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Biomedical subjects

I Martin

Publications and source records attributed to I Martin.

At least 19 recordsLinked to original sources
PubMed2006

Bone marrow mesenchymal stromal cells (BM-MSCs) from healthy donors and auto-immune disease patients reduce the proliferation of autologous- and allogeneic-stimulated lymphocytes in vitro.

OBJECTIVES: To investigate the ability of bone marrow (BM)-derived mesenchymal stromal cells (BM-MSCs) in suppressing the proliferation of stimulated lymphocytes across a range of conditions including autologous BM-MSCs derived from autoimmune disease (AD) patients. METHODS: In vitro cultures of BM-MSCs from healthy donors and AD patients were established and characterized by their differentiation potential into adipocytes and osteoblasts, and their fibroblast-colony-forming unit (CFU-F) ability and phenotype by flow cytometry. BM-MSCs (irradiated and non-irradiated) from healthy and AD patients were tested for their ability to suppress the in vitro proliferation of autologous and allogeneic peripheral blood mononuclear cells (PBMC) (from healthy donors and patients suffering from various ADs) stimulated with anti-CD3epsilon antibody alone or in combination with anti-CD28 antibody. The anti-proliferative effect of the BM-MSCs from healthy donors was tested also on transformed B-cell lines as a model of non-antigen-stimulated lymphocytes. RESULTS: BM-MSCs from healthy donors and AD patients reduced the proliferation of autologous and allogeneic PBMCs by up to 90% in a cell dose-dependent fashion. The immunosuppression was independent of the proliferation of the BM-MSCs and was also effective on already proliferating cells. It was independent also of the clinical activity of AD. An MSC dose-dependent pattern of suppression of proliferation was observed also with transformed B-cell lines, similar to that observed with proliferating PBMC. CONCLUSIONS: The BM-MSCs exhibit extensive anti-proliferative properties against lymphocytes under different conditions. This property might offer a form of immunomodulatory cellular therapy for AD patients if further confirmed in animal models.

Adipocytes↗
PubMed2006

Differential cartilaginous tissue formation by human synovial membrane, fat pad, meniscus cells and articular chondrocytes.

OBJECTIVE: To identify an appropriate cell source for the generation of meniscus substitutes, among those which would be available by arthroscopy of injured knee joints. METHODS: Human inner meniscus cells, fat pad cells (FPC), synovial membrane cells (SMC) and articular chondrocytes (AC) were expanded with or without specific growth factors (Transforming growth factor-beta1, Fibroblast growth factor-2 and Platelet-derived growth factor bb, TFP) and then induced to form three-dimensional cartilaginous tissues in pellet cultures, or using a hyaluronan-based scaffold (Hyaff-11), in culture or in nude mice. Human native menisci were assessed as reference. RESULTS: Cell expansion with TFP enhanced glycosaminoglycan (GAG) deposition by all cell types (up to 4.1-fold) and messenger RNA expression of collagen type II by FPC and SMC (up to 472-fold) following pellet culture. In all models, tissues generated by AC contained the highest fractions of GAG (up to 1.9% of wet weight) and were positively stained for collagen type II (specific of the inner avascular region of meniscus), type IV (mainly present in the outer vascularized region of meniscus) and types I, III and VI (common to both meniscus regions). Instead, inner meniscus, FPC and SMC developed tissues containing negligible GAG and no detectable collagen type II protein. Tissues generated by AC remained biochemically and phenotypically stable upon ectopic implantation. CONCLUSIONS: Under our experimental conditions, only AC generated tissues containing relevant amounts of GAG and with cell phenotypes compatible with those of the inner and outer meniscus regions. Instead, the other investigated cell sources formed tissues resembling only the outer region of meniscus. It remains to be determined whether grafts based on AC will have the ability to reach the complex structural and functional organization typical of meniscus tissue.

Adipose Tissue↗
PubMed2006

Pinoresinol-lariciresinol reductase gene expression and secoisolariciresinol diglucoside accumulation in developing flax (Linum usitatissimum) seeds.

The transcription activity of the pinoresinol-lariciresinol reductase (PLR) gene of Linum usitatissimum (so-called LuPLR), a key gene in lignan synthesis, was studied by RT-PCR and promoter-reporter transgenesis. The promoter was found to drive transcription of a GUSint reporter gene in the seed coats during the flax seed development. This fitted well with the tissue localization monitored by semi-quantitative RT-PCR of LuPLR expression. Accumulation of the main flax lignan secoisolariciresinol diglucoside was coherent with LuPLR expression during seed development. This three-way approach demonstrated that the LuPLR gene is expressed in the seed coat of flax seeds, and that the synthesis of PLR enzyme occurs where flax main lignan is found stored in mature seeds, confirming its involvement in SDG synthesis.

Base Sequence↗
PubMed2006

[Engineering 3D cartilage grafts].

The engineering ex vivo of cartilage tissue of predefined size and shape starting from autologous cells has the potential to provide orthopaedic surgeons with functional grafts for the repair of joint injuries. Despite the progress made in the generation and validation of engineered cartilage starting from animal cells, serveral challenges remain to be faced to extend these results to human chondrocytes. This review highlights the need for a highly interdisciplinary approach to effectively introduce engineered cartilage grafts in the routine clinical practice. Issues to be addressed include those related to the biology of chondrocytes, the properties of porous 3D scaffolds, the application of physical stimuli, and the development of economically viable manufacturing systems.

Adult↗
PubMed2006

Spontaneous sensory recovery in non-innervated radial forearm flaps used for head and neck reconstruction.

Although several studies have reported the use of reinnervated microvascular free flaps for oro-pharyngeal reconstruction, it has been known for some time that non-innervated flaps demonstrate spontaneous sensory recovery. This study sought to evaluate the degree of such spontaneous recovery in 50 radial forearm flaps used for mucosal reconstruction of head and neck ablative defects. The recovery of sensation to pinprick, light touch and temperature was tested a mean of 38 months (range 15-71) after surgical insetting. Two-point discrimination was also sought. Although 18 flaps (36%) remained anaesthetic, partial recovery in one or more modalities was present in 28 patients (56%). A recovery in all modalities of sensation in at least two-thirds of the flap area was recorded in 4 patients (8%). The mean 2-point static discrimination for fascio-cutaneous flaps was 18.9mm.

Age Factors↗
PubMed2006

Lower Rydberg series of methane: a combined coupled cluster linear response and molecular quantum defect orbital calculation.

Vertical excitation energies as well as related absolute photoabsorption oscillator strength data are very scarce in the literature for methane. In this study, we have characterized the three existing series of low-lying Rydberg states of CH4 by computing coupled cluster linear response (CCLR) vertical excitation energies together with oscillator strengths in the molecular-adapted quantum defect orbital formalism from a distorted Cs geometry selected on the basis of outer valence green function calculations. The present work provides a wide range of data of excitation energies and absolute oscillator strengths which correspond to the Rydberg series converging to the three lower ionization potential values of the distorted methane molecule, in energy regions for which experimentally measured data appear to be unavailable.

Journal Article↗
PubMed2006

Cartilage tissue engineering by expanded goat articular chondrocytes.

In this study we investigated whether expanded goat chondrocytes have the capacity to generate cartilaginous tissues with biochemical and biomechanical properties improving with time in culture. Goat chondrocytes were expanded in monolayer with or without combinations of FGF-2, TGF-beta1, and PDGFbb, and the postexpansion chondrogenic capacity assessed in pellet cultures. Expanded chondrocytes were also cultured for up to 6 weeks in HYAFF-M nonwoven meshes or Polyactive foams, and the resulting cartilaginous tissues were assessed histologically, biochemically, and biomechanically. Supplementation of the expansion medium with FGF-2 increased the proliferation rate of goat chondrocytes and enhanced their postexpansion chondrogenic capacity. FGF-2-expanded chondrocytes seeded in HYAFF-M or Polyactive scaffolds formed cartilaginous tissues with wet weight, glycosaminoglycan, and collagen content, increasing from 2 days to 6 weeks culture (up to respectively 2-, 8-, and 41-fold). Equilibrium and dynamic stiffness measured in HYAFF M-based constructs also increased with time, up to, respectively, 1.3- and 16-fold. This study demonstrates the feasibility to engineer goat cartilaginous tissues at different stages of development by varying culture time, and thus opens the possibility to test the effect of maturation stage of engineered cartilage on the outcome of cartilage repair in orthotopic goat models.

Animals↗
PubMed2005

Minimally invasive esophagectomy: short- and long-term outcomes.

BACKGROUND: We aimed to assess the outcomes including the effect on quality of life (QoL) of a group of patients having a minimally invasive esophagectomy (MIE). METHODS: Patients with esophageal cancer were offered MIE over a 22-month period. Data on outcomes were collected prospectively, including formal quality-of-assessments. RESULTS: There were 25 patients offered MIE. Two patients were converted to a laparotomy to improve the lymphadenectomy. There were no deaths. Respiratory problems (pneumonia, 28%) were the most common in the 64% of patients who had a complication. The median blood loss was 300 ml, time of surgery 330 min, and time to discharge 11 days. There was a decrease in the measured QoL both in general and specifically for the esophageal patients, taking 18-24 months to return to baseline. CONCLUSIONS: MIE was performed with morbidity similar to other approaches. There were no clear benefits shown in this group of patients with respect to postoperative recovery or short- to medium-term QoL.

Adenocarcinoma↗
PubMed2005

Tunneling spectroscopy of two-level systems inside a Josephson junction.

We consider a two-level system (TLS) with energy level separation plankvOmega0 inside a Josephson junction. The junction is shunted by a resistor R and is voltage V biased. If the TLS modulates the Josephson energy and/or is optically active, it is Rabi driven by the Josephson oscillations in the running phase regime near the resonance 2eV=plankvOmega0. The Rabi oscillations, in turn, translate into oscillations of current and voltage that can be detected in noise measurements. This effect provides an option to fully characterize the TLS inside Josephson junction and to find the TLS's contribution to the decoherence when the junction is used as a qubit.

Journal Article↗
PubMed2005

Symptomatic and functional outcome after laparoscopic reoperation for failed antireflux surgery.

BACKGROUND: The aim was to determine symptomatic and functional outcome after reoperative antireflux surgery for recurrent reflux, persistent dysphagia and severe gas bloat, using a primarily laparoscopic surgical approach. METHODS: This was a retrospective analysis of prospectively collected data from 118 patients, of whom 70 had reoperative surgery for recurrent reflux, 35 for dysphagia and 13 for gas bloat. DeMeester scores before and 1 year after surgery, functional symptoms after surgery and overall patient satisfaction were analysed. RESULTS: Reoperation was completed laparoscopically in 101 patients (85.6 per cent), in 28 after previous open hiatal surgery. The operation was converted from an initial laparoscopic approach to open surgery in 17 patients. One-year follow-up data were available for 104 patients (88.1 per cent). After reoperation for recurrent reflux, 84 per cent had a DeMeester heartburn score of zero or one, and 87 per cent had a regurgitation score of zero or one. After reoperation for dysphagia, 21 of 32 patients had a dysphagia score of zero or one, with improvement observed in 25. All patients undergoing reoperation for severe gas bloat were satisfied with the outcome 1 year after operation. CONCLUSION: Revisional surgery for recurrent reflux using a laparoscopic approach offered high rates of success and patient satisfaction. Swallowing returned to normal in two-thirds of patients after reoperation.

Deglutition Disorders↗
PubMed2005

Structural characterization and reliable biomechanical assessment of integrative cartilage repair.

Structural and functional characterization of integrative cartilage repair in controlled model systems can play a key role in the development of innovative strategies to improve the long-term outcome of many cartilage repair procedures. In this work, we first developed a method to reproducibly generate geometrically defined disk/ring cartilage composites and to remove outgrown fibrous layers which can encapsulate cartilaginous tissues during culture. We then used the model system to test the hypothesis that such fibrous layers lead to an overestimation of biomechanical parameters of integration at the disk/ring interface. Transmission electron microscopy images of the composites after 6 weeks of culture indicated that collagen fibrils in the fibrous tissue layer were well integrated into the collagen network of the cartilage disk and ring, whereas molecular bridging between opposing disk/ring cartilage surfaces was less pronounced and restricted to regions with narrow interfacial regions (< 2 microm). Stress-strain profiles generated from mechanical push-out tests for composites with the layers removed displayed a single and distinct peak, whereas profiles for composites with the layers left intact consisted of multiple superimposed peaks. As compared to composites with removed layers, composites with intact layers had significantly higher adhesive strengths (161+/-9 vs. 71+/-11 kPa) and adhesion energies (15.0+/-0.7 vs. 2.7+/-0.4 mJ/mm2). By combining structural and functional analyses, we demonstrated that the outgrowing tissue formed during in vitro culture of cartilaginous specimens should be eliminated in order to reliably quantify biomechanical parameters related to integrative cartilage repair.

Adhesiveness↗
PubMed2005

Chromoendoscopic surveillance in hereditary diffuse gastric cancer: an alternative to prophylactic gastrectomy?

BACKGROUND: Hereditary diffuse gastric cancer (HDGC) is defined by germline mutations in the E-cadherin gene, CDH-1. The first family in which CDH-1 mutations were identified was a large Maori kindred, where lifetime penetrance is 70%. Prophylactic gastrectomy is an unacceptable option for many mutation carriers. The results of annual chromoendoscopic surveillance using the methylene blue/congo red technique in 33 mutation carriers over a five year period are described. PATIENTS AND METHODS: Thirty three confirmed CDH-1 mutation carriers (18 males, 15 females), median age 32 years (range 14-69), were enrolled in 1999-2003. Medical records, endoscopy, and pathology were reviewed retrospectively. RESULTS: Over five years, 99 surveillance endoscopies were performed, of which 93 were chromo-dye enhanced. Sixty nine chromoendoscopies were normal. In 24 procedures, 1-6 pale areas/stomach (size 2-10 mm) were detected post chromo-dye application (totalling 56 pale lesions). One biopsy was taken from each pale lesion: 23 lesions (41%) showed signet ring cell carcinoma (10 patients), 10 lesions (18%) gastritis (four patients), and 23 (41%) normal mucosa (10 patients). No chromo-dyes were used in six procedures with macroscopic lesions (two HDGC, four ulceration). Total gastrectomies from patients with carcinoma were macroscopically normal but pathological mapping showed multiple microscopic foci of early signet ring cell carcinoma. Correlation of chromoendoscopic and gastrectomy findings showed that congo red/methylene blue detected carcinoma foci 4-10 mm in size but not foci <4 mm. CONCLUSIONS: The use of chromoendoscopy following normal white light gastroscopy facilitated detection of early gastric carcinoma foci not visible with white light gastroscopy. If these findings are validated in other HDGC kindred, chromogastroscopy represents an improved surveillance technique that can be safely considered alongside prophylactic gastrectomy.

Adolescent↗
PubMed2004

Electrical detection of the spin resonance of a single electron in a silicon field-effect transistor.

The ability to manipulate and monitor a single-electron spin using electron spin resonance is a long-sought goal. Such control would be invaluable for nanoscopic spin electronics, quantum information processing using individual electron spin qubits and magnetic resonance imaging of single molecules. There have been several examples of magnetic resonance detection of a single-electron spin in solids. Spin resonance of a nitrogen-vacancy defect centre in diamond has been detected optically, and spin precession of a localized electron spin on a surface was detected using scanning tunnelling microscopy. Spins in semiconductors are particularly attractive for study because of their very long decoherence times. Here we demonstrate electrical sensing of the magnetic resonance spin-flips of a single electron paramagnetic spin centre, formed by a defect in the gate oxide of a standard silicon transistor. The spin orientation is converted to electric charge, which we measure as a change in the source/drain channel current. Our set-up may facilitate the direct study of the physics of spin decoherence, and has the practical advantage of being composed of test transistors in a conventional, commercial, silicon integrated circuit. It is well known from the rich literature of magnetic resonance studies that there sometimes exist structural paramagnetic defects near the Si/SiO2 interface. For a small transistor, there might be only one isolated trap state that is within a tunnelling distance of the channel, and that has a charging energy close to the Fermi level.

Journal Article↗
PubMed2004

Ground and excited states of NH4: Electron propagator and quantum defect analysis.

Vertical excitation energies of the Rydberg radical NH4 are inferred from ab initio electron propagator calculations on the electron affinities of NH4+. The adiabatic ionization energy of NH4 is evaluated with coupled-cluster calculations. These predictions provide optimal parameters for the molecular-adapted quantum defect orbital method, which is used to determine Einstein emission coefficients and radiative lifetimes. Comparisons with spectroscopic data and previous calculations are discussed.

Journal Article↗
PubMed2004

Chondrogenesis of expanded adult human articular chondrocytes is enhanced by specific prostaglandins.

OBJECTIVE: To investigate the effects of the cyclooxygenase-2 (cox-2)-dependent prostaglandins D(2) (PGD(2)), E(2) (PGE(2)) and F(2)alpha (PGF(2)alpha) on the redifferentiation and cartilage matrix production of dedifferentiated articular chondrocytes. METHODS: Human articular chondrocytes from three adult donors were dedifferentiated by monolayer expansion and induced to redifferentiate by culture as 3D pellets in a defined serum-free medium containing TGF-beta(1) and dexamethasone, without or with further supplementation with PGD(2), PGE(2) or PGF(2)alpha. After 2 weeks, pellets were assessed histologically, immunohistochemically, biochemically and by real-time quantitative reverse transcriptase-polymerase chain reaction. RESULTS: All three PGs, but predominantly PGE(2), reduced the staining intensity of pellets for collagen type I, whereas PGD(2) and PGF(2)alpha increased the staining intensity of pellets for collagen type II and glycosaminoglycans (GAG). The GAG/DNA content of pellets was not affected by PGE(2) but was increased 1.5- and 2.1-fold by PGD(2) and PGF(2)alpha respectively. PGE(2) reduced the expression of collagen type I mRNA (9.0-fold), whereas PGD(2) and PGF(2)alpha increased the mRNA expression of collagen type II (6.2- and 4.1-fold respectively) and aggrecan (29.8- and 10.7-fold respectively). CONCLUSION: In contrast to PGE(2), PGD(2) and PGF(2)alpha enhanced chondrogenic differentiation and hyaline cartilage matrix deposition by expanded human articular chondrocytes, and could thus be used to improve in vitro or in vivo cartilage regeneration approaches based on these cells.

Adult↗