[Choosing the best population development goal].
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Economics↗
Biomedical subjects
Q Yu
Publications and source records attributed to Q Yu.
[A prevalence survey of hepatitis B virus infection among Lisu national minorities].
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Adolescent↗
Unbuffered osmium staining of cell organelles: alterations induced by cell injury.
We have studied the localization of osmium reduction products to investigate the functional state of organelles as well as organelle interrelationships during cell injury. In normal hepatocytes osmium deposits of variable intensity are seen in nuclear envelope, endoplasmic reticulum. Golgi cisternae and vesicles and lysosomes. Buffering of osmium with s- collidine (pH 7.4) prevents the deposition of osmium. Reversible (30 min) and irreversible (60 min) ischemia without reflow causes no change in the pattern of osmium deposition. Irreversible ischemia followed by reflow causes decreased staining of endoplasmic reticulum (ER) and redistribution of the osmium deposits through the cytoplasm. Reversibly injured pancreatic acinar cells in cultured explants manifest a similar loss of osmium staining in the endoplasmic reticulum cisternae. The administration of antimicrotubule drugs induces an accentuation of osmium staining in localized cisternal elements of hepatocytes. These heavily stained cisternae appear to give rise to the bounding membranes of drug-induced autophagic vacuoles. Cytoplasmic organelles sequestered inside the autophagic vacuoles acquire intense staining when they begin to undergo degradation. In homogenized liver tissue all the subcellular organelles show osmium deposits. The deposits are preferentially localized along the organelle membranes. In particular the dense deposits in the ER lumen are not seen in the subcellular fractions. Phospholipase A2 (3 units/mg protein) enhances the deposition of osmium in the lumen of microsomal vesicles, whereas the presence of detergent has no such effect. Addition of EDTA to the homogenizing medium enhances the ultrastructural preservation of the subcellular fractions but has little effect on the deposition of osmium. OsO4 deposition occurs at acid pH and the intensity and pattern of the stain can be modified in vivo and in vitro. Osmium tetroxide deposition is induced at sites of membrane transformation (autophagic vacuoles) and degradation (lysosomes). Calcium influx and phospholipase activation (ischemia, tissue homogenization, phospholipase addition) enhance osmium deposition and/or influence the localization of the staining pattern.
Animals↗
Tandem peptide ligation for synthetic and natural biologicals.
We describe the concept and methods of peptide ligation and tandem peptide ligation for preparing synthetic and natural biologicals. Peptide ligation is a segment coupling method for free peptides or proteins through an amide bond without the use of a coupling reagent or a protecting group scheme. Because unprotected peptides or proteins prepared from either a chemical or biochemical source are being used as building blocks, the ligation removes the size limitation for peptide and protein synthesis. A key feature of the peptide ligation is that the coupling reaction is orthogonal, i.e. it is specific to a particular alpha-amino terminus (NT). This NT-amino acid-specific feature permits the development of a tandem peptide ligation method employing three unprotected peptide segments containing different NT-amino acids to form consecutively two amide bonds, an Xaa-SPro (thiaproline) and then an Xaa-Cys. This strategy was tested in peptides ranging from 28 to 70 amino acid residues, including analogues of somatostatins and two CC-chemokines MIP-1alpha and MIP-1beta. The thiaproline replacements in these peptides and proteins did not result in altered biological activity. By eliminating the protecting group scheme and coupling reagents, tandem ligation of multiple free peptide segments in aqueous solutions enhances the scope of protein synthesis and may provide a useful approach for preparing protein biologicals and synthetic vaccines.
Amino Acid Sequence↗
Immune responses to self peptides naturally presented by murine class II major histocompatibility complex molecules.
Peptides eluted from murine Major Histocompatibility Complex (MHC) class II molecules are predominantly fragments of self proteins, which include apolipoprotein E, cystatin-c, transferrin receptor, MHC class II and Ii chains. These naturally processed self peptides are expected to be presented during ontogeny. Therefore, immune responses to these peptides in syngeneic hosts may be under physiological control so as to modulate auto-reactivity. As would be expected from our current understanding, T cells reactive to such antigens should be deleted or clonally anergized. To explore this possibility, we investigated the immunogenicity of a number of these self peptides in mice that express MHC class II, from which these peptides were eluted. T cell and antibody responses were measured following immunization of mice with the appropriate peptide. Surprisingly, many of these peptides were highly immunogenic in normal mice. T cells reactive to these self peptides are restricted by syngeneic MHC class II and were blocked by alpha CD4 antibodies. T cells primed with the native protein in vivo could be challenged with the appropriate self peptide in vitro. Some of the self epitopes induce Th1 cells as indicated by IFN-gamma but not IL-4 production and others induce Th2 cells. Antipeptide antibodies were detected only at higher doses of antigen. Our results suggest that T cells specific for many of the naturally processed self peptides are not deleted but tolerance to these peptides is still maintained in vivo. Presumably the high-affinity self-reactive T cells are deleted in the thymus and the low-affinity self peptide reactive T cells remain unresponsive to antigen challenge in vitro. Upon antigen priming in vivo, many of these self-reactive T cells become activated and readily respond to antigen challenge in vitro. These results point to the physiological control of the maintenance of tolerance to naturally processed self peptides.
Amino Acid Sequence↗
A Drosophila Minute gene encodes a ribosomal protein.
Minute genes have long constituted a special problem in Drosophila genetics. For at least 50-60 different genes scattered throughout the genome, dominant mutations and/or deficiencies have been recognized which result in a common phenotype consisting of short thin bristles, slow development, reduced viability, rough eyes, small body size and etched tergites. Schultz proposed that the Minute loci encode similar but separate functions involved in growth and division common to all cells. Atwood and Ritossa suggested that Minute loci encode components of the protein synthetic machinery, specifically the transfer RNA genes; this now seems unlikely on grounds of both mapping and mutability studies. More recently, we and others suggested that the Minute loci are ribosomal protein genes. We report here that transformation with a cloned 3.3-kilobase (kb) region containing the gene encoding the large subunit ribosomal protein 49 (rp49) suppresses the dominant phenotypes of Minute (3)99D, a previously undescribed Minute associated with a chromosomal deficiency of the 99D interval. This activity is specific to the 99D Minute as it does not suppress other Minute loci elsewhere in the genome. This result provides direct evidence that the Minute locus at the 99D interval encodes the ribosomal protein 49.
Animals↗
A family of unusually spliced biologically active transcripts encoded by a Drosophila clock gene.
Complementary DNA cloning of the transcripts of the Drosophila clock gene period reveals three distinct transcripts. These result from unusual splicing pathways, one involving a CG 3' splice site and one resulting in the use of two different reading frames in one exon, and they predict three separate proteins. Two of the cloned cDNAs can restore clock function to mutant arrhythmic flies.
Animals↗
Behaviour modification by in vitro mutagenesis of a variable region within the period gene of Drosophila.
The period gene of Drosophila melanogaster, implicated in the control of both the circadian and male courtship song rhythms, is found to be polymorphic. Alleles differ in the length of a region of the gene encoding a series of threonine-glycine repeat units. The phenotypes of transformed fruit flies, in which the only functional period gene lacks the entire perfect threonine-glycine repeat region, show that the effects of the period gene on the circadian and male courtship song rhythms can be dissociated.
Alleles↗
In vivo short-term expression of a hypertrophic cardiomyopathy mutation in adult rabbit myocardium: myofibrillar incorporation without early disarray.
Cardiac myocyte disarray is the pathological hallmark of hypertrophic cardiomyopathy (HCM), a disease of sarcomeric proteins. Mutations in the cardiac troponin T (cTnT), a major gene responsible for HCM, are associated with severe myocyte disarray. To study the pathogenesis of cardiac myocyte disarray, we expressed normal and mutant cTnT proteins in the myocardium of adult rabbits via direct intramyocardial injection of recombinant adenoviruses. Aliquots of 1010 plaque-forming units of normal (Ad/CMV/cTnT-Arg92) and mutant (Ad/CMV/cTnT-Gln92) recombinant viruses or a control vector (Ad/DeltaE) virus were mixed with equal aliquots of a reporter virus (Ad/CMV/Lac-Z) and co-injected into the myocardium of adult rabbits (n = 12). One week following gene transfer, thin myocardial sections were obtained and analyzed for beta-galactosidase, messenger RNA (mRNA) and protein expression, hematoxylin and eosin, Masson's trichrome, immunofluorescence staining, and electron microscopy. The efficiency of gene transfer varied from 2% to 60% of the cells in an area approximately 2.5 mm in length. Northern blotting confirmed expression of the transgenes into mRNA. Immunoblotting of the myofibrillar protein extracts and indirect immunofluorescence staining confirmed expression and incorporation of the transgene proteins into myofibrils. Expression of the mutant cTnT was up to 18% of the endogenous. Light and electron microscopic studies showed normal cardiac myocyte and sarcomere structures. Thus, despite incorporation of the mutant cTnT-Gln92, stable myofibrillar formation and sarcomere assembly proceeded in vivo. The absence of myocyte and sarcomere disarray may reflect the duration, or the level of expression, or the extent of myofibrillar incorporation of the mutant cTnT-Gln92, as well as the site and timing of expression of the transgenes, and interspecies variation in the pathogenesis of HCM.
Adenoviridae↗
Genetic diversity and relationships in native Hawaiian Saccharum officinarum sugarcane.
Commercial sugarcane hybrid cultivars currently in production are high-yielding, disease-resistant, millable canes and are the result of years of breeding work. In Hawaii, these commercial hybrids are quite distinct from many Saccharum officinarum canes still in existence that were brought to the islands and cultivated by the native Polynesians. The actual genetic relationships among the native canes and the extent to which they contributed to the commercial hybrid germplasm has been the subject of speculation over the years. Genetic analysis of 43 presumed native Hawaiian S. officinarum clones using 228 DNA markers confirmed them to be a group distinct from the modern hybrid cultivars. The resulting dendrogram tended to confirm that there were several separate S. officinarum introductions that, owing to selections of somatic mutations, diverged into a number of cluster groups. When the "Sandwich Isles" were discovered by Captain James Cook in 1778, the Hawaiians were found to be growing sugarcane, S. officinarum ( Cook 1785). Sugarcane (ko, in the Hawaiian language) appeared in a variety of stalk and leaf colors, often with stripes (the "ribbon canes"). In the interest of preserving this historic germplasm, a collection was assembled in the 1920s by Edward L. Caum of the Hawaiian Sugar Planters' Association and W. W. G. Moir of American Factors. Histories and descriptions of the canes were reported by Moir (1932).
Cluster Analysis↗
An artificial-intelligence approach to ECG analysis.
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Algorithms↗
Capillary electrophoresis in China.
The application of capillary electrophoresis (CE) to many fields and the development of relevant CE techniques in China are presented, based mainly on the contents of the two national symposia on CE, which were held in 1993 and 1995 separately with a total of about 200 papers presented. The technique has been involved in the widespread fields of industry, agriculture, medicine, environmental sciences, etc. The method and technique development involves all aspects including columns, detectors, and whole machines.
Agriculture↗