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1.
Biotribology (Oxf) ; 242020 Dec.
Article in English | MEDLINE | ID: mdl-33015276

ABSTRACT

Tribocorrosion of implants has been widely addressed in the orthopedic and dental research fields. This study is a systematic scoping review about research methods that combine tribocorrosion tests with cells/tissues cultures, aimed to identify related current problems and future challenges. We used 4 different databases to identify 1022 records responding to an articulated keywords search-strategy. After removing the duplicates and the articles that didn't meet the search-criteria, we assessed 20 full-text articles for eligibility. Of the 20 eligible articles, we charted 8 records on cell cultures combined with tribocorrosion tests on implant materials (titanium, CoCrMo, and/or stainless steel). The year of publication ranged from 1991 to 2019. The cell line used was mostly murine. Two records used fretting tests, while 6 used reciprocating sliding with pin-on-disc tribometers. An electrochemical three-electrode setup was used in 4 records. We identified overall two experimental approaches: cells cultured on the metal (5 records), and cells cultured near the metal (3 records). Research activities on tribocorrosion processes in the presence of cells have been undertaken worldwide by a few groups. After a limited initial interest on this topic in the 1990's, research activities have restarted in the last decade, renewing the topic with technologically more advanced setups and analytical tools. We identified the main problems to be the lack of test reproducibility and wear particle characterization. We believe that the main challenges lay in the interdisciplinary approach, the inter-laboratory validation of experiments, and the interpretation of results, particularly in relation to potential clinical significance.

2.
J Laryngol Otol Suppl ; (27): 50-3, 2000.
Article in English | MEDLINE | ID: mdl-11211440

ABSTRACT

Since 1994, a US Food and Drug Administration clinical trial evaluated the multichannel auditory brainstem implant (ABI) on 92 subjects with neurofibromatosis type 2 (NF2). The trial has shown that 85 per cent of patients receive auditory sensations. A small number of patients demonstrate a clinically significant degree of open-set sentence recognition in the sound-alone condition; however, when the ABI is combined with lip-reading cues, 93 per cent of patients demonstrate improved sentence understanding at three to six months. In addition, the majority of recipients report daily use of their devices, and satisfaction with the decision to receive the ABI.


Subject(s)
Brain Stem/surgery , Hearing Loss, Central/surgery , Neurofibromatosis 2/surgery , Prosthesis Implantation/methods , Adolescent , Adult , Aged , Child , Correction of Hearing Impairment , Female , Hearing Loss, Central/complications , Humans , Male , Middle Aged , Neurofibromatosis 2/complications , Psychophysics , Speech Perception
3.
Med Sci Monit ; 6(5): 1013-7, 2000.
Article in English | MEDLINE | ID: mdl-11208448

ABSTRACT

The case of a potentially life-threatening complication related to the use of implanted port device in a 8 year old Non-Hodgkin's Lymphoma patient receiving chemotherapy is described. The device was inserted in early 1997 and used repeatedly for chemotherapy without any complications. In late 1997 during routine screening for cardiac left ventricular function before re-introduction of chemotherapy, an abnormal 1.43 x 1.53 cm mass, consistent with a non-mobile thrombus was found in the right atrium. The initial thrombolytic therapy with recombinant tissue plasmin activator (rt-PA) infused by a central venous catheter was combined with daily echocardiographic examination in order to assess both the timing and mode of thrombus resolution. After 8 days systemic fibrinolytic therapy was discontinued as major hemorrhage from venipuncture sites occurred and the clot dissolution was not obtained. Patient underwent right atriotomy utilizing cardiopulmonary bypass and subsequent surgical thrombus removal was successful. The study evaluated the contribution of two-dimensional echocardiography (2D) in the follow-up of vascuport and other central venous catheter (CVC) location and early diagnosis of related complications such as thrombi. The authors consider that pulmonary flow analyzed with Doppler echocardiography as a reliable, suitable and non-invasive method to evaluate increased pulmonary artery pressure in children with right atrial thrombi and probability of pulmonary microembolism or embolism. As the incidence of right atrial thrombi is highly associated with the catheter tip position in the right atrium, in contrast to their positioning in the superior vena cava or in its junction with the right atrium, the authors recommend that special attention and effort should be given to placing of the catheter tip in the superior vena cava or in its junction with the right atrium avoiding the right atrium during the implantation procedure. The surgical right atrium thrombus removal in patients with no clot dissolution despite systemic thrombolytic treatment underscores the importance of surgical therapy in treating this life-threatening complication of indwelling catheters.


Subject(s)
Catheters, Indwelling/adverse effects , Coronary Thrombosis/diagnostic imaging , Coronary Thrombosis/etiology , Antineoplastic Agents/administration & dosage , Child , Coronary Thrombosis/surgery , Echocardiography, Doppler , Heart Atria/diagnostic imaging , Humans , Lymphoma, Non-Hodgkin/drug therapy , Male , Pulmonary Circulation , Thrombolytic Therapy
4.
Perception ; 27(1): 105-22, 1998.
Article in English | MEDLINE | ID: mdl-9692091

ABSTRACT

A study is reported of the effect of early visual experience on the development of auditory space perception. The spatial hearing of thirty-five children with visual disabilities (twenty-two with congenital total blindness) was compared with that of eighteen sighted children and seventeen sighted adults. The tests provided a comprehensive assessment of spatial-hearing ability, including psychophysical estimates of spatial resolution in the horizontal, vertical, and distance dimensions, as well as measures of reaching and walking to the locations of sound sources. The spatial hearing of the children with visual disabilities was comparable to or somewhat better than that of the sighted children and adults. This pattern held even when the group with visual disabilities was restricted to those children with congenital total blindness; in fact, some of those children had exceptionally good spatial hearing. These findings imply that the developmental calibration of human spatial hearing is not dependent on a history of visual experience. It seems likely that this calibration arises from the experience of changes in sound-localization cues arising from self-motion, such as turning the head or walking. As a practical matter, orientation and mobility instructors may reasonably assume that individuals with visual disabilities can use their hearing effectively in day-to-day travel situations.


Subject(s)
Auditory Perception , Vision Disorders/psychology , Adolescent , Adult , Blindness/congenital , Blindness/psychology , Child , Female , Hearing Tests , Humans , Male
5.
Wiad Lek ; 51 Suppl 4: 266-9, 1998.
Article in Polish | MEDLINE | ID: mdl-10731981

ABSTRACT

The atrial catheter (subcutaneous port) was used in a 5 year old boy with Hodgkin's disease for the administration of antineoplastic agents and other drugs. Catheter was flushed daily or every 2 weeks with heparin solution (5 U/ml)). The complications including infection and occlusion were not observed in this patient during observation time. Routine echocardiography performed after eight months of usage of the catheter showed right atrial thrombus. Because of the failure of 14 days fibrinolytic therapy (Actylise) surgical thrombectomy was performed. Bacteriological culture of the surgical specimen was positive for Pseudomonas aeruginosa. The post-operative period passed without complications. Follow-up echocardiography findings were normal. The probable reason of thrombus formation could be damage of the right atrium by stream of drugs or balloting ending of the catheter.


Subject(s)
Antineoplastic Agents/administration & dosage , Catheterization, Central Venous/adverse effects , Heart Atria , Hodgkin Disease/drug therapy , Thrombosis/etiology , Child, Preschool , Female , Humans , Male , Pseudomonas Infections/etiology , Thrombosis/microbiology , Thrombosis/surgery
6.
J Biomol Struct Dyn ; 12(5): 1121-7, 1995 Apr.
Article in English | MEDLINE | ID: mdl-7626244

ABSTRACT

The interaction between polynucleotides: poly(dA)-poly(dT), poly(dA-dT), poly(am2dA-dT), and the AT-specific compounds of benzimidazol group has been studied. It is been shown that these compounds bind to poly(dA)-poly(dT) and poly(dA-dT) at low and high salt concentration in solution. Poly(am2dA-dT) interacts with AT-specific compounds only at low salt, where this polynucleotide is in a B-form, but not at high salt, when the polynucleotide converts to another conformation. Thus, the interaction specificity of the groove-binding ligands is influenced not only by the minor groove substituents, but the peculiarities of the secondary structure of polynucleotides.


Subject(s)
Benzimidazoles/chemistry , Poly dA-dT/chemistry , Benzimidazoles/chemical synthesis , Benzimidazoles/metabolism , Circular Dichroism , Hydrogen Bonding , Osmolar Concentration , Poly dA-dT/metabolism , Sodium Chloride
7.
Biochemistry ; 33(13): 3801-6, 1994 Apr 05.
Article in English | MEDLINE | ID: mdl-8142382

ABSTRACT

Poly(amino2dA-dT) easily isomerizes into a non-B conformer which most authors think is an A-form. We synthesized new DNA analogs poly(amino2dA-ethyl5dU) and poly(amino2dA-dU) to show that they do not prefer this conformer. Hence the putative A-form is, like Z-DNA of poly(dG-dC) but unlike A-DNA, strongly stabilized by the methyl group in position 5 of the pyrimidine base. In addition, the putative A-form is induced by divalent cations while it does not need any alcohol to be stable, both properties being typical for Z-DNA again but quite unusual with A-DNA. Despite these similarities, the putative A-form is also distinct from Z-DNA, as poly(amino2dA-dT) is shown to isomerize into a Z-form in the NaCl + NiCl2 solvent system like poly(dA-dT). The present data indicate that the putative A-form of poly(amino2dA-dT) differs in a significant way from all canonical conformers of DNA. Furthermore, the studies of the poly(amino2dA-dT) family of polydeoxynucleotides reveal a novel type of conformational switch in DNA. We also report the B-Z transitions of poly(amino2dA-ethyl5dU) and poly(amino2dA-dU) and their transitions into the putative A-form in aqueous alcohol solutions.


Subject(s)
Nucleic Acid Conformation , Poly dA-dT/chemistry , Thymine/chemistry , Circular Dichroism , Ethanol/chemistry , Isomerism , Magnesium Chloride/chemistry , Spectrophotometry, Ultraviolet , Structure-Activity Relationship
8.
J Biomol Struct Dyn ; 10(4): 681-92, 1993 Feb.
Article in English | MEDLINE | ID: mdl-8466673

ABSTRACT

We have synthesized poly(dA,dPu-dT) and poly(dA,n2dPu-dT) containing, respectively, 5.7% of purine and 7.4% of amino2purine in place of adenine to demonstrate that these apparently negligible perturbations of the primary structure have dramatic consequences for the polynucleotide conformational isomerizations. The replacement of adenine by amino2purine, preserving the number of hydrogen bonds between the complementary bases, has a stronger effect on the polynucleotide conformational isomerizations than the replacement with purine that is bound only by a single hydrogen bond to thymine. Nevertheless, poly(dA,dPu-dT) forms a more thermostable duplex than poly(dA,n2dPu-dT). Furthermore the few amino2purines in poly(dA,n2dPu-dT) inhibit its isomerization into X-DNA, stabilize but modify A-DNA and stabilize Z-DNA. Kinetics of the B-Z transition of poly(dA,n2dPu-dT) is fast to indicate that the amino groups in the double helix minor groove substantially decrease the kinetic barrier between B- and Z-DNA. On the other hand, the replacement of adenine by purine destabilizes both Z-DNA and A-DNA, and the destabilization of X-DNA is weaker than with amino2purine. A-form and B-form perhaps coexist in poly(dA,dPu-dT) at high concentrations of ethanol.


Subject(s)
Adenine/chemistry , DNA/chemistry , Nucleic Acid Conformation , Poly dA-dT/chemistry , Purines/chemistry , Aminopyrine/chemistry , Hydrogen Bonding , Spectrophotometry, Ultraviolet , Stereoisomerism
10.
J Biomol Struct Dyn ; 7(5): 1073-82, 1990 Apr.
Article in English | MEDLINE | ID: mdl-2360999

ABSTRACT

The alternating copolymer poly(amino2dA-dT) isomerizes into the unusual X-DNA double helix at low-salt aqueous conditions (Vorlicková et al., J. Biomolec. Struct. Dyn. 6, 503-510 (1988)). This observation allowed us to start studies on how the X-DNA is recognized, copied and hydrolyzed by various enzymes. In the present paper X-DNA replication, transcription and digestion by various polymerases and nucleases, respectively, are examined and compared to appropriate controls. It is found that X-DNA is a poor primer-template for DNA synthesis by the E. coli Klenow DNA polymerase (12% of the activity observed with B-DNA), the Micrococcus luteus DNA polymerase I (25%) and the AMV reverse transcriptase (51%). In contrast, X-DNA is a better template by 74% than B-DNA for calf thymus DNA polymerase alpha. For transcription by E. coli RNA polymerase enzyme poly(amino2dA-dT) did not serve as a template at all in either B or X conformation. Poly(amino2dA-dT) in its B form proved to be much more stable than poly(dA-dT) against hydrolysis by pancreatic DNase and snake venom phosphodiesterase. Formation of the X conformation in poly(amino2dA-dT) decreased this large difference in nuclease stability.


Subject(s)
Polydeoxyribonucleotides/metabolism , DNA Replication , DNA-Directed DNA Polymerase/metabolism , DNA-Directed RNA Polymerases/metabolism , Deoxyribonucleases/metabolism , Nucleic Acid Conformation , Transcription, Genetic
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