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Genome-guided purification of high amounts of the siderophore ornibactin and detection of potentially novel burkholdine derivatives produced by Burkholderia catarinensis 89T. J Appl Microbiol 2024; 135:lxae040. [PMID: 38364306 DOI: 10.1093/jambio/lxae040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/13/2024] [Accepted: 02/12/2024] [Indexed: 02/18/2024]
Abstract
AIM The increased availability of genome sequences has enabled the development of valuable tools for the prediction and identification of bacterial natural products. Burkholderia catarinensis 89T produces siderophores and an unknown potent antifungal metabolite. The aim of this work was to identify and purify natural products of B. catarinensis 89T through a genome-guided approach. MATERIALS AND METHODS The analysis of B. catarinensis 89T genome revealed 16 clusters putatively related to secondary metabolism and antibiotics production. Of particular note was the identification of a nonribosomal peptide synthetase (NRPS) cluster related to the production of the siderophore ornibactin, a hybrid NRPS-polyketide synthase Type 1 cluster for the production of the antifungal glycolipopeptide burkholdine, and a gene cluster encoding homoserine lactones (HSL), probably involved in the regulation of both metabolites. We were able to purify high amounts of the ornibactin derivatives D/C6 and F/C8, while also detecting the derivative B/C4 in mass spectrometry investigations. A group of metabolites with molecular masses ranging from 1188 to 1272 Da could be detected in MS experiments, which we postulate to be new burkholdine analogs produced by B. catarinensis. The comparison of B. catarinensis BGCs with other Bcc members corroborates the hypothesis that this bacterium could produce new derivatives of these metabolites. Moreover, the quorum sensing metabolites C6-HSL, C8-HSL, and 3OH-C8-HSL were observed in LC-MS/MS analysis. CONCLUSION The new species B. catarinensis is a potential source of new bioactive secondary metabolites. Our results highlight the importance of genome-guided purification and identification of metabolites of biotechnological importance.
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dRNA-seq transcriptional profiling of the FK506 biosynthetic gene cluster in Streptomyces tsukubaensis NRRL18488 and general analysis of the transcriptome. RNA Biol 2017; 14:1617-1626. [PMID: 28665778 DOI: 10.1080/15476286.2017.1341020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
FK506 (tacrolimus) is a valuable immunosuppressant produced by several Streptomyces strains. In the genome of the wild type producer Streptomyces tsukubaensis NRRL18488, FK506 biosynthesis is encoded by a gene cluster that spans 83.5 (kb). A whole transcriptome differential shotgun sequencing (dRNA-seq) of S. tsukubaensis was performed to analyze transcription at 2 different time points; before and during active FK506 production. In total, 8,914 transcription start sites were identified in either condition, which enabled precise determination of the 5'-UTR length of the corresponding transcripts as well as the identification of 2 consensus sequence motifs in the promoter regions. The transcription start sites of all gene operons within the FK506 cluster were identified, including 3 examples of leaderless RNA transcripts. These data provide detailed insight into the transcription of the FK506 biosynthetic gene cluster to support future regulatory studies, genetic manipulation, and industrial production.
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Die Biosynthese der β-Lacton-haltigen Proteasominhibitoren Belactosin und Cystargolid. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201612076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Biosynthesis of the β-Lactone Proteasome Inhibitors Belactosin and Cystargolide. Angew Chem Int Ed Engl 2017; 56:6665-6668. [PMID: 28452105 DOI: 10.1002/anie.201612076] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Indexed: 01/06/2023]
Abstract
Belactosins and cystargolides are natural product proteasome inhibitors from Actinobacteria. Both feature dipeptidic backbones and a unique β-lactone building block. Herein, we present a detailed investigation of their biosynthesis. Identification and analysis of the corresponding gene clusters indicated that both compounds are assembled by rare single-enzyme amino acid ligases. Feeding experiments with isotope-labeled precursors and in vitro biochemistry showed that the formation of the β-lactone warhead is unprecedented and reminiscent of leucine biosynthesis, and that it involves the action of isopropylmalate synthase homologues.
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The Systematic Investigation of the Quorum Sensing System of the Biocontrol Strain Pseudomonas chlororaphis subsp. aurantiaca PB-St2 Unveils aurI to Be a Biosynthetic Origin for 3-Oxo-Homoserine Lactones. PLoS One 2016; 11:e0167002. [PMID: 27861617 PMCID: PMC5115851 DOI: 10.1371/journal.pone.0167002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 11/07/2016] [Indexed: 11/30/2022] Open
Abstract
The shoot endophytic biocontrol strain Pseudomonas chlororaphis subsp. aurantiaca PB-St2 produces a wide range of exoproducts, including enzymes and antibiotics. The production of exoproducts is commonly tightly regulated. In order to get a deeper insight into the regulatory network of PB-St2, the strain was systematically investigated regarding its quorum sensing systems, both on the genetic and metabolic level. The genome analysis of PB-St2 revealed the presence of four putative acyl homoserine lactone (AHL) biosynthesis genes: phzI, csaI, aurI, and hdtS. LC-MS/MS analyses of the crude supernatant extracts demonstrated that PB-St2 produces eight AHLs. In addition, the concentration of all AHL derivatives was quantified time-resolved in parallel over a period of 42 h during the growth of P. aurantiaca PB-St2, resulting in production curves, which showed differences regarding the maximum levels of the AHLs (14.6 nM– 1.75 μM) and the production period. Cloning and heterologous overexpression of all identified AHL synthase genes in Escherichia coli proved the functionality of the resulting synthases PhzI, CsaI, and AurI. A clear AHL production pattern was assigned to each of these three AHL synthases, while the HdtS synthase did not lead to any AHL production. Furthermore, the heterologous expression study demonstrated unequivocally and for the first time that AurI directs the synthesis of two 3-oxo-AHLs.
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Biosynthetic Origin of the Antibiotic Pseudopyronines A and B in Pseudomonas putida BW11M1. Chembiochem 2015; 16:2491-7. [PMID: 26507104 DOI: 10.1002/cbic.201500413] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Indexed: 11/08/2022]
Abstract
Within the framework of our effort to discover new antibiotics from pseudomonads, pseudopyronines A and B were isolated from the plant-derived Pseudomonas putida BW11M1. Pseudopyronines are 3,6-dialkyl-4-hydroxy-2-pyrones and displayed high in vitro activities against several human pathogens, and in our hands also towards the plant pathogen Pseudomonas savastanoi. Here, the biosynthesis of pseudopyronine B was studied by a combination of feeding experiments with isotopically labeled precursors, genomic sequence analysis, and gene deletion experiments. The studies resulted in the deduction of all acetate units and revealed that the biosynthesis of these α-pyrones occurs with a single PpyS-homologous ketosynthase. It fuses, with some substrate flexibility, a 3-oxo-fatty acid and a further unbranched saturated fatty acid, both of medium chain-length and provided by primary metabolism.
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A Membrane-Bound Prenyltransferase Catalyzes the O-Prenylation of 1,6-Dihydroxyphenazine in the Marine BacteriumStreptomycessp. CNQ-509. Chembiochem 2014; 15:2385-92. [DOI: 10.1002/cbic.201402394] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Indexed: 12/17/2022]
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Double inversion recovery sequence of the cervical spinal cord in multiple sclerosis and related inflammatory diseases. AJNR Am J Neuroradiol 2014; 36:219-25. [PMID: 25169924 DOI: 10.3174/ajnr.a4093] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE MR imaging plays an important role in diagnosing MS and other related inflammatory diseases; however, imaging of the spinal cord is still challenging. We hypothesized that a 3D double inversion recovery sequence for cervical spinal cord imaging would be more sensitive in detecting inflammatory lesions than a conventional 2D T2-weighted TSE sequence at 3T. MATERIALS AND METHODS On a 3T MR imaging scanner, we examined 30 patients with suspected or established MS (MS, n = 16; clinically isolated syndrome, n = 12; isolated myelitis, n = 2) and 10 healthy controls. Newly developed 3D double inversion recovery and conventional 2D axial and sagittal T2-weighted TSE images of the cervical spinal cord were acquired. Two blinded neuroradiologists independently assessed the scans in pseudorandomized order for lesion numbers and rated lesion visibility and overall image quality on 5-point scales. A subsequent consensus reading delivered definite lesion counts. Standardized contrast-to-noise ratios were calculated in representative lesions of each patient. RESULTS Overall, 28% more lesions could be detected with 3D double inversion recovery than with conventional T2WI (119 versus 93, P < .002). On average, the standardized contrast-to-noise ratio was significantly higher (P < .001) in double inversion recovery than in T2WI. Lesion visibility was rated significantly higher (P < .001) in double inversion recovery compared with T2WI despite lower image quality. CONCLUSIONS The novel 3D double inversion recovery sequence allowed better detection of lesions in MS and related inflammatory diseases of the cervical spinal cord, compared with conventional 2D T2WI.
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High-resolution bone imaging for osteoporosis diagnostics and therapy monitoring using clinical MDCT and MRI. Curr Med Chem 2014; 20:4844-52. [PMID: 24083607 DOI: 10.2174/09298673113206660279] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 08/21/2013] [Accepted: 09/23/2013] [Indexed: 11/22/2022]
Abstract
Osteoporosis is classified as a public health problem due to its increased risk for fragility fractures. Osteoporotic fractures, in particular spine and hip fractures, are associated with a high morbidity and mortality, and generate immense financial cost. The World Health Organisation (WHO) based the diagnosis of osteoporosis on the measurement of bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA). However, BMD values of subjects with versus without osteoporotic fractures overlap. Furthermore, it was reported that the anti-fracture effects of drugs could be only partially explained by their effects on BMD. Bone strength reflects the integration of BMD and bone quality. The later can be partly determined by measurements of bone microstructure. Therefore, substantial research efforts have been undertaken to assess bone microstructure by using high-resolution imaging techniques, including high-resolution peripheral quantitative computed tomography (hr-pQCT), high-resolution multi-detector computed tomography (MDCT), and high-resolution magnetic resonance imaging (MRI). Clinical MDCT and MRI systems are broadly available and allow an adequate depiction of the bone microstructure at the clinically most important fracture sites, i.e. radius, spine and hip. Bone microstructure parameters and finite element models can be computed in high-resolution MDCT and MR images. These measurements improved the prediction of bone strength beyond the DXA-derived BMD and revealed pharmacotherapy effects, which are partly not captured by BMD. Therefore, high-resolution bone imaging using clinical MDCT and MRI may be beneficial for osteoporosis diagnostics and allow a highly sensitive monitoring of drug treatment, which plays an important role in the prevention of fragility fractures.
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Genome-based discovery of a novel membrane-bound 1,6-dihydroxyphenazine prenyltransferase from a marine actinomycete. PLoS One 2014; 9:e99122. [PMID: 24892559 PMCID: PMC4044012 DOI: 10.1371/journal.pone.0099122] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/11/2014] [Indexed: 12/02/2022] Open
Abstract
Recently, novel prenylated derivatives of 1,6-dihydroxyphenazine have been isolated from the marine sponge-associated Streptomyces sp. SpC080624SC-11. Genome sequencing of this strain now revealed a gene cluster containing all genes necessary for the synthesis of the phenazine and the isoprenoid moieties. Unexpectedly, however, the cluster did not contain a gene with similarity to previously investigated phenazine prenyltransferases, but instead a gene with modest similarity to the membrane-bound prenyltransferases of ubiquinone and menaquinone biosynthesis. Expression of this gene in E. coli and isolation of the membrane fraction proved that the encoded enzyme, Mpz10, catalyzes two successive prenylations of 1,6-dihydroxyphenazine. Mpz10 is the first example of a membrane-bound enzyme catalyzing the prenylation of a phenazine substrate, and one of few examples of membrane-bound enzymes involved in the prenylation of aromatic secondary metabolites in microorganisms.
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Alignment does not influence cartilage T2 in asymptomatic knee joints. Knee Surg Sports Traumatol Arthrosc 2014; 22:1396-403. [PMID: 24292942 DOI: 10.1007/s00167-013-2756-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Accepted: 10/28/2013] [Indexed: 01/23/2023]
Abstract
PURPOSE To investigate whether the static knee alignment affects articular cartilage ultrastructures when measured using T2 relaxation among asymptomatic subjects. METHODS Both knee joints (n = 96) of 48 asymptomatic volunteers (26 females, 22 males; 25.4 ± 1.7 years; no history of major knee trauma or surgery) were evaluated clinically (Lysholm, Tegner) and by MRI (hip-knee-ankle angle, standard knee protocol, T2 mapping). Group (n = 4) division was as follows: neutral (<1° varus/valgus), mild varus (2°-4° varus), severe varus (>4° varus) and valgus (2°-4° valgus) deformity with n = 12 subjects/group; n = 24 knees/group. Regions of interest (ROI) for T2 assessment were placed within full-thickness cartilage across the whole joint surface and were divided respecting compartmental as well as functional joint anatomy. RESULTS Leg alignment was 0.7° ± 0.5° varus among neutral, 3.0° ± 0.6° varus among mild varus, 5.0° ± 1.1° varus among severe varus and 2.5° ± 0.7° valgus among valgus group subjects and thus significantly different. No differences between the groups emerged from clinical measures. No morphological pathology was detected in any knee joint. Global T2 values (42.3 ± 2.3; 37.7-47.9 ms) of ROIs placed within every knee joint per subject were not different between alignment groups or between genders, respectively. CONCLUSION Static frontal plane leg malalignment does not affect cartilage ultrastructure among young, asymptomatic individuals as measured by T2 quantitative imaging. LEVEL OF EVIDENCE Cross-sectional study, Level II-III.
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Quantitative MR Bildgebung des Sprunggelenkes: Der Effekt axialer Traktion auf T2 Relaxationszeiten und Diffusionswerte des Gelenkknorpels. ROFO-FORTSCHR RONTG 2014. [DOI: 10.1055/s-0034-1373295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Bone mineral density values derived from routine lumbar spine multidetector row CT predict osteoporotic vertebral fractures and screw loosening. AJNR Am J Neuroradiol 2014; 35:1628-33. [PMID: 24627455 DOI: 10.3174/ajnr.a3893] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND AND PURPOSE Established methods of assessing bone mineral density are associated with additional radiation exposure to the patient. In this study, we aimed to validate a method of assessing bone mineral density in routine multidetector row CT of the lumbar spine. MATERIALS AND METHODS In 38 patients, bone mineral density was assessed in quantitative CT as a standard of reference and in sagittal reformations derived from standard multidetector row CT studies without IV contrast. MDCT-to-quantitative CT conversion equations were calculated and then applied to baseline multidetector row scans of another 62 patients. After a mean follow-up of 15 ± 6 months, patients were re-assessed for incidental fractures and screw loosening after spondylodesis (n = 49). RESULTS We observed conversion equations bone mineral densityMDCT = 0.78 × Hounsfield unitMDCTmg/mL (correlation with bone mineral densityquantitative CT, R(2) = 0.92, P < .001) for 120 kV(peak) tube voltage and bone mineral densityMDCT = 0.86 × Hounsfield unitMDCTmg/mL (R(2) = 0.81, P < .001) for 140 kVp, respectively. Seven patients (11.3%) had existing osteoporotic vertebral fractures at baseline, while 8 patients (12.9%) showed incidental osteoporotic vertebral fractures. Screw loosening was detected in 28 patients (57.1% of patients with spondylodesis). Patients with existing vertebral fractures showed significantly lower bone mineral densityMDCT than patients without fractures (P < .01). At follow-up, patients with incidental fractures and screw loosening after spondylodesis, respectively, showed significantly lower baseline bone mineral densityMDCT (P < .001 each). CONCLUSIONS This longitudinal study demonstrated that converted bone mineral density values derived from routine lumbar spine multidetector row CT adequately differentiated patients with and without osteoporotic fractures and could predict incidental fractures and screw loosening after spondylodesis.
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MR Bildgebung des Gelenkknorpels am OSG: Bessere Beurteilbarkeit durch axiale Traktion? ROFO-FORTSCHR RONTG 2013. [DOI: 10.1055/s-0033-1346223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Trabekuläre Knochenstrukturanalyse von Wirbelkörpern mittels klinischen MDCT: Kann damit die mechanische Versagenslast vorhergesagt werden? ROFO-FORTSCHR RONTG 2013. [DOI: 10.1055/s-0033-1346285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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View-Angle Tilting (VAT) und Slice-encoding Metal Artifact Correction (SEMAC) zur MR Bildgebung orthopädischer Tumor-Prothesen. ROFO-FORTSCHR RONTG 2013. [DOI: 10.1055/s-0033-1346225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Bone mineral density measurements of the proximal femur from routine contrast-enhanced MDCT data sets correlate with dual-energy X-ray absorptiometry. Eur Radiol 2012; 23:505-12. [PMID: 22932742 DOI: 10.1007/s00330-012-2629-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 07/13/2012] [Accepted: 07/25/2012] [Indexed: 01/15/2023]
Abstract
OBJECTIVES To evaluate the utility of femoral bone mineral density (BMD) measurements in routine contrast-enhanced multi-detector computed tomography (ceMDCT) using dual-energy X-ray absorptiometry (DXA) as the reference standard. METHODS Forty-one patients (33 women, 8 men) underwent DXA measurement of the proximal femur. Subsequently, transverse sections of routine ceMDCT of these patients were used to measure BMD of the femoral head and femoral neck. The MDCT-to-DXA conversion equations for BMD and T-score were calculated using linear regression analysis. The conversion equations were applied to the MDCT data sets of 382 patients (120 women, 262 men) of whom 74 had osteoporotic fractures. RESULTS A correlation coefficient of r = 0.84 (P < 0.05) was calculated for BMD(MDCT) values of the femoral head and DXA T-scores of the total proximal femur using the conversion equation T-score = 0.021 × BMD(MDCT) - 5.90. The correlation coefficient for the femoral neck was r = 0.79 (P < 0.05) with the conversion equation T-score = 0.016 × BMD(MDCT) - 4.28. Accordingly, converted T-scores for the femoral neck in patients with versus those without osteoporotic fractures were significantly different (female, -1.83 versus -1.47; male, -1.86 versus -1.47; P < 0.05). CONCLUSION BMD measurements of the proximal femur were computed in routine contrast-enhanced MDCT and converted to DXA T-scores, which adequately differentiated patients with and without osteoporotic fractures.
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Clinical pilot study for the automatic segmentation and recognition of abdominal adipose tissue compartments from MRI data. ROFO-FORTSCHR RONTG 2012; 184:548-55. [PMID: 22434368 DOI: 10.1055/s-0031-1299376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
PURPOSE In the diagnosis and risk assessment of obesity, both the amount and distribution of adipose tissue compartments are critical factors. We present a hybrid method for the quantitative measurement of human body fat compartments. MATERIALS AND METHODS MRI imaging was performed on a 1.5 T scanner. In a pre-processing step, the images were corrected for bias field inhomogeneity. For segmentation and recognition a hybrid algorithm was developed to automatically differentiate between different adipose tissue compartments. The presented algorithm is designed with a combination of shape and intensity-based techniques. To incorporate the presented algorithm into the clinical routine, we developed a graphical user interface. Results from our methods were compared with the known volume of an adipose tissue phantom. To evaluate our method, we analyzed 40 clinical MRI scans of the abdominal region. RESULTS Relatively low segmentation errors were found for subcutaneous adipose tissue (3.56 %) and visceral adipose tissue (0.29 %) in phantom studies. The clinical results indicated high correlations between the distribution of adipose tissue compartments and obesity. CONCLUSION We present an approach that rapidly identifies and quantifies adipose tissue depots of interest. With this method examination and analysis can be performed in a clinically feasible timeframe.
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3D-Knochenstrukturanalyse des distalen Radius mittels der Finite Element Methode (FEM) in der Vorhersage von osteoporotischen Wirbelkörperfrakturen. ROFO-FORTSCHR RONTG 2011. [DOI: 10.1055/s-0031-1279339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Bestimmung der mechanische Kompetenz des trabekulären Knochens mit Finiter Element Analyse von µCT und MDCT Daten: Welche räumliche Auflösung ist notwendig? ROFO-FORTSCHR RONTG 2011. [DOI: 10.1055/s-0031-1279301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Automated 3D trabecular bone structure analysis of the proximal femur--prediction of biomechanical strength by CT and DXA. Osteoporos Int 2010; 21:1553-64. [PMID: 19859642 PMCID: PMC2912724 DOI: 10.1007/s00198-009-1090-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Accepted: 10/01/2009] [Indexed: 12/19/2022]
Abstract
SUMMARY The standard diagnostic technique for assessing osteoporosis is dual X-ray absorptiometry (DXA) measuring bone mass parameters. In this study, a combination of DXA and trabecular structure parameters (acquired by computed tomography [CT]) most accurately predicted the biomechanical strength of the proximal femur and allowed for a better prediction than DXA alone. INTRODUCTION An automated 3D segmentation algorithm was applied to determine specific structure parameters of the trabecular bone in CT images of the proximal femur. This was done to evaluate the ability of these parameters for predicting biomechanical femoral bone strength in comparison with bone mineral content (BMC) and bone mineral density (BMD) acquired by DXA as standard diagnostic technique. METHODS One hundred eighty-seven proximal femur specimens were harvested from formalin-fixed human cadavers. BMC and BMD were determined by DXA. Structure parameters of the trabecular bone (i.e., morphometry, fuzzy logic, Minkowski functionals, and the scaling index method [SIM]) were computed from CT images. Absolute femoral bone strength was assessed with a biomechanical side-impact test measuring failure load (FL). Adjusted FL parameters for appraisal of relative bone strength were calculated by dividing FL by influencing variables such as body height, weight, or femoral head diameter. RESULTS The best single parameter predicting FL and adjusted FL parameters was apparent trabecular separation (morphometry) or DXA-derived BMC or BMD with correlations up to r = 0.802. In combination with DXA, structure parameters (most notably the SIM and morphometry) added in linear regression models significant information in predicting FL and all adjusted FL parameters (up to R(adj) = 0.872) and allowed for a significant better prediction than DXA alone. CONCLUSION A combination of bone mass (DXA) and structure parameters of the trabecular bone (linear and nonlinear, global and local) most accurately predicted absolute and relative femoral bone strength.
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Ganzkörper-MRT bei Patienten mit systemischer Mastozytose. ROFO-FORTSCHR RONTG 2010. [DOI: 10.1055/s-0030-1252578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Vergleich der Finite Element Methode (FEM) mit nichtlinearen Strukturparametern in der Vorhersagekraft der mechanischen Knochenfestigkeit der Wirbelsäule. ROFO-FORTSCHR RONTG 2010. [DOI: 10.1055/s-0030-1252581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Quantifizierung von T2-Zeit und Morphologie verschiedener Knorpeltransplantate – Osteochondrale Autografts versus Matrix assistierte Knorpelzelltransplantation. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1221580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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MRT-Perfusions- und Diffusionsmessungen des proximalen Femurs bei Patienten mit transientem Knochenmarködem, avaskulärer Knochennekrose und subchondraler Insuffizienzfraktur – Erste Ergebnisse. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1221618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Bestimmung der Körperfettmasse von Säuglingen mittels Ganzkörper-MRT. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1221262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Einfluss von Rasterwahl und Dosis auf die Detektion von Knochenläsionen des Beckens: experimentelle Untersuchung unter Verwendung eine Flachbettdetektorsystems. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1221495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Detektion von osteoporotischen Wirbelkörperfrakturen der Wirbelsäule mittels sagittalen Rekonstruktionen von Thorax- und Abdomen-Multislice-CT. ROFO-FORTSCHR RONTG 2008. [DOI: 10.1055/s-2008-1073768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Hochauflösende MRT der trabekulären Mikrostruktur des Calcaneus: Worin liegen die Vorteile von 3T gegenüber 1,5T? ROFO-FORTSCHR RONTG 2008. [DOI: 10.1055/s-2008-1073662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Nichtlineare Analyse der trabekulären Mikrostruktur des Calcaneus: Vergleich von 1,5T und 3,0T MRT für die Osteoporosediagnostik. ROFO-FORTSCHR RONTG 2007. [DOI: 10.1055/s-2007-977103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Charakterisierung verschiedener struktureller Elemente des trabekulären Knochens mittels nichtlinearer Strukturanalyse: Verbesserungen für die Osteoporosediagnostik. ROFO-FORTSCHR RONTG 2007. [DOI: 10.1055/s-2007-977104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Tumorzell-Markierung mit einem neuen positiven Folat-Rezeptor-spezifischen MR-Kontrastmittel. ROFO-FORTSCHR RONTG 2007. [DOI: 10.1055/s-2007-977328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
As life expectancy rises the prevalence of osteoporosis also increases, which represents a growing burden for the populace and the healthcare system. Vertebral fractures are the most frequent type of all osteoporotic fractures. Since they can be diagnosed by radiology, these examinations are particularly important for devising suitable treatment strategies. The goal of activities undertaken by osteoporosis organizations is to put across to radiologists the importance of accurate evaluation of these fractures. Identification of osteoporotic vertebral fractures is however problematic since the transition from healthy vertebral bodies to those deformed by osteoporosis constitutes a continuum and it is often difficult in deformed vertebral bodies to distinguish between an osteoporotic fracture and a non-osteoporotic deformity. This overview attempts to heighten awareness of the significant role the radiologist plays in the diagnostic work-up of osteoporosis and to provide diagnostic aids for assessing osteoporotic vertebral fractures including differential diagnoses.
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Structural analysis of trabecular bone of the proximal femur using multislice computed tomography: a comparison with dual X-ray absorptiometry for predicting biomechanical strength in vitro. Calcif Tissue Int 2006; 78:78-89. [PMID: 16467973 DOI: 10.1007/s00223-005-0070-3] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Accepted: 10/08/2005] [Indexed: 10/25/2022]
Abstract
We investigated whether trabecular microstructural parameters determined in multislice spiral computed tomographic (MSCT) images of proximal femur specimens differed in male and female donors and improved the prediction of biomechanical strength of the femur compared to bone mineral density (BMD) and content (BMC) determined with dual X-ray absorptiometry (DXA) as the standard diagnostic technique. Proximal femur specimens (n = 119) were harvested from formalin-fixed human cadavers (mean age 80 +/- 10 years). BMD was determined using DXA. Trabecular microstructural parameters (bone volume fraction, fractal dimension, and trabecular thickness, spacing, and number) were calculated in MSCT-derived images of the proximal femur. Failure load (FL) was measured using a biomechanical side-impact test. An age-, height-, and weight-matched subgroup (n = 54) was chosen to compare male and female donors. BMC, BMD, and structural parameters correlated significantly with FL, with r up to 0.75, 0.71, and 0.71, respectively. In a multiple regression model, an increase up to r = 0.82 was obtained when combining trabecular structural parameters and BMC. BMD differed between males and females only at the trochanter. BMC showed significant gender differences in all regions. This experimental study showed that a combination of BMC and microstructural parameters could improve the prediction of FL, suggesting that bone mass and trabecular structure carry overlapping but complementary information and that a combination of the two provides the best prediction of bone strength. Male donors had larger femora even after adjustment for body size and height, but no differences in trabecular structure were found between males and females.
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MRT des Sprunggelenkknorpels: 3,0 versus 1,5 Tesla. ROFO-FORTSCHR RONTG 2006. [DOI: 10.1055/s-2006-941004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Detection of osteoporotic vertebral fractures using multidetector CT. Osteoporos Int 2006; 17:608-15. [PMID: 16437195 DOI: 10.1007/s00198-005-0023-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Accepted: 09/29/2005] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Goals were to compare the performance of lateral radiographs and sagittal reformations (SR) of axial computed tomography (CT) datasets in identification of osteoporotic vertebral fractures and to assess for optimal slice thickness in axial CT datasets needed for reliable classification of these fractures. METHODS Sixty-five vertebrae were harvested from 21 human cadaver spines and examined with a 64-row multidetector CT scanner. Axial images were acquired with a slice thickness of 0.6, 1, 2, 3 and 5 mm and SR were obtained using these datasets. In addition, specimens were radiographed in antero-posterior and lateral orientation. Vertebrae visualized in the different image datasets were separately graded by four radiologists according to the spinal fracture index (SFI) classification. Fracture status determined in a consensus reading of interactive reformations of the 0.6-mm CT dataset in all three dimensions served as a standard of reference in combination with pathological examinations. RESULTS The average agreement for the 0.6-mm SR obtained between each radiologist and standard of reference for the grading of the fractures was very good (kappa=0.81). It was good for the 1-, 2- and 3-mm SR (kappa=0.70, 0.69 and 0.64), but only moderate for the radiographs (kappa=0.52), and fair for the 5-mm SR (kappa=0.33). When focusing only on detection of fractures, independent of the grading, all kappa values improved by about 0.15, resulting in excellent values for the 0.6-mm through 3-mm SR (0.95<kappa<0.79) and good values for the radiographs (kappa=0.72). Ninety-five percent of the fractures could be identified using the 1-mm SR, but 18% of the fractures were missed on the radiographs. CONCLUSIONS Sagittal CT reformations could more accurately assess vertebral fractures than standard radiographs. But for reliable detection of these fractures, SR derived from axial images with a slice thickness of 3 mm or less are required. The thinnest available axial slice thickness performed best in fracture grading.
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Trabekuläre Strukturanalyse des proximalen Femur mittels Multislice-CT – Ein Vergleich mit DXA für die Vorhersage der biomechanischen Knochenfestigkeit und des Frakturstatus. ROFO-FORTSCHR RONTG 2006. [DOI: 10.1055/s-2006-940663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Detektion osteoporotischer Wirbelkörperfrakturen mittels Mehrzeilen CT. ROFO-FORTSCHR RONTG 2006. [DOI: 10.1055/s-2006-940742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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[Multislice-CT for structure analysis of trabecular bone - a comparison with micro-CT and biomechanical strength]. ROFO-FORTSCHR RONTG 2004; 176:709-18. [PMID: 15122470 DOI: 10.1055/s-2004-813078] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
OBJECTIVES MS-CT (Multislice-Spiral-CT) has a higher spatial resolution compared to the SS-CT (Singleslice-CT). The purpose of this study was to investigate, if the higher spatial resolution of the MS-CT has advantages for structural analyses in the assessment of osteoporosis. MATERIAL AND METHODS 20 cylindrical trabecular bone specimens (diameter 12 mm, length 15 - 20 mm) were harvested from formalin-fixed human thoracic spines. All specimens were examined by Micro-CT and quantitative, histomorphologic parameters were determined. Analogous structural parameters were calculated from the high-resolution images acquired by both MS- and SS-CT. Additionally, the BMD (bone mineral density) was measured by QCT (quantitative CT). The maximum compressive strength (MCS) was determined in a biomechanical test. The structural parameters were correlated with the histomorphologic parameters and with the MCS. RESULTS The parameters bone fraction and trabecular separation correlated significantly in both MS- and SS-CT with the analogous parameters from Micro-CT (r (2) = 0.84, p < 0.01) and the MCS (r (2) = 0.81, p < 0.01). The highest correlation with the MCS was calculated using the trabecular number measured by MS-CT in the superior region near the endplate of the vertebra with the high-resolution kernel U90 u (r (2) = 0.85, p < 0.01). This correlation was significantly higher than the correlation between MCS and BMD (r (2) = 0.49, p < 0.01). CONCLUSION Micro-CT- and MS-CT-determined structural parameters of the trabecular bone showed significant, high correlations. Thus, a characterisation of the trabecular structure seems to be possible. The biomechanical stability of the bone can also be predicted well. The structural parameters acquired by MS-CT show higher correlations with the MCS than the BMD or structural parameters determined by SS-CT do. In this study MS-CT was best suited to predict biomechanical strength of trabecular bone.
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The alpha 5 beta 1 integrin fibronectin receptor, but not the alpha 5 cytoplasmic domain, functions in an early and essential step in fibronectin matrix assembly. J Biol Chem 1993; 268:21883-8. [PMID: 7691819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The alpha 5 beta 1 integrin mediates cell adhesion and migration on fibronectin, a glycoprotein critical for normal vertebrate embryonic development. Indirect evidence reported to date suggests that this receptor also functions in the deposition of fibronectin matrices. We used a molecular genetic approach to critically evaluate this role of alpha 5 beta 1 integrins. Mutant Chinese hamster ovary (CHO) cells deficient in alpha 5 integrin expression could not assemble a fibronectin matrix. Reconstituting alpha 5 beta 1 integrin expression by transfecting them with a full-length cDNA encoding the human alpha 5 chain completely restored fibronectin matrix assembly. CHO cells expressing an alpha 5 chain lacking the cytoplasmic domain also assembled a fibronectin matrix. Removing the cytoplasmic domain of alpha 5 appears to increase its activity in fibronectin matrix assembly. In addition to alpha 5 beta 1 integrin binding to fibronectin's RGD-containing domain, cells must bind with high affinity to fibronectin's amino-terminal 29-kDa matrix assembly domain to form a fibronectin matrix. Studies with the alpha 5-deficient CHO cells show that the expression of alpha 5 beta 1 integrin is also necessary for cells to bind fragments containing this distinct site in fibronectin and that a fibronectin matrix increases binding of the 29-kDa fragment. Thus, alpha 5 beta 1 integrins not only mediate cell adhesion to fibronectin, but also play an essential role in the assembly of a fibronectin matrix. This role includes direct binding to fibronectin and modulating a distinct binding event involving the interaction of fibronectin's amino-terminal matrix assembly domain with the cell surface.
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The alpha v beta 1 integrin functions as a fibronectin receptor but does not support fibronectin matrix assembly and cell migration on fibronectin. J Biophys Biochem Cytol 1993; 122:235-42. [PMID: 8314844 PMCID: PMC2119613 DOI: 10.1083/jcb.122.1.235] [Citation(s) in RCA: 167] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The fibronectin receptor, alpha 5 beta 1, has been shown to be required for fibronectin matrix assembly and plays an important role in cell migration on fibronectin. However, it is not clear whether other fibronectin binding integrins can take the place of alpha 5 beta 1 during matrix assembly and cell migration. To test this, we expressed the human alpha v subunit in the CHO cell line CHO-B2 that lacks the alpha 5 subunit. We found that the human alpha v combined with CHO cell beta 1 to form the integrin alpha v beta 1. Cells that expressed alpha v beta 1 attached to and spread well on fibronectin-coated dishes, but did so less well on vitronectin-coated dishes. This, along with other data, indicated that alpha v beta 1 functions as a fibronectin receptor in CHO-B2 cells. The alpha v beta 1-expressing cells failed to produce a fibronectin matrix or to migrate on fibronectin, although the same cells transfected with alpha 5 do produce a matrix and migrate on fibronectin. The affinity of the alpha v beta 1-expressing cells for fibronectin was fourfold lower than that of the alpha 5 beta 1-expressing cells. In addition, alpha v beta 1 was distributed diffusely throughout the cell surface, whereas alpha 5 beta 1 was localized to focal adhesions when cells were seeded onto fibronectin-coated surfaces. Thus, of the two fibronectin receptors, alpha v beta 1 and alpha 5 beta 1, only alpha 5 beta 1 supports fibronectin matrix assembly and promotes cell migration on fibronectin in the CHO-B2 cells. Possible reasons for this difference in the activities of alpha v beta 1 and alpha 5 beta 1 include the lower affinity of alpha v beta 1 for fibronectin and the failure of this integrin to localize in adhesion plaques on a fibronectin substrate. These results show that two integrins with similar ligand specificities and cell attachment functions may be quite different in their ability to support fibronectin matrix assembly and cell motility on fibronectin.
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Abstract
The purpose of this study was to explore the functional role of the cytoplasmic domain of the alpha subunit of the alpha 5/beta 1 integrin, a fibronectin receptor. Mutant CHO cells that express very low levels of endogenous hamster alpha 5 subunit (CHO clone B2) were transfected with an expression vector containing full-length or truncated human alpha 5 cDNAs to form chimeric human alpha 5/hamster beta 1 integrins. Three transfectants were examined: B2a27 expresses a full-length human alpha 5 subunit with 27 amino acids in the cytoplasmic domain; B2a10 expresses an alpha 5 with a 17-amino acid cytoplasmic truncation; B2a1 expresses an alpha 5 with a 26-amino acid truncation. Levels of alpha 5/beta 1 surface expression in B2a27 and B2a10 cells were similar to that in wild type CHO cells. The expression of alpha 5/beta 1 in B2a1 cells was less, amounting to 15-20% of WT levels, despite message levels that were three to five times greater than those of B2a27. The transfectants were used to examine the role of the alpha 5 cytoplasmic domain in cell adhesion, cell motility, cytoskeletal organization, and integrin-mediated tyrosine phosphorylation. The adhesion characteristics of B2a27 and B2a10 cells on fibronectin substrata were similar to each other and to wild type CHO cells. B2a1 cells displayed slight reductions in the strength and rate of adhesion to fibronectin. Cell motility in the presence of fibronectin was similar for B2a27, B2a10, and wild type CHO cells, while the B2a1 cells were substantially less motile. Comparable degrees of cell spreading and extensive organization of actin filaments were observed for B2a27, B2a10, and wild type CHO cells on fibronectin substrata. The B2a1 cells spread to a lesser degree, and some organization of actin was observed; the untransfected B2 cells remained round on fibronectin substrata and showed no actin reorganization. Since the reduced motility and cell spreading observed in the B2a1 cells might be due either to reduced surface expression of alpha 5/beta 1 or to the truncation in the alpha 5 cytoplasmic domain, we used flow cytometric cell sorting to select populations of B2a1 and B2a27 cells expressing similar levels of cell surface alpha 5. The deficits in spreading and motility were present in B2a1 cells expressing high levels of alpha 5. Thus the region of the alpha 5 cytoplasmic domain adjacent to the membrane seems to play an important role in cytoskeletal organization and cell motility. We also examined whether alpha subunit truncation would affect integrin-mediated tyrosine phosphorylation.(ABSTRACT TRUNCATED AT 400 WORDS)
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Fusion evaporation-residue cross sections for 28Si+40Ca at E(28Si)=309, 397, and 452 MeV. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1992; 45:1784-1790. [PMID: 9967931 DOI: 10.1103/physrevc.45.1784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Motility of fibronectin receptor-deficient cells on fibronectin and vitronectin: collaborative interactions among integrins. J Cell Biol 1992; 116:477-87. [PMID: 1370495 PMCID: PMC2289293 DOI: 10.1083/jcb.116.2.477] [Citation(s) in RCA: 120] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Cells are capable of adhering to and migrating on protein components of the extracellular matrix. These cell-matrix interactions are thought to be mediated largely through a family of cell surface receptors termed integrins. However, the manner in which individual integrins are involved in cell adhesion and motility has not been fully determined. To explore this issue, we previously selected a series of CHO variants that are deficient in expression of the integrin alpha 5 beta 1, the "classical" fibronectin receptor. Two sets of subclones of these variants were defined which respectively express approximately 20% or 2% of fibronectin receptor on the cell surface when compared to wild- type cells (Schreiner, C. L., J. S. Bauer, Y. N. Danilov, S. Hussein, M. M. Sczekan, and R. L. Juliano. 1989. J. Cell Biol. 109:3157-3167). In the current study, the variant clones were tested for haptotactic motility on substrata coated with fibronectin or vitronectin. Data from assays using fibronectin show that cellular motility of the 20% variants was substantially decreased (30-75% of wild type), while the motility of the 2% variants was nearly abolished (2-20% of wild type). Surprisingly, a similar pattern was seen for haptotactic motility of both 2% and 20% variants when vitronectin was used (approximately 20- 30% of wild type). The reduced haptotactic motility of the fibronectin receptor-deficient variant clones on vitronectin was shown not to be due to reduced vitronectin receptor (alpha v beta 3) expression nor to a failure of these variants to adhere to vitronectin substrata. Transfection of the deficient variants with a cDNA for the human alpha 5 subunit resulted in normal levels of fibronectin receptor expression (as a human alpha 5/hamster beta 1 chimera) and restored the motility of the CHO variants on fibronectin and vitronectin. This indicates that expression of the alpha 5 subunit is required for normal haptotactic motility on vitronectin substrata and suggests that the fibronectin receptor (alpha 5 beta 1) plays a cooperative role with vitronectin receptors in cell motility.
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Energy dependence of fusion evaporation-residue cross sections in the 28Si+28Si reaction. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1990; 41:1005-1013. [PMID: 9966441 DOI: 10.1103/physrevc.41.1005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Isolation and characterization of Chinese hamster ovary cell variants deficient in the expression of fibronectin receptor. J Biophys Biochem Cytol 1989; 109:3157-67. [PMID: 2531750 PMCID: PMC2115957 DOI: 10.1083/jcb.109.6.3157] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Chinese hamster ovary cell populations were enriched for cells displaying low surface expression of the 140-kD integrin fibronectin receptor (FnR) by means of fluorescence-activated cell sorting using monoclonal anti-FnR antibodies. Selected cells were cloned by limiting dilution, and the resulting clones were screened for low cell surface FnR expression by ELISA. Two multiply sorted populations gave rise to variant clones possessing approximately 20 or 2% FnR expression, respectively, compared with wild-type cells. Growth rates of the "20%" and "2%" clones on serum-coated plastic dishes were similar to that of wild-type cells. Variant cells expressing 20% FnR could attach and spread on substrata coated with purified fibronectin, although somewhat more slowly than wild-type cells, while cells expressing 2% FnR could not attach or spread. Cells from all variant clones attached normally to vitronectin substrata, but some of the 2% clones displayed altered morphology on this type of substratum. Motility assays in blind well chambers showed a correlation of movement with level of expression of FnR. The number of cells migrating in response to fibronectin was greatly reduced compared with wild-type cells for the 20% FnR variant clones, while variant clones with 2% FnR showed virtually no migratory activity. Surface labeling with 125I and immunoaffinity purification of FnR showed reduced levels of intact FnR on the plasma membranes of variants with 20% FnR, while none was detected in variants expressing 2% FnR. Nevertheless, beta subunits were detected on the surfaces of all variant clones. Immunoblots of cell lysates from wild-type cells and from both types of variant clones showed substantial amounts of FnR beta chain as well as enhanced amounts of a pre-beta moiety in the variants. alpha chain was markedly reduced in the 20% variants and essentially absent in the 2% variants, indicating that failure to assemble intact FnR in these variants was due to deficiencies of alpha chain production. Dot blots of total mRNA from a representative clone expressing 20% FnR showed reduced levels of material hybridizing to an 0.97-kb hamster FnR alpha chain cDNA probe as compared with wild type, while mRNA from a representative clone expressing 2% FnR had no detectable hybridizable RNA; this seems to agree well with the results obtained by immunoblotting. Thus, the defect in the variant clones seems to be due to reduced levels of alpha chain mRNA leading to a deficit of mature FnR and consequent alterations in cell adhesion and motility on fibronectin substrata.
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Evaluating health care facilities. THE JOURNAL OF HEALTH ADMINISTRATION EDUCATION 1989; 6:819-31. [PMID: 10291626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Much lip service is given to the idea of post-occupancy evaluation by planners and architects, but examples are rare. The firm these authors represent has had a formal and documented post-occupancy evaluation (POE) program in place since the mid-1960s. In this article, the authors offer a model POE process involving the project team and users working together at the project site. Subjective and objective data are combined in a quantitative scoring format, and lessons learned are documented for use by both the institution (operationally) and the planner/designer team (in future projects). The POE model is demonstrated by application to a project recently completed for the University of Washington Hospitals and Clinics in Seattle.
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Secretion, subcellular localization and metabolic status of inorganic pyrophosphate in human platelets. A major constituent of the amine-storing granules. Biochem J 1980; 192:99-105. [PMID: 6118133 PMCID: PMC1162312 DOI: 10.1042/bj1920099] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The platelet content of PPi is 1.90 +/- mumol/10(11) platelets (S.E.M., n = 19) or about 10.5 nmol/mg of protein, several hundred times that found for rat liver. Some 80% of this PPi is secreted by platelets treated with thrombin with a time course and dose-response relationship similar to secretion of ATP, ADP and 5-hydroxytryptamine (serotonin) from the platelet dense granules. During platelet aggregation induced by ADP and adrenaline, substantial amounts of PPi were secreted, but no release of acid hydrolases was observed. Subcellular-fractionation studies showed that the PPi is highly enriched in the same fraction that contains the storage organelles which store ATP, ADP, Ca2+ and 5-hydroxytryptamine. Inorganic pyrophosphatase was present mainly in the soluble fraction and in the mitochondria. Secretion studies done with platelets prelabelled with [32P]Pi showed that the sequestered PPi was relatively metabolically inactive, as is the ATP and ADP in the storage organelles. The possible participation of PPi in the formation of a bivalent-cation-nucleotide complex associated with amine storage is discussed.
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Abstract
Pretreatment of human platelets with the metabolic inhibitors rotenone and 2-deoxyglucose, before French press homogenization, has led to the isolation of dense storage granules in an overall yield of about 20%. The concentrations of serotonin, ATP and ADP were estimated in the dense granules. Serotonin was 40--60-fold enriched in the dense granules compared to the platelet homogenate. Stored ATP and ADP were also 40-fold enriched in the dense granules compared to the estimated storage nucleotide pool in intact platelets. The ATP to ADP ratio in the isolated dense granules was 0.68-0.70, the same as the ratio of the secreted ATP and ADP. In platelets prelabeled with [3H]adenine, the specific radioactivities of the ATP and ADP in the isolated dense granules and of the secreted ATP and ADP were both negligible, whereas the estimated specific radioactivity of the metabolically active ATP and ADP was 2,000 cpm/nmol. These results confirm that the ATP and ADP in the isolated dense granules are the same as the secreted ATP and ADP in terms of metabolic inactivity and their ATP to ADP ratios.
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