the two major groups. RESULTS: Bond strength of GIC to clean enamel was 2.46+/-0.79 MPa while the bond strength of GIC to wet contaminated enamel was significantly reduced to 1.28+/-0.32 MPa (p<0.01). However, the bond strengths were restored when the contaminated enamel surfaces were air-dried (2.19+/-0.38 MPa) or applied with either maleic acid (2.80+/-0.63 MPa) or Scotchbond primer (2.13+/-0.65 MPa) before placing GIC over the enamels. CONCLUSIONS: Air drying, or application of maleic acid or Scotchbond primer to the contaminated enamel without rinsing prior to GIC placement can restore the tensile bond strength to a level similar to that of non-contaminated control.

Acetone↗
PubMedDate not supplied

Prevalence and treatment costs of infant caries in Northern California.

To determine the prevalence of infant caries in low-socioeconomic-status children and to analyze the costs of their treatment, we retrospectively evaluated 357 children, ages eight months to seven years, who were treated during 1992 at a university-associated medical center in Northern California. Infant caries was diagnosed by several different standards, and prevalence varied according to the diagnostic criteria employed: 27 percent by the presence of any labiolingual lesion on the maxillary incisors; 32 percent by the presence of at least two carious maxillary incisors; 27 percent by the presence of at least three carious maxillary incisors; and 36 percent by a dmft > or = 5. Prevalence was higher among boys than girls (37 percent versus 27 percent), and highest in the group ages 3-4 years (43 percent). The cost of dental treatment increased with deft and ranged from $408 for deft 2-5 to $1725 for deft 16-20. Many patients failed to comply with recommended treatment for reasons of cost. Our results showed that (1) the prevalence of infant caries varies depending upon the clinical criteria used for diagnosis; (2) the cost of rehabilitating primary dentition increases in proportion to the number of teeth involved; and (3) low-income patients avoid treatment of infant caries for a variety of reasons related to the cost involved.

California↗