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Biomedical subjects

A Becker

Publications and source records attributed to A Becker.

At least 91 records · Page 5Linked to original sources
PubMed2001

Fatal myeloencephalopathy due to accidental intrathecal vincristin administration: a report of two cases.

We report on two fatal cases of accidental intrathecal vincristine instillation in a 5-year old girl with recurrent acute lymphoblastic leucemia and a 57-year old man with lymphoblastic lymphoma. The girl died seven days, the man four weeks after intrathecal injection of vincristine. Clinically, the onset was characterized by the signs of opistothonus, sensory and motor dysfunction and ascending paralysis. Histological and immunohistochemical investigations (HE-LFB, CD-68, Neurofilament) revealed degeneration of myelin and axons as well as pseudocystic transformation in areas exposed to vincristine, accompanied by secondary changes with numerous prominent macrophages. The clinical course and histopathological results of the two cases are presented. A review of all reported cases in the literature is given. A better controlled regimen for administering vincristine and intrathecal chemotherapy is recommended.

Antineoplastic Agents, Phytogenic↗
PubMed2001

Soluble guanylate cyclase is required during development for visual system function in Drosophila.

A requirement for nitric oxide (NO) in visual system development has been demonstrated in many model systems, but the role of potential downstream effector molecules has not been established. Developing Drosophila photoreceptors express an NO-sensitive soluble guanylate cyclase (sGC), whereas the optic lobe targets express NO synthase. Both of these molecules are expressed after photoreceptor outgrowth to the optic lobe, when retinal growth cones are actively selecting their postsynaptic partners. We have previously shown that inhibition of the NO-cGMP pathway in vitro leads to overgrowth of retinal axons. Here we examined flies mutant for the alpha subunit gene of the Drosophila sGC (Gcalpha1). This mutation severely reduced but did not abolish GCalpha1 protein levels and NO-stimulated sGC activity in the developing photoreceptors. Although few mutant individuals possessed a disorganized retinal projection pattern, pharmacological NOS inhibition during metamorphosis increased this disorganization in mutants to a greater degree than in the wild type. Adult mutants lacked phototactic behavior, and the off-transient component of electroretinograms was frequently absent or greatly reduced in amplitude. Normal phototaxis and off-transient amplitude were restored by heat shock-mediated Gcalpha1 expression applied during metamorphosis but not in the adult. We propose that diminished sGC activity in the visual system during development causes inappropriate or inadequate formation of first-order retinal synapses, leading to defects in visual system function and visually mediated behavior.

Animals↗
PubMed2001

Usefulness of calcium scoring using electron beam computed tomography and noninvasive coronary angiography in patients with suspected coronary artery disease.

The aim of this study was to investigate the reliability of calcium scoring (CS) and electron beam computed tomographic angiography (EBCTA) as a noninvasive tool in the diagnosis of coronary artery disease (CAD): 93 consecutive patients (aged 59 +/- 9 years) with symptoms suspicious for CAD underwent CS. In 87 of these subjects, an additional EBCTA investigation was performed. Using receiver-operating characteristic curve analysis, we determined a calcium score cut point providing an overall sensitivity of 80% and a specificity of 72% in detecting patients with CAD. For clinical purposes the use of cut points is difficult. We therefore determined score ranges providing >80% specificity (high score range) and >85% sensitivity (low score range) and determined the scores between these ranges as equivocal borderline scores. Calculated on a per-segment basis in assessable proximal and midcoronary segments, the sensitivity for detecting coronary stenoses >50% was 78%, and the specificity was 93%. Thus, 32 of 44 patients with significant CAD and 24 of 49 patients without CAD were correctly classified. The combination of CS and EBCTA predicted CAD in 77% (72 of 93) of patients. No or low calcium scores provided high specificity for ruling out CAD. The addition of EBCTA in those patients improved sensitivity. In patients with high calcium scores, accuracy of EBCTA was not significantly different from CS alone (72% vs 83%), whereas in patients with borderline scores it was significantly superior (80% vs 58%, p <0.03). Thus, the complementary use of CS and EBCTA appears beneficial, particularly in patients with borderline scores, and could improve sensitivity in the low score range. In the presence of high scores, no major diagnostic gain from an additional EBCTA versus CS alone could be observed.

Calcinosis↗
PubMed2001

Analysis of the chromosome sequence of the legume symbiont Sinorhizobium meliloti strain 1021.

Sinorhizobium meliloti is an alpha-proteobacterium that forms agronomically important N(2)-fixing root nodules in legumes. We report here the complete sequence of the largest constituent of its genome, a 62.7% GC-rich 3,654,135-bp circular chromosome. Annotation allowed assignment of a function to 59% of the 3,341 predicted protein-coding ORFs, the rest exhibiting partial, weak, or no similarity with any known sequence. Unexpectedly, the level of reiteration within this replicon is low, with only two genes duplicated with more than 90% nucleotide sequence identity, transposon elements accounting for 2.2% of the sequence, and a few hundred short repeated palindromic motifs (RIME1, RIME2, and C) widespread over the chromosome. Three regions with a significantly lower GC content are most likely of external origin. Detailed annotation revealed that this replicon contains all housekeeping genes except two essential genes that are located on pSymB. Amino acid/peptide transport and degradation and sugar metabolism appear as two major features of the S. meliloti chromosome. The presence in this replicon of a large number of nucleotide cyclases with a peculiar structure, as well as of genes homologous to virulence determinants of animal and plant pathogens, opens perspectives in the study of this bacterium both as a free-living soil microorganism and as a plant symbiont.

Bacterial Proteins↗
PubMed2001

The complete sequence of the 1,683-kb pSymB megaplasmid from the N2-fixing endosymbiont Sinorhizobium meliloti.

Analysis of the 1,683,333-nt sequence of the pSymB megaplasmid from the symbiotic N(2)-fixing bacterium Sinorhizobium meliloti revealed that the replicon has a high gene density with a total of 1,570 protein-coding regions, with few insertion elements and regions duplicated elsewhere in the genome. The only copies of an essential arg-tRNA gene and the minCDE genes are located on pSymB. Almost 20% of the pSymB sequence carries genes encoding solute uptake systems, most of which were of the ATP-binding cassette family. Many previously unsuspected genes involved in polysaccharide biosynthesis were identified and these, together with the two known distinct exopolysaccharide synthesis gene clusters, show that 14% of the pSymB sequence is dedicated to polysaccharide synthesis. Other recognizable gene clusters include many involved in catabolic activities such as protocatechuate utilization and phosphonate degradation. The functions of these genes are consistent with the notion that pSymB plays a major role in the saprophytic competence of the bacteria in the soil environment.

Bacterial Proteins↗
PubMed2001

The composite genome of the legume symbiont Sinorhizobium meliloti.

The scarcity of usable nitrogen frequently limits plant growth. A tight metabolic association with rhizobial bacteria allows legumes to obtain nitrogen compounds by bacterial reduction of dinitrogen (N2) to ammonium (NH4+). We present here the annotated DNA sequence of the alpha-proteobacterium Sinorhizobium meliloti, the symbiont of alfalfa. The tripartite 6.7-megabase (Mb) genome comprises a 3.65-Mb chromosome, and 1.35-Mb pSymA and 1.68-Mb pSymB megaplasmids. Genome sequence analysis indicates that all three elements contribute, in varying degrees, to symbiosis and reveals how this genome may have emerged during evolution. The genome sequence will be useful in understanding the dynamics of interkingdom associations and of life in soil environments.

Bacterial Adhesion↗
PubMed2001

Tumor hypoxia, p53, and prognosis in cervical cancers.

BACKGROUND: The p53 protein is involved in the regulation of initiation of apoptosis. In vitro, p53-deficient cells do not respond to hypoxia with apoptosis as do p53-normal cells, and this may lead to a relative growth advantage of cells without a functioning p53 under hypoxia. On the basis of this hypothesis, a selection of cells with a functionally inactive p53 may occur in hypoxic tumors. The development of uterine cervical carcinomas is closely associated with infections of human papilloma viruses, which may cause a degradation of the tumor suppressor gene p53, resulting in a restriction of apoptosis. Thus, cervical cancers have often a functionally inactive p53. The purpose of our clinical study was therefore to investigate the association between p53, hypoxia, and prognosis in cervical cancers in which the oxygenation status can be determined by clinical methods. MATERIAL AND METHODS: Seventy patients with locally advanced squamous cell cervical cancer Stages IIB (n = 14), IIIB (n = 49), and IVA (n = 7) were investigated in the period from 1996 through 1999. All were treated with definitive radiotherapy with curative intent by a combination of external radiotherapy plus high-dose-rate afterloading. Before therapy, tumor oxygenation was measured with a needle probe polarographically using the Eppendorf histograph. Hypoxic tumors were defined as those with pO(2) measurements below 5 mm Hg (HF5). Pretreatment biopsies were taken and analyzed immunohistologically for p53 protein expression with the DO-7 antibody. The DNA index was measured by flow cytometry. The statistical data analysis was done with SPSS 9.0 for Windows. RESULTS: The 3-year overall survival was 55% for the whole group of patients. Clinical prognostic factors in a multivariate analysis were pretreatment hemoglobin level (3-year survival 62% for patients with a pretreatment hemoglobin > or =11 g/dl vs. 27% for hemoglobin <11 g/dl, p = 0.006) and FIGO stage (Stage IIB: 65%; Stage IIIB: 60%; Stage IVA: 29%, p = 0.01). Sixty of the 70 tumors showed positive immunohistologic staining for p53 protein (transformed p53 = tp53), and 10/70 were negative (wild-type p53 = wtp53); p53 expression had no significant impact on survival (50% for tp53 vs. 79% for wtp53, p = 0.11). FIGO stage and anemia had no impact on p53 expression. Forty-nine of 70 tumors were hypoxic (HF5+), and 21 showed no hypoxia (HF5-). Hypoxic carcinomas were more frequently positive for p53 as compared to nonhypoxic tumors (27% vs. 13%, p = 0.011) and showed a trend toward a lower survival (48% vs. 70%, p = 0.07). In a further multivariate analysis, the impact of a combination of p53 expression and hypoxia on survival was examined. After adjusting for FIGO stage and pretreatment anemia, patients with wtp53 tumors had the best prognosis (3-year survival 79%) followed by tp53-HF5(-) patients (57%), and the most unfavorable prognosis was observed for tp53-HF5(+) patients (47%). The DNA index was higher in tp53 carcinomas compared to wtp53 tumors, 1.97 +/- 0.4 vs. 1.67 +/- 0.1, p = 0.05. The highest DNA index was found in hypoxic tumors with transformed p53 (2.2 +/- 3.1). CONCLUSIONS: Advanced stage and pretreatment hemoglobin level are independent prognostic factors in cervical carcinomas. The immunohistologic detection of (a functionally inactive) p53 and the presence of hypoxia had no prognostic impact, if analyzed as single parameters. However, the combination of both parameters was able to discriminate different prognostic subgroups. Moreover, hypoxic cancers were more often immunohistologically positive for tp53 protein and had a higher DNA index with the highest DNA index in tumors with both hypoxia and tp53 protein expression. These findings in summary support the theory that the tumor's microenvironment may influence the biologic behavior via hypoxia.

Adult↗
PubMed2001

Prospective, multicenter evaluation of risk factors associated with invasive bacterial infection in children with cancer, neutropenia, and fever.

PURPOSE: To identify clinical and laboratory parameters present at the time of a first evaluation that could help predict which children with cancer, fever, and neutropenia were at high risk or low risk for an invasive bacterial infection. PATIENTS AND METHODS: Over a 17-month period, all children with cancer, fever, and neutropenia admitted to five hospitals in Santiago, Chile, were enrolled onto a prospective protocol. Associations between admission parameters and risk for invasive bacterial infection were assessed by univariate and logistic regression analyses. RESULTS: A total of 447 febrile neutropenic episodes occurred in 257 children. Five parameters were statistically independent risk factors for an invasive bacterial infection. Ranked by order of significance, they were as follows: C-reactive protein levels of 90 mg/L or higher (relative risk [RR], 4.2; 95% confidence interval [CI], 3.6 to 4.8); presence of hypotension (RR, 2.7; 95% CI, 2.3 to 3.2); relapse of leukemia as cancer type (RR, 1.8, 95% CI, 1.7 to 2.3); platelet count less than or equal to 50,000/mm(3) (RR, 1.7; 95% CI, 1.4 to 2.2); and recent (< or = 7 days) chemotherapy (RR, 1.3; 95% CI, 1.1 to 1.6). Other previously postulated risk factors (magnitude of fever, monocyte count) were not independent risk factors in this study population. CONCLUSION: In a large population of children, common clinical and laboratory admission parameters were identified that can help predict the risk for an invasive bacterial infection. These results encourage the possibility of a more selective management strategy for these children.

Adolescent↗
PubMed2001

Presenilin-1-associated abnormalities in regional cerebral perfusion.

OBJECTIVE: To investigate the influence of the presenilin-1 gene (PS-1) mutation on regional cerebral perfusion, SPECT was evaluated in 57 individuals. The subjects were members of a large pedigree from Colombia, South America, many of whom carry a PS-1 mutation for early-onset AD. METHODS: Members of this large kindred who were cognitively normal and did not carry the PS-1 mutation (n = 23) were compared with subjects who were carriers of the mutation but were asymptomatic (n = 18) and with individuals with the mutation and a clinical diagnosis of AD (n = 16). Cerebral perfusion was measured in each subject using hexamethylpropyleneamine oxime SPECT. The data were analyzed in two ways: 1) Mean cerebral perfusion in each of 4320 voxels in the brain was compared among the groups using t-tests (t-maps); and 2) each individual received a weighted score on 20 vectors (factors), based on a large normative sample (n = 200), using a method known as singular value decomposition (SVD). RESULTS: Based on t-maps, subjects with the PS-1 mutation who were asymptomatic demonstrated reduced perfusion in comparison with the normal control subjects in the hippocampal complex, anterior and posterior cingulate, posterior parietal lobe, and anterior frontal lobe. The AD patients demonstrated decreased perfusion in the posterior parietal and superior frontal cortex in comparison with the normal control subjects. Discriminant function analysis of the vector scores derived from SVD (adjusted for age and gender) accurately discriminated 86% of the subjects in the three groups (p < 0.0005). CONCLUSION: Regional cerebral perfusion abnormalities based on SPECT are detectable before development of the clinical symptoms of AD in carriers of the PS-1 mutation.

Adult↗
PubMed2001

Antagonistic effects of hypertrehalosemic neuropeptide on the activities of 6-phosphofructo-1-kinase and fructose-1,6-bisphosphatase in cockroach fat body.

Hypertrehalosemic neuropeptides from the corpora cardiaca such as the decapeptide Bld HrTH bring about a profound switch in the metabolic activity of cockroach fat body during which production of the blood sugar trehalose is stimulated while the catabolism of carbohydrate (glycolysis) is inhibited. The mechanisms of the metabolic switch are not fully understood. Incubation of isolated fat body from the cockroach Blaptica dubia with 10(-8) M Bld HrTH, for 10-60 min, stimulated glycogen breakdown and increased the content of the substrates of both the glycolytic enzyme 6-phosphofructo-1-kinase (PFK, EC 2.7.1.11) and the gluconeogenic enzyme fructose-1,6-bisphosphatase (FBPase, EC 3.1.3.11) in the tissue. The glycolytic signal fructose 2,6-bisphosphate was markedly decreased in fat body on incubation with Bld HrTH. The content of ATP was slightly reduced, while the contents of ADP and AMP were increased after incubation with the hormone. Fructose 2,6-bisphosphate is a potent activator of PFK and a strong inhibitor of FBPase purified from fat body. The activity of PFK was decreased by about 90% when the hormone-dependent changes in effectors and substrates in fat body were simulated in vitro. FBPase, in contrast, was activated about 25-fold under these conditions, suggesting the hormone to stimulate gluconeogenesis in fat body. The data support the view that fructose 2,6-bisphosphate is a pivotal intracellular messenger in the hormone-induced metabolic switch from carbohydrate degradation to trehalose production in cockroach fat body.

Adenosine Monophosphate↗
PubMed2001

[Prophylactic prescription of low-molecular-weight heparin in the non-surgical setting: impact of recommendations].

OBJECTIVE: Low-molecular-weight heparins (LMWH) had official approval for use for venous thromboembolism prophylaxis only for surgery patients when this survey was conducted, but were nevertheless often used in non-surgery patients. We conducted this "before and after" survey from May 1998 to April 1999 to assess the impact of the recommendations implemented in the beginning of 1999. METHODS: Data on the use of LMWH were collected on three different days within a three week interval in all non-surgery departments at the Tenon hospital before distribution of expert recommendations early in 1999. Published in La Presse Médicale in January 2000, these recommendations issued from an external panel of 43 experts who were contacted to establish a consensus opinion using the Delphi method. Data were again collected on three different days after implementation of the recommendations. Implementation was based on a patient-specific prescription order form requested by the hospital pharmacy for delivery to the department. RESULTS: Data were collected for 121 prescriptions prior to the recommendations and for 158 after. Sex-ratio, mean age and percentage of LMWH prescriptions did not differ significantly between the two periods. There was a lower number of non-appropriate prescriptions after implementation of the recommendations from 54.5% to 35.4% (p = 0.01) with better conformity for recommendation A (high-risk patients) (36% versus 43%, NS) and for recommendation B (= 2 risk situations or = 1 risk situation and = 2 aggravating factors) (10% versus 22%, p = 0.01). Better conformity of LMWH prescriptions in oncology and radiotherapy departments partially explained this general improvement, but the difference remained significant when excluding these two departments (p = 0.04). CONCLUSION: This study shows that physician compliance with recognized expert recommendations can improve their implementation. This procedure is now in general use in the Tenon hospital.

Aged↗
PubMed2001

Magnetic resonance imaging and miniarthroscopy of metacarpophalangeal joints: sensitive detection of morphologic changes in rheumatoid arthritis.

OBJECTIVE: To evaluate and characterize magnetic resonance imaging (MRI) findings in the metacarpophalangeal (MCP) joints of rheumatoid arthritis (RA) patients macroscopically, using miniarthroscopy (MA; needle arthroscopy). METHODS: The second MCP joint of the dominant hand of 22 RA patients (13 with various RA activities/stages; 9 with early RA [< or = 1.5 years' duration]) was examined by MRI followed by MA. Findings were evaluated by standardized semiquantitative measures of synovial and bony pathologic changes of the MCP joint, and were compared with the clinical and conventional radiologic findings. RESULTS: Erosions and pre-erosions were detected in 17 of 22 patients by MRI; 2 of the other 5 patients (all early RA) displayed bony changes on MA. All 10 joints with pre-erosions on MRI (grade I bony alterations on MRI) exhibited significant cartilaginous and bony pathology on MA. Synovial membrane pathology was detected in all but 1 patient by MRI and in all patients by MA, although findings of plain radiography were normal in 6 of the 22 patients and another 9 patients had a Larsen score of 1. Semiquantitative analysis of synovial findings of MRI revealed gadolinium diethylenetriaminepentaacetic acid enhancement as a significant marker of macroscopically varied synovial vascularity and hyperemia, both of which strongly correlated with clinical activity (as measured by the Disease Activity Score). The extent of synovitis/synovial proliferation shown by MA and MRI were significantly correlated with each other, but not with any other activity or damage parameter analyzed. CONCLUSION: In RA, both MRI and MA findings support early detection and staging of synovial changes. Ongoing longitudinal studies are aimed at evaluating the value of synovial proliferation as visualized by both methods.

Adult↗
PubMed2001

Predictive value of the tumor oxygenation by means of pO2 histography in patients with advanced head and neck cancer.

PURPOSE: The purpose of this analysis was to evaluate the potential of the tumor oxygenation by means of Eppendorf pO2 histography as a predictive test to select patients for treatment alternatives. PATIENTS AND METHODS: Pretreatment tumor pO2 histographies of locoregional lymph node metastases were assessed in 194 patients with squamous cell carcinoma of the head and neck. Included in the analysis were 134 patients who received a primary radio- or radiochemotherapy with a radiation dose of > or = 60 Gy, and who had no distant metastasis at beginning of the therapy. RESULTS: The Cox regression analysis revealed the fraction of pO2 values < or = 2.5 mm Hg (p = 0.004), age (p = 0.04) and radiotherapy/radiochemotherapy (p = 0.03) as significant independent prognostic factors for the survival. The positive and negative predictive values were calculated using different cut-off values of the fraction of pO2 values < or = 2.5 mm Hg and the survival status at 1 or 2 years after beginning of the therapy as endpoint. The highest positive and negative predictive values of all cut-off values were 0.50 and 0.41 at 1 year, and 0.81 and 0.26 at 2 years. CONCLUSIONS: Our data confirm the influence of the tumor oxygenation on the prognosis of patients with squamous cell carcinoma of the head and neck after radiotherapy. However, the calculated positive and negative predictive values suggest that the pO2 histography alone is not sufficient to be used as a predictive test to successfully select patients for treatment alternatives.

Adult↗
PubMed2001

Tumor hypoxia and systemic levels of vascular endothelial growth factor (VEGF) in head and neck cancers.

BACKGROUND: Hypoxia is the most important stimulus for the up-regulation of vascular endothelial growth factor (VEGF), one of the key cytokines for angiogenesis. We have investigated the possible relationship between tumor hypoxia and systemic levels of VEGF. PATIENTS AND METHODS: 56 patients with head and neck cancers underwent measurement of tumor volume (pretreatment CT scans), tumor oxygenation (pO2 histography) and serum levels of VEGF. The hemoglobin level ranged from 9.1 to 16 g/dl. The absolute amount of hypoxic tumor (hypoxic tumor volume) was determined as the product of the absolute tumor volume and the relative frequency of hypoxic (< 5 mm Hg) measurements in the pO2 histography. RESULTS: The serum VEGF levels in the 56 head and neck cancer patients ranged from 102 to 1699 pg/ml (median 405 pg/ml, mean 527 +/- 396 pg/ml). Elevated serum-VEGF levels (> 700 pg/ml) were found in 14/56 patients (25%). Serum-levels of VEGF were significantly and independently correlated with hypoxic tumor volume (R2 = 0.63, p < 0.001), but also with total tumor volume, hemoglobin levels, platelet counts and tumor hypoxia. There was no correlation with T and N category, histological grading, and age. CONCLUSIONS: The strong and independent impact of the hypoxic tumor volume on systemic VEGF levels suggests that the absolute amount of hypoxia within a tumor represents the most important stimulus for up-regulation of angiogenesis. Anemia acts as a co-factor via worsening of tumor tissue oxygenation.

Adult↗
PubMed2001

Loss of locomotor sensitisation in response to morphine in D1 receptor deficient mice.

Mice lacking D1 receptors were used to study the role of these receptors in morphine-induced antinociception and locomotor sensitisation. In the hot-plate test D1 receptor deficient (-/-) and wild-type (+/+) mice showed similar reaction times under basal conditions. A single injection of 1.25 mg/kg and 2.5 mg/kg morphine resulted in a stronger antinociceptive response in D1 receptor deficient mice than in wild-type animals. Tolerance to the analgesic effect did not develop in both groups of animals when 12.5 mg/kg morphine was chronically applied twice daily for 13 days. There was no change in basal locomotor activity between saline-injected wild-type and D1 receptor deficient mice. After chronic treatment wild-type mice showed a continuous increase in locomotor activity, indicating the development of sensitisation. In contrast, a subchronic administration of morphine did not change locomotor activity in mutant mice. The lack of the development of locomotor sensitisation in D1 deficient mice was associated with reduced levels of immunoreactive mu opioid receptors in dorsal striatal patches as compared to wild-type mice. In contrast, no change in the distribution of immunoreactive mu receptors could be detected in areas related to pain pathways such as the spinal cord. Taken together, these results suggest an involvement of D1 receptors in morphine-induced locomotor activity and analgesia.

Analgesics, Opioid↗
PubMed2001

Xanthomonas campestris pv. campestris secretes the endoglucanases ENGXCA and ENGXCB: construction of an endoglucanase-deficient mutant for industrial xanthan production.

Xanthomonas campestris pv. campestris secretes at least two cellulose-degrading endoglucanases. One of these endoglucanases is encoded by the engXCA gene of X. c. pv. campestris 8400 that was previously characterized by Gough et al. [Gene (1990) 89: 53-59]. An additional endoglucanase encoded by the engXCB gene was identified in X. c. pv. campestris 8400 and FC2. The engXCB gene product that was grouped into the endoglucanase family E contains a putative N-terminal signal peptide, suggesting a secretion by the type II secretion system. The ENGXCB protein contributed approximately 8% to the cellulase activity in xanthan preparations. Deletion of engXCA and engXCB resulted in a fivefold reduction of the cellulose-degrading activity in xanthan preparations. The cellulase activity determined in xanthan preparations of the engXCA-engXCB mutant was only slightly higher than the activity found in preparations that were subjected to heat treatment. Mutations in engXCA and engXCB did not affect the growth rate and xanthan production of X. c. pv. campestris FC2 under several cultivation conditions. The engXCA-engXCB deletion mutant is markerless, which makes this mutant a valuable strain for xanthan production and approaches aimed at inactivating further genes encoding extracellular enzymes.

Amino Acid Sequence↗
PubMed2001

[Exclusion of coronary calcium with electron beam tomography: an effective filter before invasive diagnosis in symptomatic patients?].

Electron beam computed tomography (EBCT) is the most sensitive and accurate method of measuring coronary calcium which indicates coronary atherosclerosis. We performed a prospective study in 1764 symptomatic patients who were referred to our hospital for coronary angiography because of suspected coronary artery disease. In all of these patients cardiac catheterization and coronary calcium scanning was performed within 3.2 +/- 4 days. 454/1225 men (37.0%) and 165/539 women (30.6%) had significant coronary stenoses > or = 75%. Only two men (0.4%) and no single woman (0.0%) with stenoses > or = 75% and only 3/323 patients (0.9%) with moderate stenoses (50-75%) did not exhibit coronary calcium. Coronary angiography excluded stenoses in 822 patients. Of these patients 261 (29.4%) did not reveal coronary calcium. In younger patients (< 60 years) without stenosis exclusion of coronary calcium was a frequent finding: 31% of men and 55.8% of women were free of coronary calcium. Thus, exclusion of coronary calcium with electron beam tomography defines a substantial subgroup of patients who have an extremely low risk of significant coronary stenosis despite suspected coronary artery disease in history and non-invasive testing. Determination of coronary calcium might, therefore, be an effective filter before invasive angiography in selected groups of symptomatic patients.

Adult↗