Simple technique for estimation of biofilm accumulation.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
D Liu
Publications and source records attributed to D Liu.
Effects of lead on root growth, cell division, and nucleolus of Allium cepa.
The effects of different concentrations of lead nitrate on root growth, cell division, chromosome morphology and nucleolus in root tip cells of Allium cepa were studied. The concentrations of lead nitrate (Pb(NO(3))(2)) were 10(-7), 10(-6), 10(-5), 10(-4), 10(-3) and 10(-2) m. It was observed that lead reduces root growth and causes mitotic irregularities, including c-mitosis, anaphase bridges, and chromosome stickiness. Also, interphase cells with micronuclei, irregularly shaped nuclei and nuclei with decomposed nuclear material were noticed. The c-mitotic effect reached its maximum in the meristem at above 10(-4) m Pb, when practically almost all the anomalous dividing cells are of this type. After treatment with Pb, there were many similar silver-stained particulate materials scattered in the nucleus in short, rounded meristem cells and in long, oblong root cap cells.
Journal Article↗
A retrospective study of clinical and laboratory characteristics of ovine footrot.
The infection of the feet of sheep by the anaerobic bacterium Dichelobacter nodosus results in a spectrum of diseases ranging from virulent through intermediate to benign footrot. By examining the clinical characteristics of various forms of footrot from 22 properties in Victoria, Australia in association with the results of several laboratory tests including the gene probe-based dot blot hybridisation, it was shown that virulent footrot could not be differentiated from intermediate footrot using the clinical characteristics alone. In addition, D. nodosus isolates from sheep with benign footrot as diagnosed by the clinical manifestations might in fact show characteristics associated with those causing virulent, intermediate or benign footrot as determined by the laboratory tests. Although the elastase test, gelatin gel test and dot blot were in agreement with isolates from 9 of the 22 properties under investigation, they displayed differences from one another in many other cases, especially those with clinical benign footrot. The results of the elastase test appeared to be slightly closer to those of the dot blot compared with the gelatin gel test. Like any other tests based on the measurements of phenotypic characteristics of D. nodosus bacteria, the elastase test and gelatin gel test are subject to changes with factors that affect bacterial growth and metabolism. The use of DNA based detection methods would eliminate many of the problems associated with the conventional tests for differentiating strains causing virulent, intermediate and benign footrot.
Animals↗
A NaCl-regulated plant gene encoding a brain protein homology that activates ADP ribosyltransferase and inhibits protein kinase C.
A cDNA clone pCZ1, with a 1.1 kb insert, was isolated from a NaCl-adapted tobacco cell cDNA library that encodes an apparently full-length 29 kDa protein (251 amino acids) with a calculated pI of 5.7. The encoded peptide had a high amino acid sequence identity with bovine 14-3-3 protein which was originally found as an abundant protein in the animal central nervous system. Recently, proteins with sequence identity to 14-3-3 protein have also been found in plants, insects and yeast, and appear to have diverse physiological functions. Similar to the bovine brain 14-3-3 protein, the recombinant pCZ1 protein stimulated ADP-ribosylation of protein substrate by ADP-ribosyltransferase from the plant and animal pathogenic bacterium Pseudomonas aeruginosa. This recombinant protein also inhibited protein kinase C activity in vitro. Southern blot analyses indicated that most likely five genes encoding 14-3-3-like proteins are present in tobacco. The pCZ1 cDNA insert hybridized to a single mRNA of 1.1 kb from cultured tobacco cells. The level of this mRNA transcript in tobacco cells was downregulated upon adaptation to NaCl but was unaffected by short-term treatment with NaCl, ABA or ethylene. In tobacco plants, expression of transcript that hybridized to pCZ1 was tissue specific, and was most abundant in roots and flower parts. Monoclonal antibody raised against GF14 protein, a maize protein with substantial sequence identity with 14-3-3 protein detected two bands on SDS-PAGE of total proteins from unadapted tobacco cells and only a single band from cells adapted to NaCl. The GF14 antibody was also used to illustrate that the G-box element of a salt-induced gene is associated with a 14-3-3-type protein.
14-3-3 Proteins↗
Hydroxyl radicals generated in vivo kill neurons in the rat spinal cord: electrophysiological, histological, and neurochemical results.
We have used microdialysis to establish an experimental model to characterize mechanisms whereby released substances cause secondary damage in spinal cord injury. We use this model here to characterize damaging effects of the hydroxyl radical (OH.) in vivo in the spinal cord. OH. was generated in vivo by pumping H2O2 and FeCl2/EDTA through parallel microdialysis fibers inserted into the spinal cord. These agents mixed in the tissue to produce OH. by Fenton's reaction. Two types of control experiments were also conducted, one administering only 5 mM H2O2 and the other only 0.5 mM FeCl2/0.82 mM EDTA. During administration of these chemicals, electrical conduction was recorded as one test for deterioration. OH. blocked conduction completely in 2.5-5 h and Fe2+/EDTA partly blocked conduction, but H2O2 alone did not cause detectable blockage. Histological examination supported the hypothesis that neurons were killed by OH., as Fe2+/EDTA and H2O2 alone did not destroy significant numbers of neurons. OH., H2O2, and Fe2+ all caused gradual increases in extracellular amino acid levels. These results are consistent with Fe(2+)-catalyzed free radical generation playing a role in tissue damage upon spinal cord injury.
Animals↗
Blindness after blow-out fracture repair.
Blindness following uncomplicated repair of orbital blow-out fracture has been reported previously. Mechanisms that have been implicated in this devastating complication include direct intraoperative injury to the optic nerve, increased orbital pressure, retrobulbar hemorrhage, and bone spicule impingement on the optic nerve. Two additional cases of blindness following uneventful surgical repair of a blow-out fracture are described herein. The first patient had sustained severe blunt trauma to the forehead after discharge from the hospital. The computed tomography (CT) scan of his orbit suggested a swollen optic nerve, and he was thus assumed to have traumatic optic neuropathy secondary to postoperative blunt trauma to the forehead. The second patient had prolonged, severe orbital edema. The operated eye had been patched, and the patient took analgesics ad lib to control orbital pain. Intraoperative and postoperative measures to help prevent such complications are emphasized.
Adult↗
Treating locally aggressive sinus disease.
Explore the source record for details and available documents.
Humans↗
Escherichia coli K12 regains its O antigen.
Extant Escherichia coli K12 strains are phenotypically rough, their lipopolysaccharide having a complete core structure, but no O antigen. We used DNA hybridization and DNA sequencing to show that the rough phenotype of this strain is due to the presence of one of two independent mutations in the rfb gene cluster. The rfb-50 mutation, consisting of an IS5 insertion at the downstream end of rfb, is present in strain EMG2, which is representative of most K12 derivatives. The rfb-51 mutation is a deletion at the upstream end of rfb, and was found in strain WG1. A gene cloned from strain WG1 could complement the rfb-50 mutation in strain EMG2, and the complemented strain produced O antigen which was typed as O16 with cross reaction to O17.
Amino Acid Sequence↗
Subcritical-supercritical bifurcation crossover in directional solidification.
Explore the source record for details and available documents.
Journal Article↗
Structure of the O antigen of Escherichia coli K-12 and the sequence of its rfb gene cluster.
Escherichia coli K-12 has long been known not to produce an O antigen. We recently identified two independent mutations in different lineages of K-12 which had led to loss of O antigen synthesis (D. Liu and P. R. Reeves, Microbiology 140:49-57, 1994) and constructed a strain with all rfb (O antigen) genes intact which synthesized a variant of O antigen O16, giving cross-reaction with anti-O17 antibody. We determined the structure of this O antigen to be -->2)-beta-D-Galf-(1-->6)-alpha-D-Glcp- (1-->3)-alpha-L-Rhap-(1-->3)-alpha-D-GlcpNAc-(1-->, with an O-acetyl group on C-2 of the rhamnose and a side chain alpha-D-Glcp on C-6 of GlcNAc. O antigen synthesis is rfe dependent, and D-GlcpNAc is the first sugar of the biological repeat unit. We sequenced the rfb (O antigen) gene cluster and found 11 open reading frames. Four rhamnose pathway genes are identified by similarity to those of other strains, the rhamnose transferase gene is identified by assay of its product, and the identities of other genes are predicted with various degrees of confidence. We interpret earlier observations on interaction between the rfb region of Escherichia coli K-12 and those of E. coli O4 and E. coli Flexneri. All K-12 rfb genes were of low G+C content for E. coli. The rhamnose pathway genes were similar in sequence to those of (Shigella) Dysenteriae 1 and Flexneri, but the other genes showed distant or no similarity. We suggest that the K-12 gene cluster is a member of a family of rfb gene clusters, including those of Dysenteriae 1 and Flexneri, which evolved outside E. coli and was acquired by lateral gene transfer.
Acetylation↗
Comparison of PCR with culture for detection of Ureaplasma urealyticum in clinical samples from patients with urogenital infections.
PCR was compared with culture for the detection of Ureaplasma urealyticum in 50 specimens, including sperm, urine, and prostate secretions, from hospital patients with urogenital infections. Five positive and a further four doubtful diagnoses were made by culture, whereas PCR detected U. urealyticum in 12 samples. PCR also was faster than culturing. The increased sensitivity and shorter time requirement of PCR support its further development for the diagnosis of U. urealyticum infection.
Adult↗
The chinook salmon gonadotropin II beta subunit gene contains a strong minimal promoter with a proximal negative element.
The salmon pituitary expresses two distinct gonadotropins, gonadotropin I (GTHI) and gonadotropin II (GTHII). These two hormones are synthesized in distinct pituitary cells and secreted at different stages during the reproductive cycle. To study the transcriptional regulation of the hormone-specific beta-subunit of GTHII (sGTHII beta) gene, approximately 3.5 kilobases of the 5'-flanking region was characterized and sequenced. The pituitary specificity of sGTHII beta was examined by analyzing sGTHII beta promoter activity in homologous primary pituitary cells derived from spawning rainbow trout and in a collection of heterologous cell lines. Various lengths of the 5'-flanking region of the sGTHII beta gene were ligated into a vector encoding the bacterial chloramphenicol acetyltransferase (CAT) gene, and the resulting sGTHII beta/CAT chimeric constructs were analyzed using transient expression systems. Several constructs (-3500CAT, -1260CAT, -563CAT, and -39CAT) displayed readily detectable CAT activity in the pituitary cells derived from spawning male and female rainbow trout. In contrast, three of the constructs (-3500CAT, -1260CAT, and -563CAT) were expressed only at background levels in a variety of heterologous cell lines, suggesting that the 5'-flanking sequence of sGTHII beta contains information dictating its pituitary specificity. A silencer sequence (-95 to -35, pSil) was identified, which might function to repress sGTHII beta gene expression in the nongonadotropes or in the gonadotropes at developmental stages that precede final maturation and spawning.
Animals↗
Differential recruitment of steroid hormone response elements may dictate the expression of the pituitary gonadotropin II beta subunit gene during salmon maturation.
The role of testosterone (T) and 17 beta-estradiol (E2) in the control of chinook salmon gonadotropin II beta subunit (sGTHII beta) gene was examined. Both E2 and T specifically stimulated GTHII beta gene expression in cultured juvenile rainbow trout pituitary cells. 5'-Flanking regions of the sGTHII beta gene linked to the chloramphenicol acetyltransferase (CAT) expression vector were transfected into these pituitary cells, and cultures were treated with steroid hormones. Estrogen-stimulated CAT activity occurred with constructs containing a 13-base pair estrogen responsive element (ERE) sequence [proximal ERE (pERE)] located at -273 to -260 upstream of its transcriptional start site. Binding specificity of pERE was confirmed by mobility shift and DNA methylation interference assays using the DNA binding domain of the human estrogen receptor. Interestingly, the pERE functioned to derepress the activity of the proximal silencer (pSil) only in the pituitary cells of juvenile trout but not in cells derived from maturing and sexually matured fish. Another potential ERE sequence comprised of three tandemly linked half-ERE palindromes was located from -2736 to -2659 [distal ERE (dERE)] of the sGTHII beta gene. Distal ERE might be responsible for the steroid responsiveness of the longest sGTHII beta/CAT construct (-3500CAT) observed in the pituitary cells of maturing fish. The function of pERE and dERE were further examined in the heterologous HeLa cells by mutagenesis and cotransfection with a rainbow trout estrogen receptor expression vector. Disruption of the palindromic structure of pERE severely impaired its function. When the sequences between pERE and dERE were deleted, a 200-fold increase in CAT activity was observed in response to E2. A model is proposed to describe the regulation of GTHII beta gene expression at different reproductive stages.
Animals↗
Intraorbital foreign bodies.
A high index of suspicion is important in evaluating any penetrating orbital injury. Likewise, any chronically infected orbit must be suspected of harboring an IOrbFB. Careful history and examination are mandatory for both clinical and medicolegal purposes. Appropriate imaging studies, usually including CT scanning, must be employed. Antibiotic therapy may be crucial in preventing infectious complications, including those involving the central nervous system. The decision regarding surgery must be individualized and should consider visual status, form and composition, and localization of an IOrbFB. The possibility of orbitocranial extension should always be considered and ruled out. Following these general rules, an injury with a small but real potential for clinical disaster may be mitigated, and visual and neurological outcome may be optimized.
Brain Injuries↗
[Combinations of methods for the monitoring of the cerebral microcirculation].
Any single method for measuring changes in local cerebral blood flow (LCBF) or blood vessels during physiological stimuli has individual strengths and deficiencies. The coupling of multiple methods based on different physical principles permits simultaneous measurements and tests of interrelated cerebrovascular changes and mechanisms. The present paper describes combined recordings of LCBF by H2 clearance with inhalation (H2Cl-Inh) and with steady electrochemical generation (H2Cl-Gen), by laser Doppler flowmetry (LDF) and by dimensional changes in surface vessels with videomicroscopy through acute cranial windows in rats anesthetized with urethane 1g/kg or urethane (0.6 g/kg) plus chloralose (0.05 g/kg)ip. For H2Cl-Gen recordings paired or quadred Pt sharped block of electrodes (diameter 0.04-0.06 mm) with distance between single electrode 0.3-0.5 mm, was inserted to brain tissue in barrel cortex. One electrode was used for H2 generation and others for LCBF recordings and their position in brain tissue was examined morphologically. Increase local blood flow in barrel cortex and arterial dilation were stimulated by inhalation of 7% CO2 and mechanical stimulation of the contralateral whiskers. H2Cl-Inh was a "gold standard" for quantitative measurements of LCBF within a tissue radius 0.3-0.5 mm from the recording electrode during related tests during steady states at the same site. H2Cl-Gen was very sensitive to transient changes in flow and could record latencies. H2Cl-Gen was calibrated for quantitative measurements of changes in LCBF by pairing with H2Cl-Inh responses to CO2 inhalation. The laser Doppler miniature probe recorded the time course and normalized intensity changes within an approximate 1 mm3 volume of cortex but with more background noise and less sensitivity compared to H2Cl-Gen. Bright illumination of the cranial window increased LCBF by both methods in these experiments. The diameters of surface arterioles and venues were measured in single video frames with date-time markers for correlation with electrical recordings. Changes in diameter were small and were slower compared to H2Cl-Gen and LDF in the present recordings. Received data permit to conclude that there are two optimal combinations of methods were (1) H2Cl-Gen and H2Cl-Inh for both dynamic sensitivity and quantitative LCBF during systemic and neuronal stimulation, and (2) H2Cl-Gen, LDF, and videomicroscopy for multidimensional monitoring of cerebral circulation.
Animals↗
Presence of different O antigen forms in three isolates of one clone of Escherichia coli.
Escherichia coli strains ECOR2, ECOR3 and K-12 are very closely related in genotype as indicated by multilocus enzyme electrophoresis. We show that they have very different rfb regions indicating that recombination has occurred in this region, and we suggest that it may be associated with niche adaptation.
Antigens, Bacterial↗
Experimental studies on electrolytic dosage of ECT for dog's oesophageal injury and clinical effects of ECT for oesophageal anastomotic opening stenosis and oesophageal carcinoma.
Experimental and clinical studies have been performed to explore the potential benefits of electrochemical therapy (ECT) in oesophageal cancer. In a dog experiment, the oesophageal injury induced by ECT was evaluated. The provision of 7.5 volts (V) and 25-100 coulomb (C) was associated with a slight injury of the mucosa, which was completely healed after two weeks. Ten patients with oesophageal stenosis were treated with ECT (4.5-5.5 V, 20-50 mA and 85-180 C). In all patients there was a significant dilatation of the stenotic area and the patients could eat a normal diet after three to four weeks. The clinical effectiveness in 35 patients treated with ECT for inoperable oesophagela carcinoma was found to be satisfactory. Complete and partial response was obtained in 15 cases (42.8%), and dysphagia was relieved for five to 13 months. In conclusion, oesophageal cancer may be successfully treated with a specially designed electrode and a specified dosage of electricity.
Aged↗
Electrostatic therapy (EST) of lung cancer and pulmonary metastasis: report of 15 cases.
Fifteen patients with primary lung cancer or pulmonary metastases were treated with electrostatic therapy (EST). The patients were treated with either low voltage (200 to 1200 V), high voltage (500 to 2500 V), or high voltage together with high magnetic field. At six months after EST, tumour regression was observed in two cases, relief of symptoms, but no change in tumour size, in five cases, and no effect of EST in nine patients. In conclusion, no marked effect of EST for treatment of cancer could be observed.
Adult↗