Induction of an adaptive response to dominant lethality and to chromosome damage of mouse germ cells by low dose radiation

In the present paper, dominant lethal mutations, chromosome aberrations in spermatocytes and reciprocal translocations in stem spermatogonia were analyzed after whole body exposure of mice to X-radiation. Results both from chromosome aberrations in spermatocytes and for reciprocal translocations in spermatogonia showed that pre-exposure to low doses up to 200 mGy could induce a significant dose-dependent reduction in adapted mice compared to the non-adapted mice; the lower the adaptive dose, the greater the reduction. For dominant lethal mutations, it was found that spermatogonia (both stem cells and differentiated cells) and spermatocytes adapted to 50 mGy X-rays could show an adaptive response, but spermatids and spermatozoa could not.

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.

A physiological role of peptide YY on exocrine pancreatic secretion in rats

BACKGROUND

Peptide YY (PYY) given intravenously was shown to inhibit pancreatic exocrine secretion both in the dog and the rat. However, a possible physiological role of PYY on the pancreatic secretion has not been clarified. The present study was undertaken to investigate its physiological role on the exocrine pancreas.

METHODS

In conscious rats, plasma PYY was determined in response to oral ingestion of a 6-mL meal and intravenous infusion of PYY; small intestinal transit time was measured by phenol red as a nonabsorbable marker, and pancreatic secretory studies were performed in rats with pancreatic fistulas and jugular vein catheters.

RESULTS

Oral ingestion of the meal (containing phenol red, 1.6 mg/100 mL) significantly increased plasma PYY within 30 minutes. During this period, most (97%) of the phenol red was detected in the proximal two-thirds of the small intestine. Intravenous infusion of PYY in 25, 50, and 100 pmol.kg-1 x h-1 produced a dose-dependent increase in plasma PYY. The dose of PYY that simulated the peak postprandial level was 50 pmol.kg-1 x h-1, and this dose of PYY significantly inhibited the pancreatic secretion stimulated by physiological doses of secretin and cholecystokinin-8 (CCK-8). After the meal, pancreatic secretion of bicarbonate and protein significantly increased in rats pretreated with normal rabbit serum, whereas this increase was significantly augmented in rats pretreated with an anti-PYY serum because the postprandial increase in plasma PYY was abolished.

CONCLUSIONS

PYY plays a regulatory role in the postprandial pancreatic exocrine secretion in rats.

Serological evidence of Coxiella burnetii infection in wild animals in Japan

One hundred and thirty-four (26%) of 511 sera from 11 wild animal species in eight prefectures in Japan had antibody titers to Coxiella burnetii by the enzyme-linked immunosorbent assay. High prevalences were observed in Japanese black bears (Ursus thibetanus) (78%), Hokkaido deer (Cervus nippon yesoensis) (69%), Japanese hares (Lepus brachyurus) (63%), Japanese deer (Cervus nippon centralis) (56%), and to some extent in Japanese monkeys (Macaca fuscata) (28%). A low prevalence (13%) was observed in nutrias (Myocastor coypus). Japanese serows (Capricornis crispus), wild rats (Muroides sp.), raccoon dogs (Nyctereutes procyonoides viverrinus), wild pigs (Sus scrofa leucomystax), and masked palm civets (Paguma larvata) had no detectable antibodies to C. burnetii. Thus, six of 11 wild animal species in Japan were exposed to C. burnetii. Based on the high prevalences in some species, they may be a potential source of infection to both domestic animal and human populations.

Prevention of thrombus growth by antithrombin III-dependent and two direct thrombin inhibitors in rabbits: implications for antithrombotic therapy

We compared the abilities of heparin and two direct thrombin inhibitors to prevent fibrin accretion onto pre-existing thrombi in rabbits. Inhibition of thrombus growth was measured as the ability of each test compound to inhibit the accretion of 125I-fibrin onto thrombi pre-formed in jugular veins of rabbits. When administered as a continuous infusion, the two direct (i.e. antithrombin III-independent) thrombin inhibitors, r-hirudin and a tripeptide, Ac(D)-Phe-Pro-bor-Arg (P-8714) inhibited fibrin accretion as effectively as heparin, but did so in doses which generated little systemic anticoagulation, as compared to the marked anticoagulation associated with the heparin effect. However, both r-hirudin and P-8714 were more effective when they were administered as a single bolus injection than as a continuous infusion. Under the former conditions, there was only a transient systemic anticoagulant effect. We conclude that direct or antithrombin III-independent thrombin inhibitors are more effective than heparin in preventing thrombus growth. The limited effect of heparin is likely due to fibrin impairing the ability of heparin/antithrombin III to inactivate thrombin.

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.

[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.

[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.

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.

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.

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.

[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.