Biomedical subjects

D Lin

Publications and source records attributed to D Lin.

256 records · Page 15Linked to original sources

PubMedDate not supplied

Physical and cDNA mapping in the DBH region of human chromosome 9q34.

Chromosome 9q34 has been extensively studied and mapped due to the presence of known disease genes, principally tuberous sclerosis 1 (TSC1), in this region. During the course of our mapping of this region we constructed a 555-kb contig beginning approximately 50 kb proximal to the dopamine-beta-hydroxylase (DBH) gene and extending, with one small deletion, distal to the D9S114 marker. The contig consists of 11 P1 clones, four PAC clones, one BAC clone and six cosmid clones and contains 27 new nonpolymorphic STSs. We have found the region to be unstable in P1, PAC and BAC cloning vehicles and have identified several deleted genomic clones. In addition, we have isolated and mapped the 3' portions of three putative genes located within or immediately distal to the DBH gene, including one large gene that runs on the opposite strand to DBH and utilizes portions of two DBH exons. The genomic clones of the contig, cDNAs and new STSs will be useful reagents for the further study and mapping of this region.

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PubMedDate not supplied

Isolation and manipulation of rostral mesencephalic tegmental progenitor cells from rat.

A technique for isolating mitotic progenitor cells from the embryonic rostral mesencephalon is described. Culture of the progenitor cells in complete media with subsequent staining for neuron specific enolase (NSE) revealed that only 0.6% of the cells were NSE immunoreactive. Co-culturing the progenitor cells with established striatal cultures did not result in conversion of any of the cells to the dopamine neuron phenotype (tyrosine hydroxylase immunoreactive (THir) neurons). In contrast, co-culture of progenitor cells with established mesencephalic cultures produced a statistically significant, and in some cases (three of twelve), dramatic increase in the number of THir cells. The THir cells that were present had more pronounced process extension than those observed in mesencephalic mono-cultures. Culturing progenitor cells in transwell baskets that were continuously exposed to media but physically separated from established mesencephalic cultures growing underneath the baskets led to the conversion of only a few progenitor cells to THir neurons in four of twelve transwell studies suggesting that cell-cell contact between progenitor cells and mesencephalic cells is required for the conversion. This co-culture technique also increased the number of THir neurons in the mesencephalic cultures although the increase was not profound enough to explain the increase observed in traditional co-culture. These data suggest that mitotic progenitor cells can be isolated from fetal rat tissue and successfully converted to the dopamine neuron phenotype.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMedDate not supplied

A newly developed porcine heart valve bioprosthesis fixed with an epoxy compound. An experimental evaluation.

Concerns with currently available bioprostheses are calcification, long-term durability, and functional and hemodynamic performance. It has been well known that these concerns are all more or less related to the fixatives, glutaraldehyde or formaldehyde, used in preserving bioprostheses. To address these concerns, we undertook the development of a porcine bioprosthesis fixed with an epoxy compound. It was discovered that the porcine leaflets fixed with the epoxy compound appeared more natural than those preserved with glutaraldehyde. The performance of this newly developed epoxy compound bioprosthesis (three samples) was evaluated in a juvenile sheep model. The results were compared to those of its glutaraldehyde counterpart (three samples). Two-dimensional echocardiographic inspection of the valvular leaflet motion indicated that the epoxy compound leaflets were more pliable than their glutaraldehyde counterparts. In addition, the epoxy compound valve appeared to open more widely than the glutaraldehyde valve. Color Doppler flow mapping demonstrated that the blood flow distal to the epoxy compound valve was slightly broader than that observed distal to the glutaraldehyde valve. Moreover, at retrieval, less calcium and pannus ingrowth were observed in the epoxy compound valve than its glutaraldehyde counterpart. The results of this preliminary evaluation indicated that the performance of this newly developed epoxy compound valve was at least equivalent to its glutaraldehyde counterpart, if not better.

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PubMedDate not supplied

Comparison of the cross-linking characteristics of porcine heart valves fixed with glutaraldehyde or epoxy compounds.

The concerns about currently available bioprosthetic heart valves are calcification, long-term durability, and functional and hemodynamic performance. These concerns are all more or less related to the cross-linking reagents, glutaraldehyde or formaldehyde, used in fixing bioprostheses. To address these concerns, the authors undertook the development of a porcine heart valve cross-linked with an epoxy compound. This study compared the cross-linking characteristics, shrink temperature, and moisture content of porcine heart valves fixed with epoxy compounds or glutaraldehyde. Two types of epoxy compounds, Denacol EX-313 and EX-810, or a 0.625% glutaraldehyde were used to fix the porcine aortic valves procured from a slaughter house. Samples of each group were removed at various elapsed fixation times. The shrink temperature and moisture content of the valvular leaflet and distinct layers of aortic wall of each sample were measured. Fresh porcine aortic valve was used as a control. It was found that the shrink temperature of the glutaraldehyde leaflet was the highest, whereas the moisture content of the EX-313 leaflet was the greatest among the three test groups. No significant difference in shrink temperature was observed among the epoxy compound fixed inner, middle, outer, and entire aortic walls. This implied that the cross-linking density of the epoxy compound valve was uniform throughout the entire aortic wall. The same also was observed for the glutaraldehyde fixed aortic wall.(ABSTRACT TRUNCATED AT 250 WORDS)

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