Biomedical subjects
Publications and source records attributed to A Dai.
Epistaxis is common in the paediatric population and is usually minor and self limiting. This case illustrates an atypical presentation of epistaxis with hypovolaemic shock due to a dissecting false aneurysm of the internal carotid artery caused by an impalement injury to the oropharynx.
Locally advanced breast cancer (LABC) has a poor prognosis with a high risk of local recurrence and distant metastasis. Preoperative combined chemotherapy with or without granulocyte colony-stimulating factor (G-CSF) support does not improve the long-term survival rate. In our report, two patients with LABC received preoperative high-dose chemotherapy with peripheral blood stem cell support (HDC/PBSCs). Prior to high-dose chemotherapy with peripheral blood stem cell support, they both received induction chemotherapy of cyclophosphamide, epirubicin and 5-fluorouracil (FEC) for two cycles which resulted in a partial response. PBSC mobilization and collection were carried out following the second cycle of induction chemotherapy followed by G-CSF. High-dose cyclophosphamide (2500 mg/m2), carboplatin (600 mg/m2) and etoposide (600 mg/m2) were administered with PBSC support. A radical mastectomy was performed followed by adjuvant chemotherapy with FEC regimen for four cycles, followed by local irradiation, and endocrine therapy with tamoxifen. Both patients achieved a remarkable response in the primary lesion after HDC/PBSCs and tolerated the whole treatment well. Preoperative HDC/PBSCs as a new strategy in the treatment of LABC seems practical but it needs to be studied more deeply.
Bell's palsy (idiopathic facial paralysis) is the most common cause of unilateral peripheral facial neuropathy. Bilateral involvement occurs in less than 10% of cases. The authors describe a 20-year-old man with bilateral idiopathic facial weakness. Brain magnetic resonance imaging (MRI) showed abnormal bilateral enhancement of the proximal intracanalicular segments of VII/VIII nerve complexes. The enhancement was most prominent in the leptomeningeal regions. There was no facial nerve swelling. Three months later he had improving residual bifacial weakness. To the authors' knowledge, this is the first report of abnormal MRI findings in bilateral Bell's palsy.
We have previously shown, in a neonatal rat cell line, that angiotensin II (Ang II)-induced proliferation in vascular smooth muscle cells is extracellular matrix (ECM) dependent. We hypothesized that such an effect might be mediated via differences in Ang II-induced increases in the transcriptional factor early growth response-1 (Egr-1) gene and, consequently, in platelet-derived growth factor (PDGF). Cultured human newborn aortic smooth muscle cells were studied on 4 different surfaces: (1) plastic, (2) laminin, (3) collagen, and (4) fibronectin. Ang II-induced increases in DNA synthesis were significantly greater on collagen (2.0+/-0.3-fold) and fibronectin (1.9+/-0.3-fold) than on laminin (1.0+/-0.2-fold) or plastic (1.4+/-0.2-fold). As with DNA synthesis, at 48 and 72 hours, Ang II-induced increases in cell numbers occurred only in cells grown on collagen and fibronectin culture plates and were blocked by an antagonist to the angiotensin type 1 (losartan, 10 micromol/L) but not the angiotensin type 2 (PD 123319, 10 micromol/L) receptor. Anti-PDGF AA antibody (6 microg/mL) blocked the increase in DNA synthesis by 60% to 64% in cells on collagen or fibronectin cultures but not on plastic cultures. When PDGF-AA (10 ng/mL) and Ang II were added together, DNA synthesis increased 2-fold and did not differ on the various ECM proteins. Increases in PDGF A-chain mRNA were observed only in cells grown on collagen (3.21+/-0.65-fold) and fibronectin (2.86+/-0.49-fold) plates 2 to 8 hours after the addition of Ang II and were blocked by losartan but not PD 123319. Expression of Egr-1, an early growth response gene, increased at 15 minutes, peaked at 30 minutes, and returned to normal after 2 hours with Ang II treatment. Ang II-induced increases in Egr-1 mRNA were greater on collagen (4. 82+/-0.66-fold at maximum) and fibronectin (4.01+/-0.56-fold) than on laminin (2.74+/-0.45-fold) or plastic (2.53+/-0.40-fold) and were blocked by losartan but not PD 123319. Thus, in human vascular smooth muscle cells in culture, Ang II-induced proliferation is mediated via the angiotensin type 1 receptor, dependent on ECM proteins, and regulated by differential gene expression of Egr-1 and PDGF-1.
Bone is modeled during embryonic development by endochondral and membranous ossification and is continuously remodeled thereafter under the influence of local and systemic factors to provide structural support and assist in calcium homeostasis. Recent studies of knockout and transgenic mice have increased understanding of the regulation of bone modeling during development and of remodeling of mature bone and have shed new light on the pathogenesis of a number of bone disorders. For example, fibroblast growth factor receptor-3, parathyroid hormone-related protein, and tartrate-resistant acid phosphatase affect the function of chondrocytes during endochondral ossification (the latter two by regulating their life spans and thus growth plate thickness and bone length). Some ubiquitously expressed genes seem unexpectedly to have unique functions that are largely confined to bone cells: M-CSF, C-Fos, PU.1, and NF-kappaB are required for osteoclast formation, whereas c-Src and Mitf (microphthalmia transcription factor) are required for osteoclast activity after the cells have formed. Knockout of these genes results in osteopetrosis, a disorder characterized by persistence in marrow cavities of unresorbed osteocartilaginous matrix and, as in some affected humans, by increased mortality. Some proteins seem to act as negative regulators of bone cell function, for example osteoprotegerin (a soluble TNF receptor) in osteoclasts; osteocalcin, bone sialoprotein, and 5-lipoxygenase in osteoblasts. Regulation of osteoclast life span may be an important mechanism by which estrogen and bisphosphonates prevent bone loss in conditions characterized by increased bone resorption, such as postmenopausal osteoporosis. The unique requirement of bone cells for certain gene products raises the possibility that these cells may have specific responses to inhibitory or stimulatory agents, and that signaling molecules in these response pathways could be specific targets for novel therapies to treat or prevent common bone diseases.
BACKGROUND: The role of aminophylline (ethylene diamine salt of theophylline) in the treatment of acute exacerbation of asthma has not been well established in children. OBJECTIVE: The aim of the study was to determine the additional therapeutic benefit of intravenous aminophylline in the treatment of children hospitalized for acute asthmatic exacerbation and treated with inhaled bronchodilators and glucocorticoid therapy. METHODS: Thirty-eight children aged from 2 to 16 years (mean age 5.64 +/- 3.31), admitted for acute exacerbation of asthma, participated in a prospective, randomized, double-blind, placebo-controlled study. All the subjects received methylprednisolone, administered intravenously, and nebulized salbutamol. The treatment group received intravenous aminophylline therapy and the placebo group received 0.9% saline solution for 24 hours. RESULTS: The number of salbutamol nebulizations needed and the clinical asthma scoring were recorded both at onset and at the end of 24 hours. There was no significant difference in either the mean number of nebulizations or the clinical asthma scores between the two groups (P = .7843, P = .8452). CONCLUSION: Intravenous aminophylline (ethylene diamine salt of theophylline) demonstrated no additional beneficial effect to the combination of beta adrenergic agonists and glucocorticoid treatment in acute asthma attack in children.
OBJECTIVE: To evaluate safety and efficacy of high-dose epirubicin combined with cyclophosphamide and fluorouracil for advanced breast cancer. METHODS: Thirty two cases with stage III and IV breast cancer were treated with epirubicin (EPI) 90-110 mg/m2, cyclophosphamide (CTX) 600 mg/m2 and 5-fluorouracil (5-Fu) 900 mg/m2 every 21 days. The therapeutic effect was compared with that in patients treated with low-dose EPI(50 mg/m2). RESULTS: The response rate (RR) in patients treated with high-dose EPI was 71.9% (CR = 4, PR = 19) which was significantly better than that in the low-dose EPI-treated patients (CR = 2, PR = 5). The therapeutic effect was slightly better in patients initially diagnosed than in patients in recurrence (RR: 80% vs 68.2%) the median remission and surriving peroid was 7.4 months and 12.5 months, respectively. The major side effect was leukopenia. Mild to moderate GI tract side effects were obsevved. There was no significant cardiotoxicity. CONCLUSION: High-dose EPI combined with CTX, 5-Fu is a safe and effective regimen for patients with advanced breast cancer worthy of further clinical trial.
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Postmenopausal osteoporosis, the most common bone disease in the developed world, is associated with estrogen deficiency. This deficiency induces increased generation and activity of osteoclasts, which perforate bone trabeculae, thus reducing their strength and increasing fracture risk. Estrogen replacement prevents these effects, indicating that estrogen negatively regulates osteoclast formation and function, but how it does this is unclear. Because functional osteoclast life span and thus the amount of bone that osteoclasts resorb could also be enhanced following estrogen deficiency, and since sex steroids regulate apoptosis in other target tissues, we investigated whether estrogen may affect osteoclast function by promoting apoptosis. 17 beta-Estradiol promoted apoptosis of murine osteoclasts in vitro and in vivo by two- to threefold. Tamoxifen, which has estrogenic effects on bone resorption, and transforming growth factor-beta 1 (TGF-beta), whose production by osteoblasts is increased by estrogen, had similar effects in vitro. Anti-TGF-beta antibody inhibited TGF-beta-, estrogen- and tamoxifen-induced osteoclast apoptosis, indicating that TGF-beta might mediate this effect. These findings suggest that estrogen may prevent excessive bone loss before and after the menopause by limiting osteoclast life span through promotion of apoptosis. The development of analogues to promote this mechanism specifically could be a useful and novel therapeutic approach to prevent postmenopausal osteoporosis.
We used an immunohistochemical assay with an antigen-retrieval technique to study plasminogen activator inhibitor type-1 (PAI-1) expression in paraffin-embedded breast tissue samples at different stages of malignant transformation. We detected PAI-1 in 15/20 invasive tumors. In several cases staining was localized to the stromal component. PAI-1-positive fibroblasts could be seen surrounding tumor nodules or at tumor margins. In addition, tumor-infiltrating macrophages (13 cases) and endothelial cells (5 cases) were positive. In 11 specimens PAI-1-positive cancer cells were also detected. In 2 strongly positive cases secreted PAI-1 was visible in the extracellular matrix surrounding the cells. Six of 9 samples of carcinoma in situ (DCIS) were weakly positive. No staining of endothelial cells was visible in DCIS. Only a few positive adenomatous epithelial cells could be seen in 3 of 7 papillomas. All biopsies of normal breast tissue were negative, with the exception of one sample, obtained from a patient with a previous segmental mastectomy for DCIS. PAI-1 production by invasive breast cancers could reflect a general upregulation of the plasminogen activation system in proliferating cancer cells, as suggested by the finding that normal mammary epithelium cultures expressed PAI-1 in all cases examined. In addition, production of PAI-1 by the tumor stroma could protect the tumor itself from excessive proteolysis.
Seven children with asthma were included in a trial of recombinant interferon-alpha 2a (rIFN-alpha 2a). Patients received either 2 million U/m2 rIFN-alpha 2a (n = 4) or placebo (n = 3) three times a week for 4 weeks. Pulmonary function test, peak expiratory flow rates (PEFR), and clinical symptom scores were monitored throughout the trial. Serum interleukin-4, soluble low-affinity receptor for IgE Fc epsilon RII/CD23 (sCD23), and immunoglobulin E (IgE) levels were measured at the beginning of the trial, and at the second week, fourth week, and sixth week. Compared with placebo, rIFN-alpha 2a therapy did not result in a significant change in the above-mentioned parameters. Further studies with a larger number of patients are needed to draw firmer conclusions in regard to efficacy of rIFN-alpha 2a therapy in childhood asthma.
The aim of the study is to investigate whether hypoxia might affect nitric oxide synthase (NOS) activity or mRNA expression of cultured pulmonary artery endothelial cells in pigs by means of NADPH-diaphorase cytochemical stain and DNA-RNA dot blot hybridization respectively. The NOS activity and mRNA expression were highly present in normoxic group as well as 6 and 24 hours serum-free control groups, but significantly lowered in 6 and 24 hours hypoxic groups. The mRNA expression of NOS gene was almost absent in 48 hours hypoxic cells. The results indicate that hypoxia can attenuate the activity and mRNA expression of NOS in cultured pulmonary artery endothelial cells, which may lay an important role in modulating acute hypoxic pulmonary vasocontriction and chronic hypoxic pulmonary arterial hypertension.
Oncogene amplification in tumor cells results in the overexpression of proteins that confer a growth advantage in vitro and in vivo. Amplified oncogenes can reside intrachromosomally, within homogeneously staining regions (HSRs), or extrachromosomally, within double minute chromosomes (DMs). Since previous studies have shown that low concentrations of hydroxyurea (HU) can eliminate DMs, we studied the use of HU as a gene-targeting agent in tumor cells containing extrachromosomally amplified oncogenes. In a neuroendocrine cell line (COLO 320), we have shown that HU can eliminate amplified copies of c-myc located on DMs, leading to a reduction in tumorigenicity in vitro and in vivo. To determine whether the observed reduction in tumorigenicity was due to differentiation, we next investigated whether HU could induce differentiation in HL60 cells containing extrachromosomally amplified c-myc. We compared the effects of HU, as well as two other known differentiating agents (dimethyl sulfoxide and retinoic acid), on c-myc gene copy number, c-myc expression, and differentiation in HL60 cells containing amplified c-myc genes either on DMs or HSRs. We discovered that HU and dimethyl sulfoxide reduced both c-myc gene copy number and expression and induced differentiation in cells containing c-myc amplified on DMs. These agents failed to have similar effects on HL60 cells with amplified c-myc in HSRs. By contrast, retinoic acid induced differentiation independent of the localization of amplified c-myc. These data illustrate the utility of targeting extrachromosomal DNA to modulate tumor phenotype and reveal that both HU and dimethyl sulfoxide induce differentiation in HL60 cells through DM elimination.
Hpa II site H8 is in the CpG-rich 5' untranslated region of the human X chromosome-linked gene for phosphoglycerate kinase 1 (PGK1). It is the only Hpa II site in the CpG "island" whose methylation pattern is perfectly correlated with transcriptional silence of this gene. We measured DNA methylation at site H8 in fetal oogonia and oocytes and found, using a quantitative assay based on the polymerase chain reaction, that purified germ cells isolated by micromanipulation were unmethylated in 47-day to 110-day fetuses, whereas ovaries depleted of germ cells and non-ovary tissues were methylated. We conclude that site H8 is unmethylated in germ cells prior to the onset of meiosis and reactivation of the X chromosome.
We have found that the single nucleotide primer extension assay, a PCR-based assay currently used qualitatively to measure allelic differences in DNA, can be used quantitatively to measure allele-specific transcripts differing by only a single nucleotide. We show that total RNA containing the Pgk-1a transcript can be specifically detected even in a 1000-fold excess of RNA containing the Pgk-1b transcript.