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M Yi

Publications and source records attributed to M Yi.

27 records · Page 2Linked to original sources
PubMed1994

Immunogenetic aspects of IgE-mediated responses.

The reported significant HLA association is consistent with the codominant expression of MHC-linked Ir genes. Similar studies are needed in the case of the other HLA-immune response associations. It seems unlikely that any unique HLA-D genetic sequence will be found only among subjects responding to a particular Ag. It is likely, however, that we will find that a particular sequence is a necessary, but not sufficient, requirement for responsiveness to a particular antigenic epitope. Previous family studies, in which failed to observed parent-to-child transmission of specific immune responsiveness to a particular allergen, suggest that further genetic and/or environmental factors are required for the expression of specific immune responsiveness. These factors include variations in the degree of antigenic exposure. Of particular importance is the need for Ag-specific TcR genes to be expressed in the mature T-cell repertoire. In study of the specific immune response, there have been several studies of the protein and DNA sequences of allergenic proteins; therefore, in regard to understanding the genetics of specific immune responsiveness to allergens and its relationship to atopic diseases, rapid advances can be anticipated over the next several years.

Allergens↗
PubMed1992

A procedure for the construction of linear restriction fragment maps of a 50- to 100-kb DNA.

A simple and effective procedure for the construction of linear restriction fragment maps was developed. Using a two-enzyme digestion, two-dimensional (2-D) electrophoresis procedure, all the restriction fragments in a 50- to 100-kb DNA can be individually resolved and displayed on a 2-D plane. This 2-D gel pattern, with appropriate markers, provides a fixed set of x, y coordinates for each fragment obtained from the single and double digestion as well as the relationship between the two steps. A matrix is constructed from the 2-D pattern. The vertical column shows all the singly digested individual fragments and their sizes obtained from each restriction enzyme treatment, and the dividing horizontal row shows all the doubly digested DNA fragments and their sizes after treatment with two enzymes. The order of arrangement is always from the smallest to the largest fragments. Using this matrix, two linear DNA restriction maps for these two enzymes can be simultaneously constructed in a self-reconfirming manner. As examples for this procedure, we describe the construction of two linear restriction fragment maps, a combination of EcoRI and BamHI digestion as well as a combination of EcoRI and HindIII digestion of lambda-phage DNA.

Bacteriophage lambda↗
PubMed1992

[Synthesis and pharmacological activities of the 1-substituted 4-methoxycarbonyl fentanyl derivatives].

Five derivatives of 4-methoxycarbonyl fentanyl were synthesized, four of them carry in the molecules some radicals that may alkylate opiate receptors. Their analgesic activities were measured and the irreversible inhibitory effects of all compounds on the electrically elicited contraction of MVD were investigated. The analgesic test showed that the compounds in this series possess analgesic activity with typical morphine--like action. The isolated tissue experiment indicated that these new compounds were all capable of binding with opiate receptors, and that compounds 2, 4 and 5 were determined to be a new irreversible ligand of opiate receptors.

Analgesics, Opioid↗
PubMed1990

Monitoring mammalian genome rearrangement with mid-repetitive sequences as probes.

By utilization of mid-repetitive sequences, the intracisternal A particle (IAP) gene, as a probe, genome rearrangement involving IAP genes and their neighboring sequences in rodent cells can be monitored. This is based on electrophoretic separation of the twice digested restriction fragments of genomic DNA in a 2-D pattern. The first digestion was done in solution followed by electrophoresis of the restriction fragments in the first dimension. A second restriction enzyme digestion was carried out in situ in the gel followed by electrophoresis in a second dimension perpendicular to the first electrophoresis. After Southern blotting, the DNA on the filter is hybridized with a probe that is a fragment located near the 5' end of the IAP gene, but does not overlap with the 5' long terminal repeat (LTR). The exposed X-ray film revealed about 370 distinct spots in the 2-D maps. In comparing the 2-D maps, genome rearrangement involving IAP was detected.

Animals↗
PubMed1990

Response of fibroblast cultures from ataxia-telangiectasia patients to oxidative stress.

The object of this study was to determine whether ataxia-telangiectasia (AT) cells are more sensitive than normal cells to reduced oxygen species generated either during normal cell processes or resulting from metabolism of xenoblotics. To test this hypothesis four AT and four normal fibroblast cultures were exposed to hydrogen peroxide (H2O2) and the induction of micronucleated cells was assayed. AT cultures responded to the H2O2 treatment with a greater increase in micronucleus frequencies than that observed in normal cultures (P less than 0.01). At time course study showed that an elevation in micronucleus frequencies occurred earlier in AT cultures (significant increase by 1.5 h after treatment) than in normal cultures, possibly indicating a G2-phase sensitivity of AT cells to H2O2. The addition of an aqueous extract of areca nut to the cultures, as an example of exogenous stress, induced a greater frequency of micronucleated cells in AT cultures than in the normal cultures. These results suggest that the AT syndrome may serve as a model for investigating the role of reduced oxygen species in cancer.

Areca↗
PubMed1990

Enhanced resolution of DNA restriction fragments: a procedure by two-dimensional electrophoresis and double-labeling.

A probe-free method was developed to detect DNA rearrangement in bacteria based on the electrophoretic separation of twice-digested restriction fragments of genomic DNA into a two-dimensional (2-D) pattern. The first restriction enzyme digestion was done in solution, followed by electrophoresis of the restriction fragments in one dimension. A second restriction enzyme digestion was carried out in situ in the gel, followed by electrophoresis in a second dimension perpendicular to the first electrophoresis. The 2-D pattern provides for the resolution of 300-400 spots, which are defined and indexed by an "x,y" coordinate system with size markers. This approach has greatly increased the resolution power over conventional one-dimensional (1-D) electrophoresis. To study DNA rearrangement, a 2-D pattern from a test strain was compared with the 2-D pattern from a reference strain. After the first digestion, genomic DNA fragments from the test strain were labeled with 35S, while those from the reference strain were labeled with 35P. This was done to utilize the difference in the energy emission of 35S and 32P isotopes for autoradiography when two x-ray films were exposed simultaneously on top of the gel after the 2-D electrophoresis. The irradiation from the decay of 35S exposed only the lower film, whereas the irradiation from the decay of 32P exposed both the lower and upper films. Different DNA fragments existed in the test DNA compared with the reference DNA can be identified unambiguously by the differential two 2-D patterns produced on two films upon exposure to the 35S and 32P fragments in the same gel. An appropriate photographic procedure further simplified the process, allowing only the difference in DNA fragments between these two patterns to be shown in the map. We have utilized the difference map obtained from Escherichia coli strains HB101 and HB101 (lambda) genomic DNA to show the incorporation of one copy of phage lambda DNA without the use of a lambda DNA probe. This is the same test system that was used previously.

Bacteriophage lambda↗
PubMedDate not supplied

Old players in a new role: mitochondria-associated membranes, VDAC, and ryanodine receptors as contributors to calcium signal propagation from endoplasmic reticulum to the mitochondria.

In many cell types, IP(3) and ryanodine receptor (IP(3)R/RyR)-mediated Ca(2+) mobilization from the sarcoendoplasmic reticulum (ER/SR) results in an elevation of mitochondrial matrix [Ca(2+)]. Although delivery of the released Ca(2+) to the mitochondria has been established as a fundamental signaling process, the molecular mechanism underlying mitochondrial Ca(2+) uptake remains a challenge for future studies. The Ca(2+) uptake can be divided into the following three steps: (1) Ca(2+) movement from the IP(3)R/RyR to the outer mitochondrial membrane (OMM); (2) Ca(2+) transport through the OMM; and (3) Ca(2+) transport through the inner mitochondrial membrane (IMM). Evidence has been presented that Ca(2+) delivery to the OMM is facilitated by a local coupling between closely apposed regions of the ER/SR and mitochondria. Recent studies of the dynamic changes in mitochondrial morphology and visualization of the subcellular pattern of the calcium signal provide important clues to the organization of the ER/SR-mitochondrial interface. Interestingly, key steps of phospholipid synthesis and transfer to the mitochondria have also been confined to subdomains of the ER tightly associated with the mitochondria, referred as mitochondria-associated membranes (MAMs). Through the OMM, the voltage-dependent anion channels (VDAC, porin) have been thought to permit free passage of ions and other small molecules. However, recent studies suggest that the VDAC may represent a regulated step in Ca(2+) transport from IP(3)R/RyR to the IMM. A novel proposal regarding the IMM Ca(2+) uptake site is a mitochondrial RyR that would mediate rapid Ca(2+) uptake by mitochondria in excitable cells. An overview of the progress in these directions is described in the present paper.

Animals↗