Biomedical subjects

A Wilk

Publications and source records attributed to A Wilk.

At least 19 recordsLinked to original sources

PubMed1998

The effect of two antipodal fluorine-induced sugar puckers on the conformation and stability of the Dickerson-Drew dodecamer duplex [d(CGCGAATTCGCG)]2.

UV thermal melting studies, CD and NMR spectroscopies were employed to assess the contribution of antipodal sugar conformations on the stability of the canonical B-DNA conformation of the Dickerson-Drew dodecamer duplex [[d(CGCGAATTCGCG)]2, (ODN 1)]. Different oligodeoxynucleotide versions of ODN 1 were synthesized with modified thymidine units favoring distinct sugar conformations by using a 3'- endo (north) 2'-fluoro-2'-deoxyribofuranosyl thymine (1) or a 2'- endo (south) 2'-fluoro-2'-deoxyarabinofuranosyl thymine (2). The results showed that two south thymidines greatly stabilized the double helix, whereas two north thymidines destabilized it by inducing a more A-like conformation in the middle of the duplex. Use of combinations of north and south thymidine conformers in the same oligo destabilized the double helix even further, but without inducing a conformational change. The critical length for establishing a detectable A-like conformation in the middle of a B-DNA ODN appears to be 4 bp. Our results suggest that manipulation of the conformation of DNA in a sequence-independent manner is possible.

DNA↗

PubMed1998

Determination of the external forces applied to the mandible during various static chewing tasks.

The purpose of this study is to determine the external forces that are brought to bear on the mandible during 14 masticatory tasks, exerted in three defined mandibular positions. A static two-dimensional mandibular model is presented, taking into account projections in the sagittal plane of the forces exerted by six muscle groups and the joint reaction force. In calculating these external forces, two working hypotheses are adopted: the existence of a linear relationship between cross-sectional surface of the muscle and its maximum force of contraction, and the existence of a linear relationship between the electrical signal emitted by a muscle and the force the muscle then develops. Our first results are provided and compared with data from the literature. Individual variations recorded in the measurement of the different parameters involved in the equilibrium equations are such that they must be taken into account in the calculation of the forces. Moreover, the functional value of the muscles appears to be closely dependent on the mandibular position with which they are associated, which is not brought out in earlier studies. Finally, intra-joint action proves to be intense, although its direction varies according to the mandibular position and the type of exercise performed.

Bite Force↗

PubMed1998

[Methods proposed for the determination of external forces applied to the mandible during mastication. Initial results].

The purpose of this study is to determine the external forces that are brought to bear on the mandible during various masticatory exercises. An analysis is presented of a static two-dimensional mandibular model taking into account projections in the sagittal plane of the forces exerted by six muscle groups and the joint reaction. In calculating the external forces, two working hypotheses are adopted: the existence of a linear relationship between cross-sectional surface of the muscle and its maximum force of contraction; the existence of a linear relationship between the electrical signal emitted by a muscle and the force the muscle then develops. It follows that, in order to calculate, the muscle forces, there is a need to measure the intensity of masticatory effort, the cross-sectional surface and the electromyographic activity of the different muscles involved. These values are then used for working out the equations of equilibrium. Results are provided for 14 masticatory exercises effected in three different mandibular positions and compared with data from literature. Individual variations recorded in the measurement of the different parameters involved in the equilibrium equations are such that they must be taken into account for the calculation of the forces. Moreover, the functional value of the muscles appears to be closely dependent on the mandibular position with which they are associated, which is not brought out in earlier studies. Finally, intra-joint action proves to be intense, although its direction varies according not only to the mandibular position but also the type of exercise performed.

Algorithms↗

PubMed1998

[Combined Latissimus dorsi and Serratus anterior reverse flow pedicle flap. Report of a clinical case].

The authors report a new local combined flap involving the distally based Latissimus dorsi muscle pedicled on the lumber perforating arteries and prolonged by the last three digitations of the Serratus anterior muscle supplied by the thoracic branch of the thoraco-dorsal artery. This artifice, never previously described, increased the bulk and arc of rotation of the dorsalis flap. It was thus possible to cover a wide defect on the posterior aspect of the sacro-iliac region in a patient previously operated for a highly malignant histiocytofibroma. The anatomic considerations, harvesting technique and advantages and drawbacks of this flap are discussed.

Adult↗

PubMed1998

[Long-term outcome of surgically treated orbital floor fractures. Apropos of a series of 242 patients].

Over a period extending from January 1993 to December 1995, we treated 242 patients with 268 orbital floor fractures in our department. Surgical indications were broad and relied on clinical criteria (enophthalmos, diplopia, hypoesthesia) and/or CT analysis (bony collapse, extrusion of orbital contents, suspicion of muscular entrapment, dislocation of the infraorbital rim). Two years after surgery, 91% of the patients showed good results (absence of diplopia or severe enophthalmos). The analysis of these results points out that the degree of sequelar enophthamos was not only related to the degree of initial bony collapse but above all to the quality of the bony reconstruction. Sequelar diplopia was linked with the presence of a preoperative diplopia and its severity was a direct function of operative delay. Hypoesthesia in the infraorbital nerve territory was the most common sequela; some were postoperative complications. The type of material used for the restoration of the orbital floor was not involved in the development of these sequela. Our good results suggest that an interventionist attitude is warranted in these kind of fractures, the more so as the X-ray examinations often underestimate injuries.

Adolescent↗

PubMed1997

Biodegradation and aquatic toxicity of beta-alaninediacetic acid (beta-ADA).

The aquatic toxicity and biodegradability of the new chelating agent beta-alaninediacetic acid (beta-ADA) were investigated. There is no inhibition effect of beta-ADA in the daphnia magna 24 h test up to a concentration of 1000 mg/L. The algal growth inhibition test resulted in an EC 50 of 19.7 mg/L. An EC 20 of 740 mg/L was determined in the luminescent bacteria test. An EC 50 was not obtained in this test up to a concentration of 2000 mg/L beta-ADA. The degree of biodegradation of beta-ADA was determined in a static and a continuous test. The beta-ADA removal reached 98% at the end of the test after eight weeks in the continuous test which was carried out with laboratory activated sludge units simulating a waste water treatment plant. Further, biodegradation and toxicity tests were coupled, i.e. the effluents of the laboratory activated sludge units were applied in the toxicity tests. A higher toxicity of the effluents of the test units in comparison with the control unit was not observed.

Acetic Acid↗

PubMed1997

CD44 isoforms with exon v6 and metastasis of primary N0M0 breast carcinomas.

New isoforms of CD44 with alternatively spliced exons have recently been described. Expression of exon v6 seems to be of particular interest. It has indeed been associated with poorer outcome of breast cancer patients with node invasion at diagnosis. However, no data were available for patients N0M0 (with neither metastasis nor node invasion at diagnosis). Moreover, previous statistical analyses were realized using immunohistochemical methods to detect CD44v6 expression although several variants with exon v6 have been described. We investigated expression of isoforms containing CD44v6 using an RT-PCR approach and a panel of 25 normal breast specimens, 10 mammary fibroadenomas, 8 cystic samples and 52 primary breast tumors (38 invasive N0M0). Normal breasts, fibroadenomas, and cysts all express the same variant, A (with exon v6 only), while several transcripts are amplified in tumors. Expression of variants other than A correlates with acquisition of a malignant phenotype. Invasive cancers also express additional variants in comparison with in situ carcinomas. Metastasis capacities seem to be associated with transcription of variants other than A but also with no transcription of some of them, variants D (with exons v6 and v10) and L (with exons v6 to v10). Expression of variants D and L correlates with higher percentages of disease-free survival and better outcome. Expression of CD44 splice variants with exon v6, as detected by RT-PCR, might be a useful prognostic factor for breast cancer. However, since the series size is small, our results need to be confirmed by later studies on a larger number of patients.

Adult↗

PubMed1997

[Osteosynthesis of subcondylar fractures using a rectangular 3-dimensional stabilization plate].

The current international opinion for the treatment of displaced subcondylar fractures has become more aggressive after the rediscovery of the submandibular incision and the creation of new fixation material. We report 19 patients with displaced subcondylar fractures who were treated with reinforced rectangular plates. The pure titanium plates are slightly concave and measure 13 by 9 mm. We evaluated dental articulation, mouth opening, propulsion and duction and observed rapid recovery of mandibular kinetics and mandibular function. Use of this plate is a major progress in the treatment of fractures of the condyle.

Biocompatible Materials↗

PubMed1996

Cleavage of oligodeoxyribonucleotides from controlled-pore glass supports and their rapid deprotection by gaseous amines.

A novel method for the deprotection of oligodeoxyribonucleotides has been developed. Gaseous amines such as ammonia or methylamine were employed under pressure to achieve mild and rapid deprotection conditions. For example, oligodeoxyribonucleotides having a (tert-butyl)phenoxyacetyl group for the protection of the exocyclic amino function of cytosine, adenine and guanine were released from controlled-pore glass supports and fully deprotected by ammonia or methylamine under gas phase conditions, at room temperature, within 35 or 2 min respectively.

Adenine↗

PubMed1996

Chiral phosphorothioates as probes of protein interactions with individual DNA phosphoryl oxygens: essential interactions of EcoRI endonuclease with the phosphate at pGAATTC.

The contact between EcoRI endonuclease and the "primary clamp" phosphate of its recognition site pGAATTC is absolutely required for recognition of the canonical and all variant DNA sites. We have probed this contact using oligonucleotides containing single stereospecific (Rp)- or (Sp)- phosphorothioates (Ps). At the GAApTTC position, where the endonuclease interacts with only one phosphoryl oxygen at the central DNA kink, Rp-Ps inhibits and Sp-Ps stimulates binding and cleavage [Lesser et al. (1992) J. Biol. Chem. 267, 24810-24818]: in contrast, at the pGAATTC position both diastereomers inhibit binding. For single-strand substitution, the penalty in binding free energy (delta delta G0bind) is slightly greater for Sp-Ps (+ 0.9 kcal/mol) than for Rp-Ps (+ 0.7 kcal/mol). Binding penalties are approximately additive for double-strand substitution (Rp,Rp-Ps or Sp,Sp-Ps). Neither Ps diastereomer in one DNA strand affects the first-order rate constants for cleavage in the unmodified DNA strand, and only Sp-Ps inhibits the cleavage rate constant (3-fold) in the modified DNA strand. Thus, the second-order cleavage rate (including binding and catalysis) is inhibited 14-fold by Sp-Ps and 45-fold by Sp,Sp-Ps. In the canonical complex, the phosphate at pGAATTC is completely surrounded by protein and each nonbridging phosphoryl oxygen receives two hydrogen bonds from the endonuclease, such that in either orientation the increased bond length of P-S- inhibits binding. However, the pro-Sp oxygen interacts with residues that are connected (by proximity or inter-side-chain hydrogen bonding) to side chains with essential roles in catalysis, so cleavage is preferentially inhibited when these side chains are slightly displaced by the Sp-Ps diastereomer.

Base Sequence↗

PubMed1996

CD44 exon 6 expression as a possible early prognostic factor in primary node negative breast carcinoma.

Breast cancer is the most common female malignancy affecting approximately one woman in eight. Many attempts have been made to define markers which may have potential clinical applications in diagnosis as well as therapy. New isoforms of CD44 with alternative spliced exons have recently been described. We studied the expression of CD44 exon 6 using a semi-quantitative RT-PCR reaction on a panel of 25 normal breast specimens, 10 mammary fibroadenomas, eight cystic samples and 52 primary breast tumors. Significant correlation was found between CD44 exon 6 expression and the overall survival of the N-M-population, P = 0.032, (logrank test by Mantel's method). The same result was also observed for the disease-free survival, P = 0.000002 (logrank test by Mantel's method). CD44 exon 6 expression, as detected by our RT-PCR-based method, might be a useful prognostic indicator of metastasis in breast cancer. However, these preliminary results need to be confirmed by later retrospective and prospective studies on a larger number of patients.

Adult↗

PubMed1996

E-cadherin mRNA expression in breast carcinomas correlates with overall and disease-free survival.

E-cadherin (Epithelial-cadherin) is a subclass of the cadherin family that plays a major role in the maintenance of intercellular junctions in epithelial tissues. E-cadherin is also involved in the interactions between epithelial cells and T lymphocytes. In order to explore the relationship between E-cadherin expression, cancer invasion and metastases in vivo, we estimated its expression in normal breast specimens, fibroadenomas, cystic samples and primary breast carcinomas using a semiquantitative reverse transcription-polymerase chain reaction. The relationship between E-cadherin expression, survival and disease-free survival was also investigated. In comparison with normal breasts, 70% of the primary tumors showed reduced expression of E-cadherin suggesting that downregulation of this cell adhesion molecule is a common event in breast carcinoma. Significant correlation was found between E-cadherin expression and the histological classification. Most of the advanced tumors grades (10/13 tumors with grade III) presented decreased E-cadherin expression. No correlation was found between E-cadherin expression, estrogen and progesteron receptors, age and menopausal status at diagnosis. However, disease-free and overall survival was associated with E-cadherin expression. Patients showing poorly expressed E-cadherin in tumor tissue had a worse prognosis. The same results were observed for women without lymph node invasion or metastasis at diagnosis even when they were grouped according to their histological grade for statistical analysis. Therefore, E-cadherin mRNA expression in invasive breast carcinomas might be an early prognostic factor of metastasis.

Adult↗

PubMed1996

[The coral orbital floor. Its value in traumatology. The results of a multicenter study of 83 cases].

A madreporic coral graft was used for orbital floor reconstruction following facial trauma. This report presents a multicentric study of 83 patients with a follow-up period of 15 to 24 months. The results of this study indicate no significant rejection or infection opposed to so many synthetic implants outcome. The radiological follow-up demonstrates a partially resorption of the implant within about 2 years and its replacements by new bone. Coral implant was used to correct enophthalmos or diplopia due to enlarged orbital dimensions. It was technically easy to insert and its anatomic shape does not require to be fashioned before use. Its inflexibility allows to bridge large bone defects and this implant should be considered as an attractive alternative to autogenous grafts, avoiding a second surgical site, in reconstructing orbital floor fractures.

Adolescent↗

PubMed1995

Analysis of oligo(deoxynucleoside phosphorothioate)s and their diastereomeric composition.

Short oligo(deoxynucleoside phosphorothioate)s were analyzed as a pool of individual diastereomeric species. The composition of such mixtures, determined by means of HPLC, indicates that consecutive couplings in commonly used phosphoramidite chemistry lead to increasing contents of the Rp isomer. Methods of analysis and mathematical basis for diastereomeric composition are discussed. Data presented include all 16 possible combinations of nucleosides in dinucleotide phosphorothioates, as well as examples of trimers and tetramers.

Chromatography, High Pressure Liquid↗

PubMed1995

Hospital-based alcohol and drug specialty consultation service: does it work?

The goals of this report are to describe the development of an inpatient-based alcohol and drug abuse consultation service in a university hospital. At the University of Wisconsin Hospital, we collected data on baseline diagnosis, health services, and costs for inpatients who received such a consultation in 1992-1993 (n = 1,098, 3.5% of all admissions). Follow-up interviews were conducted on a sample of 175 subjects. At the initial assessment, 65% were nicotine dependent, and 50% met criteria for alcohol dependence, 19% for alcohol abuse, 13% for alcohol and drug abuse/dependence. The average cost to patients for a consultation was $220. At the 6-month follow-up interview (n = 175), 42% of the subjects reported complete abstinence, 70% reported reductions in use, and 56% participated in an alcohol and drug treatment program. An inpatient-based alcohol and drug abuse consultation service provides a critical benefit that has not previously been offered in most academic medical centers.

Adolescent↗

PubMed1995

[The value of 3-dimensional computed tomography in the preoperative evaluation of mandibular condyle fractures].

The recent expansion of surgical treatment for displaced condylar neck fractures should rely on a precise and careful preoperative radiological assessment. Two goals must be achieved. First the diagnosis must be confirmed by usually sufficient conventional imaging. Secondly, all the features of the fracture have to be analysed to come to the surgical decision and to choose the best osteosynthesis technique. Compared to traditional imaging, three dimensional computed tomography offers the possibility of a direct viewing. The extend of the fracture, the aspect and degree of displacement of the condylar fragment in relation to the ramus or the fossa are easily assessed. The examination and the integration of multiple axial or coronal bidimensional CT scan sections are no more necessary. The clearer perception of both the spacial relationships and delineation of these condylar fractures results in a better choice for surgical planning.

Adult↗

PubMed1995

[Does the choice of mammoplasty pedicle influence the shape of reduced the reduced-sized breast?].

Thirty seven patients with breast hypertrophy were restrospectively reviewed with a mean follow-up of 2 years. Reduction mammoplasty was performed with 3 different pedicles (superior, inferior and both) involving a glandular resection of a least 500 g on each side in all cases. The results were evaluated according to both objective and subjective criteria. The choice of pedicle had a considerable influence on the results. The vertical limb usually increased with time (months), although its intraoperative length was 5 cm. The increasing length of the vertical limb varies according to the type of pedicle chosen. The mean length increase was 1.52 cm; 4.18 cm; 4.15 cm for superior, inferior, and both pedicles respectively. The different increase was statistically significant (p < 0.001) when the technic involving a superior pedicle was compared to a technic involving an inferior pedicle. No statistically significant difference was observed between technics using the inferior and both pedicles. A superior pedicle technic entails the lowest increase of the vertical limb length which in turns leads to better long-term cosmetic results.

Adult↗

PubMed1994

[Decubitus ulcer].

Bedsores are caused by prolonged pressure of soft tissues. Prevention is now better established. Better adapted mattresses should be used systematically. High fever and denutrition should be especially watched. Correct medical treatment has to provide faster cicatrisation if the pressure sore unfortunately occurs. Surgical treatment by muscular flaps has now really good results but costs a lot more in management of occasional or chronic bedridden patients.

Extremities↗