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D Hsu

Publications and source records attributed to D Hsu.

At least 37 records · Page 2Linked to original sources
PubMed1992

Characterization of insulin-like growth factor (IGF) binding proteins and their role in modulating IGF-I action in BHK cells.

We have found that over one-half of the total cell surface 125I-insulin-like growth factor I (IGF-I) binding to BHK cells represents binding to IGF binding proteins (IGFBPs) rather than to the IGF-I receptor. In addition to a number of secreted IGFBPs, we have now characterized two cell-associated IGFBPs with unique characteristics. The cell-associated IGFBPs have molecular weights of 30,000 (30K) and 25,000 (25K), as determined by the Western ligand blot technique. IGFBP-30K is located at the cell surface and can be readily labeled by affinity cross-linking with 125I-IGF-I. Surface expression of IGFBP-30K increases 5.4 +/- 1.2-fold (n = 11) with serum starvation. This induction is fully evident by 4 h, plateauing by 24 h, and is completely inhibitable by cycloheximide. The fasting-induced increase in IGFBP-30K is inhibited by IGF-I and by des-IGF-I and, to a lesser extent, by insulin. Unlike cell-associated IGFBP-30K, secretion of IGFBP was stimulated (6.8 +/- 0.5-fold, n = 2) by IGF-I, whereas IGFBP secretion was inhibited 54% by insulin. These results demonstrate coordinate regulation of IGFBP by serum starvation and IGF-I, such that at low concentrations of IGF-I, cell surface binding protein increases whereas binding protein secretion decreases. At high concentrations of IGF-I, IGFBP secretion increases and cell surface IGF-I receptor, as well as IGFBP, decreases. Taken together, these regulatory events regulate the availability of IGF-I for biologic signalling.

Affinity Labels↗
PubMed1992

Maintenance of amelogenin gene expression by transformed epithelial cells of mouse enamel organ.

Electroporation was used to introduce foreign genes into cells derived from the mouse enamel organ epithelia (EOE). Optimal conditions for this electroporation were established. The introduction of a plasmid construct bearing the coding region for the large T-antigen from polyoma virus into EOE cells permitted the establishment of a derivative cell line that has the following characteristics: (1) the cells could be passaged many times; (2) they expressed a keratin-containing cytoskeleton; and (3) approx. 60% of the cells expressed amelogenin, a tissue-specific gene product unique to ameloblasts. Potential uses for such a cell line include analysis of: (1) the upstream regulatory regions required for temporally and spatially restricted expression of amelogenin; (2) the post-translational modification of amelogenin in synchronized cells and (3) the organization and biomineralization of enamel extracellular matrix in monolayer culture.

Amelogenin↗
PubMed1992

Diversity of cleavage patterns of Salmonella 23S rRNA.

The recent discovery of the phenomenon that some prokaryotes fragment their 23S rRNA during post-transcriptional processing of precursor rRNA has been shown to be particularly prevalent among strains and species of Salmonella. Some strains of Salmonella cleaved 23S rRNA at multiple sites producing several fragments. The cleavage patterns of 23S rRNA differed among Salmonella strains and sometimes among the rRNA operons in the same strain. Fragmentation of 23S rRNA was not observed in strains of the closely related species Escherichia coli. Fragmentation of 23S rRNA occurred in Brucella and Agrobacterium but the cleavage pattern was not as diverse as that demonstrated in Salmonella. Introduction of cleavage sites into precursor 23S rRNA of Salmonella is probably a recent evolutionary event.

Blotting, Northern↗
PubMed1992

Cardiac transplantation after prolonged graft preservation with the University of Wisconsin solution.

We tested the ability of University of Wisconsin solution to extend hypothermic preservation of the nonperfused heart during orthotopic baboon allotransplantation. Seven baboons received hearts after cardioplegia and storage (4 degrees C) with University of Wisconsin solution, with a preservation time of 14.2 +/- 1.6 hours. One animal died as a result of a technical error. Six survivors were immunosuppressed for 45 days and then put to death. Preservation did not alter heart weight or histologic features according to light and electron microscopy. Animals were weaned from bypass and returned to their cages without intravenous support within 3.9 +/- 0.8 hours. Weekly biopsies, electrocardiograms, enzyme analyses, echocardiograms, and right heart catheterizations demonstrated excellent cardiac function. University of Wisconsin solution can extend hypothermic cardiac preservation and has no deleterious effects on long-term myocardial function (up to 45 days). This study validates the rationale for human trials with preservation and storage in University of Wisconsin solution toward the goal of improving and prolonging donor heart preservation.

Adenosine↗
PubMed1991

Complete nucleotide and deduced amino acid sequence of genome segment 5 encoding the outer capsid protein, VP5, of a U.S. isolate of bluetongue virus serotype 11.

The complete nucleotide sequence of the RNA genome segment coding for the outer capsid protein, VP5, of the United States prototypic strain of bluetongue virus (BTV) serotype 11 was determined from two overlapping cDNA clones. The genome segment was found to be 1638 nucleotides in length with a single open reading frame coding for a 526 amino acid protein of MW 59,278 and having a net charge of -4.0 at neutral pH. Comparisons of the predicted amino acid sequence of VP5 of BTV 11 with those of the United States serotypes 2, 10, and 13 and two isolates of BTV 1 from Australia and South Africa confirmed earlier reports that VP5 is a conserved protein with no clear regions of variability. A computer generated consensus sequence suggested VP5 of BTV 2 to be representative of the average VP5 sequences reported thus far.

Amino Acid Sequence↗
PubMed1991

On the use of hidden Markov modelling for recognition of dysarthric speech.

Recognition of the speech of severely dysarthric individuals requires a technique which is robust to extraordinary conditions of high variability and very little training data. A hidden Markov model approach to isolated word recognition is used in an attempt to automatically model the enormous variability of the speech, while signal preprocessing measures and model modifications are employed to make better use of the existing data. Two findings are contrary to general experience with normal speech recognition. The first is that an ergodic model is found to outperform a standard left-to-right (Bakis) model structure. The second is that automated clipping of transitional acoustics in the speech is found to significantly enhance recognition. Experimental results using utterances of cerebral palsied persons with an array of articulatory abilities are presented.

Adult↗
PubMed1991

Sequence of changes in rat buccal mucosa induced by zinc deficiency.

In weanling rats, after receiving a zinc-deficient diet (less than 1 ppm) for 4 wk, the buccal mucosa appears hyperplastic. This study determines changes at earlier stages of the lesion. After 9 days of deficiency, the keratin layer had partially converted to parakeratosis and thickened, and the size of the capillary bed was increased. After 18 days, the keratin layer was fully parakeratotic and thickened further. The cellular layer was thickened. The mitotic rate was doubled and rete ridges were convoluted. After 27 days, the keratin and cellular layers were further thickened, and the mitotic rate remained elevated. The rete ridges were further convoluted. The number of mast cells was doubled and the size of the vascular bed had increased further. These findings suggest early and late interactions between the epithelium and lamina propria. After four days on a control diet following 27 days of zinc deficiency, the mucosa returned normal.

Animals↗
PubMed1991

Improved heart preservation with University of Wisconsin solution: experimental and preliminary human experience.

We tested the ability of University of Wisconsin solution (UWS) to extend hypothermic nonperfused heart preservation in baboons and then proceeded to human transplantation. Orthotopic transplantation was performed in five baboons (UWS cardioplegia and storage [4 degrees C]; preservation time 10.3 +/- 0.6 hours). Four survivors were immunosuppressed for 45 days and killed. One animal died from disruption of the aortic anastomosis due to technical error. Preservation did not alter histology under light and electron microscopy or heart weight (at harvest, 51.4 +/- 11.6 g; before implant, 52.5 +/- 11.1 g). Animals were weaned from bypass (mean, 23 +/- 12 minutes) and returned to their cages without intravenous support within 3.6 +/- 0.6 hours. Weekly biopsy, electrocardiogram, enzyme analysis, echocardiogram, and right heart catheterization demonstrated excellent cardiac function. Following success in baboons, UWS was applied to human transplantation (n = 2, UWS cardioplegia and storage [4 degrees C]; preservation time 4.2 and 2.1 hours). The hearts returned to sinus rhythm within 4 minutes of reperfusion without defibrillation, and enzymatic and hemodynamic data reveal excellent heart preservation. Preliminary data suggest the ability of UWS to prolong heart preservation in baboons and be used safely in humans. Further studies are required to compare UWS with crystalloid cardioplegia and saline storage and to prolong donor heart preservation in humans.

Adenosine↗
PubMed1990

A diagnostic method to detect alcelaphine herpesvirus-1 of malignant catarrhal fever using the polymerase chain reaction.

A sensitive diagnostic method specific for alcelaphine herpesvirus-1, causative agent of malignant catarrhal fever, has been developed. Based on the nucleotide sequence of the alcelaphine herpesvirus-1 genomic DNA, a pair of 30 nucleotide primers was selected and synthesized for detecting the virus genome using the polymerase chain reaction (PCR). The virus genome was detected in crude cell lysate using the amplification reaction.

Animals↗
PubMed1990

Nucleotide sequence of a 3.5 kilobase fragment of malignant catarrhal fever virus strain WC11.

A 3.5 kilobase DNA fragment of the malignant catarrhal fever virus (MCFV), strain WC11, was mapped with a number of restriction enzymes, subcloned and sequenced. The fragment was subcloned into plasmid vector, pUC19, for direct sequencing. A complete open reading frame of 2,058 base pairs and a partial open reading frame of 630 base pairs were identified. The sequence of 3,389 nucleotides was compared to other herpesviruses. A 310 base pairs sequence in gene A was 57% homologous to a sequence in reading frame BXLF1 of Epstein-Barr virus strain B95-8.

Amino Acid Sequence↗
PubMed1990

Unique ribosome structure of Leptospira interrogans is composed of four rRNA components.

All known ribosomes of procaryotic organisms are made up of three rRNA components that are 23, 16, and 5S in size. We now report that in some Leptospira interrogans strains, the classical 23S rRNA is further processed to generate 14 and 17S rRNAs. This processing step was previously known to occur only in some eucaryotes and in a small group of procaryotes. The implications of this finding are discussed.

Leptospira interrogans↗
PubMed1989

Cell-specific and developmental regulation of a nerve growth factor-human growth hormone fusion gene in transgenic mice.

We recently showed that a nerve growth factor-human growth hormone (NGF-hGH) fusion gene containing the promoter and 750 bp of 5' flanking region is transcriptionally active in the NGF-secreting L929 mouse fibroblast cell line. For the present experiments, we extended the 5' flank by 5 kb and constructed transgenic mice. These mice began to secrete hGH into saliva at puberty. hGH was detected immunocytochemically in the granulated convoluted tubular cells of the submandibular gland (SMG). SMG levels of hGH mRNA were 10-fold higher in adult males than in females. hGH mRNA was very abundant in SMG, moderately abundant in heart, brain, and kidney, rare in skin and adrenal gland, and undetectable in lung, liver, and spleen. Thus, the NGF-hGH gene reflects NGF gene expression. We conclude that basal NGF gene transcription is regulated by sequences in the cloned NGF gene fragment.

Animals↗