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Phosphatidylinositol-4-phosphate 5-kinase (PIP5K) phosphorylates phosphatidylinositol-4-phosphate to produce phosphatidylinositol-4,5-bisphosphate as a precursor of two second messengers, inositol-1,4,5-triphosphate and diacylglycerol, and as a regulator of many cellular proteins involved in signal transduction and cytoskeletal organization. Despite PIP5K playing such an essential role in a number of physiological processes, much still remains to be made clear about its association with plants. Searching the Arabidopsis expression sequence tag database against already known yeast and mammalian PIP5K cDNAs, we identified two clones which partly encode the same Arabidopsis PIP5K and isolated a corresponding full-length cDNA encoding a protein that we designated AtPIP5K1. Recombinant AtPIP5K1 expressed in Escherichia coli possessed a PIP5K activity in vitro. Due to some structural and biochemical differences, AtPIP5K1 was not categorized as either a type I or type II PIP5K. The expression of the AtPIP5K1 mRNA was induced rapidly by treating Arabidopsis plants with drought, salt and abscisic acid, which suggests that AtPIP5K11 is involved in water-stress signal transduction. These data give evidence for a close link between phosphoinositide signaling cascades and water-stress responses in plants.  相似文献   
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Twenty-six patients with squamous cell cancer of the cervix were treated with i.v. paclitaxel, 250 mg/m2 over 3 h every 21 days. They received steroid, H1 and H2 blocker premedications, and granulocyte-colony-stimulating factor (G-CSF) support (5 microgram/kg/day). No prior chemotherapy, except as a radiation sensitizer, was allowed. The median age was 50 (range, 36-81) years, and performance status Zubrod was 1 (range, 0-2). Eight (33%) patients had prior surgery, and 22 (92%) had prior radiation therapy. Twenty-four patients were evaluable for response; 2 were later found to be ineligible. Five patients had partial responses (21%; 95% confidence interval, 6-40%), and 14 (58%; 95% confidence interval, 35-78%) had stable disease. The median duration of response was 10 (range, 3-27+) weeks. The responses were within the radiation port (four responses) and outside of it (one response). The median interval from the start of irradiation to the start of paclitaxel in responding patients was 94 weeks, whereas in patients with stable disease it was 68 weeks, and in patients whose disease progressed it was 46 weeks. Eighty-eight percent of the 105 cycles of paclitaxel were administered at a dose of 250 mg/m2 or higher. Granulocytopenia was brief and noncumulative, with grades 3 and 4 experienced by 5 and 3 patients, respectively. G-CSF was used for a median of 7 (range, 2-14) days/cycle. Anemia was mild, with G3 noted in 3 patients, and thrombocytopenia was not significant. Infections and musculoskeletal pain were mild and infrequent. Sensory (14 patients G1 or G2 and 2 patients G3) and motor (4 patients G1 or G2 and 1 patient G3) neurotoxicity was noted. There was no significant cardiovascular toxicity. Paclitaxel is active in patients with squamous cell cancer of the cervix and is well tolerated at this dose schedule with G-CSF support.  相似文献   
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Mechanosensitive ion channels play a critical role in transducing physical stresses at the cell membrane into an electrochemical response. The MscL family of large-conductance mechanosensitive channels is widely distributed among prokaryotes and may participate in the regulation of osmotic pressure changes within the cell. In an effort to better understand the structural basis for the function of these channels, the structure of the MscL homolog from Mycobacterium tuberculosis was determined by x-ray crystallography to 3.5 angstroms resolution. This channel is organized as a homopentamer, with each subunit containing two transmembrane alpha helices and a third cytoplasmic alpha helix. From the extracellular side, a water-filled opening approximately 18 angstroms in diameter leads into a pore lined with hydrophilic residues which narrows at the cytoplasmic side to an occluded hydrophobic apex that may act as the channel gate. This structure may serve as a model for other mechanosensitive channels, as well as the broader class of pentameric ligand-gated ion channels exemplified by the nicotinic acetylcholine receptor.  相似文献   
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PURPOSE: To study the safety and efficacy of scleral intraocular lens (IOL) fixation in children. SETTING: A university practice. METHODS: This retrospective review evaluated the results and complications in 6 consecutive eyes of 3 children who had anterior vitrectomy, with or without lensectomy, and scleral IOL fixation to correct ectopia lentis or aphakia. RESULTS: At a mean follow-up of 17.3 months (range 13 to 21 months), all eyes had a stable and well-positioned posterior chamber IOL and good visual improvement. The only complication was asymptomatic pupillary capture of the IOL in 3 eyes. Reversal of the pupillary capture was achieved by pupil dilation with the patient in a supine position. CONCLUSIONS: The preliminary results of scleral IOL fixation in children are encouraging. The procedure's application in well-selected cases can be considered. However, its long-term safety and efficacy must be further assessed through studies with larger sample sizes and a longer follow-up.  相似文献   
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BACKGROUND: Echographic biometry of the ocular axial length is a helpful criterion in diagnosis and follow-up of primary congenital glaucoma. However, quantitative assessment of ocular growth following successful primary glaucoma surgery in the first year of life is hardly to find in literature. PATIENTS AND METHODS: In 36 eyes from 21 patients (mean age 4.4 +/- 2.4 months) with primary congenital glaucoma Ascan biometry was performed under general anesthesia before and 7.2 +/- 4.2 months following successful primary glaucoma surgery and retrospectively summarized. RESULTS: Preoperative axial length was 21.7 +/- 2.5 mm, postoperative axial length was 22.4 +/- 1.6 mm. Ocular growth was significantly stronger in eyes with a preoperative axial length < 20 mm (p = 0.0012) and in children younger than 3 months at surgery (p = 0.0004). CONCLUSIONS: Preoperative axial length and age are basic factors for the interpretation of ocular growth following glaucoma surgery in primary congenital glaucoma. Temporary cessation of ocular growth is a frequent finding after successful pressure-reducing surgery in eyes with axial length > 22 mm and in children aged 3 months or older.  相似文献   
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