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Biomedical subjects

S Girod

Publications and source records attributed to S Girod.

At least 19 recordsLinked to original sources
PubMed2006

Viability and functionality of bovine chromaffin cells encapsulated into alginate-PLL microcapsules with a liquefied inner core.

Implantation of adrenal medullary bovine chromaffin cells (BCC), which synthesize and secrete a combination of pain-reducing neuroactive compounds including catecholamines and opioid peptides, has been proposed for the treatment of intractable cancer pain. Macro- or microencapsulation of such cells within semipermeable membranes is expected to protect the transplant from the host's immune system. In the present study, we report the viability and functionality of BCC encapsulated into microcapsules of alginate-poly-L-lysine (PLL) with a liquefied inner core. The experiment was carried out during 44 days. Empty microcapsules were characterized in terms of morphology, permeability, and mechanical resistance. At the same time, the viability and functionality of both encapsulated and nonencapsulated BCC were evaluated in vitro. We obtained viable BCC with excellent functionality: immunocytochemical analysis revealed robust survival of chromaffin cells 30 days after isolation and microencapsulation. HPLC assay showed that encapsulated BCC released catecholamines basally during the time course study. Taken together, these results demonstrate that viable BCC can be successfully encapsulated into alginate-PLL microcapsules with a liquefied inner core.

Alginates↗
PubMed2003

Three-dimensional simulation and prediction of craniofacial surgery.

The treatment of patients with complex facial deformities is one of the most challenging multidisciplinary tasks in plastic surgery. Due to advancements in medical technology and surgical techniques in the last 20 years correction of severe malformations has become possible and is performed by highly specialized teams frequently in a single operation. Recent developments in three-dimensional (3-D) imaging techniques have already greatly facilitated diagnosis of complex craniofacial deformities. Computer-based simulation methods for surgical procedures that are based on imaging data have the potential to improve surgical treatment by providing the ability to perform 'virtual surgery' preoperatively and thus reduce patient risk and morbidity intraoperatively. A method is presented for interactive computer-assisted craniofacial plastic surgery planning and visualization, especially simulation of soft tissue changes using an experimental Craniofacial Surgery Planner. The system computes non-linear soft-tissue deformation because of bone realignment. It is capable of simulating bone cutting and bone realignment with integrated interactive collision detection. Furthermore, soft-tissue deformation and cutting due to surgical instruments can be visualized. Simulation processes are based on an individual patient's preoperative 3-D computed tomography and on a 3-D, photo-realistic model of the patient's preoperative appearance obtained by a laser range scanner. Very fast and robust prediction of non-linear soft-tissue deformation is computed by optimizing a non-linear cost function.

Computer Simulation↗
PubMed2002

On-line direct determination of the second virial coefficient of a natural polysaccharide using size-exclusion chromatography and multi-angle laser light scattering.

By combining a size-exclusion chromatographic (SEC) separation and an on-line multi-angle light scattering (MALLS) analysis, we have elaborated an original methodology permitting on-line direct determination of the second virial coefficient of molar mass fractions of polydisperse polysaccharides. By assimilating the SEC-MALLS data to a batch mode acquisition, we have obtained on-line the complete Zimm plot of the eluted fractions, leading to knowledge of their weight-average molar mass Mw, radius of gyration r(g) and second virial coefficient A2. Our methodology was successfully applied to a iota carrageenan sample in LiCl 100 mM, EDTA 1 g/l.

Chromatography, Gel↗
PubMed2001

Computer-aided 3-D simulation and prediction of craniofacial surgery: a new approach.

Background: In plastic and reconstructive craniofacial surgery, careful preoperative planning is essential. In complex cases of craniofacial synostosis, rapid prototyping models are used to simulate the surgery and reduce operating time. Recently, 3-D CT model surgery has been introduced for presurgical planning and prediction of the postoperative result. Objective: For simulation of craniofacial surgery a computer-based system was developed that allows visualization and manipulation of CT-data using computer graphics techniques. Surgical procedures in all areas of the bony skull can be performed interactively. Results: The case of a child with scaphocephalus is presented. Surgery is planned using the craniofacial surgery simulator described above. Conclusion: The computer-based interactive surgery simulation systems presented here allow precise visualization of craniofacial surgery. The accurate computer-aided 3-D simulation of bone displacements is also the prerequisite for transfer of the simulated surgery using a navigation system for surgery. Thus the preoperatively planned procedure could be transferred directly to the operating table. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.

Journal Article↗
PubMed2001

[Value of CT bursography in the evaluation of rotator cuff tears].

PURPOSE: To describe the technique and assess the value of subacromial CT bursography in patients with partial surface tear of the rotator cuff tendon. MATERIALS AND METHODS: 15 patients with shoulder pain suggestive of tendinopathy or tear of the rotator cuff were evaluated with subacromial CT bursography. RESULTS: Subacromial CT bursography was normal in 4 patients. Partial surface tear was detected in 7 patients [irregularities (n=2), defect (n=2), superficial tear (n=3)]. Full thickness tear was detected in 4 patients. CONCLUSION: The authors described the technique for subacromial CT bursography to visualize partial surface tears of the rotator cuff tendon. This simple and reliable technique could be an alternative to MR imaging, especially when MR evaluation is not possible.

Adult↗
PubMed2001

3-D simulation of craniofacial surgical procedures.

An integrated system for simulating craniofacial surgical procedures is presented. The system computes nonlinear soft-tissue deformation due to bone realignment. It is capable of simulating bone cutting and bone realignment with integrated interactive collision detection. Furthermore, soft-tissue deformation and cutting due to surgical instruments can be visualized. The system has been tested with several individual patient data sets. Simulation processes are based on a 3-D model of a patient's preoperative bone structure of the skull derived from a computer tomography scan and on a 3-D, photorealistic model of the patient's preoperative appearance obtained by a laser range scanner. The multi-layer soft-tissue model is represented by nonlinear springs. Very fast and robust prediction of nonlinear soft-tissue deformation is computed by optimizing a nonlinear cost function.

Cephalometry↗
PubMed1998

Deformable modeling of facial tissue for craniofacial surgery simulation.

While deformable object modeling has been studied by computer graphics specialists for more than two decades, only a few applications in the field of surgical simulation have been developed which provide both real-time and physically realistic modeling of complex, nonlinear tissue deformations. Particularly in craniofacial surgery, the prediction of soft-tissue changes--which result from alterations in the underlying bone structure--is critical to the surgical outcome. The prediction these tissue changes and, therefore, the prognosis of the postoperative appearance of the patient, is still based on empirical studies of the relationship between bone and tissue movements: There exists no physical model which takes into account the individual patient anatomy to simulate the resulting tissue changes during craniofacial surgery. In this article we present two different deformable tissue models which are intergrated in an interactive surgical simulation test bed. Both techniques allow precise preoperative simulation of the resulting soft tissue changes during craniofacial surgery and visualization of the patient's postoperative appearance. The different deformable models are described in detail and both are applied to the same craniofacial case study. The simulation results are shown and compared with regard to the speed and accuracy of the prediction of the patient's postoperative appearance.

Computer Simulation↗
PubMed1998

Oral squamous cell carcinomas are characterized by a rather uniform pattern of genomic imbalances detected by comparative genomic hybridisation.

Total genomic DNA sampled from 20 oral squamous cell carcinomas (SCCs) and from four SCC cell lines, was examined for genomic imbalances using comparative genomic hybridisation (CGH). Gains and losses of DNA copy number aberrations (CNAs) were found in the primary tumours, but also in the cell lines at a varying number. The patterns of CNAs proved to be rather peculiar in oral SCCs, gains of genetic material clearly dominating compared with losses, and a rather high uniformity of these patterns was an impressive finding. Hypersomies of whole chromosomes, e.g. numbers 17 and 19 or of whole chromosome arms, e.g. 20q, were particularly evident. The segments most frequently gained in oral SCCs were 3q26-q27, 5p15 and 9q34 (16 of 20 tumours each), as well as 1p36.3, 8q24, 10q26, 19 and 20q (15/20 each). Among the 15 tumours with more than 10 CNAs, all showed these imbalances. 11q13 was a band often involved in increases (14/20 tumours), but in several tumours was involved in amplification of DNA copy number. Several other chromosomal segments over represented in more than 60% of the tumours, as, for example, 12q24, 15q22-q24, 16p13.2 and 17q (14/20 tumours each), 6q26-qter, 7p22, 12p12.2-p13, 14q31-q32.2 (13/20) and 1q32-q41, 2q37, 16q23-q24 (12/20 each). In contrast, loss of material affected only a few chromosomal segments, as, for example, 3p12 (12 of the 20 tumours), 5q21 (10/20), 6q13 (8/20). The peculiarities of these findings, in some respect, differ from those found in other epithelial tumours, suggesting a high impact of environmental factors in the generation and progression of these tumours.

Adult↗
PubMed1998

Gain of DNA copy number on chromosomes 3q26-qter and 5p14-pter is a frequent finding in head and neck squamous cell carcinomas.

Comparative genomic hybridization (CGH) was used to study genomic imbalances in 77 squamous cell carcinomas of the head and neck (HNSCC) and in four cell lines derived from oral carcinomas. Particular attention was paid to all tumors characterized by a gain of two specific chromosomal segments, i.e. 3q26-qter and 5p14-p15. The 57 tumors containing both or one of the two imbalances were compared with 20 tumors lacking both with regard to genomic complexity, as well as to associated genomic, histopathologic and clinical peculiarities. 60% of the oral, and 66% of the non-oral cancers exhibited a gain of 3q26-qter, while a gain of 5p14-p15 was found in 66% of the oral, but only in 48% of the non-oral tumors. 48% of all tumors were characterized by both gains together, 26% exhibited only one of the two alterations. It could be shown that presence of both, gain of 3q26-qter and 5p14-p15, was clearly associated with a significantly higher complexity of genomic changes which was not only expressed as a high frequency of DNA copy number alterations (CNAs) but was also connected with a considerable number of additional amplifications of various chromosomal segments and a high conformity of the patterns of genomic imbalances in these tumors. Clear differences of the extent and of the patterns of genomic imbalance could be observed between oral and non-oral tumors. With respect to histopathological parameters, no clear association could be found for specific imbalances to the grade of differentiation, nor the invasiveness or metastatic status of the tumors. However, a higher number of patients with tumors characterized by gain of 3q26-qter plus 5p14-p15 died within a short period (i.e. less than 15 months) after excision of the tumor compared to the group without these imbalances. The implications of these findings are discussed from the oncogenetic and clinical aspects and in comparison with other reports.

Journal Article↗
PubMed1998

CGH-detected DNA sequence copy number amplifications can be confirmed by interphase-FISH: new possiblities for prognostic approaches in oral squamous cell carcinomas.

In order to control the data obtained by comparative genomic hybridization (CGH) on DNA sequence copy number amplifications, 20 oral squamous cell carcinomas (SCC) were subjected to interphase fluorescence in situ hybridization (I-FISH) examination using specific DNA probes for the oncogenes int2 and erbB-2, and the corresponding centromeric probes of chromosomes 11 and 17. In all cases characterized by distinct peaks of the CGH profile on the critical chromosomal segment 11q13, these data could be clearly substantiated by the I-FISH analyses using the int2 probe and estimating the signal index, the int2/centromer 11 relation, and the fraction of nuclei with high int2 signal numbers. In addition, I-FISH detected smaller cell fractions with high signal numbers (and/or signal clusters) in some tumors which were not definitely conspicuous in CGH. In contrast to int2, erbB-2 amplification apparently does not play a major role in oral SCCs, as the blurred peaks of CGH profiles on chromosome 17ql 1.2-q12 corresponded well with the findings of I-FISH using the erbB-2 probe. Gain of a whole chromosome 17 is apparently a rather common feature of these tumors. In conclusion, the combination of interphase FISH with oncogene-specific probes and CGH is regarded as a valuable means of practical molecular cytogenetic analysis of oral SCCs which could eventually achieve high practical importance in the pathologic analysis of these tumors and in prognosis of their development.

Adult↗
PubMed1998

Pattern of genomic imbalances in oral squamous cell carcinomas with and without an increased copy number of 11q13.

Among 23 squamous cell carcinomas (SCC) of the oral cavity which were screened for DNA copy number alterations (CNAs) using comparative genomic hybridization, 14 showed a gain of, and 5 of these 14 even an amplification of band 11q13. Amplification of 11q13 was also detected in three of the four studied SCC cell lines and was confirmed by interphase FISH. The number of CNAs in addition to 11q13 varied from 14 to 47 in these carcinomas. All these tumors had seven other specific CNAs in common, i.e. gain on 1p36.3-36.6, 5p15, 9q34, 12p12-13, 14q32, 19 and 20q, all but one showed also an increase of copy number in 7p22, 8q24, 10q26, 12q26, 15q24-25, 16p, 16q23-24, 17q and 22q12-qter. These imbalances were distinctly rarer in the tumors without CNA in 11q13. Loss of material apparently played a minor role in these tumors with gain of 11q13, the most frequent losses (3p12-14 and 5q21) being present in 10 of the 14 cases and loss of 9p13-21 in 5/14 tumors. The three tumors with the highest number of CNAs in addition to 11q13, were histologically classified as pT4, three of the five tumors with 11q13 amplification were highly node-positive (pN 2b-2c). Two of the pT4 tumors shared as many as 23 specific chromosomal segments affected by CNA. Thus, gain of 11q13, though being found at different stages of karyotypic evolution, is apparently associated with a rather specific pattern of other CNAs and involved in progressed stages of malignancy in oral squamous cell carcinoma. In addition, the proportion of patients deceased within one year after diagnosis was clearly higher in the group whose tumors showed an increased 11q13 copy number as compared to the group without this increase. This could point to an association of gain in 11q13 and aggressiveness of the respective tumor.

Aged↗
PubMed1995

Advances in interactive craniofacial surgery planning by 3D simulation and visualization.

In craniofacial surgery careful preoperative planning is essential. Traditional preoperative work-up consists of cast model surgery, cephalometric prediction tracing and analysis of photographs. Recently, we introduced 3-dimensional (3D) computed tomography (CT) model surgery in our preoperative work-up and presurgical prediction of the postoperative result. However, only limited information can be extracted concerning soft tissue changes which are most important for the patients' postoperative appearance. We propose a new system which will allow a precise preoperative visualization of not only bony structures but also the soft tissue surfaces. 3D CT data of the skull are integrated with 3D surface data acquired by laser scanning. Based on the 3D CT data the bony structures are segmented automatically and processed interactively to simulate the planned surgical procedure. Afterwards, the 3D soft tissue changes resulting from the shifting of bony segments are computed. The postoperative appearance of the patient is visualized using computer animation techniques.

Algorithms↗
PubMed1992

Phospholipid composition and surface-active properties of tracheobronchial secretions from patients with cystic fibrosis and chronic obstructive pulmonary diseases.

Among the various components of tracheobronchial secretions, lipids and particularly phospholipids have been shown to influence rheological properties of airway secretions in patients with cystic fibrosis. We studied the phospholipid composition of tracheobronchial secretions, collected from patients suffering from cystic fibrosis (CF) and other chronic obstructive pulmonary diseases (COPD), and we analyzed the possible relationship between the phospholipid profile and the wettability of tracheobronchial secretions evaluated by the measurement of contact angle. Although total phospholipid content and contact angle of tracheobronchial secretions were significantly increased (P less than 0.01) in CF compared to COPD, no significant relationship existed between these two parameters. The concentrations of the different phospholipid subclasses were not homogeneously modified according to the origin of the secretions. Compared to COPD secretions, the CF secretions were characterized by a significant (P less than 0.001) increase in rigidifying fractions such as sphingomyelin and phosphatidylserine/phosphatidylinositol and a significant (P less than 0.001) decrease in surface-active fractions, such as phosphatidylcholine and phosphatidylglycerol (PG) (P less than 0.001). In the two groups, the surface-active phospholipid fraction, PG, was negatively correlated to the contact angle of tracheobronchial secretions. These results suggest that a decrease in PG content in CF secretions may be one factor responsible for an increase in their adhesivity to the respiratory mucosa, and, consequently, for mucus stasis and severity of bronchial obstruction in cystic fibrosis.

Adolescent↗
PubMed1992

Role of the physiochemical properties of mucus in the protection of the respiratory epithelium.

The respiratory mucus is a very complex biological material, which possesses both flow and deformation rheological properties, characterized by non-linear and time-dependent viscoelasticity and physical properties of adhesiveness and wettability. Viscosity and elasticity are directly involved in the transport capacity of mucus, whereas wettability and adhesiveness contribute to the optimal interface properties between the mucus and the epithelial surface. Optimal conditions for the protective and lubricant properties of respiratory mucus are represented by high wettability, and adhesiveness high enough not to induce flow of mucus in the respiratory bronchioles under gravity but low enough to mobilize mucus by airflow during coughing. An intermediate viscoelasticity is also required for an optimal mucociliary transport. Different biochemical constituents such as glycoproteins, proteins, proteoglycans and lipids are involved in the gel properties of respiratory mucus. During bronchial infection and particularly in cystic fibrosis, the loss of water and the increase in macromolecules result in a marked increase in viscosity and adhesiveness responsible for the mucus transport impairment. The various lipids present in mucus contribute differently to the physicochemical properties. Surface-active phospholipids, such as phosphatidylcholine and phosphatidylglycerol improve the wettability of mucus, whereas neutral lipids and glycosphyngolipids contribute to the hyperviscosity of mucus during infection. Phospholipids and associated mucins are also implicated in the interaction between bacteria and epithelial cells. Therefore, the respiratory mucus needs appropriate physicochemical properties for the protection, hydration and lubrication of the underlying airway epithelium.

Adhesiveness↗
PubMed1991

Semi-automatic quantitation of dense markers in cytochemistry.

The quantitation of electron dense labelling is very tedious when it is done "by hand". Accordingly we developed software allowing, at electron microscopic level, a semi-automatic counting of dense markers in biological specimens. It includes the digitization of images and extraction of dense particles from the grey level of the background. The definition of the areas of interest was carried out by the observer but all quantitative calculations were done automatically. This method was applied to different biological materials (phospholipid and lysozyme labelling in secretory granules of human submucosal bronchial gland cells). The results obtained by this semi-automatic procedure were in good agreement with those obtained by manual counting of colloidal gold labelling (r = 0.97).

Automation↗
PubMed1991

Role of phospholipid lining on respiratory mucus clearance by cough.

Phospholipid lining, present at the respiratory mucus-mucosa interface, may have an important role in the protective function of the airways by its abhesive properties and may also facilitate mucus transport. To mimic respiratory mucus-mucosa interface, monolayers of three different forms of phosphatidylglycerol (PG) have been deposited on glass slides by the Langmuir-Blodgett technique. Mucus adhesion and clearance by cough of mucus on these PG-coated or noncoated surfaces have been analyzed and compared, using frog respiratory mucus as "normal" mucus. Among the three PG types studied, the phosphatidylglycerol distearoyl, which is the phospholipid with the longest saturated fatty acid chain, was found to significantly improve the mucus cough clearance by decreasing the mucus work of adhesion compared with the noncoated surfaces. On the other hand, phosphatidylglycerol dipalmitoyl did not improve mucus cough clearance although it decreased mucus adhesion, and phosphatidylglycerol dioleyl did not improve either mucus cough clearance or mucus adhesion.

Animals↗