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1.
Sci Total Environ ; 708: 135152, 2020 Mar 15.
Article in English | MEDLINE | ID: mdl-31812384

ABSTRACT

Natural attenuation represents all processes that govern contaminant mass removal, which mainly occurs via microbial degradation in the environment. Although this process is intrinsic its rate and efficiency depend on multiple factors. This study aimed to characterize the microbial taxonomic and functional diversity in different aquifer sediments collected in the saturated zone and in situ microcosms (BACTRAP®s) amended with hydrocarbons (13C-labeled and non-labeled benzene, toluene and naphthalene) using 16S rRNA gene and "shotgun" Illumina high throughput sequencing at a jet-fuel contaminated site. The BACTRAP®s were installed to assess hydrocarbon metabolism by native bacteria. Results indicated that Proteobacteria, Actinobacteria and Firmicutes were the most dominant phyla (~98%) in the aquifer sediment samples. Meanwhile, in the benzene- and toluene-amended BACTRAP®s the phyla Firmicutes and Proteobacteria accounted for about 90% of total community. In the naphthalene-amended BACTRAP®, members of the SR-FBR-L83 family (Order Ignavibacteriales) accounted for almost 80% of bacterial community. Functional annotation of metagenomes showed that only the sediment sample located at the source zone border and with the lowest BTEX concentration, has metabolic potential to degrade hydrocarbons aerobically. On the other hand, in situ BACTRAP®s allowed enrichment of hydrocarbon-degrading bacteria. Metagenomic data suggest that fumarate addition is the main mechanism for hydrocarbon activation of toluene. Also, indications for methylation, hydroxylation and carboxylation as activation mechanisms for benzene anaerobic conversion were found. After 120 days of exposure in the contaminated groundwater, the isotopic analysis of fatty acids extracted from BACTRAP®s demonstrated the assimilation of isotopic labeled compounds in the cells of microbes expressed by strong isotopic enrichment. We propose that the microbiota in this jet-fuel contaminated site has metabolic potential to degrade benzene and toluene by a syntrophic process, between members of the families Geobacteraceae and Peptococcaceae (genus Pelotomaculum), coupled to nitrate, iron and/or sulfate reduction.


Subject(s)
Metagenome , Microbiota , Biodegradation, Environmental , Hydrocarbons , RNA, Ribosomal, 16S
2.
Acta Biomater ; 98: 186-195, 2019 10 15.
Article in English | MEDLINE | ID: mdl-31352109

ABSTRACT

Volume stable barrier membranes made of magnesium are very promising in Guided Bone Regeneration (GBR) to treat periodontal bone defects in dentistry due to their excellent biocompatibility and biodegradability. During the degradation process the cells are exposed to the alteration of various parameters, so called physical cues, involving surface alterations due to the formed corrosion layer and medium alterations arising from the dissolved corrosion products. Cell migration of human gingival fibroblasts (HGF), as a crucial parameter for optimal healing process in GBR, has been investigated on magnesium membranes and revealed that medium alterations by dissolved corrosion products have a higher impact on cell migration than surface alterations. However, the effect of each altered medium parameter on cell migration has not been adequately studied, but their roles are crucial to explain the slower migration rate on magnesium surfaces compared to titanium and tissue culture plastic surfaces. Our study investigates the single effect of Mg2+, Ca2+, H2 and increased osmolality as well as the effect of magnesium extracts, which contain a dynamic mixture of previous parameters on cell migration, proliferation and viability of HGF. We showed that at 75 mM Mg2+ concentration and at 0 mM Ca2+, respectively, the cell migration rate is greatly reduced. In complex magnesium extract media, we found that a temporarily increased ratio of Mg2+ to Ca2+ conditioned a slow HGF migration rate. Based on these findings and the characterization of supernatants from HGF migration assays on Mg membranes, we propose, that the slower migration rate of HGF can be explained by the altered ratio of Mg2+ to Ca2+, caused by increasing concentrations of Mg2+ and decreasing concentrations of Ca2+ in the vicinity of the corroding Mg implant, combined with a constantly increased molecular hydrogen concentration in the supernatant. These results are cell type specific and should be checked carefully, if necessary, for Mg implant performance. STATEMENT OF SIGNIFICANCE: The study is providing a systematic approach to explain the main effects of extract medium parameters (physical cues) such as magnesium or calcium ion concentration, osmolality and dissolved molecular hydrogen and CO2 in cell culture media modified by co-incubating with corroding magnesium implants on the migration rate of human gingival fibroblasts (HGF). This study uncovers for the first time the combinatory effect of slightly increased molecular hydrogen and the change in Mg2+/Ca2+ ratio on HGF cell migration.


Subject(s)
Absorbable Implants , Fibroblasts/cytology , Gingiva/cytology , Magnesium/pharmacology , Calcium/pharmacology , Cell Movement/drug effects , Corrosion , Culture Media , Fibroblasts/drug effects , Humans , Hydrogen/pharmacology , Ions
3.
Acta Biomater ; 44: 355-65, 2016 10 15.
Article in English | MEDLINE | ID: mdl-27497845

ABSTRACT

UNLABELLED: Magnesium as basic implant material has long been the center of orthopedic research. Latest progress is achieved with a European certification and clinical use of a magnesium based compression screw. However, long term studies with implantation duration that exceed one year considerably do not exist. The present examinations analyzed the degradation progress from nine months to 3.5year after implantation of cylindrical pins into the medullary cavity of New Zealand White rabbits. Evaluation included clinical assessment, in vivo µ-computed tomography, analysis of the implants by three-point-bending and examination of the adjacent tissue by means of histology and of inner organs by mass- and optical emission spectrometry using inductively coupled plasma. Clinical acceptance was without objections in all animals. Immoderate reaction of the surrounding bone could be found in neither of the applied techniques. While in vivo µ-computed tomography showed a very slow degradation rate up to 72weeks, three-point-bending revealed a percentage loss of F(max) of 41.1% for implants after 9months implantation and 88.47% for the implant after 3.5years implantation. Although the total amounts of RE detected in the inner organs were very low, the organs of rabbits with LAE442 cylinders showed 10-20-fold increased concentrations of the alloying elements lanthanum, cerium, neodymium and praseodymium compared to animals without any implanted material. STATEMENT OF SIGNIFICANCE: This is the first animal study investigating the degradation process of a magnesium alloy in vivo for up to 3.5years. Currently available data from different other in vivo studies cover only implantation durations up to one year. Therefore, the analysis of these long-time effects in the present study is highly significant and of great interest. Comprehensive outcome achieved by different techniques was assessed. The degradation process was slow and homogenous. Maximum applied force (F(max)) reduced by 41.1% for implants after 9months and by 88.47% for the implant after 3.5years implantation. Total amounts of RE detected in the inner organs were very low; the organs of rabbits with LAE442 cylinders showed 10-20-fold increased concentrations.


Subject(s)
Alloys/pharmacology , Biocompatible Materials/pharmacology , Implants, Experimental , Magnesium/pharmacology , Animals , Corrosion , Disease Models, Animal , Female , Materials Testing , Rabbits , Spectrometry, X-Ray Emission , Tibia/physiology , X-Ray Microtomography
4.
Ultrasound Obstet Gynecol ; 48(2): 232-8, 2016 Aug.
Article in English | MEDLINE | ID: mdl-26423450

ABSTRACT

OBJECTIVE: A prenatal ultrasound examination and a postmortem examination provide the basis for correct diagnosis in fetuses terminated due to congenital anomalies. The aim of this study was to correlate fetal anomalies detected by ultrasound examination with those identified at autopsy following termination of pregnancy (TOP) over a 30-year period, and to evaluate the correlation between findings at different gestational ages and assess these trends over time. METHODS: The study group consisted of 1029 TOPs performed over a 30-year period, from 1985 to 2014. The gestational age ranged between 11 and 33 weeks. Prenatal ultrasound examinations were performed at the National Center for Fetal Medicine, St Olavs Hospital, Trondheim, Norway. Autopsies were performed at the Department of Pathology and Medical Genetics at the same hospital or a collaborating hospital. RESULTS: There was full agreement between ultrasound and autopsy findings in 88.1% (907/1029) of TOPs, and the main diagnosis was correct in 97.9% (1007/1029). When comparing the 15-year period of 2000-2014 with that of 1985-1999, the difference in the rates of full agreement and agreement in the main diagnosis was statistically significant. In 1.3% (13/1029) of cases, ultrasound findings were not confirmed at autopsy. There were no false-positive diagnoses leading to TOP. Throughout the 30-year period, there was an increase in early TOPs, whereas late TOPs declined. CONCLUSIONS: Our study demonstrates that there is a clear correlation between ultrasound and autopsy findings, which is continuously improving. Despite this high correlation, there is reason to continue the practice of validation to ensure the safety of the diagnostic process leading to TOP. The trend towards an earlier termination emphasizes the necessity of such a practice. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.


Subject(s)
Abnormalities, Multiple/pathology , Abortion, Eugenic/trends , Ultrasonography, Prenatal/methods , Abnormalities, Multiple/diagnostic imaging , Abnormalities, Multiple/epidemiology , Abortion, Eugenic/statistics & numerical data , Adolescent , Adult , Autopsy , Female , Gestational Age , Humans , Maternal Age , Norway/epidemiology , Pregnancy , Sensitivity and Specificity , Ultrasonography, Prenatal/statistics & numerical data , Young Adult
6.
Acta Biomater ; 9(10): 8611-23, 2013 Nov.
Article in English | MEDLINE | ID: mdl-23542554

ABSTRACT

A cytocompatible and biocompatible, degradable, open-porous, mechanically adaptable metal scaffold made of magnesium alloy W4 melt-extracted short fibres was fabricated by liquid phase sintering. Cylindrical samples (3×5 mm) of sintered W4 short fibres were evaluated under in vitro (L929, HOB, eudiometer, weight loss) and in vivo conditions (rabbits: 6 and 12 weeks). The in vitro corrosion environment (e.g., temperature, flow, composition of corrosion solution, exposure time) significantly influenced the corrosion rates of W4 scaffolds compared with corrosion in vivo. Corrosion rates under cell culture conditions for 72 h varied from 1.05 to 3.43 mm y(-1) depending on the media composition. Corrosion rates measured in eudiometric systems for 24 h were ~24-27 times higher (3.88-4.43 mm y(-1)) than corrosion in vivo after 6 weeks (0.16 mm y(-1)). Moreover, it was found that the cell culture media composition significantly influences the ionic composition of the extract by selectively dissolving ions from W4 samples or their corrosion products. A pilot in vivo study for 6 and 12 weeks demonstrated active bone remodelling, no foreign body reaction and no clinical observation of gas formation during W4 scaffold implantation. Long-term in vivo studies need to be conducted to prove complete degradation of the W4 scaffold and total replacement by the host tissue.


Subject(s)
Alloys/pharmacology , Biocompatible Materials/pharmacology , Tissue Scaffolds/chemistry , Animals , Cell Proliferation/drug effects , Cell Survival/drug effects , Cells, Cultured , Compressive Strength/drug effects , Corrosion , Culture Media/chemistry , Female , Humans , Image Processing, Computer-Assisted , Mice , Microscopy, Electron, Scanning , Osteogenesis/drug effects , Porosity , Prosthesis Implantation , Rabbits
8.
Ultrasound Obstet Gynecol ; 40(2): 230-4, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22374812

ABSTRACT

Autopsies of fetuses with thanatophoric dysplasia (TD) have shown abnormal gyration of the temporal lobes. In addition, the head is relatively large compared with the abdomen. We evaluated by ultrasound six consecutive cases of TD at 19 + 0 to 19 + 6 gestational weeks based on last menstrual period. We observed abnormal and deep transverse sulci in the temporal lobes in all cases; these features were confirmed at autopsy. We performed biometric assessment, including biparietal diameter (BPD) and mean abdominal diameter (MAD). For each MAD value in the TD fetuses, we computed mean and SD of the corresponding BPD values from a population-based registry in the relevant age range, and used them to calculate Z-scores for each BPD/MAD ratio. In the general population, the average BPD/MAD ratio was 1.05. In the TD fetuses, the mean BPD was 51.5 (range, 49-54) mm, the MAD was 45 (range, 41-47) mm and the BPD/MAD ratio was 1.15 (range, 1.09-1.20). The average Z-score of the ratios for TD fetuses was 2.44 (range, 1.05-3.39). The ratios for the TD fetuses were significantly higher than were the population ratios (P = 0.016). At autopsy, the mean brain-to-body weight ratio was 20.6% (range, 15.4-24.1%), which was greater than the corresponding mean ratio of 14.9% in normal fetuses. We conclude that abnormal and deep transverse gyration of the temporal lobes can be visualized by ultrasound in mid-second-trimester fetuses with TD. Due to megalencephaly, fetuses with TD have significantly different body proportions, with a larger BPD compared with normal fetuses.


Subject(s)
Megalencephaly/diagnostic imaging , Temporal Lobe/abnormalities , Temporal Lobe/diagnostic imaging , Thanatophoric Dysplasia/diagnostic imaging , Ultrasonography, Prenatal/methods , Biometry , Female , Humans , Pregnancy
9.
Ultrasound Obstet Gynecol ; 39(6): 666-72, 2012 Jun.
Article in English | MEDLINE | ID: mdl-21953982

ABSTRACT

OBJECTIVE: To determine if postmortem examinations of fetuses and infants change the diagnosis obtained at prenatal ultrasound and affect counseling of future pregnancies, and if there has been a change over recent years in the accuracy of prenatal ultrasound diagnosis. METHODS: This was a retrospective review of 455 autopsies of fetuses and infants with developmental anomalies performed at Trondheim University Hospital between 1995 and 2004 and with a prenatal ultrasound examination performed at a tertiary referral center. The routine ultrasound examinations were performed by specially trained midwives and obstetricians, referral scans by fetal medicine experts and autopsies by consultant pathologists with experience in perinatal pathology. The results of this study were also compared with those of a previous similar study performed between 1985 and 1995, with fetuses and infants coming from the same population and diagnosed at the same center. RESULTS: Of all cases analyzed during the study period, there was complete agreement between prenatal ultrasound and postmortem findings in 84% (384/455), i.e. prenatal ultrasound diagnoses were supplemented by postmortem examinations in 16% (71/455). Autopsy findings in four of these cases influenced further counseling. There was agreement regarding the main diagnosis in 98% (445/455) of cases. In the previous 10-year period, there was complete agreement in 75% and the main diagnosis was correct in 90% of cases. These differences between the two time periods were statistically significant (P = 0.0004 and P < 0.0001, respectively). The most frequent defects involved the central nervous system, heart and urinary tract. For these defects, detection rates for the main diagnoses were significantly better in 1995-2004 compared with in the previous 10-year period (P = 0.0125, P = 0.0111 and P = 0.0241, respectively). CONCLUSION: The accuracy of prenatal sonographic detection of developmental anomalies has increased in recent years. However, postmortem examination is still necessary to verify or improve the prenatal diagnosis and may influence future counseling.


Subject(s)
Autopsy , Congenital Abnormalities/diagnosis , Fetal Death , Fetal Diseases/diagnosis , Fetus/abnormalities , Ultrasonography, Prenatal , Adult , Congenital Abnormalities/diagnostic imaging , Congenital Abnormalities/mortality , Female , Fetal Diseases/diagnostic imaging , Fetal Diseases/mortality , Fetus/pathology , Humans , Infant, Newborn , Informed Consent , Norway , Pregnancy , Reproducibility of Results , Retrospective Studies
10.
Z Gastroenterol ; 49(6): 740-8, 2011 Jun.
Article in German | MEDLINE | ID: mdl-21638241

ABSTRACT

Surgery has been the mainstay of therapy in patients with gastrointestinal perforations, leakage or fistulas. New techniques for endoscopic closure of gastrointestinal perforations provide tools for an effective treatment by less invasive procedures. Temporary placement of covered self-expanding stents is an established therapy for oesophageal perforations and anastomotic leaks. Using conventional endoclips small perforations and leaks in the oesophagus and gastrointestinal tract may be closed. With the new over-the-scope-clips a more effective endoscopic full wall closure is possible in the upper gastrointestinal tract and the rectum. Endoscopically guided endoluminal vacuum therapy using polyurethane sponges is an established method for treating rectal leaks and is now increasingly used also in oesophageal leaks. Biliary leakage following endoscopic or surgical interventions is effectively treated with temporary bile stenting in most cases, but closure using metal stents or coiling may be necessary. Pancreatic leaks are a major therapeutic problem and may require multimodal therapies.


Subject(s)
Bile Duct Diseases/surgery , Endoscopy, Digestive System/methods , Endoscopy, Digestive System/trends , Gastrointestinal Diseases/surgery , Minimally Invasive Surgical Procedures/methods , Minimally Invasive Surgical Procedures/trends , Pancreatic Diseases/surgery , Bile Duct Diseases/pathology , Gastrointestinal Diseases/pathology , Humans , Pancreatic Diseases/pathology
11.
Aktuelle Urol ; 42(3): 179-83, 2011 May.
Article in German | MEDLINE | ID: mdl-21409742

ABSTRACT

PURPOSE: The EAU guidelines recommend extended pelvic lymphadenectomy (ePLND) or sentinel-guided PLND (SLNE) for lymph node (LN) stag-ing in prostate cancer. However, the additional expenditure and increased morbidity of ePLND has led to a limitation of the PLND area and so to a reduced detection of metastases in many clinics. The SLNE offers the advantage of selective removal of sentinel LN. Therefore, we have compared the complications of SLNE and other different PLND techniques. MATERIALS AND METHODS: Patients with prostate cancer who had received an open PLND (PLND: n = 90, PLND + radical retropubic prostatectomy: n = 409) were assessed. The complications of three PLND techniques were compared: group 1 (n = 216): SLNE, group 2 (n = 117): SLNE + modified (m) PLND (fossa obturatoria- und Iliaca-externa-region), group 3 (n = 163): SLNE + ePLND (fossa obturatoria- + Iliaca-externa- + Iliaca-interna-region). The complications were evaluated with special reference to the PLND-induced morbidity (e. g., lymphoceles). RESULTS: In SLNE the total complications were low-er than in the two more extended PLND variants. The lymphatic complications (11.2 %) were significant (χ (2) = 8.616, p = 0.013) lower than in SLNE + mPLND (21.2 %) and SLNE + ePLND (22.0 %). With an increasing number of dissected LN the complication rate increased significantly. If ≥ 15 LN have been removed total and lymphatic complications increased significantly (χ (2) = 11.578, p = 0.021; χ (2) = 12.271, p = 0.015). CONCLUSIONS: In PLND the lymphatic complications increase significantly with the number of dissected LN. The SLNE has, in spite of the dissection of LN in difficultly accessible regions (presacral, iliaca-interna-region), a low complication rate. As a method with a small number of LN to be removed, the SLNE offers a good compromise between high sensitivity and low morbidity and is therefore preferable to the more extended PLND variants.


Subject(s)
Lymph Node Excision/adverse effects , Postoperative Complications/etiology , Prostatic Neoplasms/surgery , Aged , Combined Modality Therapy , Cross-Sectional Studies , Diagnostic Imaging , Humans , Lymph Node Excision/methods , Lymphatic Metastasis/pathology , Male , Neoplasm Staging , Postoperative Complications/epidemiology , Prognosis , Prostatectomy , Prostatic Neoplasms/pathology , Prostatic Neoplasms/radiotherapy , Radiotherapy, Adjuvant , Retrospective Studies , Risk Factors , Sensitivity and Specificity , Sentinel Lymph Node Biopsy/adverse effects , Sentinel Lymph Node Biopsy/methods
12.
J Appl Microbiol ; 109(6): 1937-45, 2010 Dec.
Article in English | MEDLINE | ID: mdl-21070515

ABSTRACT

AIMS: This study intended to unravel the physiological interplay in an anaerobic microbial community that degrades toluene under sulfate-reducing conditions combining proteomic and genetic techniques. METHODS AND RESULTS: An enriched toluene-degrading community (Zz5-7) growing in batch cultures was investigated by DNA- and protein-based analyses. The affiliation and diversity of the community were analysed using 16S ribosomal RNA (rRNA) genes as a phylogenetic marker as well as bssA and dsrAB genes as functional markers. Metaproteome analysis was carried out by a global protein extraction and a subsequent protein separation by two-dimensional gel electrophoresis (2-DE). About 85% of the proteins in the spots were identified by nano-liquid chromatography coupled with electrospray mass spectrometry (nano-LC-ESI-MS/MS) analysis. DNA sequencing of bssA and the most abundant dsrAB amplicons revealed high similarities to a member of the Desulfobulbaceae, which was also predominant according to 16S rRNA gene amplicons. Metaproteome analysis provided 202 unambiguous protein identifications derived from 236 unique protein spots. The proteins involved in anaerobic toluene activation, dissimilatory sulfate reduction, hydrogen production/consumption and autotrophic carbon fixation were mainly affiliated to members of the Desulfobulbaceae and several other Deltaproteobacteria. CONCLUSION: Phylogenetic and metaproteomic analyses revealed a member of the Desulfobulbaceae as the key player of anaerobic toluene degradation in a sulfate-reducing consortium. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study that combines genetic and proteomic analyses to indicate the interactions in an anaerobic toluene-degrading microbial consortium.


Subject(s)
Microbial Consortia , Phylogeny , Proteome/metabolism , Toluene/metabolism , Biodegradation, Environmental , Chromatography, Liquid , DNA, Bacterial/genetics , Deltaproteobacteria/genetics , Deltaproteobacteria/metabolism , Electrophoresis, Gel, Two-Dimensional , Polymorphism, Restriction Fragment Length , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Tandem Mass Spectrometry
13.
J Physiol Pharmacol ; 61(1): 45-52, 2010 Feb.
Article in English | MEDLINE | ID: mdl-20228414

ABSTRACT

Diabetes is associated with endothelial dysfunction and platelet activation, both of which contribute to increased cardiovascular risk. We investigated whether the selective mineralocorticoid receptor (MR) antagonist eplerenone improves endothelial dysfunction and reduces platelet activation in diabetic rats. Male Wistar-rats were injected with streptozotocin (50 mg/kg i.v.) to induce insulin-deficient diabetes. After 2 weeks, treatment with eplerenone (100 mg/kg/day) or vehicle was initiated for 2 weeks. Aortic superoxide production determined by lucigenin-enhanced chemiluminescence and 2-hydroxyethidium formation was significantly increased in rats with diabetes and reduced by treatment with eplerenone (chemiluminescence: control 2045+/-227, STZ-placebo 3977+/-340, p<0.05 vs. control, STZ-eplerenone 1762+/-307, p<0.05 vs. STZ-placebo). Endothelium-dependent vasorelaxation was significantly attenuated in diabetic rats and was normalized by eplerenone (maximum relaxation in % of precontraction: control 95+/-3, STZ-placebo 82+/-3, p<0.01 vs. control, STZ-eplerenone 99+/-1, p<0.01 vs. STZ-placebo). Treatment with the selective MR antagonist significantly reduced fibrinogen-binding on activated GPIIb/IIIa (immunofluorescence: control 161+/-7, STZ-placebo 208+/-16, p<0.05 vs. control, STZ-eplerenone 173+/-6, p<0.05 vs. STZ-placebo). Eplerenone improves endothelial function by reducing superoxide formation and increasing NO bioavailability in diabetic rats. Platelet activation was significantly reduced by eplerenone. Selective MR blockade may constitute a useful therapeutic approach for treatment of vascular dysfunction in diabetes.


Subject(s)
Diabetes Mellitus, Experimental/drug therapy , Endothelium, Vascular/physiology , Platelet Aggregation Inhibitors/therapeutic use , Spironolactone/analogs & derivatives , Animals , Diabetes Mellitus, Experimental/physiopathology , Dose-Response Relationship, Drug , Endothelium, Vascular/drug effects , Eplerenone , Male , Platelet Aggregation Inhibitors/pharmacology , Rats , Rats, Wistar , Spironolactone/pharmacology , Spironolactone/therapeutic use , Vasodilation/drug effects , Vasodilation/physiology
14.
Acta Biomater ; 6(5): 1714-25, 2010 May.
Article in English | MEDLINE | ID: mdl-19788945

ABSTRACT

Magnesium alloys have attracted increasing interest in the past years due to their potential as implant materials. This interest is based on the fact that magnesium and its alloys are degradable during their time of service in the human body. Moreover magnesium alloys offer a property profile that is very close or even similar to that of human bone. The chemical composition triggers the resulting microstructure and features of degradation. In addition, the entire manufacturing route has an influence on the morphology of the microstructure after processing. Therefore the composition and the manufacturing route have to be chosen carefully with regard to the requirements of an application. This paper discusses the influence of composition and heat treatments on the microstructure, mechanical properties and corrosion behaviour of cast Mg-Gd alloys. Recommendations are given for the design of future degradable magnesium based implant materials.


Subject(s)
Alloys/chemistry , Gadolinium/chemistry , Magnesium/chemistry , Materials Testing/methods , Prostheses and Implants , Corrosion , Guidelines as Topic , Humans , Mechanical Phenomena , Microscopy, Electron, Scanning , Particle Size , Phase Transition , Tensile Strength , X-Ray Diffraction
15.
Acta Biomater ; 6(5): 1792-9, 2010 May.
Article in English | MEDLINE | ID: mdl-19822226

ABSTRACT

The aim of this study was to investigate whether the extruded magnesium alloy LAE442 reacts in vivo with an appropriate host response and to investigate how an additional magnesium fluoride (MgF(2)) coating influences the in vivo corrosion rate. Forty cylinders were machined from extruded LAE442 and 20 of these were coated additionally with MgF(2) and implanted into the medial femur condyle of adult rabbits. Synchrotron-radiation-based X-ray computed micro-tomography (SRmicroCT) was used to quantitatively analyse corrosion non-destructively in vivo and comparisons were made to magnesium degradation rates based on area measurements of the remaining metal on uncalcified sections. Blood concentrations of the alloying elements were measured below toxicological limits. The MgF(2) layer was no longer detected after 4 weeks of implantation by particle-induced gamma emission, and the MgF(2) coating reduced the blood content of alloying elements during the first 6 weeks of implantation with no elevated fluoride concentration in the adjacent bone. Histopathological examinations of liver showed in 9 out of 40 cases minimal infiltrations of heterophil granulocytes of unknown origin (5 LAE442, 4 LAE442+MgF(2)). The kidneys were mainly regular in structure. The synovial tissue showed a granular cell infiltration as a temporary observation in the LAE442+MgF(2) group after 2 weeks. No subcutaneous gas cavities were observed clinically and on postoperative X-rays in all animals. All specimens were scanned by SRmicroCT at 2, 4, 6 and 12 weeks postoperatively before uncalcified sections were performed. All magnesium implants have been observed in direct bone contact and without a fibrous capsule. Localized pitting corrosion occurred in coated and uncoated magnesium implants. This study shows that the extruded magnesium alloy LAE442 provides low corrosion rates and reacts in vivo with an acceptable host response. The in vivo corrosion rate can be further reduced by additional MgF(2) coating.


Subject(s)
Alloys/pharmacology , Magnesium/pharmacology , Animals , Coated Materials, Biocompatible , Corrosion , Elements , Female , Femur/drug effects , Femur/pathology , Fluorides/pharmacology , Hydrogen/chemistry , Implants, Experimental , Magnesium Compounds/pharmacology , Rabbits , Synchrotrons , Time Factors , X-Ray Microtomography
16.
Acta Biomater ; 6(5): 1861-8, 2010 May.
Article in English | MEDLINE | ID: mdl-20035905

ABSTRACT

Repeated observations of enhanced bone growth around various degradable magnesium alloys in vivo raise the question: what is the major mutual origin of this biological stimulus? Several possible origins, e.g. the metal surface properties, electrochemical interactions and biological effects of alloying elements, can be excluded by investigating the sole bone response to the purified major corrosion product of all magnesium alloys, magnesium hydroxide (Mg(OH)(2)). Isostatically compressed cylinders of pure Mg(OH)(2) were implanted into rabbit femur condyles for 2-6 weeks. We observed a temporarily increased bone volume (BV/TV) in the vicinity of Mg(OH)(2) at 4 weeks that returned to a level that was equal to the control at 6 weeks. The osteoclast surface (OcS/BS) was significantly reduced during the first four weeks around the Mg(OH)(2) cylinder, while an increase in osteoid surface (OS/BS) was observed at the same time. At 6 weeks, the OcS/BS adjacent to the Mg(OH)(2) cylinder was back within the same range of the control. The mineral apposition rate (MAR) was extensively enhanced until 4 weeks in the Mg(OH)(2) group before matching the control. Thus, the enhanced bone formation and temporarily decreased bone resorption resulted in a higher bone mass around the slowly dissolving Mg(OH)(2) cylinder. These data support the hypothesis that the major corrosion product Mg(OH)(2) from any magnesium alloy is the major origin of the observed enhanced bone growth in vivo. Further studies have to evaluate if the enhanced bone growth is mainly due to the local magnesium ion concentration or the local alkalosis accompanying the Mg(OH)(2) dissolution.


Subject(s)
Bone Remodeling/drug effects , Implants, Experimental , Magnesium Hydroxide/pharmacology , Osteoblasts/cytology , Osteoclasts/cytology , Animals , Biocompatible Materials/pharmacology , Bone and Bones/drug effects , Bone and Bones/pathology , Cell Count , Female , Fluorescence , Materials Testing , Minerals/metabolism , Osteoblasts/drug effects , Osteoclasts/drug effects , Osteogenesis/drug effects , Prosthesis Implantation , Rabbits , Staining and Labeling
17.
Ultraschall Med ; 30(6): 544-50, 2009 Dec.
Article in English | MEDLINE | ID: mdl-19998208

ABSTRACT

PURPOSE: The aim of the study was to characterize SonoVue enhancement in hepatocellular carcinoma in correlation to both lesion diameter and histological differentiation of the lesion. MATERIALS AND METHODS: In a prospective study 130 patients (72 male, 58 female, 62 +/- 10 years) with HCC lesions detected by B-mode sonography were examined. After injection of 1.2 - 2.4 ml SonoVue, HCC lesions were examined continuously for up to 5 min using "low MI" sonography. RESULTS: Arterial hypervascularization was found in 72 % of the HCC lesions without correlation to the lesion diameter or histological grading, when analyzed for the total group. However, the analysis of the G 1 subgroup showed significant correlation between lesion diameter and arterial hypervascularization. Arterial hypervascularization was found in 95 % of the G 1 lesions > 3 cm but in only 43 % of the G 1 lesions < 3 cm (p < 0.001). In contrast, analysis of the remaining HCC lesions (without G 1) showed arterial hypervascularization in 69 % of the lesions < 3 cm and in 72 % of the lesions > 3 cm (n. s.) without correlation to the diameter. In the late phase in the G 1 subgroup, hypoechoic demarcation was found in 95 % of the G 1 lesions > 3 cm, but in only 64 % of the G 1 lesions < 3 cm (p < 0.001). In contrast, in the less differentiated HCC lesions (without G 1), hypoechoic demarcation was found in 91 % (HCC > 3 cm) and in 82 % (HCC < 3 cm) of the lesions (n. s.). CONCLUSION: In well-differentiated HCCs (G1) hyperechoic enhancement in the arterial phase and hypoechoic demarcation in the late phase correlate to the diameter.


Subject(s)
Carcinoma, Hepatocellular/diagnostic imaging , Liver Neoplasms/diagnostic imaging , Phospholipids , Sulfur Hexafluoride , Aged , Carcinoma, Hepatocellular/pathology , Cell Differentiation , Contrast Media , Diagnosis, Differential , Female , Humans , Image Enhancement , Liver/diagnostic imaging , Liver/pathology , Liver Neoplasms/pathology , Male , Middle Aged , Prospective Studies , Sensitivity and Specificity , Ultrasonography
18.
Br J Pharmacol ; 153(5): 886-93, 2008 Mar.
Article in English | MEDLINE | ID: mdl-17891166

ABSTRACT

BACKGROUND AND PURPOSE: Diabetes-associated vascular dysfunction contributes to increased cardiovascular risk. We investigated whether the phosphodiesterase-5 inhibitor sildenafil would improve vascular function in diabetic rats. EXPERIMENTAL APPROACH: Male Wistar rats were injected with streptozotocin (50 mg kg(-1), i.v.) to induce insulin-deficient diabetes. Direct effects of sildenafil as well as modification of endothelium-dependent and -independent vasorelaxation were investigated in vitro. The effects of acute and chronic (2 week) treatment in vivo of sildenafil on vascular function were also characterized in isolated aortic segments in organ bath chambers 4 weeks after diabetes induction. KEY RESULTS: Sildenafil induced a concentration-dependent vasorelaxation, which was attenuated by the nitric oxide (NO) synthase inhibitor, N(G)-nitro-L-arginine. Acetylcholine-induced endothelium-dependent as well as endothelium-independent relaxation induced by the NO donor, DEA-NONOate, was significantly reduced in aortae from diabetic rats. Incubation with sildenafil in vitro normalized both endothelium-dependent and -independent relaxation in aortae from diabetic rats. Acute as well as chronic in vivo treatment with sildenafil resulted in enhanced endothelium-dependent and -independent vasorelaxation. Superoxide formation was increased in diabetes, associated with enhanced membrane expression of the NAD(P)H oxidase subunit gp91(phox) and Rac, which were both reduced by chronic treatment with sildenafil. CONCLUSIONS AND IMPLICATIONS: We demonstrate that sildenafil treatment rapidly and chronically improves vascular relaxation in diabetic rats. Treatment with sildenafil might provide a similarly beneficial effect in diabetic patients.


Subject(s)
Diabetes Mellitus, Experimental/drug therapy , Phosphodiesterase Inhibitors/pharmacology , Piperazines/pharmacology , Sulfones/pharmacology , Vasodilation/drug effects , Acetylcholine/pharmacology , Animals , Aorta, Thoracic/metabolism , Diabetes Mellitus, Experimental/physiopathology , Dose-Response Relationship, Drug , Drug Administration Schedule , Endothelium, Vascular/drug effects , Male , Nitric Oxide Synthase/metabolism , Oxidative Stress/drug effects , Phosphodiesterase Inhibitors/administration & dosage , Piperazines/administration & dosage , Purines/administration & dosage , Purines/pharmacology , Rats , Rats, Wistar , Sildenafil Citrate , Streptozocin , Sulfones/administration & dosage , Superoxides/metabolism
19.
Dtsch Med Wochenschr ; 132(47): 2500-4, 2007 Nov.
Article in German | MEDLINE | ID: mdl-18027324

ABSTRACT

INTRODUCTION: Insulin clearance and the degree of insulin resistance change in type 1 diabetes in patients with reduced kidney function and make it more difficult to achieve good metabolic control. For some years different analogue insulins have become available. Their pharmacological characteristics in renal failure have not as yet been investigated in detail. The aim of the present retrospective study was to determine the insulin dosage in relation to kidney function in patients with type 1 diabetes treated with human or analogue insulin. METHODS: Insulin dosage of 68 patients treated with human insulin and 74 patients treated with analogue insulin was related to the creatinine clearance (calculated with the Cockcroft-Gault formula). In addition, diabetes-related laboratory parameters, the prevalence of hypertension and the kind of antihypertensive therapy were analysed in both groups. RESULTS: Patients with type 1 diabetes treated with human or analogue insulin have different insulin demands if their renal function is decreased. In analogue-treated patients, insulin dosage significantly decreased with reduced creatinine clearance (r = 0,257; p = 0,026) in contrast to human insulin treated patients who did not show such a decrease (r = 0,159; p = 0,165). There were no significant differences between treatment groups with respect to demographic data, metabolic control or antihypertensive therapy. Linear regression analysis revealed kidney function as a significant factor influencing insulin dosage in the analogue group, while the corresponding factors in the human insulin group were metabolic control and age. CONCLUSION: The results indicate that insulin clearance and/or the metabolic activity of human and analogue insulin differ if renal function is reduced. This may be due to different pharmacokinetic or pharmacodynamic characteristics of these insulins in renal failure, a finding which needs further investigation.


Subject(s)
Diabetes Mellitus, Type 1/drug therapy , Diabetic Nephropathies/complications , Hypoglycemic Agents/therapeutic use , Insulin/analogs & derivatives , Insulin/therapeutic use , Renal Insufficiency/complications , Creatinine/metabolism , Diabetes Mellitus, Type 1/complications , Diabetes Mellitus, Type 1/metabolism , Diabetic Nephropathies/drug therapy , Diabetic Nephropathies/metabolism , Female , Humans , Hypertension/complications , Hypertension/drug therapy , Hypoglycemic Agents/pharmacokinetics , Insulin/pharmacokinetics , Kidney/physiopathology , Kidney Function Tests , Linear Models , Male , Metabolic Clearance Rate , Middle Aged , Renal Insufficiency/metabolism , Renal Insufficiency/physiopathology , Retrospective Studies
20.
Ultraschall Med ; 28(2): 168-75, 2007 Apr.
Article in English | MEDLINE | ID: mdl-17447216

ABSTRACT

PURPOSE: SonoVue and Levovist (SH U 508A) are both ultrasound contrast agents, which are helpful in characterization and detection of malignant liver lesions. This study was performed to compare both contrast agents according to the capability to diagnose hepatocellular carcinoma (HCC). MATERIALS AND METHODS: In a prospective study, 65 patients with histologically proven hepatocellular carcinoma (HCC) were examined with both, Levovist and SonoVue. In all patients HCC lesions had been detected by B-mode sonography before the study start. After injection of 2.4 ml SonoVue i. v., the liver was examined continuously for up to three minutes using "low MI"-pulse inversion sonography. For the Levovist-examinations 2.5 g Levovist were injected i. v. After a delay of at least 2.5 minutes without scanning, the liver was examined with three different scans using "high-MI"-pulse-inversion sonography. RESULTS: The examination was technically sufficient in 98% after SonoVue-injection and in 92% after Levovist-injection (n. s.). Comparison of the results was performed for the 60/65 patients (61 lesions), in which both methods were technically sufficient. After SonoVue-injection contrast-enhancement in the arterial phase was found in 79% (48/61) of the lesions. Demarcation of the HCC-lesion in the late phase was found in 89% of the SonoVue-examinations and in 98% of the Levovist-examinations (p < 0.05). Early SonoVue-enhancement and/or demarcation in SonoVue late-phase was found in 93% of the HCC-lesions (n. s. compared to Levovist-late phase). CONCLUSION: Levovist-late phase has a higher sensitivity in predicting lesion dignity of HCC-lesions compared to SonoVue-late phase, but not compared to combination of SonoVue-early phase and late phase.


Subject(s)
Carcinoma, Hepatocellular/diagnostic imaging , Liver Neoplasms/diagnostic imaging , Phospholipids , Polysaccharides , Sulfur Hexafluoride , Biopsy , Carcinoma, Hepatocellular/pathology , Contrast Media , Humans , Image Processing, Computer-Assisted , Liver/pathology , Liver Neoplasms/pathology , Phospholipids/adverse effects , Polysaccharides/adverse effects , Prospective Studies , Sulfur Hexafluoride/adverse effects , Ultrasonography
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