Fibroblast growth factor receptor-1 (FGFR-1) is essential for normal neural tube and limb development

Fibroblast growth factor receptor-1 (FGFR-1) is a membrane-spanning tyrosine kinase that serves as a high-affinity receptor for fibroblast growth factors. It has recently been shown that FGFR-1 mutant embryos die during gastrulation displaying severe growth retardation and defective mesodermal structures. This early lethality has obscured functions of FGFR-1 that might occur later in development. To circumvent these embryonic defects, we generated chimeras by injecting FGFR-1-deficient (R1-/-) ES cells into wild-type blastocysts. We found that the fgfr-1 gene plays an important role after gastrulation and that it acts in a cell-autonomous fashion. Embryos with a high contribution of R1-/- cells replicate the FGFR-1 null phenotype and die during gastrulation. In contrast, the majority of embryos with a low contribution of R1-/- cells complete gastrulation and display malformations of posterior structures at later stages of embryogenesis. These abnormalities include truncation of embryonic structures, limb bud malformation, partial duplication of the neural tube, tail distortion, and spina bifida caused by the amplification of neural tissue in the posterior portion of the spinal cord. Thus, FGFR-1 plays a role in neurulation, suggesting that there may be a connection between FGFR-1-mediated signal pathways and neural tube defects, the most common malformations in the human central nervous system.

[The impact of different incisions on visual acuity and corneal refractivity in cataract surgery]

OBJECTIVE

To research the impact of different incisions of cataract surgery on post-operative visual acuity and corneal refractivity.

METHODS

The visual acuity and corneal refractivity in 243 eyes having undergone extracapsular cataract extraction and phacoemulsification with 5 mm tunnel incision or 7 mm frown-shaped incision were examined and compared at three post-operative periods.

RESULTS

The mean increase in corneal refractivity in phacoemulsification group was significantly less (P < 0.05) and the corrected visual acuity was much better (P < 0.05) than that in conventional extracapsular cataract extraction (ECCE) group at post-operative 1/2 month, 3 months and 6 months (P < 0.05). In the phacoemuisification group, the increase of the post-operative refractivity in 7 mm frown-shaped incision group was less than that in 5 mm tunnel incision group at 1/2 month and 3 months (P < 0.05).

CONCLUSION

7 mm frown-shaped incision of phacoemulsification is the most effective method to control the post-operative corneal astigmatism in cataract surgery.

The Saccharomyces cerevisiae kinesin-related motor Kar3p acts at preanaphase spindle poles to limit the number and length of cytoplasmic microtubules

The Saccharomyces cerevisiae kinesin-related motor Kar3p, though known to be required for karyogamy, plays a poorly defined, nonessential role during vegetative growth. We have found evidence suggesting that Kar3p functions to limit the number and length of cytoplasmic microtubules in a cell cycle-specific manner. Deletion of KAR3 leads to a dramatic increase in cytoplasmic microtubules, a phenotype which is most pronounced from START through the onset of anaphase but less so during late anaphase in synchronized cultures. We have immunolocalized HA-tagged Kar3p to the spindle pole body region, and fittingly, Kar3p was not detected by late anaphase. A microtubule depolymerizing activity may be the major vegetative role for Kar3p. Addition of the microtubule polymerization inhibitors nocodazol or benomyl to the medium or deletion of the nonessential alpha-tubulin TUB3 gene can mostly correct the abnormal microtubule arrays and other growth defects of kar3 mutants, suggesting that these phenotypes result from excessive microtubule polymerization. Microtubule depolymerization may also be the mechanism by which Kar3p acts in opposition to the anaphase B motors Cin8p and Kip1p. A preanaphase spindle collapse phenotype of cin8 kip1 mutants, previously shown to involve Kar3p, is markedly delayed when microtubule depolymerization is inhibited by the tub2-150 mutation. These results suggest that the Kar3p motor may act to regulate the length and number of microtubules in the preanaphase spindle.

Activation of Stat1 by mutant fibroblast growth-factor receptor in thanatophoric dysplasia type II dwarfism

The achondroplasia class of chondrodysplasias comprises the most common genetic forms of dwarfism in humans and includes achondroplasia, hypochondroplasia and thanatophoric dysplasia types I and II (TDI and TDII), which are caused by different mutations in a fibroblast growth-factor receptor FGFR3 (ref. 1). The molecular mechanism and the mediators of these FGFR3-related growth abnormalities are not known. Here we show that mutant TDII FGFR3 has a constitutive tyrosine kinase activity which can specifically activate the transcription factor Stat1 (for signal transducer and activator of transcription). Furthermore, expression of TDII FGFR3 induced nuclear translocation of Stat1, expression of the cell-cycle inhibitor p21(WAF1/CIP1), and growth arrest of the cell. Thus, TDII FGFR3 may use Stat1 as a mediator of growth retardation in bone development. Consistent with this, Stat1 activation and increased p21(WAF1/CIP1) expression was found in the cartilage cells from the TDII fetus, but not in those from the normal fetus. Thus, abnormal STAT activation and p21(WAF1/CIP1) expression by the TDII mutant receptor may be responsible for this FGFR3-related bone disease.

Effects of beta-adrenoceptor subtype stimulation on obese gene messenger ribonucleic acid and on leptin secretion in mouse brown adipocytes differentiated in culture

The ob gene product is known to control food intake and energy expenditure. To determine whether thermogenic agents directly control ob gene expression, the effects of beta-adrenoceptor agonists on the level of the ob gene messenger RNA (mRNA) and on leptin secretion have been studied in mouse brown adipocytes differentiated in culture. These cells highly expressed the beta 3-adrenoceptor, the uncoupling protein, and the ob gene mRNAs. The ob gene was expressed in mouse brown adipocytes earlier than in mouse white adipocytes under the same culture conditions and to a similar level. The beta 3-, beta L-, and beta 2-adrenoceptor agonists BRL 37344, dobutamine, and terbutaline inhibited ob gene expression in mouse brown adipocytes differentiated in culture with EC50 values of 0.3, 1.0, and 85 nM, respectively. Leptin secretion by the cells under basal conditions was 78 +/- 10 pg/microgram DNA-4 h and was decreased by exposure to the beta-adrenoceptor agonists. The ob gene mRNA half-life was 9.4 h and was decreased to 2.4 h by 1 nM BRL 37344, indicating that the inhibitory effect of the beta 3-agonist might be due to destabilization of ob gene mRNA. (Bu)2cAMP (10-100 microM) and forskolin (20 microM) mimicked the effect of the beta-adrenoceptor agonists. FFA (150-800 microM) had only a small inhibitory effect on ob gene mRNA expression. The results suggest the existence in brown adipose tissue of a retroregulatory pathway by which leptin production in inhibited when the sympathetic nervous system is stimulated.

IFN-alpha therapy is effective in suppressing the clinical experimental myasthenia gravis

To study the therapeutic efficacy of IFN-alpha after the onset of clinical signs of experimental autoimmune myasthenia gravis (EAMG), we treated mice with clinical EAMG with recombinant human IFN-alpha or mouse IFN-alpha. In the first experiment, 7 of 16 (44%) mice had a complete clinical remission in the recombinant human IFN-alpha-treated group, in contrast to none in the placebo group (0/14) (p = 0.006). There was a higher incidence of death and severe disease in the placebo group (7/14) relative to the IFN-alpha group (4/16). In the second experiment, 6 of 18 (33%) mice in the mouse IFN-alpha-treated group had a complete clinical remission, while none of 17 (0%) mice in the placebo-treated group had remission (p = 0.011). Again, more mice died or worsened in the placebo group (11/17) compared with the IFN-alpha group (7/18). IFN-alpha treatment significantly reduced the anti-acetylcholine receptor (AChR) Ab levels, especially the IgG1 and IgG2b isotypes, and the amount of anti-AChR Abs bound to muscle AChR. IFN-alpha treatment also lowered CD4 cells in the lymph nodes and spleen, and suppressed the in vitro lymphocyte proliferative response to AChR and its dominant peptide in a dose-dependent manner.

IFN-alpha therapy is effective in suppressing the clinical experimental myasthenia gravis

To study the therapeutic efficacy of IFN-alpha after the onset of clinical signs of experimental autoimmune myasthenia gravis (EAMG), we treated mice with clinical EAMG with recombinant human IFN-alpha or mouse IFN-alpha. In the first experiment, 7 of 16 (44%) mice had a complete clinical remission in the recombinant human IFN-alpha-treated group, in contrast to none in the placebo group (0/14) (p = 0.006). There was a higher incidence of death and severe disease in the placebo group (7/14) relative to the IFN-alpha group (4/16). In the second experiment, 6 of 18 (33%) mice in the mouse IFN-alpha-treated group had a complete clinical remission, while none of 17 (0%) mice in the placebo-treated group had remission (p = 0.011). Again, more mice died or worsened in the placebo group (11/17) compared with the IFN-alpha group (7/18). IFN-alpha treatment significantly reduced the anti-acetylcholine receptor (AChR) Ab levels, especially the IgG1 and IgG2b isotypes, and the amount of anti-AChR Abs bound to muscle AChR. IFN-alpha treatment also lowered CD4 cells in the lymph nodes and spleen, and suppressed the in vitro lymphocyte proliferative response to AChR and its dominant peptide in a dose-dependent manner.

Involvement of p21cip-1 and p27kip-1 in the molecular mechanisms of steel factor-induced proliferative synergy in vitro and of p21cip-1 in the maintenance of stem/progenitor cells in vivo

Steel factor (SLF) is a hematopoietic cytokine that synergizes with other growth factors to induce a greatly enhanced proliferative state of hematopoietic progenitor cells and factor-dependent cell lines. Even though the in vivo importance of SLF in the maintenance and responsiveness of stem and progenitor cells is well documented, the molecular mechanism involved in its synergistic effects are mainly unknown. Some factor-dependent myeloid cell lines respond to the synergistic proliferative effects of SLF plus other cytokines in a manner similar to that of normal myeloid progenitor cells from bone marrow and cord blood. We show here that SLF can synergize with granulocyte-macrophage colony-stimulating factor (GM-CSF) to induce an enhanced phosphorylation of the retinoblastoma gene product and a synergistic increase in the total intracellular protein level of the cyclin-dependent kinase inhibitor, p21cip-1, which is correlated with a simultaneous decrease in p27kip-1 in the human factor-dependent myeloid cell line, M07e. Moreover, these cytokines synergize to increase p21cip-1 binding and decrease p27kip-1 binding to cyclin-dependent kinase-2 (cdk2), an enzyme required for normal cell cycle progression; these inverse events correlated with increased cdk2 kinase activity. It is also shown that exogenous purified p21cip-1 can displace p27kip-1 already bound to cdk2 in vitro. These data implicate increased p21cip-1 and decreased p27kip-1 intracellular concentrations and their stoichiometric interplay in the enhanced proliferative status of cells stimulated by the combination of SLF and GM-CSF. In support of these findings, it is shown that hematopoietic progenitor cells from mice lacking p21cip-1 are defective in SLF synergistic proliferative response in vitro. Moreover, the cycling status of marrow and spleen progenitors and absolute numbers of marrow progenitors were significantly decreased in the p21cip-1 -/-, compared with the +/+ mice. We conclude that the cdk threshold regulators p21cip-1 and p27kip-1 play a critical role in the normal mitogenic response of M07e cells and murine myeloid progenitor cells to these cytokines and particularly in the SLF synergistic proliferative response that is important to the normal maintenance of the stem/progenitor cell compartment.

Mouse decay-accelerating factor: selective and tissue-specific induction by estrogen of the gene encoding the glycosylphosphatidylinositol-anchored form

Neonatal exposure of mice to estrogen (diethylstilbestrol) results in a high incidence (90%) of uterine tumor later in life. In an effort to screen for estrogen-regulated genes in the uterus of the neonatal mouse, we have isolated a murine homologue of the human decay-accelerating factor (DAF), a glycosylphosphatidylinositol (GPI)-anchored membrane glycoprotein and a member of the regulators of complement activation family of proteins that function to prevent autologous complement-mediated tissue damage. The induced mouse DAF cDNA has a 64% sequence identity with the human counterpart at the nucleotide level and a 50% identity in the deduced amino acid sequence. It consists of 390 amino acids and contains four short consensus repeats of internal homology characteristic of human DAF. It also contains a hydrophobic C-terminal that most likely serves as a signal for GPI anchor attachment. Sequence comparison with the recently reported mouse DAF cDNAs confirmed that the estrogen-inducible gene corresponds to the mouse GPI DAF gene. The induction of mouse DAF by estrogen is tissue specific and can be mimicked by the antiestrogen tamoxifen. Furthermore, the regulation of uterine DAF expression by estrogen is limited to the GPI DAF gene. The transmembrane DAF gene is not expressed in the mouse uterus, either with or without estrogen stimulation. These results suggest that the two mouse DAF genes are differentially regulated, and that the GPI-anchored DAF may play important roles in estrogen responses and other physiologic or pathophysiologic processes of the female reproductive system.

Mouse decay-accelerating factor: selective and tissue-specific induction by estrogen of the gene encoding the glycosylphosphatidylinositol-anchored form

Neonatal exposure of mice to estrogen (diethylstilbestrol) results in a high incidence (90%) of uterine tumor later in life. In an effort to screen for estrogen-regulated genes in the uterus of the neonatal mouse, we have isolated a murine homologue of the human decay-accelerating factor (DAF), a glycosylphosphatidylinositol (GPI)-anchored membrane glycoprotein and a member of the regulators of complement activation family of proteins that function to prevent autologous complement-mediated tissue damage. The induced mouse DAF cDNA has a 64% sequence identity with the human counterpart at the nucleotide level and a 50% identity in the deduced amino acid sequence. It consists of 390 amino acids and contains four short consensus repeats of internal homology characteristic of human DAF. It also contains a hydrophobic C-terminal that most likely serves as a signal for GPI anchor attachment. Sequence comparison with the recently reported mouse DAF cDNAs confirmed that the estrogen-inducible gene corresponds to the mouse GPI DAF gene. The induction of mouse DAF by estrogen is tissue specific and can be mimicked by the antiestrogen tamoxifen. Furthermore, the regulation of uterine DAF expression by estrogen is limited to the GPI DAF gene. The transmembrane DAF gene is not expressed in the mouse uterus, either with or without estrogen stimulation. These results suggest that the two mouse DAF genes are differentially regulated, and that the GPI-anchored DAF may play important roles in estrogen responses and other physiologic or pathophysiologic processes of the female reproductive system.

Respective degree of expression of beta 1-, beta 2- and beta 3-adrenoceptors in human brown and white adipose tissues

1. The possible existence of a beta 3-adrenoceptor in human brown and white adipose tissues was investigated by mRNA expression and binding studies. 2. The relative amounts of beta 1-, beta 2- and beta 3-adrenoceptor mRNA, as determined by total RNA Northern blot analysis in newborn brown adipose tissue, were 28, 63 and 9% respectively of the total beta-adrenoceptor mRNA. 3. The beta 1/beta 2-adrenoceptors of human brown adipose tissue plasma membranes were characterized using [3H]-CGP 12177 as a ligand. Their Kd and Bmax values were 1.9 nM and 156 fmol mg-1 of membrane proteins, respectively. The beta 3-adrenoceptor was characterized by use of the new specific radioligand [3H]-SB 206606. The binding of this ligand was stereospecifically displaced by the active R,R- or the inactive S,S-enantiomer of BRL 37344 up to a concentration of about 10 microM. The Kd and Bmax values of the brown adipose tissue membrane beta 3-adrenoceptors were 87 nM and 167 fmol mg-1 of proteins, respectively. A low affinity [3H]-CGP 12177 binding site population was also detected in these membranes. 4. In human omental white adipose tissue, no beta 3-adrenoceptor mRNA could be detected in total RNA Northern blots and the beta 1-and beta 2-adrenoceptor mRNAs represented 9 and 91%, respectively of the total beta-adrenoceptor mRNA, and no specific binding of [3H]-SB 206606 could be measured.

Fibroblast growth factor receptor 3 is a negative regulator of bone growth

Endochondral ossification is a major mode of bone that occurs as chondrocytes undergo proliferation, hypertrophy, cell death, and osteoblastic replacement. We have identified a role for fibroblast growth factor receptor 3 (FGFR-3) in this process by disrupting the murine Fgfr-3 gene to produce severe and progressive bone dysplasia with enhanced and prolonged endochondral bone growth. This growth is accompanied by expansion of proliferating and hypertrophic chondrocytes within the cartilaginous growth plate. Thus, FGFR-3 appears to regulate endochondral ossification by an essentially negative mechanism, limiting rather than promoting osteogenesis. In light of these mouse results, certain human disorders, such as achondroplasia, can be interpreted as gain-of-function mutations that activate the fundamentally negative growth control exerted by the FGFR-3 kinase.

[Pharmacokinetic study of intraperitoneal chemotherapy with high-dose cisplatin for advanced ovarian cancer]

OBJECTIVE

To determine the characteristics of pharmacokinetics with high-dose cisplatin (DDP) instilled intraperitoneally and its toxicity as compared with that by intravenous (i.v.) route of administration (i.p.).

METHODS

Sixteen patients with advanced ovarian cancer, not previously treated, were randomly divided into two groups: every patient in group I received intraperitoneal administration of DDP (100mg/m2) and those in group II received the same dose of DDP by intravenous route. The blood, ascitic fluid and urine were collected in different intervals as scheduled for 8 days after administration of these drugs. The total platinum of all samples were measured by a flameless type of atomic absorption spectrometry.

RESULTS

The concentration of total platinum in the ascitic fluid was very high in i.p. group. The area under the concentration-time curve (AUC) for total platinum in ascitic fluid after i.p. therapy was 5 folds greater than that after i.v. therapy (P < 0.05). The total platinum concentration in serum after i.p. therapy was about the same as that after i.v. therapy. The half-life time for the elimination phase of total platinum from ascitic fluid and serum after i.p. administration was longer than that after i.v. administration. The toxicity of high-dose DDP given i.p. was not increased as compared with that given i.v..

CONCLUSIONS

This study indicates that high-dose DDP i.p. therapy offers some advantages in the treatment of ovarian cancer. The tumor tissues and peritoneal growths could be bathed in a high concentrations of DDP with a longer duration, so that the tumorcidal effect may be increased. The drug concentration in serum after i.p. therapy was as high as i.v. route. The toxicity of high-dose DDP i.p. therapy was not higher than that of i.v. therapy.

Expression of Brca1 is associated with terminal differentiation of ectodermally and mesodermally derived tissues in mice

We have isolated genomic and cDNA clones of Brca1, a mouse homolog of the recently cloned breast cancer-associated gene, BRCA1. Brca1 encodes an 1812-amino-acid protein with a conserved zinc finger domain and significant homology to the human protein. Brca1 maps to Chromosome 11 within a region of conserved synteny with human chromosome 17, consistent with the mapping of the human gene to 17q21. Brca1 transcripts are expressed in a variety of cultured cells but reveal a specific and dynamic expression pattern during embryonic development. For example, expression is observed first in the otic vesicle of embryonic day 9.5 (E9.5) embryos. This expression diminishes and is replaced by expression in the neuroectoderm at E10.5. By E11-12.5, higher levels are observed in differentiating keratinocytes and in whisker pad primordia. Transcripts also become evident in epithelial cells of the E14-17 kidney. Brca1 expression occurs in differentiating epithelial cells of several adult organs as well, suggesting a general role in the functional maturation of these tissues. Consistent with this, Brca1 transcripts are expressed in both alveolar and ductal epithelial cells of the mammary gland. During pregnancy, there is a large increase in Brca1 mRNA in mammary epithelial cells, an increase that parallels their functional differentiation. Because high rates of breast cancer are associated with loss of BRCA1 in humans, it is possible that this gene provides an important growth regulatory function in mammary epithelial cells. In addition, increased transcription of mammary Brca1 during pregnancy might contribute, in part, to the reduced cancer risk associated with exposure to pregnancy and lactation.

Modulation of obese gene expression in rat brown and white adipose tissues

The ob gene mRNA expression in rat brown adipose tissue (BAT) and epididymal white adipose tissue (WAT) was measured on Northern blots hybridized with a rat ob gene probe. The level of ob gene mRNA in BAT was about 40% of that in WAT. Fasting (36 h) or semi-starvation (10 days) decreased the ob gene mRNA level in both tissues by 62-68%, and cold exposure at 6 degrees C (24 h) decreased it in BAT (-84%) but not in WAT. Acute administration of the beta 3-adrenergic agonist Ro 16-8714 decreased the ob gene mRNA level in BAT (-51%) and WAT (-28%) of lean Zucker rats and only in BAT (-74%) of obese falfa rats. This study demonstrates that, in the rat, the ob gene is not only expressed in WAT but also in BAT, and suggests that in these two tissues, the modulation of the ob gene expression might be more closely associated with known alterations in cell lipid content than with changes in sympathetic activity.

[Clinical significance of detection of plasma fibronectin in respiratory failure]

Plasma fibronectin (PFn) level was measured with immumoelectrophoresis in 40 healthy adults and 174 patients (221 person-times) with respiratory insufficiency (R I). The levels of PFn in 40 healthy adults, 85 person-times of R I, 27 person-times of Type I respiratory failure (RF I), 82 person-times of RF II, and 27 person-times of iatrogenic RF (IRF) were 292.48 +/- 43.11 mg/L, 253.12 +/- 67.00 mg/L 141.97 +/- 70.84 mg/L, 180.48 +/- 49.96 mg/L and 263.49 +/- 70.05 mg/L respectively. The levels of PFn of patients with R I, RF I and RF II were significantly lower than that in healthy adults (P < 0.001). The level of PFn of patients with TRF was significantly lower than that in healthy adults (P < 0.05). There was positive correlation between the levels of PFn and PaO2 in 221 person-times of R I (r = 0.5358, P < 0.001), RF I r = 0.3822, P < 0.05). RF II (r = 0.3050, P < 0.01), and IRF (r = 0.4963, P < 0.02). There was negative correlation between the levels of PFn and PaCO2 in 221 person-times of R I (r = -0.2053, P < 0.005) and RF II (r = -0.2181, P < 0.05). In 34 patients with RF, the PFn before treatment was significantly lower than that two weeks after treatment (147.80 +/0 61.59 mg/L vs 214.56 +/- 56.12 mg/L) (P < 0.001). Among 33 cases of RF whose level of PFn was < 150 mg/L, 18 cases complicated multiple system organ failure and 4 cases complicated adult respiratory distress syndrome. The average level of PFn in 3 death cases was lower than 100 mg/L. It is suggested that PFn level might be used as an index in making early diagnosis, monitoring RF and predicating progosis of RF.

Mice lacking p21CIP1/WAF1 undergo normal development, but are defective in G1 checkpoint control

p21CIP1/WAF1 is a CDK inhibitor regulated by the tumor suppressor p53 and is hypothesized to mediate G1 arrest. p53 has been suggested to derive anti-oncogenic properties from this relationship. To test these notions, we created mice lacking p21CIP1/WAF1. They develop normally and (unlike p53-/- mice) have not developed spontaneous malignancies during 7 months of observation. Nonetheless, p21-/- embryonic fibroblasts are significantly deficient in their ability to arrest in G1 in response to DNA damage and nucleotide pool perturbation. p21-/- cells also exhibit a significant growth alteration in vitro, achieving a saturation density as high as that observed in p53-/- cells. In contrast, other aspects of p53 function, such as thymocytic apoptosis and the mitotic spindle checkpoint, appear normal. These results establish the role of p21CIP1/WAF1 in the G1 checkpoint, but suggest that the anti-apoptotic and the anti-oncogenic effects of p53 are more complex.

The MMTV/c-myc transgene and p53 null alleles collaborate to induce T-cell lymphomas, but not mammary carcinomas in transgenic mice

A number of properties of the cancer-related genes c-myc and p53 suggest that they might collaborate to induce tumorigenesis. To test this notion, we produced doubly heterozygotic mice bearing disrupted p53 alleles and a fusion transgene consisting of the mouse mammary tumor virus (MMTV) LTR and the oncogene c-myc. Mice bearing both the MMT/c-myc transgene and a single p53- allele develop very aggressive pre-T- and T-cell lymphomas with a significantly shorter latency than mice carrying either the p53- allele or the c-myc transgene alone. Moreover, every lymphoma occurring in these animals has lost or suffers an inactivation of its wild type p53 allele indicating that loss of p53 activity is necessary for this c-myc-accelerated lymphomagenesis. Nonetheless, p53 inactivation and expression of the MMTV/c-myc transgene are not sufficient for lymphoid transformation. Tumors that arise in homozygous p53- mice carrying the c-myc transgene are monoclonal, suggesting that at least one additional event is necessary for their transformation. Moreover, since mice bearing only the MMTV/c-myc transgene predominantly develop mammary carcinomas, it was surprising that the p53- allele failed to accelerate the incidence of mammary carcinomas. Further, in contrast to the lymphomas, only one in four mammary tumors that arose in the double heterozygotic mice had lost its wild type p53 allele. Apparently cell context influences the ability of c-myc and p53- to cooperate in inducing oncogenesis.

[Radiolabelling and assay of Chinese agkistrodon acutus venom with carrier-free Na 125I]

Chinese agkistroden acutus venom (CAAV) was radiolabelled with carrier-free Na 125I by the method of Iodogen. The specific activity and radiochemical purity for radiolabelled products were 4236.5 x 10(10) Bq/mmol and 98%, respectively. Each CAAV molecule carried 0.52 125I atom. Physical and chemical characterization of radiolabelled CAAV was similar to unradiolabelled CAAV. Binding analysis showed that 125I-CAAV was bound to platelet in a saturable manner. Binding sites per platelet were 13,255 +/- 6292/platelet. The dissociation constant (Kd) was 3.2 +/- 0.69 x 10(-10) mol/L. These results are similar to binding sites of other snake venom on platelet. The investigation showed that radiolabelled CAAV made by our laboratory was useful for radioligand binding assay.

[Establishment of a human fetal thymocyte cell line and observation of its biological properties]

Thymocytes were isolated from a five month fetus after caesarean section and cultured in vitro. A cell line named human fetal thymocyte 8810 (HFT8810) was established and cultured continuously for 2 years in our lab, and grew well after recovery from the state of being frozen in liquid nitrogen. The HFT 8810 cells retained their ability to secrete thymosin after many generations in vitro culture.

Active anaphylaxis in IgE-deficient mice

The IgE-triggered release of mast cell mediators in response to antigen is thought to be the primary event in immediate hypersensitivity reactions such as systemic anaphylaxis. Although mast cells and basophils can be activated in vitro by non-IgE stimuli, it is not known whether these triggers lead to physiological changes in vivo. To investigate this possibility, we generated mice with a homozygous null mutation of the C epsilon gene. Such mice make no IgE, but produce other immunoglobulin isotypes normally. We report that despite the IgE deficiency, sensitized mutant mice become anaphylactic on antigen challenge and display tachycardia and pulmonary function changes similar to those seen in wild-type animals. These responses are accompanied by vascular leak, sharply elevated plasma histamine and rapid death. IgE-independent anaphylaxis does not depend on complement activation, but, as indicated in studies using genetically immunodeficient RAG-2- and SCID mice, does require a functional immune system. Such results clearly demonstrate that non-IgE pathways for hypersensitivity reactions exist in mice.

[Studies on the detection of Legionella pneumophila by the application of polymerase chain reaction (PCR)]

DNA fragment of Legionella pneumophila, the PCR was performed with a pair of artificial synthesized primer. Results of agarose electrophoresis and EB staining showed that there was a 870 bp band shared by serogroups 1-14 of L.pneumophila. The sensitivity of PCR in detecting Legionella from water was 350cfu/ml, however, the specific DNA probe labeled with 32P was .43cfu/ml by blot hybridization. The positive rate of tissue specimens from infected guinea-pigs with Legionella pneumophila was 83.3% by PCR detection, and only 26.6% by bacteriological culture method. An outbeak caused by Lp10 was verified by PCR. The result showed that the PCR could detect the infection of Legionella rapidly, specifically and sensitively.