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C F Chao

Publications and source records attributed to C F Chao.

36 records · Page 2Linked to original sources
PubMed1991

Human papillomavirus type-related DNA and c-myc oncogene alterations in colon cancer cell lines.

Although squamous-cell epithelium is the most frequent target site of human papillomavirus (HPV) infection, a similar infection is demonstrated in columnar epithelial cells in this paper. The papillomavirus expression in three cell lines was detected in colorectal adenocarcinoma of Chinese patients. The HPV-16 and HPV-18 DNA sequences were found in colorectal cancer cell lines, which might suggest the correlation of HPV to the etiology of colorectal cancers. In addition, c-myc oncogene was identified by amplification in all three colorectal cancer cell lines, but only normal germ-line fragments were found in control tissue. The correlation between HPV and c-myc, and the implications of these findings in colorectal cancers are also discussed.

Adenocarcinoma↗
PubMed1991

Identification of two maturation-related, wheat-germ-lectin-binding proteins on the surface of mouse sperm.

Epididymal maturation is essential for mammalian sperm to develop fertility. Wheat germ agglutinin (WGA), a lectin which specifically recognizes N-acetyl-glucosamine and sialic acid, was used to investigate membrane characteristics of epididymal sperm in the mouse. Histochemical and cytochemical localization revealed that WGA-binding sites were increased as sperm became mature. The binding sites were mainly localized in the plasma membrane of the anterior acrosome and tails. On Western blots of NP-40 extracts, two WGA-binding glycoproteins, GP-49 and GP-83, were identified on the sperm recovered from both corpus and cauda epididymidis. GP-83 was removed from the sperm surface by centrifugation and resuspension in phosphate-buffered saline (PBS) three times. GP-49 was resistant to centrifuging at 400 g for 5 min up to seven times and the treatment with 1M NaCl in PBS. These observations suggest that GP-49 is very likely an intrinsic membrane protein of the sperm, whereas GP-83 is an extrinsic protein.

Animals↗
PubMed1990

Mechanism of estrogen-induced 17-beta-hydroxysteroid dehydrogenase in ovariectomized rat uterus.

Estradiol (E2), progesterone or medroxyprogesterone acetate can induce biosynthesis of the 17-beta-hydroxysteroid dehydrogenase (17-beta-HSD) in the mammalian uterus. For further understanding the 17-beta-HSD induction which may be mediated by the conjugation of the E2 to its receptor, premature ovariectomized rats were treated with E2, or with a synthetic steroid, diethylstilbestrol (DES), an agonist for the E2 receptor but not a substrate for 17-beta-HSD. Histological observation and uterus weight were examined as parameters to evaluate uterine response to those hormones at different durations of treatment. The 17-beta-HSD in ovariectomized rat uterus of each group was also examined by histochemical and biochemical assays. The results showed that the 17-beta-HSD activity in the uterus can be induced by E2 or DES, after daily treatment for 1, 14 and 28 days, but much higher in DES treated animals. The uterus weight demonstrated a "negative linear correlation" to the enzyme activity in all E2 treated groups, but not in DES or control rats. Accordingly, it was indicated that the 17-beta-HSD induction was regulated by conjugation of E2 or DES to its receptor. Therefore, we believe that the 17-beta-HSD gene in the rat uterus is another estrogen responsive gene.

17-Hydroxysteroid Dehydrogenases↗
PubMed1989

17-beta-Hydroxysteroid dehydrogenase in rabbit bone marrow.

Because of the general presence of 17-B-hydroxysteroid dehydrogenase (17-B-HSD) in animals and human erythrocytes, it is very likely that this enzyme is also present in the erythrocyte precursor cells in bone marrow. Adult male white New Zealand rabbits were used to demonstrate the existence of the 17-B-HSD in bone marrow cells and to evaluate the biological function of 17-B-HSD in the erythropoietic system in bone marrow. Anemia was artificially induced in these animals in order to stimulate the proliferation of erythropoietic cells. This was accomplished by bleeding or by intra-peritoneal injection of 40 mg/kg of phenylhydrazine. The 17-B-HSD activities were then examined by histochemical and biochemical assays. The results showed a two to three-fold increase of the enzyme activities in both peripheral erythrocytes and bone marrow cells of anemic animals. Our experiments further demonstrate the fine control of erythropoiesis. The enzyme, which favors the conversion of oestradiol to oestrone, is itself boosted by an anemic state. As a result, the inhibitory action of hemopoiesis by oestradiol was relieved.

17-Hydroxysteroid Dehydrogenases↗
PubMed1989

Functional evaluation of cultured rabbit osteoblast-like cells.

For the improvement of the adult osteoblast culture, the osteoblasts of young adult rabbit endosteal from long bones were isolated by collagenase digesting separation. 0.1% of type-I collagen precoated culture flasks were used as substrate for isolated bone cell growth. Morphological examination of cultured cells under a phase-contrast microscope, SEM and TEM observations showed a structure similar to osteoblast in vivo. Histochemical examination of alkaline phosphatase demonstrated 97% purity of cultured osteoblasts. The presence of calcium deposit activity in cultured cells was demonstrated by Van Kossa stain. High activity of alkaline phosphatase and inorganic pyrophosphatase in cultured osteoblasts as determined by biochemical analysis. High calcium uptake in cultured osteoblasts was demonstrated by radioisotope labelled 45CaCl12. According to these methods, it was indicated that the cells isolated from young rabbit long bone endosteal were osteoblast-like and still maintained their biological function. Our system for culturing osteoblast-like cells is a successful attempt in growing bone tissue in vitro starting from isolated bone cells. Therefore, this modified method for bone cell culture on collagen precoated culture flasks could be used as the experimental model in studies concerning the osteoblasts in vitro.

Alkaline Phosphatase↗
PubMed1988

Effects of prostaglandin E2 on alveolar bone resorption during orthodontic tooth movement.

Twenty Sprague-Dawley rats weighing 280-300 g were divided into two groups of ten animals each. They were treated by daily submucosal injections of 50 micrograms prostaglandin E2 (PGE2) per kilogram body weight into the region below the apex of the left first maxillary molar (experimental), or vehicle into the region below the apex of the right first molar (control), for a period of 5 days. The animals of the first group were sacrificed immediately following the treatment period, while those of the second group were sacrificed 5 days after the treatment period. Twenty-two hours prior to sacrifice, a piece of latex orthodontic elastic was secured to the adjacent area between the first and second maxillary molars of both sides of each rat by using two mosquito hemostats. The periodontal ligament (PDL) mesial to the mesiobuccal root of the first maxillary molar was assayed for changes in PDL cell factors. The results showed that immediately following the 5-day treatment period the left PDL had a significant decrease in the total number of fibroblasts and a significant increase in the total number of both osteoclasts and nuclei per osteoclast, while no significant changes in the osteoblasts when compared with those of the right control PDL. The left PDL of animals which were sacrificed 5 days after the treatment period revealed a significant decrease in the number of total fibroblasts and only a slight decrease in both numbers of total osteoclasts and total nuclei per osteoclast, but again no significant changes in osteoblasts when compared with those of the right control PDL.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Process↗
PubMed1988

Effect of epidermal growth factor on the sheet formation of the human keratinocyte in cell culture.

Epidermal growth factor is an important element in maintaining keratinocyte proliferation and maturation. To evaluate its effect on keratinocyte growth in vitro, human foreskins were cultured. The epidermal keratinocyte growth in culture was separated into two stages by a conditional medium: the proliferation stage, in which the cells were maintained in a monolayer; and the differentiation stage, in which the cells grew to stratification and keratinization. The keratinocytes were cultured in various concentrations of epidermal growth factor, and their morphology and growth behavior were closely observed. Our results demonstrated that cultured keratinocytes grew in a confluent layer under the influence of epidermal growth factor. In contrast, in a culture without epidermal growth factor, the proliferation rate of cultured keratinocytes slowed down and eventually the cells stopped growing. During serum stimulation, with or without additional exogenous epidermal growth factor, the cultured keratinocytes grew continuously to the normal terminal differentiation. Under this two-stage culture model, the cultured keratinocytes could grow into an intact sheet of graftable epidermis.

Antibodies, Monoclonal↗
PubMed1988

Cytochemical localization and biochemical analysis of the enzyme markers in human hepatoma cell lines.

Three enzyme makers, glucose-6-phosphatase, ATPase and gamma-glutamyl transpeptidase, have been used in studying carcinogenesis of hepatocellular carcinoma. They have been investigated in animal models and human hepatocellular carcinoma in vivo and in vitro. But the inconsistent levels of these three enzymes associated with this type of carcinoma raised the possibility that the carcinoma cells might have derived from the cells originating from different stages of differentiation. To evaluate this possibility, three human cell lines, Hep G2, Hep 3B, and HA 22T, all thought to be arrested in different stages of differentiation based on their biochemical and morphological characteristics, were used as models. The three enzyme markers glucose-6-phosphatase, ATPase and gamma-glutamyl transpeptidase were examined cytochemically and biochemically. Our results showed that there was no correlation between the ATPase levels and the stages of the cell line's differentiation. But both glucose-6-phosphatase and gamma-glutamyl-transpeptidase were higher in cells that were more differentiated.

Adenosine Triphosphatases↗
PubMed1987

Presence of episomal and integrated human papillomavirus DNA sequences in cervical carcinoma.

Thirty surgical samples of squamous cell carcinoma of the cervix obtained from Chinese women were analysed for the presence of human papillomavirus (HPV) types 16 and 18 using Southern blot hybridization procedure. HPV16 was detected in 53% while HPV18 was found in only 6% of the samples analyzed. When compared with other reports, variation in the geographic distribution of these two HPV types in association with cervical carcinoma is noted. Thirty-seven and a half percent of the HPV16-positive samples contained this HPV type in episomal form and an equal number in cellular DNA-integrated form. The simultaneous presence of both episomal and integrated forms was found in the remaining 25% of the positive samples. The two HPV18-positive cases harbored only episomal viral genome and were not superinfected by HPV16. Analysis of the HPV16 integration samples showed that single integration events had probably occurred and some of the viral sequences had been lost on or subsequent to integration.

Carcinoma, Squamous Cell↗
PubMed1984

The effect of nitroimidazoles on the oxygen consumption rate and respiratory control ratio of beef heart mitochondria.

The neurotoxic effect of the nitroimidazole radiosensitizers misonidazole (MISO) and desmethylmisonidazole (DMM) has seriously compromised their clinical effectiveness. We compare here the effect of MISO and DMM on oxygen consumption in purified beef heart mitochondria. MISO has been found to significantly increase the oxygen consumption rate and decrease the respiratory control ratio in isolated mitochondria when incubated in the presence of the NAD+ dependent substrate, beta-hydroxybutyrate. DMM has a similar but less pronounced effect than MISO on these respiratory parameters. When mitochondria were incubated in the presence of these radiosensitizers for 8, 15, 30, 45, and 60 minutes, the oxygen consumption rate was decreased when succinate, a FAD dependent substrate, was added following the incubation. This decrease, which is both time and dosage dependent, is equivalent for MISO and DMM.

Animals↗
PubMed1984

The effect of nitroimidazoles on glucose utilization and lactate accumulation in mouse brain.

The radiation sensitizers misonidazole (MISO) and desmethylmisonidazole (DMM) can produce central and peripheral neuropathy in patients and laboratory animals. Behavioral and pathological investigations have indicated that in the central nervous system this primarily involves the cochlear and vestibular systems. Nitroimidazoles can also interfere with glycolysis in vitro under aerobic and anaerobic conditions. In the present work we have studied the effect of MISO or DMM on lactate production and glucose utilization in mouse brain. It is observed that these compounds result in a 25% inhibition of lactate production in brain slices relative to the control at a 10 mM level. Additionally, MISO (1.0 mg/g/day) or DMM (1.4 mg/g/day) were administered daily (oral) for 1, 4, 7, or 14 days to examine the effect of these two drugs on the regional glucose utilization in C3Hf mouse brain. Five microcuries of 2-deoxy[14C]glucose was given following the last drug dose and autoradiographs of serial brain sections were made and analyzed by a densitometer. Following a single dose of either MISO or DMM, no significant differences in glucose uptake were observed when compared with controls. However, following 4, 7, and 14 doses the rate of glucose utilization was significantly reduced in the intoxicated animals. Larger reductions were measured in specific regions including the posterior colliculus, cochlear nuclei, vestibular nuclei, and pons with increasing effects observed at later stages. These results share a degree of correspondence with the regional brain pathology produced by these nitroimidazoles.

Animals↗
PubMed1983

Behavioural and ultrastructural studies of desmethylmisonidazole-induced neurotoxicity in mice.

The hypoxic cell radiosensitiser desmethylmisonidazole (DMM, Ro-05-9963) was administered orally to C3Hf female mice at three different dose levels (1.4, 1.6 and 1.8 mg g-1 day-1). Behavioural and morphological end-points were used to evaluate the neurotoxicity of this compound at these doses. The behavioural changes present at all three dose levels appeared when the total dose approached approximately 19 mg g-1. The behavioural changes initially appeared and developed to a severe state rapidly (24 to 48 h). A pattern of haemorrhagic necrosis was observed in the brain stem and cerebellum, but no pathology was observed in the cerebrum. Peripheral nerve degeneration was also evident and appeared concurrent with the central pathology. DMM appears to affect both the central and peripheral nervous systems at the same time at these dose levels. This is in some degree different from previous experience with misonidazole where peripheral damage distinctly precedes central effects. The development of the disorder appeared to be more rapid and severe when compared with earlier experience with misonidazole.

Animals↗
PubMed1982

Haemolytic anaemia in rhesus monkeys induced by methylcellulose.

The rhesus monkey was evaluated in its haemopoietic and histological response to intraperitoneal injections of methylcellulose. The haematologic alterations included a mild haemolytic anaemia, lymphopaenia, monocytosis, a shortened survival of Cr51 -labelled autologous erythrocytes (17 . 1 vs 13 . 3 days, P less than 0.025) and normoblastic hyperplasia of the bone marrow. There was a diffuse sequestration of the polymer in the phagocytic cells of the spleen, liver, bone marrow, lymph nodes and adrenal glands. The renal glomerular endothelium also consistently stored this material. Overt splenomegaly was not induced. The monkey appears to present, along with other animals, a rather species-specific response to methylcellulose that is accompanied by fundamental responses observable in all subjects.

Anemia, Hemolytic↗
PubMed1982

Heat shock proteins and biological response to hyperthermia.

Thermotolerance is of significant interest because the resistance of pre-heated cells greatly surpasses the resistance of control cells. The induction of protein synthesis following a temperature shock (12 min, 45 degrees C) which produces thermotolerance is examined using SDS polyacrylamide gel electrophoresis. It was observed that the synthetic rates of certain proteins following heat shock significantly exceeded their synthetic rates in control (non-heat shocked) cells. The most strongly induced bands were observed at 68,000, 89,000 and 110,000 daltons. The induction of these proteins was blocked by inhibitors of transcription (actinomycin D) or translation (cycloheximide). This phenomenon strongly resembles the heat shock induction of gene transcription well studied in Drosophila melanogaster. The strong induction of gene transcription well studied in Drosophila melanogaster. The strong correlation between the kinetics of the induction of these heat shock proteins and the kinetics of thermotolerance induction is discussed.

Animals↗
PubMedDate not supplied

Nitroimidazole inhibition of lactate production in CHO cells.

Misonidazole (MISO) and desmethylmisonidazole (DMM) inhibit lactate production in CHO cells under aerobic conditions. This inhibition is time and dose dependent. At the 20 mM level DMM is stronger in producing this inhibition of lactate than is MISO. This inhibiton of lactate production suggests that these compounds are capable of inhibiting the glycolytic pathway. The resultant energy deficiency may be an explantation for the toxicity of these compounds under hypoxic as well as aerobic conditions. The increased dependency on glycolysis of hypoxic cells may correspond to the analogous increase in toxicity of hypoxic cells to nitroimidazoles.

Animals↗