IGFs stimulate zebrafish cell proliferation by activating MAP kinase and PI3-kinase-signaling pathways

Insulin-like growth factor (IGF)-I and -II have been cloned from a number of teleost species, but their cellular actions in fish are poorly defined. In this study, we show that both IGF-I and -II stimulated zebrafish embryonic cell proliferation and DNA synthesis in a concentration-dependent manner, whereas insulin had little mitogenic activity. Affinity cross-linking and immunoblotting studies revealed the presence of IGF receptors with the characteristics of the mammalian type I IGF receptor. Competitive binding assay results indicated that the binding affinities of the zebrafish IGF-I receptors to IGF-I, IGF-II, and insulin are 1.9, 2.6, and >190 nM, indicating that IGF-I and -II bind to the IGF-I receptor(s) with approximately equal high affinity. To further investigate the cellular mechanism of IGF actions, we have studied the effects of IGFs on two major signal transduction pathways: mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3 kinase). IGFs activated MAPK in zebrafish embryonic cells in a dose-dependent manner. This activation occurred within 5 min of IGF-I stimulation and disappeared after 1 h. IGF-I also caused a concentration-dependent activation of protein kinase B, a downstream target of PI3 kinase, this activation being sustained for several hours. Inhibition of MAPK activation by the MAPK kinase inhibitor PD-98059 inhibited the IGF-I-stimulated DNA synthesis. Similarly, use of the PI3 kinase inhibitor LY-294002 also inhibited IGF-I-stimulated DNA synthesis. When both the MAPK and PI3 kinase pathways were inhibited using a combination of these compounds, the IGF-I-stimulated DNA synthesis was completely negated. These results indicate that both IGF-I and -II are potent mitogens for zebrafish embryonic cells and that activation of both the MAPK and PI3 kinase-signaling pathways is required for the mitogenic action of IGFs in zebrafish embryonic cells.

[Study on the working noise in BYPC and the effects caused by working noise on the workers' vestibular and auditory function]

OBJECTIVE

In order to observe the kinds and intensity of the working noise of Yansan Petrochemical Co. and the effects caused by the working noise on the workers' vestibular and auditory function.

METHOD

The intensity and frequency of the working noise were recorded by exactolnoisemeter in the workshop. One hundred and seventeen workers were tested in routine pure-tone tested method. The SPVN and ABR were tested within fifty-one workers of all.

RESULT

The working noise of Yansan Petrochemical Co. belongs to the broad band and steady noise. The intensity of the working noise were during 85.7-104.0 dB(A) and the main frequency were during 1-8 kHz. About 59 percent workers who exposed to the working noise had hearing loss. The most hearing-loss were in the high frequency. The hearing-loss of speech frequency were slight. Workers who have more six years standing have obviously increased hearing-loss than the workers who have less five years standing. There were significant differences the ABR thresholds and wave-interval between the tested and controlled groups. The SPVN and CP were abnormal in more than 17.4 percent workers with hearing loss.

CONCLUSION

The working noise of Yansan Petrochemical Co. belongs to the broad band and steady noise. Working noise can lead to workers' hearing loss of certain degrees who exposed in the noise for a long time. Obvious correlation was not defined between the hearing-loss and the abnormal vestibular response group.

Chemoenzymatic synthesis of functionalized cyclohexylglycines and alpha-methylcyclohexylglycines via Kazmaier-Claisen rearrangement

The synthesis of homochiral functionalized cyclohexylglycines and alpha-methylcyclohexylglycines via chelated Kazmaier-Claisen rearrangement is described. These were shown to be potent scaffolds for the development of MMP inhibitors.

[Current status and distribution of deafness in the elderly in several cities in China]

OBJECTIVE

To survey the current status and distribution of deafness and its effect on daily life activities in the old population.

METHODS

Eight thousand two hundred and fifty-two elderly aged 60 years and above in the urban and rural areas of Beijing, Shanghai, Guangzhou, Chengdu, Xi'an and Shenyang were investigated, using a clustered random sampling methods.

RESULTS

Overall crude prevalence of deafness in the elderly was found to be 33.7%, but the self-reported crude prevalence was low, only 47.1% when shown by medical examination. Crude prevalence rates were increasing with ageing, with 21.6%, 30.0%, 35.6%, 42.6%, 55.5% and 61.6% respectively (P < 0.01) in the age groups of 60-, 65-, 70-, 75-, 80-, 85- years old. Rate of deafness was highest in Beijing (58.5%), among the in-house workers (48.9%) and the lowest in scientists, teacher and health workers (28.5%). Logistic regression analysis showed that the crude prevalence was related to ageing, profession and area (P respective < 0.01).

CONCLUSION

The prevalence of deafness was high in the elderly which increased with ageing with different areas, professions and the level of education. It was lower when self-reported than shown by medical examination. Prevention and treatment of deafness in the elderly should be strengthened.

Near-Infrared Spectrum of the A(2)Pi(i)-X(2)Sigma(+) (2,0) Band of CN Studied by Concentration Modulation Laser Spectroscopy

The rotational structure of (2,0) vibrational band of A(2)Pi(i)-X(2)Sigma(+) transition of CN has been studied by concentration-modulation laser spectroscopy using a Ti:sapphire laser. The CN radical was produced in the ac glow discharge of acetonitrile with helium as the carrier gas. All 12 branches including four new branches have been observed and measured with an absolute accuracy of 0.007 cm(-1) in the region 12 450-12 750 cm(-1). Analysis of the spectra has led to improved molecular parameters of the A(2)Pi(i) (v' = 2) state. Copyright 2001 Academic Press.

Changes of reliability and efficiency of micronucleus bioassay in Vicia faba after exposure to metal contamination for several generations

Mitotic root micronucleus (MCN) frequency in Vicia faba as a bioassay, is primarily based on the extent of the sentinel Vicia response in terms of cytogenetic damage quantitatively or qualitatively to indicate the presence of mutagenic contaminants. This paper describes an investigation designed to assess changes in MCN frequencies of Vicia faba from three generation plants obtained, respectively from a reference site (RS) and a metal-contaminated experimental field (EF) in the bioassay of mutagenic Cd(2+) and NaN(3). The background value, dose-response to Cd(2+) and to NaN(3) in three generation (F(1), F(2) and F(3)) plants of the EF and the initial (F(0)) plants were determined in terms of MCN frequencies. With more generations of growing Vicia plants in the EF, a higher background value of MCN frequency, a lower slope value in the regression equation, a smaller ratio of MCN frequency between the control and treatment in the same generation and larger perturbation values were observed. This denotes that the decreased reliability and efficiency are represented in Vicia plants from the EF if the plants are used as sentinels in the bioassay of mutagenic Cd(2+) and NaN(3). It was concluded that the Vicia MCN bioassay should be used as an endpoint biomarker acceptable in biomonitoring environmental mutagens when the sentinel plants were collected from clean areas. Because no place is absolutely without pollutants, it is suggested that several seed stock centers should be established for providing sentinel Vicia if Vicia MCN bioassay is used as a biomarker to identify the global environmental status.

[Prevalence of prostatic hyperplasia and its relative factors in six cities of China in 1997]

OBJECTIVE

To study crude prevalence and distribution of the elderly prostatic hyperplasia.

METHODS

Three thousand three hundred and sixty-one elderly aged 60 years and above in the urban and rural areas of Beijing, Shanghai, Guangzhou, Chengdu, Xi'an and Shenyang were investigated, using clustered random sampling methods.

RESULTS

The crude prevalence of prostatic hyperplasia was found to be 43.68% with an increase with ageing (P < 0.01). The crude prevalence rates of prostatic hyperplasia among the elderly of 60-, 65-, 70-, 75-, 80-, 85- years old were 34.48%, 40.27%, 46.77%, 51.44%, 57.32% and 60.19% respectively (P < 0.01). Rates in the urban and rural areas were 46.79%and 39.64% respectively. The crude prevalence of urban areas was higher than that of rural areas (P < 0.01) and was found higher in Beijing (63.28%) and Guangzhou (54.28%), (P < 0.01). The crude rates prevalence of managers (54.88%), teachers and business men (55.17%) were in general higher than the prevalence of the workers (41.29%) and peasant (37.26%). Logistic regression analysis showed that the crude prevalence was related to ageing, profession and residential areas (P respective < 0.01).

CONCLUSION

The prevalence of prostatic hyperplasia was higher in the elderly and became a common disease of the male elderly in China. Prevention and treatment of prostatic hyperplasia in the elderly should be strengthened.

[Endovascular embolization treatment of intracranial aneurysms]

OBJECTIVE

To evaluate the effect of endovascular embolization of intracranial aneurysms with detachable coil and detachable balloon and emphasize the mainpoint of embolic technique.

METHODS

194 patients underwent complete cerebral angiography using microcatheter under DSA imaging. 80 cases with 90 aneurysms were emboliced by MDS, 69 cases with 71 aneurysms were emboliced by GDC. 37 of 40 giant aneurysms were emboliced by detachable balloon, 2 aneurysms by GDC, 1 by MDS.

RESULTS

194 patients with 201 aneurysms were cured successfully; 191 cases recovered clinically, 3 patients died. 187 aneurysms achieved 100% embolization, 8 with 95% embolization, 4 with 90% embolization, and 1 with 80% embolization. Four aneurysms reputured during the embolization, 4 patients had cerebral infarction, one patient died by hard-treated cerebral vasospasm which was affected by microcoil escape. Two recurrent cases were cured by second GDC embolization.

CONCLUSIONS

The method of endovascular embolization to treat intracranial aneurysm is safe, reliable and effective. Those cases with giant aneurysms will have high recurrence in the future. Patients who suffer from SAH repeatedly may have great possibility of aneurysm rupture during embolization.

[Root excretion and plant resistance to metal toxicity]

Reducing the availability and toxicity of metal pollutants before they enter plant body is one of the main mechanisms of plant resistance to metals. Root system is the first entrance of metal pollutants from soil into plant. It can excrete organic acids, amino acids, sugars, growth substances etc. into rhizosphere. Root excretion affects the metal absorption by plant through changing the physical and chemical characters(such as pH, Eh) of rhizosphere. The metal pollutants are detained outside the roots by chelation, complexation and disposition with root exudates. The quantity and activity of metals in rhizosphere are changed by root exudates through changing the composition, activity and excretion of microbes there. After reviewing the research advances on root excretion and plant resistance to metals, the authors pointed out the existing problems and the major topics and significance of further research.

Phosphatidylinositol 3-kinase is required for insulin-like growth factor-I-induced vascular smooth muscle cell proliferation and migration

Insulin-like growth factor-I (IGF-I) plays an important role in regulating vascular smooth muscle cell (VSMC) proliferation and directed migration. The mitogenic and chemotactic actions of IGF-I are mediated through the IGF-I receptor, but how the activation of the IGF-I receptor leads to these biological responses is poorly understood. In this study, we examined the role of phosphatidylinositol 3-kinase (PI3 kinase) in mediating the mitogenic and chemotactic signals of IGF-I. IGF-I treatment resulted in a significant increase in phosphotyrosine-associated PI3 kinase activity in cultured primary VSMCs. To determine whether insulin receptor substrate (IRS)-1, -2, or both are involved in IGF-I signaling in VSMCs, cell lysates were immunoprecipitated with either an anti-IRS-1 or an anti-IRS-2 antibody, and the associated PI3 kinase activity was determined. IGF-I stimulation resulted in a significant increase in IRS-1- but not IRS-2-associated PI3 kinase activity, suggesting that IGF-I primarily utilizes IRS-1 to transmit its signal in VSMCs. The IGF-I-induced increase in IRS-I-associated PI3 kinase activity was concentration dependent. At the maximum concentration (50 ng/mL), IGF-I induced a 60-fold increase. This activation occurred within 5 minutes and was sustained at high levels for at least 6 hours. IGF-I also caused a concentration-dependent and long-lasting activation of protein kinase B (PKB/Akt). Inhibition of PI3 kinase activation by LY294002 or wortmannin abolished IGF-I-stimulated VSMC proliferation and reduced IGF-I-directed VSMC migration by approximately 60%. These results indicate that activation of PI3 kinase is required for both IGF-I-induced VSMC proliferation and migration.

Purification, characterization, and bioassay of prolactin and growth hormone from temperate basses, genus Morone

Prolactin (PRL) and two variants of growth hormone (GH), purified from pituitaries of striped bass (Morone saxatilis) and its hybrid with white bass (M. saxatilis x M. chrysops) by gel filtration chromatography under alkaline conditions followed by reversed-phase high pressure liquid chromatography, appear similar between species. Both the minor (GH I) and the major (GH II) forms of purified GH appeared as single bands (M(r) approximately 23,000) after sodium dodecyl sulfate-polyacrylamide gel electrophoresis, as did the purified PRL (M(r) approximately 24,000). The molecular weights of GH II and PRL determined by MALDI TOF mass spectroscopy were 21.2 and 21.3 kDa, respectively. In Western blotting experiments, an antiserum against tilapia (Oreochromis mossambicus) 24K PRL specifically recognized Morone PRL, while an antiserum against tilapia GH specifically recognized Morone GH I and II. Chemical identities of the putative PRL and GH I were further confirmed by N-terminal peptide sequencing, while internal sequence analysis was performed on GH II because it was blocked at its N-terminus. Over a stretch of 29 amino acids, Morone PRL was found to be 76% identical to tilapia 24K PRL, 72% identical to tilapia 20K PRL, 72% identical to chum salmon (Oncorhynchus keta) PRL I, and 69% identical to eel (Anguilla japonica) PRL I. Alignment of the hybrid striped bass GH sequences with those of several other advanced marine teleosts indicated 75-85% sequence identity for GH I (40 amino acids) and 95-98% identity for GH II (45 amino acids). Biological activity of striped bass GH II was confirmed using a heterologous in vitro assay of insulin-like growth factor I mRNA production by coho salmon (On. kisutch) hepatocytes. An in vivo bioassay, involving hypophysectomy of hybrid striped bass and treatment of the fish maintained in fresh water with homologous PRL, confirmed that the purified striped bass PRL was also bioactive.

Insulin-like growth factor (IGF)-I regulates IGF-binding protein-5 gene expression through the phosphatidylinositol 3-kinase, protein kinase B/Akt, and p70 S6 kinase signaling pathway

Expression of the insulin-like growth factor-binding protein 5 (IGFBP-5) gene in vascular smooth muscle cells is up-regulated by IGF-I through an IGF-I receptor-mediated mechanism. In this study, we studied the possible involvement of the mitogen-activated protein kinase (MAPK) and PI 3-kinase signaling pathways in mediating IGF-I-regulated IGFBP-5 gene expression. The addition of Des(1-3)IGF-I, an IGF analog with reduced affinity to IGFBPs, resulted in a transient activation of p44 and p42 MAPK. Inhibition of the MAPK activation by PD98059, however, did not affect IGF-I-stimulated IGFBP-5 expression. Des(1-3)IGF-I treatment also strongly activated PI 3-kinase. This activation was probably mediated through IRS-1, because IGF-I stimulation resulted in a significant increase in IRS-1- but not IRS-2-associated PI 3-kinase activity. This activation occurred within 5 min and was sustained at high levels for over 6 h. Likewise, Des(1-3)IGF-I caused a long lasting activation of PKB/Akt and p70(s6k). When LY294002 and wortmannin, two specific inhibitors of PI 3-kinase, were added with Des(1-3)IGF-I, the IGF-I-regulated IGFBP-5 expression was negated. The addition of rapamycin, which inhibits IGF-I-induced p70(s6k) activation, significantly inhibited IGF-I-regulated IGFBP-5 gene expression. These results suggest that the action of IGF-I on IGFBP-5 gene expression requires the activation of the PI 3-kinase-PKB/Akt-p70(s6k) pathway but not the MAPK pathway in vascular smooth muscle cells.

Insulin-like growth factor binding protein 2 is a growth inhibitory protein conserved in zebrafish

Fish serum contains several specific binding proteins for insulin-like growth factors (IGFBPs). The structure and physiological function of these fish IGFBPs are unknown. Here we report the complete primary sequence of a zebrafish IGFBP deduced from cDNA clones isolated by library screening and rapid amplification of cDNA ends. The full-length 1,757-bp cDNA encodes a protein of 276 aa, which contains a putative 22-residue signal peptide and a 254-residue mature protein. The mature zebrafish IGFBP has a predicted molecular size of 28,440 Da and shows high sequence identity with human IGFBP-2 (52%). The sequence identities with other human IGFBPs are <37%. Chinese hamster ovary cells stably transfected with the zebrafish IGFBP-2 cDNA secreted a 31-kDa protein, which bound to IGF-I and IGF-II with high affinity, but did not bind to Des(1-3)IGF-I or insulin. Northern blot analyses revealed that the zebrafish IGFBP-2 transcript is a 1.8-kb band expressed in many embryonic and adult tissues. In adult zebrafish, IGFBP-2 mRNA levels were greatly reduced by growth hormone treatment but increased by prolonged fasting. When overexpressed or added to cultured zebrafish and mammalian cells, the zebrafish IGFBP-2 significantly inhibited IGF-I-stimulated cell proliferation and DNA synthesis. These results indicate that zebrafish IGFBP-2 is a negative growth regulator acting downstream in the growth hormone-IGF-I axis.

Regulation of lysyl oxidase, collagen, and connective tissue growth factor by TGF-beta1 and detection in human gingiva

Gingival overgrowth is characterized by excess extracellular matrix accumulation and elevated levels of cytokines, including transforming growth factor-beta1 (TGF-beta1). The functional relationships between altered cytokine levels and extracellular matrix accumulation have not been extensively investigated in gingival cells and tissues. Lysyl oxidase catalyzes the final known enzymatic step required for cross-linking collagen and elastin in the synthesis of a functional extracellular matrix. This study investigated the regulation by TGF-beta1 of lysyl oxidase and its collagen and elastin substrates in early passage human gingival fibroblasts. In addition, TGF-beta1 regulation of connective tissue growth factor (CTGF) was assessed in human gingival cells and tissues. The results show that TGF-beta1 increases lysyl oxidase enzyme activity and mRNA levels for lysyl oxidase and alpha-1-type I collagen, but not elastin, in a dose- and time-dependent manner. Maximal stimulation of lysyl oxidase activity and mRNA levels for both lysyl oxidase and collagen occurs after 48 hours of treatment of gingival fibroblastic cells with 400 pM of TGF-beta1. This study shows for the first time that CTGF mRNA and protein are strongly and rapidly induced by TGF-beta1 in human gingival fibroblasts. Exogenous addition of 1 to 50 ng/ml CTGF to gingival fibroblasts stimulates production of lysyl oxidase enzyme activity up to 1.5-fold after 48 hours, and 50 ng/ml CTGF stimulated insoluble collagen accumulation 1.5- to 2.0-fold after 4, 11, and 18 days of treatment. It is interesting to note that the addition of CTGF-blocking antibodies in the presence of TGF-beta did not block TGF-beta stimulation of collagen mRNA levels. Thus, although CTGF itself contributes to increased insoluble collagenous extracellular matrix accumulation, CTGF does not mediate all of the effects of TGF-beta1 on stimulation of collagen mRNA levels in human gingival fibroblasts. Immunohistochemistry studies of gingival overgrowth tissue samples indicate for the first time detectable levels of CTGF protein in Dilantin-induced hyperplasia tissues also positive for TGF-beta1. CTGF was not found in TGF-beta1-negative samples. In addition, extracellular lysyl oxidase protein was detected in vivo. Taken together, these studies support mostly independent roles for TGF-beta1 and CTGF in stimulating collagenous extracellular matrix accumulation in human gingival fibroblasts and tissues.

Down-regulation of protein kinase C inhibits insulin-like growth factor I-induced vascular smooth muscle cell proliferation, migration, and gene expression

Insulin-like growth factor-I (IGF-I) plays an important role in regulating vascular smooth muscle cell (VSMC) proliferation, directed migration, differentiation, and apoptosis. The signaling mechanisms used by IGF-I to elicit these actions, however, are not well defined. In this study, we examined the role(s) of protein kinase C (PKC) in mediating the IGF-I actions in cultured porcine VSMCs. Out of the eleven known members of PKC family, PKC-alpha, -betaI, -epsilon, -eta, -lambda, -theta, and -zeta, were detectable by Western immunoblot analysis in these cells. Further analysis indicated that the subcellular distribution of several PKC isoforms is regulated by IGF-I. While IGF-I stimulated membrane translocation of PKC-eta, -epsilon, and -zeta and regulated the cytosolic levels of PKC-betaI, it had no such effect on PKC-alpha and -lambda. To examine whether PKC activation is required for the IGF-I-regulated biological responses, phorbol myristate acetate (PMA) and GF109203X were used to down-regulate or inhibit PKC activity. Both PMA (1 microM) and GF109203X (20 microM) nearly completely suppressed the total PKC activity after a 30-min incubation (> 90%), and this inhibition lasted for at least 24 h. Down-regulation or inhibition of PKC activity abolished the IGF-I-induced DNA synthesis, migration and IGFBP-5 gene expression. In contrast, the IGFBP-5 expression induced by forskolin was unaffected by PKC down-regulation or inhibition, suggesting that PKC activation is required for the IGF-regulated but not the cAMP-regulated events. Because the actions of IGF-I on DNA synthesis and IGFBP-5 gene expression in VSMCs have been shown to be mediated through the phosphatidylinositol 3-kinase (PI3 kinase) signaling pathway in porcine VSMCs, the potential role of PKC in IGF-I-induced activation of PI3 kinase and PKB/Akt were examined. Treatment with either PMA or GF109203X did not significantly affect the effects of IGF-I on PI3 kinase activation or PKB/Akt phosphorylation. These results indicated that PKC-betaI, -eta, -epsilon, and -zeta may play an essential role(s) in IGF-I regulation of VSMC migration, DNA synthesis and gene expression, and that these PKC isoforms may either act independently of the PI3 kinase pathway or act further downstream of PKB/Akt in the IGF signaling network.

Changes in phospholipids and free fatty acids in the brains of mice preconditioned by hypoxia

Changes in the composition and contents of phospholipids and free fatty acids were observed and compared in three groups: (A) unpreconditoned normal controls, (B) exposure to 1 run of hypoxia and (C) exposure to 4 runs of hypoxia. In group B, the content of phosphatidyl ethanolamine (PE), phosphatidyl serine (PS) and free fatty acids (FFAs) increased significantly and the content of phosphatidyl choline (PC) and sphingomyelin (SM) decreased significantly. While in group C the content of PE, PS, PC and FFAs changed significantly when compared with that of group B, all phospholipid (except SM) and FFA contents tended to decrease to the level of group A. No new FFA was seen in the brain homogenates in any of the three groups. These results suggest that the changes in the content of mouse brain phospholipids and FFAs may be adaptive and involved in the animals' tolerance to hypoxia.

Changes of superoxide dismutase, glutathione perioxidase and lipid peroxides in the brain of mice preconditioned by hypoxia

We have developed an animal model of hypoxic preconditioning and assumed that oxygen radicals and their endogenous scavenging enzymes may play an important role in the preconditioning. To test this hypothesis, activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and the content of lipid peroxides (LPO) were measured during the preconditioning. Compared with unpreconditioned control animals, in animals exposed to hypoxia only once, the activities of SOD and GSH-Px in whole brain were found to be significantly decreased while the LPO content in the hippocampus significantly increased. However, those in animals exposed to 4 runs of hypoxia tended to return to control levels and were lower than those in animals exposed to 1 and 2 runs of hypoxia. Our results indicate that the oxygen radicals and their specific scavenging enzymes seem to be involved in the development of tolerance to hypoxia.

Intermittent stimulation enhances function of conditioned muscle

Skeletal muscle is highly adaptable in that its metabolic and contractile characteristics are largely regulated by its pattern of use. It is known that muscle phenotype can be manipulated via chronic electrical stimulation to enhance fatigue resistance at the expense of contractile power. Type 2A fibers are fatigue resistant, powerful, and considered most desirable for cardiac assist purposes. We have found that 12-wk of intermittent-burst stimulation produces a high percentage of 2A fibers and increases fatigue resistance and power in rabbit latissimus dorsi muscle. Fixed-load endurance tests were used to quantify fatigue resistance among normal and trained muscle groups. Control muscles were found to fatigue completely within 10-20 min. Muscles stimulated continuously for 6 wk retained 35% (71.5 +/- 19.5 g. cm) of their initial stroke work at 40 min. Muscles stimulated 12 h/day for 12 wk had the highest initial stroke work (449.7 +/- 92.4 g. cm) and the highest remaining stroke work (234.7 +/- 50.1 g. cm) at 40 min. Results suggest that employing regular resting periods during conditioning preserves strength in fatigue-resistant muscle.

Antigen changes of monoclonal antibody MSH27 in process of post-testicular maturation (in mice)

An anti-mouse spermatozoon monoclonal antibody, MSH27, as well as its purified antigen, can block sperm-egg membrane fusion. As a candidate protein for sperm-egg membrane fusion, the sperm antigen was investigated in the process of post-testicular maturation (PTM). The molecule was produced in testes and located on the plasma membrane of the postacrosomal area of the spermatozoon. However, the epitope recognized by the MSH27 (MSH27Ep) was not exposed until the occurrence of the acrosome reaction. In the process of fertilization, spermatozoa must complete the acrosome reaction before penetrating across the zona pellucidas (ZPs) to approach the plasma membrane of eggs. The effects of the acrosome reaction and penetration of the ZP on the exposure of the MSH27Ep were also studied. It was shown that the percentage of the spermatozoa with the MSH27Ep exposed increased followed with their mature status in PTM. In fact, it had a linear correlativity with the rate of the acrosome reaction. After spermatozoa had passed ZPs, almost all of them became the MSH27-positive in immuno-staining compared with only a part of the spermatozoa after the acrosome reaction. In a word, the exposure of MSH27Ep was coincident with attaining the ability to penetrate the plasma membrane of eggs.

Immunolocation of antisperm monoclonal antibody 6B10 and corresponding antigen

An antisperm monoclonal antibody 6B10 was produced by hybridoma technique of the isotype IgG. The monoclonal antibody was purified by means of ammonium sulfate precipitation and protein A-Sepharose C1-4B affinity chromatography. SDS polyacrylamide gel electrophoresis was used to evaluate the purity of the antibody. Evaluation of the sperm acrosomal status was determined by chlortetracycline (CTC) staining. It was found that monoclonal antibody 6B10 can inhibit the sperm acrosome reaction induced by progesterone. The corresponding antigen recognized by monoclonal antibody 6B10 was located on the plasma membrane of the sperm acrosome by indirect immunofluorescent microscopy and immunoelectronmicroscopy. Sperm protein was extracted by 1% Triton X-100. The molecular weight of the antigen is 50 ku, detected by Western blot. The antigen is a key protein in the sperm acrosome reaction and may be the receptor of progesterone on the sperm acrosome. It may either be developed as a candidate contraceptive vaccine or be used as a tool in pest/rodent management.

[Neoplasm-inhibiting effect and sensitivity-promoting effect of indomethacin in vitro]

OBJECTIVE

To explore an anti-tumor effect of indomethacin on human colon adenocarcinoma cell line HCT116, and its mechanism.

METHODS

MTT, agarose gel electrophoresis, TdT and flow cytometry were used to study cell proliferation and apoptosis.

RESULTS

Indomethacin significantly inhibited the proliferation of HCT116 cells and induced apoptosis with a "dose-time" dependent pattern. A synergic effect of inhibiting cancer cells proliferation was observed when combined with 5-Fu.

CONCLUSION

Inhibition of proliferation and induction of apoptosis contribute to the mechanisms for anti-tumor activity of indomethacin.

[Effect of EBV-LMP and EGF autocrine on proliferation of nasopharyngeal carcinoma cell line CNE and their relationship in action]

EBV-LMP gene transfection, radioimmuno-binding assay (RIA) and colorimetric cell viability assay (MTT) were used to investigate the effect and relationship of EBV-LMP and EGF autocrine on the growth and proliferation of well differentiated nasopharyngeal carcinoma cell line (CNE1). Autocrine EGF was detected in the supernant of CNE1 cells and CNE1 cells could grow in serum-free medium, implicating that the cell proliferation-promoting effect of EGF autocrine was present in the CNE1 cell line. Nevertheless the positive signals of LMP gene polymerase chain reaction and LMP Mab immunohistochemical staining in pCMV alpha-LMP DNA transfected cells, confirmed the successful transfection of LMP gene. EGF autocrine amount and the proliferation of CNE1 cells in serum-free medium were more obvious in post-transfected cells than those in untransfected cells. The present study represents the first report on promotion of EGF autocrine in EBV-LMP-transfected cells, thus promoting cell proliferation.

Rat hindlimb muscle blood flow during level and downhill locomotion

During eccentrically biased exercise (e.g., downhill locomotion), whole body oxygen consumption and blood lactate concentrations are lower than during level locomotion. These general systemic measurements indicate that muscle metabolism is lower during downhill exercise. This study was designed to test the hypothesis that hindlimb muscle blood flow is correspondingly lower during downhill vs. level exercise. Muscle blood flow (determined by using radioactive microspheres) was measured in rats after 15 min of treadmill exercise at 15 m/min on the level (L, 0 degrees) or downhill (D, -17 degrees). Blood flow to ankle extensor muscles was either lower (e.g., white gastrocnemius muscle: D, 9 +/- 2; L, 15 +/- 1 ml. min-1. 100 g-1) or not different (e.g., soleus muscle: D, 250 +/- 35; L, 230 +/- 21 ml. min-1. 100 g-1) in downhill vs. level exercise. In contrast, blood flow to ankle flexor muscles was higher (e.g., extensor digitorum longus muscle: D, 53 +/- 5; L, 31 +/- 6 ml. min-1. 100 g-1) during downhill vs. level exercise. When individual extensor and flexor muscle flows were summed, total flow to the leg was lower during downhill exercise (D, 3.24 +/- 0.08; L, 3.47 +/- 0. 05 ml/min). These data indicate that muscle blood flow and metabolism are lower during eccentrically biased exercise but are not uniformly reduced in all active muscles; i.e., flows are equivalent in several ankle extensor muscles and higher in ankle flexor muscles.