Biomedical subjects

David D F Ma

Publications and source records attributed to David D F Ma.

5 recordsLinked to original sources

PubMed2006

A SYBR green-based real-time PCR method for detection of haemopoietic chimerism in allogeneic haemopoietic stem cell transplant recipients.

OBJECTIVE: To develop a reliable and rapid real-time quantitative polymerase chain reaction (Q-PCR) method using SYBR green to quantify chimerism in allogeneic haemopoietic stem cell transplant recipients. METHODS: Twelve specific nucleotide polymorphisms (NPs) were selected to identify informative markers for detecting chimerism in transplant donor/recipient pairs. One informative marker was then used in SYBR green Q-PCR to detect chimerism post-transplantation in each patient. The percentage of donor cells was calculated using a standard curve, constructed using artificially mixed donor/recipient chimeric DNA in 12 serial dilutions (0.01-100%). RESULTS: DNA from 37 donor/recipient pairs was screened for informative markers and 18 post-transplant samples were monitored for chimerism with SYBR green Q-PCR method. The Q-PCR was able to discriminate between recipient and donor genetic profiles in all 18 samples, and quantify the chimerism. These results were confirmed by at least one independent method, such as TaqMan Q-PCR, microsatellite and fluorescent in situ hybridisation (FISH) methods. The detection limit of this method was 0.1%, which was more sensitive than the two currently used microsatellite and FISH methods. CONCLUSION: The new single platform SYBR green Q-PCR method is capable of detecting all haemopoietic chimerism with high accuracy; hence, it may be used to replace the current detection methods.

Adult↗

PubMed2005

Increased procoagulant phospholipid activity in blood from patients with suspected acute coronary syndromes: a pilot study.

Increased platelet activation is well documented in patients with acute coronary syndromes and can be detected by various methods, including flow cytometry and enzyme-linked immunosorbent assay. However, such techniques require several steps and cannot provide quick results. Platelet activation ultimately results in procoagulant phospholipid exposure and we have previously described a simple activated factor X-activated clotting time (XACT) test that is insensitive to resting platelets but that is significantly shortened by activated platelets, microparticles and procoagulant phospholipids. Our aim was to determine whether the XACT test could be used to distinguish patients with chest pain due to cardiac ischaemia from those having chest pain due to non-cardiac causes. We thus carried out XACT tests on ethylenediamine tetraacetic acid whole blood and plasma samples obtained from 46 patients presenting to the emergency department with chest pain and from 30 controls. Sixteen cases (30%) were subsequently diagnosed as acute coronary syndromes. Blood samples from these patients displayed overall significantly shortened XACT results relative to both healthy controls (P<0.001) and chest pain not due to cardiac ischaemia (P<0.004). This discrimination was much better with whole blood samples than when platelet-poor plasmas were tested (P=0.153), suggesting that free microparticles were not the only factors responsible. Thus, the detection of increased procoagulant phospholipid activity in whole blood by shortened XACT results may be a simple and rapid diagnostic marker of some cardiac ischaemic events.

Acute Disease↗

PubMed2005

Cytokine-induced stable neuronal differentiation of human bone marrow mesenchymal stem cells in a serum/feeder cell-free condition.

The characteristics and multilineage differentiation potential of bone marrow mesenchymal stem cells (BM MSC) remain controversial. This study aimed to characterize human BM MSC isolated by plastic adherent or antibody selection and their neuronal differentiation potential using growth factors or chemical inducing agents. MSC were found to express low levels of neuronal markers: neurofilament-M, beta tubulin III, and neuron specific enolase. Under a serum- and feeder cell-free condition, basic fibroblast growth factor, epidermal growth factor, and platelet-derived growth factor induced neuronal morphology in MSC. In addition to the above markers, these cells expressed neurotransmitters or associated proteins: gamma-aminobutyric acid, tyrosine hydroxylase and serotonin. These changes were maintained for up to 3 months in all bone marrow specimens (N = 6). In contrast, butylated hydroxyanisole and dimethylsulfoxide were unable to induce sustained neuronal differentiation. Our results show that MSC isolated by two different procedures produced identical lineage differentiation with defined growth factors in a serum- and feeder cell-free condition.

Biomarkers↗

PubMed2004

Cell therapy for disc degeneration--potentials and pitfalls.

Disc degeneration is considered a major source of pain in patients with chronic low back pain. Novel strategies to cure or decrease the symptoms and increase the patient's quality of life and function are under development. Until recently conservative treatment and fusion surgery were the main therapeutic options. Disc prostheses are undergoing clinical evaluation. The potential for cell transplantation to the intervertebral disc with mature autologous disc cells, chondrocytes, or stem cells is in early stages of investigation. Cell transplantation potentially can increase proteoglycan production and induce disc regeneration or slow down the degeneration process. In animal models, transplantation of autologous disc cells and chondrocytes (derived from costal cartilage) has been demonstrated to be feasible and may slow disc degeneration.

Animals↗

PubMed2003

Evidence for transdifferentiation of human bone marrow-derived stem cells: recent progress and controversies.

Adult bone marrow-derived stem cells have traditionally been known as tissue-specific stem cells capable of producing blood cells. This concept is being challenged by a series of recent discoveries. It has been demonstrated that there are heterogeneous stem cell populations in adult bone marrow compartment. Under appropriate experimental conditions, a certain type of bone marrow stem cells appears to differentiate (or transdifferentiate) into a variety of non-haemopoietic cells of ectodermal, mesodermal and endodermal origins (such as myocytes, neural cells and hepatocytes). The plasticity, that is, the ability to regenerate cells belonging to different organs and tissues of adult (postnatal) stem cells, has raised the therapeutic possibility of using these stem cells for tissue repair and regeneration. Presently, definitive evidence for plasticity or transdifferentiation of bone marrow stem cells is lacking. Despite controversies concerning the plasticity of bone marrow-derived stem cells, early clinical trials are being conducted in patients suffering from myocardial infarct, arthritic and neurological diseases using autologous bone marrow stem cells. This review summarises recent progresses and controversies in transdifferentiation of adult bone marrow-derived stem cells to non-haemopoietic tissues.

Adult↗