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Biomedical subjects

L M Fu

Publications and source records attributed to L M Fu.

7 recordsLinked to original sources
PubMed2002

Electrokinetic injection techniques in microfluidic chips.

The separation efficiency of a microfluidic chip is influenced to a significant degree by the flow field conditions within the injection microchannel. Therefore, an understanding of the physics of the flow within this channel is beneficial in the design and operation of such a system. The configuration of an injection system is determined by the volume of the sample plug that is to be delivered to the separation process. Accordingly, this paper addresses the design and testing of injection systems with a variety of configurations, including a simple cross, a double-T, and a triple-T configuration. This paper also presents the design of a unique multi-T injection configuration. Each injection system cycles through a predetermined series of steps, in which the electric field magnitude and distribution within the various channels is strictly manipulated, to effectuate a virtual valve. The uniquemulti-T configuration injection system presented within this paper has the ability to simulate the functions of the cross, double-T, and triple-T systems through appropriate manipulations of the electric field within its various channels. In other words, the proposed design successfully combines several conventional injection systems within a single microfluidic chip.

Journal Article↗
PubMed2002

Is Mycobacterium tuberculosis a closer relative to Gram-positive or Gram-negative bacterial pathogens?

The phylogenetic position of Mycobacterium tuberculosis relative to other bacteria is controversial. Its cell wall has characteristics of both Gram-positive and Gram-negative bacteria. In the standard reference of bacterial phylogeny based on 16S ribosomal RNA sequence comparison, M. tuberculosis belongs to the high G+C Gram-positive bacteria that form a monophyletic group with the low G+C Gram-positive bacteria such as Bacillus subtilis. Some analyses indicate no particular relationship between these two groups. The availability of the complete genome sequence of M. tuberculosis allows us to reexamine this issue from genomic perspectives, as genome-based phylogenies may be more representative of the evolutionary history of whole organisms than molecular trees. In the genome tree constructed based on conserved gene content, M. tuberculosis is more related to Gram-negative than to Gram-positive bacteria as reflected by the evolutionary distance between nearest ancestral units. This conclusion may be supported by another analysis showing that M. tuberculosis shares relatively more orthologous genes for energy production and conversion with Gram-negative bacteria, in particular, Escherichia coli and Pseudomonas aeruginosa, than with Gram-positive bacteria.

Genome, Bacterial↗
PubMed2002

Thalidomide and tuberculosis.

The anti-inflammatory and immunomodulatory effects of thalidomide have led scientists to explore its clinical therapeutic values. Thalidomide is now being considered as an adjuvant treatment for tuberculosis. This literature review examines the drug's mechanism of action and clinical applications. Thalidomide affects cytokine production and T lymphocyte proliferation. It appears that thalidomide suppresses TNF-alpha production by macrophages and thereby reduces inflammatory response. Thalidomide elevates the IFN-gamma level and modulates several other cytokines as well, noteworthily IL-2 and IL-12. Thalidomide costimulates T lymphocytes, with greater effect on CD8+ than on CD4+ T cells. This finding is important, since CD8+ T cells have been shown to be contributory to the protective immune response to Mycobacterium tuberculosis infection. The clinical application of thalidomide as part of standard tuberculosis therapy is inconclusive amid variability among reports. However, thalidomide has been shown to be an effective adjuvant for tuberculosis patients complicated with severe inflammatory reaction or wasting conditions.

Animals↗
PubMed1989

Inhibitors of adenosine catabolism improve recovery of dog myocardium after ischemia.

The effects of inhibitors of adenosine catabolism on contractile function and metabolites were assessed during 15 minutes of ischemia followed by 30 minutes of reperfusion in the open-chest dog heart. As compared to sham treatment, pretreatment with erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) and dipyridamole (DP) protected contractile function during ischemia, and improved recovery of high energy phosphate content and contractile function during reperfusion following ischemia. Testing EHNA and DP in a free-radical generating system indicated both compounds have some scavenging ability, suggesting the effect of EHNA + DP may not be on adenosine nucleotide metabolism alone. Comparison of end diastolic segment lengths to contractile function indicated the results were not affected by changes in preload resulting from peripheral vasodilation.

Adenine↗
PubMed1987

Contractility, ATP, and creatine phosphate during myocardial ischaemia and reperfusion: the effects of adenosine and inhibition of adenosine catabolism in the dog heart.

Provision of AMP or adenosine to heart cells during recovery from episodes of myocardial ischaemia accelerates physiological, biochemical, and structural recovery. Inhibition of adenosine loss from the tissue during ischaemia should have a similar effect. This hypothesis was tested in dog heart by infusion of adenosine and inhibitors of adenosine catabolism prior to, during, and following ischaemia. Post-ischaemic recovery of ATP and contractile function was accelerated significantly by adenosine and by inhibitors of adenosine catabolism both singly and in combination. Contractility and ATP levels during ischaemia were also increased by these inhibitors.

Adenosine↗