Biomedical subjects

Q Xue

Publications and source records attributed to Q Xue.

At least 19 recordsLinked to original sources

PubMed2000

Development of multichannel devices with an array of electrospray tips for high-throughput mass spectrometry.

The basic principles of multichannel devices with an array of electrospray tips for high-throughput infusion electrospray ionization mass spectrometry (ESI-MS) have been developed. The prototype plastic devices were fabricated by casting from a solvent-resistant resin. The sample wells on the device were arranged in the format of the standard 96-microtiter well plate, with each sample well connected to an independent electrospray exit port via a microchannel with imbedded electrode. A second plastic plate with distribution microchannels was employed as a cover plate and pressure distributor. Nitrogen gas was used to pressurize individual wells for transport of sample into the electrospray exit port. The design of independent microchannels and electrospray exit ports allowed very high throughput and duty cycle, as well as elimination of any potential sample carryover. The device was placed on a computer-controlled translation stage for precise positioning of the electrospray exit ports in front of the mass spectrometer sampling orifice. High-throughput ESI-MS was demonstrated by analyzing 96 peptide samples in 480 s, corresponding to a potential throughput of 720 samples/h. As a model application, the device was used for the MS determination of inhibition constants of several inhibitors of HIV-1 protease.

Angiotensins↗

PubMed2000

Separation of European flat oyster, Ostrea edulis, haemocytes by density gradient centrifugation and SDS-PAGE characterisation of separated haemocyte sub-populations.

A two-step gradient centrifugation with Percoll and Ficoll successively as density medium was developed to separate European flat oyster, Ostrea edulis, haemocytes into three sub-populations representing granulocytes, large hyalinocytes and small hyalinocytes, respectively. After a Percoll gradient centrifugation, granulocytes and agranulocytes were separated and a pure fraction of granulocytes was obtained. The agranulocytes were further separated by centrifugation through a Ficoll gradient, and two haemocyte subpopulations representing large hyalinocytes and small hyalinocytes were obtained. No significant impact on the haemocyte viability was detected after separation with this two-step density gradient centrifugation. The three haemocyte sub-populations showed different protein patterns in SDS-PAGE.

Animals↗

PubMed2000

Enzymatic activities in European flat oyster, Ostrea edulis, and pacific oyster, Crassostrea gigas, hemolymph.

Enzymatic activities in the hemolymph of healthy and Bonamia-infected Ostrea edulis and Crassostrea gigas were studied with a commercial kit for the detection of 19 enzymes: 15 and 16 enzymes, respectively, were detected in the hemolymph of O. edulis and C. gigas and 10 of them showed relatively high activity levels. Most of them existed in both the cell-free fraction of the hemolymph and in the hemocytes. The cell-free hemolymph fraction of Bonamia ostreae-infected European flat oysters showed an elevated enzymatic activity level compared with that of healthy individuals. C. gigas hemocytes possessed higher enzymatic activity levels than O. edulis hemocytes. Differences in enzymatic activities existed in granulocytes and hyalinocytes in both oyster species. The enzyme release from oyster hemocytes seemed to be selective. The infection by B. ostreae induced enzymatic activity variations in European flat oysters. Higher enzyme levels within hemocytes may contribute partly to the natural resistance of C. gigas to the infection by B. ostreae.

Animals↗

PubMed2000

Invasion and metastasis of hepatocellular carcinoma in relation to urokinase-type plasminogen activator, its receptor and inhibitor.

This study was designed to investigate the relationship of urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), and plasminogen activator inhibitor type-1 (PAI-1) to invasion and metastasis of hepatocellular carcinoma (HCC). The expression of uPA, uPAR, and PAI-1 in HCC was determined by immunohistochemistry, Northern blot, and an LCI-D20 nude mouse metastatic model of HCC. The overexpression of uPA, uPAR, and PAI-1 was found in HCC, especially in the patients with portal cancer embolus, tumor invasion, and metastasis. Immunohistochemistry results showed that the rate of positive staining of uPA, uPAR, and PAI-1 were higher in HCC than those in the control groups consisting of cancer-adjacent tissue and normal liver tissue. In the case of HCC invasion, positive uPA and uPAR were seen in 16 and 19 out of 22 patients, respectively (P<0.01 and P<0.001, respectively, as compared with the patients without invasion). In those with portal cancer embolus and tumor metastasis, positive uPAR was eight out of eight and six out of six patients. In those with tumor recurrence, positive uPAR was 15 out of 17 patients (P<0.01 vs. no recurrence). In patients who died within 2 years after surgery, positive uPAR was 12 out of 12 patients (P<0.01 vs. survival), and positive PAI-1 was nine out of 12 patients (P<0.05 vs. survival). In those in which uPA, uPAR, and PAI-1 were all positive staining, stronger cancer invasiveness and higher mortality were found (P<0.05 vs. patients with all negative staining). In 30 patients tested with Northern blot analysis, the results were similar to those tested with immunohistochemistry. Higher expression of uPA mRNA and PAI-1 mRNA were detected in tumor tissues and embolus. In the patients with positive signals of uPA mRNA and PAI-1 mRNA, invasive cases were found in seven out of 19 and eight out of 18 patients, respectively, which were significantly higher than those showing negative signals (P<0.05). In the LCI-D20 nude mouse metastatic model of HCC (MMHCC), PAI-1 activity in plasma and tumor tissue increased with tumor growth, invasion, and metastasis. At an advanced stage of MMHCC, PAI-1 activity rose to 15.4+/-0.7 Au/ml in plasma and 0.8+/-0.3 Au/mg in tumor extracts, which was significantly higher than 6.2+/-1.8 Au/ml in plasma and 0.4+/-0.1 Au/mg in extracts at an early stage (P<0.05). PAI-1 activity related to the changes of serum AFP and tumor progress were r = 0.9544 and r = 0.9648, respectively (P<0.05). The data suggest that the expression of uPA, uPAR, and PAI-1 is increased in HCC, and related to the invasiveness, metastasis, and prognosis of HCC.

Animals↗

PubMed2000

Immunohistochemical inactivation of p14ARF concomitant with MDM2 overexpression inversely correlates with p53 overexpression in oral squamous cell carcinoma.

The CDKN2 gene encodes two structurally different proteins: a cyclin-dependent kinase inhibitor called p16, which regulates retinoblastoma protein (pRb)-dependent G1 arrest, and a cell cycle inhibitor designated p14ARF, which arrests cell growth in G1-S and also in G2-M. Whereas inactivation of p16 has been described as a frequent event in various cancers, including oral cancer, the current function of p14ARF is still poorly understood. A physical association between p14ARF and MDM2 blocks MDM2-induced p53 degradation, resulting in increased levels of p53, which in turn leads to cell cycle arrest. The present study immunohistochemically examined the expression of p16 and p14ARF together with pRb, MDM2 and p53 status in a series of oral cancers. The results showed that p14ARF was frequently absent in the oral cancers (15/37, 41%) as was p16 immunostaining. Concomitant immunopositivity for p14ARF and MDM2 overexpression was frequently observed in a subset of the cancers, whereas an inverse correlation between p14ARF and MDM2 expression and the diffuse staining of p53 was clearly detected. Moreover, the results showed that in most cases of oral cancer (35/37, 95%) at least one protein was altered, and lymph node metastasis was more frequent in the tumors with alterations in both the p16/pRb and p14ARF/p53 pathway (8/16, 50%) than in the tumors with one or no alteration of these two major pathways.

Adult↗

PubMed2000

High-dose and long-term therapy with interferon-alfa inhibits tumor growth and recurrence in nude mice bearing human hepatocellular carcinoma xenografts with high metastatic potential.

Postoperative recurrence of human hepatocellular carcinoma (HCC) is the major issue that must be addressed to further improve prognosis. This study was undertaken to investigate the effects of interferon-alfa-1b (IFN-alpha-1b) on recurrent tumor and metastasis after curative resection in nude mice bearing an HCC xenograft with high metastatic potential. Tumor tissues from LCI-D20, a metastatic model of HCC in nude mice, were orthotopically implanted in 105 nude mice. Eleven days later, 64 mice underwent curative resection of liver tumors. IFN-alpha at different doses was administered subcutaneously to mice with or without resection. In mice without resection, when comparison was made among control, IFN 7.5 x 10(6) U/kg/day, 1.5 x 10(7) U/kg/day for treated groups, and 3 x 10(7) U/kg/day; tumor volume was 8,475 mm(3) +/- 2,636 mm(3), 7,963 mm(3) +/- 3,214 mm(3), 769 mm(3) +/- 287 mm(3), and 13 mm(3) +/- 9 mm(3); incidence of lung metastasis being 100%, 80%, 40%, and 0%; life span was 45 +/- 4 days, 53 +/- 8 days, 81 +/- 6 days, and 105 +/- 24 days, respectively. In mice with curative resection, when comparison was made among control, IFN 5 x 10(5) U/kg/day, 1 x 10(6) U/kg/day, 4 x 10(6) U/kg/day, 7.5 x 10(6) U/kg/day, 1.5 x 10(7) U/kg/day, and 3 x 10(7) U/kg/day for treated groups; incidence of recurrent tumor was 100%, 100%, 87.5%, 100%, 87.5%, 62.5%, and 12.5%; lung metastasis being 100%, 75%, 87.5%, 50%, 62.5%, 0%, and 0%, respectively. IFN-alpha inhibited neovascularization induced by LCI-D20 tumor specimens implanted into the micropocket of nude mice corneas. In conclusion, high-dose and long-term therapy with IFN-alpha dose-dependently inhibits tumor growth and recurrence after resection of HCC. The effect of IFN-alpha may be attributed to antiangiogenesis in this experiment. These results provide potential clinical implication, particularly for the prevention of recurrence after curative resection of HCC.

Animals↗

PubMed2000

The added diagnostic value of automated QT-dispersion measurements and automated ST-segment deviations in the electrocardiographic diagnosis of acute cardiac ischemia.

The purpose of this study was to determine the added value of automated QT dispersion and ST-segment measurements to physician interpretation of 12-lead electrocardiograms (ECGs) in patients with chest pain. To date, poor reproducibility of manual measurements and lack of shown added value have limited the clinical use of QT dispersion. Twelve-lead ECGs (n = 1,161) from the Milwaukee Prehospital Chest Pain Database were independently classified by 2 physicians into 3 groups (acute myocardial infarction (AMI), acute cardiac ischemia (ACI), or nonischemic), and their consensus was obtained. QT-end and QT-peak dispersions were measured by a computerized system. The computer also identified ST-segment deviations. Sensitivity, specificity, and positive predictive values (PPVs) and negative predictive values (NPV) for AMI and ACI were evaluated independently and in combinations. For AMI, physicians' consensus classification was remarkably good (sensitivity, 48%, specificity, 99%). Independent classification by QT-end and QT-peak dispersions or ST deviations was not superior to the physicians' consensus. Optimal classification occurred by combining automated QT-end dispersion and ST deviations with physicians' consensus. This combination increased sensitivity for the diagnoses of AMI by 35% (65% vs 48%, P < .001) and ACI by 55% (62% vs 40%, P < .001) compared with physicians' consensus, while maintaining comparable specificity. This study supports a potential clinical role for automated QT dispersion when combined with other diagnostic methods for detecting AMI and ACI.

Adolescent↗

PubMed2000

Differential host inflammatory responses to viable versus antibiotic-killed bacteria in experimental microbial sepsis.

Staphylococcus aureus killed during imipenem or ceftazidime chemotherapy in mice elicited an early release of tumor necrosis factor alpha (TNF-alpha) into the systemic circulation. This response was coincident in time with an increase in leukocyte-endothelium adhesive interactions in the microvasculature. Equivalent responses were not observed without the antibiotic treatment (imipenem or ceftazidime). Protective efficacy of the same antibiotic treatment was markedly diminished in D-galactosamine-treated mice compared to controls; e.g., it dropped from 2,000-fold to 70-fold with 4 mg of imipenem per kg given at the time of challenge. Nevertheless, protection was quantitatively restored upon concurrent administration of neutralizing anti-TNF-alpha antibody or 4 mg of dexamethasone per kg to these TNF-alpha-hypersensitive mice. Importantly, protection afforded by dexamethasone was not seen when the animals were challenged with viable organisms but without the concurrent administration of antibiotic. An early TNF-alpha response could also be demonstrated upon challenge with Escherichia coli, but in this instance, neither the timing nor the magnitude of that response was influenced by treatment with these antibiotics. We conclude from these studies that the inflammatory response to viable versus killed bacteria may differ markedly depending on the particular bacterium, host sensitivity to TNF-alpha, and possibly the Gram stain classification.

Animals↗

PubMed2000

Cloning, characterization and heterologous expression of a polyketide synthase and P-450 oxidase involved in the biosynthesis of the antibiotic oleandomycin.

The gene cluster encoding the deoxyoleandolide polyketide synthase (OlePKS) was isolated from the oleandomycin producing strain Streptomnyces antibioticus. Sequencing of the first two genes encoding OlePKS, together with the previously identified third gene revealed an overall genetic and protein architecture similar to that of the erythromycin gene cluster encoding the 6-deoxyerythronolide B synthase (DEBS) from Saccharopolyspora erythraea. When the entire OlePKS (10,487 amino acids) was expressed in the heterologous host Streptomyces lividans, it produced 8,8a-deoxyoleandolide, an aglycone precursor of oleandomycin. The role of the P-450 monooxygenase, OleP, in oleandomycin biosynthesis was also examined in vivo by co-expression with DEBS in S. lividans. The production of 8,8a-dihydroxy-6-deoxyerythronolide B and other derivatives indicates that OleP is involved in the epoxidation pathway of oleandomycin biosynthesis. Since there are currently no genetic systems available for manipulation of the natural oleandomycin producing strain, the heterologous expression system reported here provides a useful tool for studying this important macrolide antibiotic.

Anti-Bacterial Agents↗

PubMed1999

Cutting edge: bacterial DNA and LPS act in synergy in inducing nitric oxide production in RAW 264.7 macrophages.

LPS is well recognized for its potent capacity to activate mouse macrophages to produce NO, an important inflammatory mediator in innate host defense. We demonstrate here that, although inducing little NO alone, DNA from both Gram-negative and Gram-positive bacteria synergizes with subthreshold concentrations of LPS (0.3 ng/ml) to induce NO in cultures of RAW 264.7 macrophages. The effects of the DNA are mimicked by synthetic CpG-containing oligodeoxynucleotides but not by non-CpG-containing oligodeoxynucleotides. This synergistic activity is not inhibited by neutralizing Abs against IFN. Preincubation of macrophages with DNA for 8-24 h suppresses subsequent synergistic macrophage responses to DNA/LPS, whereas prolonged pretreatment with LPS enhances synergy. RT-PCR analysis indicates that the mRNA levels of the inducible NO synthase gene are also coordinately suppressed or induced. These findings indicate that temporally controlled, synergistic interactions exist between microbial DNA and LPS in the induction of macrophage NO via enhanced inducible NO synthase gene expression.

Animals↗

PubMed1999

A multiplasmid approach to preparing large libraries of polyketides.

A three-plasmid system for heterologous expression of 6-deoxyerythronolide B synthase (DEBS) has been developed to facilitate combinatorial biosynthesis of polyketides made by type I modular polyketide synthases (PKSs). The eryA PKS genes encoding the three DEBS subunits were individually cloned into three compatible Streptomyces vectors carrying mutually selectable antibiotic resistance markers. A strain of Streptomyces lividans transformed with all three plasmids produced 6-deoxyerythronolide B at a level similar to that of a strain transformed with a single plasmid containing all three genes. The utility of this system in combinatorial biosynthesis was demonstrated through production of a library of modified polyketide macrolactones by using versions of each plasmid constructed to contain defined mutations. Combinations of these vector sets were introduced into S. lividans, resulting in strains producing a wide range of 6-deoxyerythronolide B analogs. This method can be extended to any modular PKS and has the potential to produce thousands of novel natural products, including ones derived from further modification of the PKS products by tailoring enzymes.

Anti-Bacterial Agents↗

PubMed1999

Invasion and metastasis of liver cancer: expression of intercellular adhesion molecule 1.

PURPOSE: To study the relationship between intercellular adhesion molecule 1 (ICAM-1) and liver cancer metastasis and to find predicting factors that could indicate the growth and metastasis of liver cancer. METHODS: ICAM-1 expression in fresh tissue of normal liver and hepatocellular cancer (HCC) was examined by immunoperoxidase staining. Serum soluble intercellular adhesion molecule 1 (sICAM-1) from patients with a benign HCC tumor, and the expression of ICAM-1 in the orthotopically transplanted LCI-D20 tumor of a nude mouse liver cancer metastasis model, and in human hepatoma, the tumor surrounding tissue and normal liver, was analyzed semiquantitatively by the immuno-dot blot method. Tissue ICAM-1 expression (mRNA level) was detected by Northern blotting. RESULTS: ICAM-1 expression in LD1-20 D metastatic liver cancer had a positive correlation with tumor size and the time after implantation. It increased suddenly as metastasis occurred being 3.03+/-0.51 before metastasis and 8.24+/-0.95 after metastasis, P < 0.01, then remained high, appending on the number of sites involved (monosite metastasis 5.48+/-0.49, multisite metastasis 10.05+/-1.17, P < 0.05). All six cases of normal liver samples were negative in anti-ICAM-1 immunohistochemical staining, 80.0% (36/45) of the HCC showed some ICAM-1 expression. The rate of positive cells was a little higher in large tumors, tumors with an intact capsule and tumors with metastasis, but there was no significant difference. It was noticed that two cancer emboli also had high ICAM-1 expression. The ICAM-1 concentration in HCC (13.43+/-0.09) was higher than that in tumor surrounding the liver (5.89+/-0.17, P < 0.01) and that in normal liver (4.27+/-0.21, P < 0.01). sICAM-1, like tissue ICAM-1, was higher in HCC patients than in patients (with benign liver tumor and normal controls. Both tissue ICAM-1 and sICAM-1 were higher in the metastasis group than in the group without metastasis (tissue ICAM-1 20.24+/-0.30 vs 10.23+/-0.12 P < 0.05; sICAM-1 12.18+/-0.25 vs 9.77+/-0.54 P < 0.05). Northern blot analysis revealed that ICAM-1 expression, as indicated by mRNA level, was also higher in HCC and in cancer emboli than in tumor surrounding liver and normal liver. CONCLUSIONS: Tissue ICAM-1 and serum sICAM-1 could indicate the stage of HCC, and the potential of hepatoma cells for invasion and metastasis. They may play an important role in the metastasis cascade.

Animals↗

PubMed1999

Review of methods to predict and detect atrial fibrillation in post-cardiac surgery patients.

Atrial fibrillation (AF) is the most common sustained arrhythmia after cardiac surgery. Postoperative AF is known to substantially lengthen hospital stay and affect patient recovery. Identification of those at risk of developing AF after surgery and early detection of AF during recovery would be extremely helpful in effective management of these patients, including targeting prophylactic therapy to prevent AF in high-risk patients. In this communication, diagnostic methods to identify those at risk of developing AF after surgery and early identification of AF before, during, and after surgery have been reviewed. Signal-averaged P wave analysis, done before surgery, identifies patients who are likely to develop AF during recovery. When combined with low ejection fraction, signal-averaged P wave can discriminate those who develop AF from those who do not. During recovery, AF can be detected early either from a detailed analysis of atrial activity in a 10-second electrocardiogram or an analysis of R-to-R intervals from an extended rhythm strip (1 minute or longer). Analysis of the 10-second electrocardiogram includes median QRST subtraction from rhythm data and detection and analysis of atrial signals in the resulting residual. AF is detected from extended rhythm strips by using a statistical model to identify the presence of characteristic irregular patterns of R-to-R intervals.

Atrial Fibrillation↗

PubMed1999

Injured primary sensory neurons switch phenotype for brain-derived neurotrophic factor in the rat.

Peripheral nerve injury results in plastic changes in the dorsal root ganglia and spinal cord, and is often complicated with neuropathic pain. The mechanisms underlying these changes are not known. We have now investigated the expression of brain-derived neurotrophic factor in the dorsal root ganglia with histochemical and biochemical methods following sciatic nerve lesion in the rat. The percentage of neurons immunoreactive for brain-derived neurotrophic factor in the ipsilateral dorsal root ganglia was significantly increased as early as 24 h after the nerve lesion and the increase lasted for at least two weeks. The level of brain-derived neurotrophic factor messenger RNA was also significantly increased in the ipsibut not contralateral dorsal root ganglia. Both neurons and satellite cells in the lesioned dorsal root ganglia synthesized brain-derived neurotrophic factor messenger RNA after the nerve lesion. There was a dramatic shift in size distribution of positive neurons towards large sizes seven days after sciatic nerve lesion. Morphometric analysis and retrograde tracing studies showed that no injured neurons smaller than 600 microm2 were immunoreactive for brain-derived neurotrophic factor, whereas the majority of large injured neurons were immunoreactive in the ipsilateral dorsal root ganglia seven days postlesion. The brain-derived neurotrophic factor-immunoreactive nerve terminals in the ipsilateral spinal cord were reduced in the central region of lamina II, but increased in more medial regions or deeper into laminae III/IV. These studies indicate that sciatic nerve injury results in a differential regulation of brain-derived neurotrophic factor in different subpopulations of sensory neurons in the dorsal root ganglia. Small neurons switched off their normal synthesis of brain-derived neurotrophic factor, whereas larger ones switched to a brain-derived neurotrophic factor phenotype. The phenotypic switch may have functional implications in neuronal plasticity and generation of neuropathic pain after nerve injury.

Animals↗

PubMed1999

New human hepatocellular carcinoma (HCC) cell line with highly metastatic potential (MHCC97) and its expressions of the factors associated with metastasis.

A new human hepatocellular carcinoma (HCC) cell line with a highly metastatic potential was established from subcutaneous xenograft of a metastatic model of human HCC in nude mice (LCI-D20) by means of alternating cell culture in vitro and growth in nude mice. The line, designated MHCC97, has been cultivated for 18 months and subcultured for more than 90 passages. The line was showed to be of human origin by karyotype analysis. The cells were either grown as compact colonies (in clusters) or as a monolayered sheet with about 31 h of population-doubling time, exhibited typical malignant epithelial in morphology and were positive for alpha-fetoprotein (AFP). Flow cytometric analysis of the cell DNA content showed an aneuploid pattern, and its index was 1.5 as compared to that of normal human peripheral blood lymphocytes. Karyotypic analyses of G- and C-banding techniques revealed that all cells presented chromosome abnormalities in number and structure. The number of cell line MHCC97 chromosome ranged from 59 to 65 with a modal number of 60 and 61. At least two common chromosome markers, i(1q) and der(4)t(4;?)(4pter-->q35::?), were present in all cells, and deletion of Y chromosome also occurred in all cells. The subcutaneous and intrahepatic xenografts were formed and metastatic lesions in lungs were found after the cells were inoculated into nude mice. The rate of metastasis to lungs was 100% using orthotopic inoculation. Reverse transcription polymerase chain reaction products revealed positive expressions of integrin alpha5 and beta1, urokinase type plasminogen activator receptor (uPAR), vascular endothelial growth factor and nm23-H1 mRNAs of cell line MHCC97. Immunostaining of c-Met, uPAR showed strongly positive in both subcutaneous xenografts and lung metastatic lesions; while positive in xenografts and negative in metastatic lesions for integrin alpha5, beta1. E-cadherin and P53 was not expressed either in xenograft or in the metastatic lesions. PCR products of HBsAg and HBxAg were both positive. The cell line MHCC97 still retained some characteristic features of original tumour. Establishment of cell line MHCC97 should be beneficial to the studies of HCC metastatic mechanisms.

Adult↗

PubMed1999

Satellite-cell-derived nerve growth factor and neurotrophin-3 are involved in noradrenergic sprouting in the dorsal root ganglia following peripheral nerve injury in the rat.

Injury to a peripheral nerve induces in the dorsal root ganglia (DRG) sprouting of sympathetic and peptidergic terminals around large-diameter sensory neurons that project in the damaged nerve. This pathological change may be implicated in the chronic pain syndromes seen in some patients with peripheral nerve injury. The mechanisms underlying the sprouting are not known. Using in situ hybridization and immunohistochemical techniques, we have now found that nerve growth factor (NGF) and neurotrophin-3 (NT3) synthesis is upregulated in satellite cells surrounding neurons in lesioned DRG as early as 48 h after nerve injury. This response lasts for at least 2 months. Quantitative analysis showed that the levels of mRNAs for NT3 and NGF increased in ipsilateral but not contralateral DRG after nerve injury. Noradrenergic sprouting around the axotomized neurons was associated with p75-immunoreactive satellite cells. Further, antibodies specific to NGF or NT3, delivered by an osmotic mini-pump to the DRG via the lesioned L5 spinal nerve, significantly reduced noradrenergic sprouting. These results implicate satellite cell-derived neurotrophins in the induction of sympathetic sprouting following peripheral nerve injury.

Animals↗

PubMed1998

The late-expressed region of the temperate coliphage 186 genome.

The late-lytic region of the genome of bacteriophage 186 encodes the phage proteins that synthesize the complex viral particle and lyse the bacterial host. We report the completion of the DNA sequence of the late region and the assignment of 18 previously identified genes to open reading frames in the sequence. The 186 late region is similar to the late region of phage P2, sharing 26 genes of known function: the single gene for activation of late gene transcription, 6 genes for construction of DNA-containing heads, 16 for tail morphogenesis, and 3 for cell lysis. We identified two 186 late genes with unknown function; one is homologous to previously unrecognised genes in P2, HP1, and phiCTX, and the other may modulate DNA packaging. The 186 late region, like the rest of the genome, lacks the lysogenic conversion genes that are carried by P2, allowing the 186 late region to be transcribed from only three late promoters rather than four. The relative absence of lysogenic conversion genes in 186 suggests that the two phages have evolved to use the lytic and lysogenic reproductive modes to different extents.

Amino Acid Sequence↗

PubMed1998

Algorithms for computerized QT analysis.

Several methods for measurement of the offset, peak, and morphology of the T wave in multilead ECGs are reviewed and compared. The T wave offset is the most important and also the most difficult measurement for analysis of QT interval dispersion. Measurement methods compared here include (1) the point at which the T wave intersects the isoelectric line plus a threshold; (2) the point at which the derivative of T wave intersects the isoelectric line plus a threshold; (3) the intersection of the maximum slope of the T wave and the isoelectric line; (4) the intersection of a line fitted by least squares to the maximum slope of the T wave and an isoelectric line (LSI); and (5) the point at which the T wave area reaches 90% of the entire T wave area (TA). The reproducibility tests show that the LSI method has the best reproducibility of all the algorithms examined. Although the T wave peak is better defined than the T wave offset, it is not simple to find the right peak when there are multiple T wave peaks and when the T wave is flat and/or noisy. Methods to find T wave patterns with multiple peaks and to locate the point at which the T wave is flat and noisy are therefore reviewed here. Finally, the principal component analysis-based T wave complexity measurement and its relation to other QT interval dispersion measurements are discussed.

Algorithms↗