Induction of a cytogenetic adaptive response by exposure of rabbits to very low dose-rate gamma-radiation.
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Adaptation, Physiological↗
Biomedical subjects
L Cai
Publications and source records attributed to L Cai.
Effect of cycloheximide on the adaptive response induced by low dose radiation.
Human lymphocytes pre-exposed to 10 mGy or 50 mGy of X-rays become less sensitive to subsequent large dose irradiation, exhibited lower rate of chromosome aberration than expected. This adaptive response could be inhibited by cycloheximide, a protein synthesis inhibitor for successive 2 h period ranging from 0.5h before to 4h after the low dose exposure, indicating that the adaptive response was directly related with the protein synthesis.
Adaptation, Physiological↗
Study on the mechanism of cytogenetic adaptive response induced by low dose radiation.
Pre-exposure of human lymphocytes to low dose radiation (D1) could induce a cytogenetic adaptive response expressed as a decrease of chromatid aberrations caused by subsequent large dose radiation (D2). There are two possible explanations for its mechanism, i.e., activation of enzymatic processes by D1 facilitating repair of chromosomal damage and induction of protective proteins by D1 reducing the number of chromosomal aberrations. The results here showed: (1) the cytogenetic adaptive response could be enhanced by hyperthermia (41 degrees C and 43 degrees C) and suppressed by hypothermia (4 degrees C); (2) hyperthermia (41 degrees C) alone could also induce the cytogenetic adaptive response; (3) the cytogenetic adaptive response could be inhibited by cycloheximide--an inhibitor of protein synthesis; (4) supernatant from cultured lymphocytes treated with D1 failed to show the protective effect. The results imply that the cytogenetic adaptive response is not only related to the activation of repair enzymes, but also to the induction of protective proteins.
Cells, Cultured↗
[A case-control study of stomach cancer in Changle, Fujian Province--by the risk state analysis].
In order to detect the risk factors of stomach cancer in Changle county, a case-control study was undertaken. The present paper reports on the results of risk-state analysis. It showed that taking mildewed and heavily salty food, having bad eating habits, family history of tumour, less consumption of fresh vegetables, meat and bean products were the risk factors of stomach cancer in this county.
Adenocarcinoma↗
[Cytogenetic adaptive response induced by low dose radiation].
Human and rabbit peripheral blood lymphocytes were irradiated in vitro with 1.5 Gy x-rays after exposure to 0.01 Gy of x-rays (dose rate: 0.01 Gy/min). The frequency of chromosome aberration in the cells pre-exposed to 0.01 Gy of x-rays at Go, G1, S and G2 phases of cell cycle respectively was markedly lower than that in the cells irradiated with 1.5 Gy alone (P less than 0.01). This adaptive response would last for 3 cell-cycles, beyond which the damage of the chromosome following the second large dose occurred with the same magnitude as that without a previous conditioning exposure. However, when the low dose was repeated after the third cell cycle the adaptive response could be revived. Meanwhile, it was found that the adaptive response could be also induced in vivo in the bone marrow cells and germ cells of mice by low dose irradiation. In addition, the effect of dose rate of the first irradiation on the induced adaptive response was also studied.
Adaptation, Physiological↗
Neutralization of enoxaparine-induced bleeding by protamine sulfate.
It has been suggested that protamine sulfate is a poor antidote for the bleeding side-effects of low molecular weight heparins (LMWHs) in vivo, since protamine sulfate does not completely neutralize the anti-factor Xa activity of LMWHs in vitro or ex vivo. Therefore, we performed experiments to compare directly the abilities of protamine sulfate to neutralize the anticoagulant activities of the LMWH, enoxaparine, and unfractionated heparin ex vivo, with its ability to neutralize the bleeding side-effects of both compounds in vivo. Bleeding was measured as the amount of blood lost from 5 cuts made in rabbits ears before and after treatment with enoxaparine or unfractionated heparin +/- protamine sulfate. Plasma anti-factor Xa and anti-thrombin activities ex vivo, were measured chromogenically. Doses of 400 and 1,500 anti-factor Xa U/kg of heparin and enoxaparine, respectively, were required to enhance blood loss to the same extent. Protamine sulfate completely neutralized blood loss induced by both compounds, but did not neutralize the anti-factor Xa nor antithrombin activities ex vivo. We conclude that protamine sulfate is an effective antidote for the bleeding side-effects of enoxaparine and unfractionated heparin, despite its inability to completely neutralize their anticoagulant activities.
Animals↗
Structural analysis of bovine pancreatic thread protein.
Pancreatic thread protein (PTP) forms double helical threads in the neutral pH range after purification, undergoing freely reversible, pH-dependent globule-fibril transformation. The purified bovine PTP consists on SDS gels of two carbohydrate-free polypeptide chains (Gross et al., 1985). Plasma desorption mass spectrometry and amino acid sequence analysis now confirm that bovine PTP contains two disulfide-bonded polypeptides, an A chain of 101 amino acid residues with a molecular weight of 11,073 and a B chain of 35 residues with a molecular weight of 3970. The intact protein exhibits a molecular weight of 15,036, agreeing greater than 99.9% with the molecular weight calculated from the sequence. The B chain sequence was determined by gas-phase Edman degradation of the intact polypeptide. The A chain sequence was determined from overlapping peptides generated by cleavage at lysyl, tryptophanyl, and aspartyl-prolyl residues. Based upon the bovine PTP cDNA structure, the two chains of the protein result from cleavage of a single polypeptide with removal of a dipeptide between the NH2-terminal A chain and COOH-terminal B chain. Comparison of bovine PTP with other proteins reveals significant structural relatedness with the single-chain homologues from human and rat pancreas and with the motif associated with Ca2(+)-dependent carbohydrate recognition domains. The physiological role of PTP has not yet been resolved. The protein is present in very high concentration in pancreatic secretion and it has been detected in brain lesions in Alzheimer's disease and Down syndrome and in regenerating rat pancreatic islets. The present results provide a firm protein base for ongoing molecular, physical-chemical, and structure-function studies of this unusual protein.
Amino Acid Sequence↗
Induction of cytogenetic adaptive response of somatic and germ cells in vivo and in vitro by low-dose X-irradiation.
The cytogenetic adaptive response induced by low-level radiation was studied using human and rabbit lymphocytes in vitro and bone marrow cells and germ cells in vivo. The inductive dose of X-rays was 10 mGy for the in vitro studies at a dose rate of 10 mGy/min, and 2, 10, 50, 75 and 100 mGy for the in vivo studies at a dose rate of 50 mGy/min. The challenging dose was 1.5 Gy X-rays for the in vitro experiments and 0.65 or 0.75 Gy for the in vivo experiments at a dose rate of 0.44 Gy/min. The results reported here, in addition to those that have appeared in the literature, show the following characteristics documented for the first time: (1) 10 mGy could induce the adaptive response in human as well as rabbit lymphocytes irradiated not only in G1, S and G2 phases, but also in the Go state; (2) although the induced adaptive response could only last three cell cycles, it could be revived when the inductive dose was repeated after the third cell cycle; (3) the adaptive response could be induced by low-dose X-rays in somatic cells, both in vitro (lymphocytes) and in vivo (bone marrow cells), and also in germ cells (spermatocytes); (4) the magnitude of the adaptive response induced by whole-body irradiation was found to be dose-dependent--the lower the inductive dose the more the reduction of the frequency of chromatid aberrations following the challenging dose.
Adaptation, Biological↗
[Mechanism of cytogenetic adaptive response induced by low dose radiation].
Cytogenetic observation on human lymphocytes indicated that pre-exposure of 10, 50 and 75 mGy X-rays could induced the adaptive response. Experimental results with different temperature treatment showed that the adaptive response induced by low dose radiation could be enhanced by 41 degrees C and 43 degrees C, but inhibited by 4 degrees C in addition the treatment by 41 degrees C for one hour could also cause the adaptive response as did low dose radiation. Results showed that adaptive response induced by low dose radiation (10 or 50 mGy X-rays) could be eliminated by the protein synthesis inhibitor, implying that the adaptive response is related with the metabolism of cells, especially with the production of certain protective proteins.
Adaptation, Physiological↗
Effect of low-dose radiation on repair of DNA and chromosome damage.
In this report results of studies on the effect of different doses of low LET (linear energy transfer) radiations on the unscheduled DNA synthesis (UDS) and DNA polymerase activity as well as the induction of adaptive response in bone marrow cells (BMC) by low dose radiation were presented. It was found that whole-body irradiation (WBI) with X-ray doses above 0.5 Gy caused a dose-dependent depression of both UD5 and DNA polymerase activity, while low dose radiation below 250 mGy could stimulate the DNA repair synthesis and the enzyme activity. WBI of mice with low doses of X-rays in the range of 2-100 mGy at a dose rate of 57.3 mGy per minute induced an adaptive response in the BMC expressed as a reduction of chromosome aberrations following a second exposure to a larger dose (0.65 mGy). It was demonstrated that the magnitude of the adaptive response seemed to be inversely related to the induction dose. The possibility of induction of adaptive response in GO phase of the cell cycle and the possibility of a second induction of the adaptive response were discussed.
Adaptation, Physiological↗
Studies on fermented corn flour food poisoning in rural areas of China. II. Isolation and identification of causal microorganisms.
Using potato dextrose agar medium, 40 strains of microorganisms were isolated from leftover fermented corn flour samples involved in outbreaks of food poisoning. All strains produced powerful toxins which caused the same intoxication to mice, dogs, and monkeys as the leftover food samples. On the basis of results obtained from the morphology of this bacteria and its colony, from biochemical tests, and from the G-C mole percentage in DNA, the bacteria was identified as Flavobacterium farinofermentans nov. sp. (Meng, Z. and Wang, D.).
Agglutination Tests↗
[PSD-007 luminescence in the diagnosis of exfoliative cells from malignant tumors].
This paper presents the first report in China on the use of luminescence method with hematoporphyrin derivative PSD-007 in the analysis of the exfoliative malignant cells. By this method, pleurorrhea and ascites from 226 suspicious patients were detected. The results showed that its positive rate was 42.23% higher than that of Wright's stain and its positive conformation rate to HE stain could reach as high as 90.2%. Especially, cancer cells could be distinguished from various kinds of non-cancer cells by an objective quantitative analysis of the cellular fluorescent intensity using microfluorophotometer. This new method, being simple, economical and highly specific, is used not only in the qualitative study of the exfoliative tumor cells, but also in the quantitative analysis.
Ascitic Fluid↗
Effects of lead exposure on long-term potentiation induced by 2-deoxy-D-glucose in area CA1 of rat hippocampus in vitro.
Chronic developmental lead exposure is known to be associated with cognitive dysfunction in children. Previous studies have demonstrated that chronic lead exposure could impair the induction and maintenance of long-term potentiation induced by high-frequency stimulation (HFS-LTP). In area CA1 of rat hippocampus, long-term potentiation could also be induced following temporary replacement of 10 mM 2-deoxy-D-glucose (2-DG) for 10 mM glucose in the normal perfusate (artificial cerebrospinal fluid). The present study was carried out to investigate whether chronic lead exposure affected long-term potentiation induced by 2-DG (2-DG-LTP). Neonatal Wistar rats were exposed to lead from parturition to weaning via milk of dams whose drinking water contained 0.2% lead acetate. Field excitatory postsynaptic potentials (EPSPs) in area CA1 of hippocampus were recorded on postnatal days 25-30. 2-DG application was followed by an increase in EPSP slopes in a time-course-dependent manner in both control and lead-exposed rats, while the amplitude of 2-DG-LTP in the lead-exposed rats (225.9+/-19.0%, n=12) was significantly greater than that in controls (155.2+/-9.8%, n=12). In contrast to the effects of lead exposure on 2-DG-LTP, the amplitude of HFS-LTP in the lead-exposed rats (121.5+/-13.7%, n=12) was significantly less than that in controls (183.9+/-18.6%, n=12). These results indicate that chronic lead exposure had opposite effects on the two types of LTP induced by HFS and 2-DG. This would suggest that the effects of lead on HFS-LTP and 2-DG-LTP are the result of different sites of lead toxicity.
Animals↗
Endometrial expression of mRNA encoding epidermal growth factor receptor in normal and leiomyomatous uteri throughout the menstrual cycle.
PROBLEM: To investigate the relationship between the histologic phase and the quantitative expression of epidermal growth factor receptor (EGFR) mRNA in the endometrium of normal and leiomyomatous uteri. METHODS: To test this relationship, endometrium was collected at hysterectomy from 38 women with a history of regular cycles. Total RNA (20 micrograms) was isolated and analyzed by Northern blot using a human EGFR-specific 32P labeled cDNA probe. The hybridization signals were quantified by densitometry, standardized, and reported in densitometry signal units. Separate portions of the same endometrial specimens were simultaneously prepared for histologic evaluation. The differences between menstrual phases were evaluated by Student's t-test. RESULTS: EGFR mRNA was expressed in all endometrial tissues tested. Levels were higher in the midproliferative phase than in all other phases for both myomatous and nonmyomatous uteri (P < .05). Myomatous uteri showed lower expression than nonmyomatous uteri in the early and late proliferative phase (P < .05). Age did not appear to alter endometrial EGFR mRNA expression. CONCLUSION: This data suggest that endometrial EGFR mRNA expression varies in association with the histologic changes of the normal menstrual cycle, and may be associated with the presence of leiomyomata uteri.
Adult↗
Endothelins and their receptors in cirrhotic and neoplastic livers of Canadian and Chinese populations.
BACKGROUND: Endothelins (ETs) are 21 amino acid peptides with widespread tissue distribution and functions. In this study, we retrospectively investigated immunoreactive ET-1, ET-3 as well as ET receptors by ligand binding and autoradiography in hepatic cirrhosis and neoplasms. MATERIALS AND METHODS: Formalin fixed paraffin embedded tissues from 30 hepatocellular carcinomas (HCC), 4 fibrolamellar carcinomas (FLC), and 7 liver metastatic adenocarcinomas (Ad) from colon were collected from the Pathology Department of London Health Science Centre. Adjacent cirrhotic livers were obtained from 17 cases and adjacent normal liver was present in 12 cases. In addition, 15 HCCs, 6 cirrhotic and 8 normal livers were obtained from Normal Bethune University for Medical Sciences in China. The slides were stained for ET-1 and ET-3 with a polyclonal antibody and scored. Autoradiographic localization of ET-receptors with 125I-ET-1 was carried out in some of the cases. RESULTS: In the normal liver, hepatocytes, biliary epithelium, vascular endothelium and smooth muscle cells were positive for both ET-1 and ET-3. Higher immnunoreactivity for ET-1 and ET-3 was seen in cirrhosis. HCCs showed variation in immunoreactivity, with overall scoring not different from normal livers. FLCs showed consistent higher immunoreactivity for both ET-1 and ET-3, while in Ads the immunoreactivity was decreased. Increased ET-receptors, representing both ETA and ETB subtypes were seen in both cirrhosis and in HCC. CONCLUSION: Alterations in both ETs and their receptors were found in cirrhosis and neoplastic liver diseases.
Adenocarcinoma↗
Improved metastatic animal model of human prostate carcinoma using surgical orthotopic implantation (SOI).
BACKGROUND: An animal model demonstrating high metastasis of human prostate carcinoma is of importance in studying the biology and therapy of human prostate carcinoma Dr. Hoffman's group recently used surgical orthotopic implantation (SOI) of human prostate cells to nude mice to establish an animal model with high metastatic activity. To confirm the animal model by SOI reproducible in other laboratories and shorten the period requiring for the metastasis, we adopted SOI technique with a modification using PC-3M human prostate cell line which showed a higher metastatic activity than PC-3. MATERIALS AND METHODS: Intact tissue of the human prostate carcinoma cell line PC-3M was prepared by growth of this cell subcutaneous in a nude mouse. One piece of 1.5 mm3 intact tumor tissue was implanted by orthotopical surgery to the ventral lateral lobes of the prostate gland of 10 nude mice. Mice were sacrificed when they were found to be moribund. Metastasis in other tissues was evaluated by gross and microscopic morphology. RESULTS: All 10 mice showed the tumorigenesis in the prostate gland and metastasis of human prostate tumor cells into periaortic lymph nodes without other organ's metastasis. The time when mice with PC-3M SOI start moribund is 28-32 days after SOI. CONCLUSIONS: SOI is good technique to establish the efficiently metastatic animal mode. SOI using PC-3M human prostate cell line will leads to 100% metastasis of prostate tumor cells. So far, this model is much quicker and more efficient than those reported in literatures.
Animals↗
Transforming growth factor-beta1 (TGF-beta1) in penile and prostate growth in the rat during sexual maturation.
The goal of this study was to determine whether transforming growth factor-beta1 (TGF-beta1) may contribute to the arrest of penile growth and the down-regulation of androgen receptors (AR) that occur during sexual maturation in the rat penis. For this purpose, body, penis, and prostate weights were obtained from male rats of increasing ages, and penis and prostate TGF-beta1 concentrations were determined by a sandwich enzyme-linked immunosorbent assay. The cytosol fraction was obtained from the shafts and glandes of immature (19-day-old) and adult (90-day-old) rat penises, and ARs were measured by a western blot assay. The effect of exogenous TGF-beta1 on penile growth was examined in vivo in two groups of immature rats (21 and 27 days old) implanted with miniosmotic pumps delivering either human TGF-beta1 or vehicle only directly into the corpora cavernosa for 6 days. The penises, prostates, and testes were weighed, and the AR content was estimated by western blot. The growth rate of the penis declined after 8 weeks of age, whereas the ventral prostate growth rate increased until 14 weeks of age and then slowed down. The content of penile AR protein decreased seven-fold in the adult rats compared to the immature animals. Penile TGF-beta1 concentration increased nearly three-fold from the 19-day-old rats to a peak at 60 days of age and then decreased over the next 4 months to the initial levels. In contrast, TGF-beta1 concentration in the prostate was not significantly affected by age and remained below the lowest penile values in all age groups. Transforming growth factor-beta1 given locally to the penis reduced penile shaft weight by 38 and 22% in two groups of immature rats, while the weights of the penile glans, testis, and ventral prostate remained unaffected. Androgen receptor content was higher in the glans than in the shaft and was not changed by TGF-beta1 treatment. These results suggest that the increase of TGF-beta1 levels in the penis may reinforce growth arrest caused by the down-regulation of penile ARs, whereas the maintenance of a high content of ARs and a low TGF-beta1 concentration may allow prostate growth to continue.
Aging↗
Metallothionein and apoptosis in primary human hepatocellular carcinoma (HCC) from northern China.
BACKGROUND: Metallothionein (MT), acting as an antioxidant and zinc binding protein, may play an important role in regulation of apoptosis. Its differential expression has been documented in various human tumours. MATERIALS AND METHODS: MT expression by immunohistochemical staining with a polyclonal antibody and apoptotic cells (APC) by TUNEL technique were investigated in 20 cases of hepatocellular carcinoma (HCC) and 2 normal livers from Northern China. Adjacent normal liver was available from 9 of these cases and 6 had adjacent cirrhotic tissue. There was no difference for MT staining and incidence of APC between normal liver and adjacent normal liver, and thus both were used as control liver. RESULTS: Control liver had consistent MT staining with very low incidence of APC. Adjacent cirrhotic liver showed the same intensity of MT staining, with a similar incidence of APC to control liver. Twelve of 20 HCC cases (60%) showed no MT staining, and the rest also showed a low grade of MT staining as compared with control or adjacent cirrhotic livers. The incidence of APC in HCC was markedly higher than that in control liver or adjacent cirrhotic liver. The negative correlation of numbers of APC with MT expression was statistically significant (p < 0.005). The high incidence of APC in liver with a low MT expression was confirmed in double staining for MT and APC. CONCLUSIONS: The present investigation from Northern Chinese samples has shown that MT expression in HCC was different from that in other human tumours, such as breast carcinoma. This suggests a different pattern of expression of MT protein in these two kinds of cancer. This investigation is important in understanding the mechanisms of the drug resistance of tumour cells, and may help to design better treatment strategies.
Adult↗