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Y K Huo

Publications and source records attributed to Y K Huo.

10 recordsLinked to original sources
PubMed1998

Physical and comparative mapping of distal mouse chromosome 16. 5 p5.

Distal mouse Chromosome 16 (Chr. 16) includes a region of conserved linkage with human Chromosome 21 (Chr. 21). Mouse models of Down syndrome based on trisomy of distal Chr. 16 have several phenotypes similar to those seen in human patients and have proven useful for correlating dosage imbalance of specific genes with specific developmental anomalies. The degree to which such findings can be related to Down syndrome depends on how well the conserved synteny is maintained. Twenty-four genes have been mapped in both species and there are no discordancies, but the region could carry hundreds of genes. Comparative sequence represents the ultimate comparative map and will aid in identification of genes and their regulatory sequences. A physical map of the distal 4.5 Mb of Chr. 16 has been assembled as an essential step toward a map of sequence-ready templates. The map consists of 51 YACs and 15 BACs and includes 18 transcripts, 9 of which are mapped for the first time in mouse, and 3 of which are, for the first time, described in either species. YAC fragmentation was used to precisely localize the 49 markers on the map. Comparison of this physical map with that of the corresponding region on Chr. 21 shows conservation not only of gene order but of size in the 3 Mb from Cbr1 to Ets2; distal to Ets2, the human map is expanded.

Animals↗
PubMed1995

Isolation and characterization of a candidate gene for progressive myoclonus epilepsy on 21q22.3.

The Unverricht-Lundborg type of progressive myoclonus epilepsy (EPM1) and autoimmune polyglandular disease type I (APECED) have been mapped to human chromosome 21q22.3 by genetic linkage analysis and/or linkage disequilibrium studies. In order to isolate the genes for these disorders, we have constructed BAC contigs in this region and a 14 week trisomy 21 fetal brain cDNA library. A direct cDNA selection technique, modified to permit the recovery 5' and 3' ends of cDNA, was applied to gene identification using the BAC contigs. We have isolated and characterized a novel gene defined by three overlapping but distinct cDNAs of 5, 3, and 3 kb in size all named EHOC-1 (Epilepsy, HOloprosencephaly Candidate-1). This gene maps less than 45 kb centromeric of D21S25, and spans at least 56 kb of genomic DNA. Northern analysis of the 5 kb cDNA revealed that 8, 7.5 and 5.3 kb transcripts are ubiquitously expressed in adult tissues. DNA sequence analysis of the 5 kb cDNA showed a complete coding sequence of 3570 bp that has multiple putative transmembrane domains and has partial homologies to transmembrane proteins including sodium channel proteins. This gene (EHOC-1) is a good candidate for APECED, and particularly for EPM1 because of the location, size, structure and homologies.

Amino Acid Sequence↗
PubMed1994

Radiosensitivity of ataxia-telangiectasia, X-linked agammaglobulinemia, and related syndromes using a modified colony survival assay.

We used a modified colony survival assay to measure the sensitivity to ionizing radiation of more than 50 lymphoblastoid cell lines from normal individuals and from patients with ataxia-telangiectasia, Nijmegen breakage syndrome variants, and X-linked agammaglobulinemia. All of these disorders are associated with an increased frequency of cancer. Lymphoblastoid cell lines from patients with ataxia-telangiectasia complementation groups A, C, D, and E; ATFresno; Nijmegen breakage syndrome variants V1 and V2; and X-linked agammaglobulinemia showed marked radiosensitivity, whereas ataxia-telangiectasia heterozygotes were similar to controls. Friedreich's ataxia is not associated with increased cancer risk; lymphoblastoid cell lines from two such patients showed normal radiosensitivity. Taken together, these results suggest that some forms of X-ray sensitivity and cancer susceptibility share a common mechanism, such as an enzyme that is necessary both for the repair of radiation damage to DNA and for gene rearrangements during V(D)J recombination.

Agammaglobulinemia↗
PubMed1994

G2/M-phase arrest and release in ataxia telangiectasia and normal cells after exposure to ionizing radiation.

Cells from patients with ataxia telangiectasia (AT) are abnormal in their response to irradiation as judged by clonogenic survival and accumulation in G2 phase. The relationship of the results of these two assays, however, is still a matter of controversy. Flow cytometry was used to measure the distribution of cells in the phases of the cell cycle after 2 Gy irradiation in Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs) and SV40-transformed fibroblasts. AT cells showed increased and prolonged accumulation in G2/M phase regardless of the cell type (lymphoblastoid or fibroblast) or complementation group (A, C or D). To test the hypothesis that prolonged accumulation of AT cells in G2 phase after irradiation was not simply a reflection of their radiosensitivity, we gave iso-survival radiation doses to SV40-transformed fibroblasts of two AT and one control cell lines. The two AT cell lines exited from the G2/M-phase block more slowly than control cells after each dose tested. This implies that prolonged accumulation in G2/M phase in AT cells is not directly related to radiosensitivity as measured by clonogenic survival, but that factors involved in the exit from G2 phase after irradiation may be abnormally regulated. We found that G2-phase arrest of AT cells did not necessarily result in a fatal consequence in the first cell cycle after irradiation. Furthermore, G2-phase arrest did not lead to detectable DNA fragmentation characteristic of apoptosis as judged by gel electrophoresis.

Ataxia Telangiectasia↗
PubMed1985

Osteoporosis: a bone morphogenetic protein auto-immune disorder.

Simultaneous reduction in the bone formation phase, and a normal or accelerated bone resorption phase of the bone remodelling process occurs in patients with severe osteoporosis having normal calcium or mineral intake, endocrine function, and exercise patterns. A large body of research suggests that the resorption phase is under the control of the immune system, cell mediated, and involves interaction of macrophages and T-lymphocytes. Much less is known about the bone formation phase. The present hypothesis is based upon speculation on the immunosuppressive effects of B-cell-synthesized humoral antibody (anti-BMP) against bone morphogenetic protein, subsequently reducing osteoprogenitor cell differentiation and causing either gradual or precipitous decline in bone mass. The hypothesis assumes that approximately 74% of white Caucasian women of postmenopausal age, and nearly all of the black population in the USA who do not develop osteoporosis, maintain a low anti-BMP titre. The hypothesis emphasizes a recorded (albeit low) incidence of osteoporosis in children, postpartum women, young men, exogenous adrenal hypercorticoidism, various endocrinopathies who warrant investigation for auto-immune disease. Based upon a high anti-BMP titre, and a low BMP anti-BMP ratio in 10 patients with severe osteoporosis, the hypothesis proposes investigation of an auto-immune disorder in the 26% of the female population who become disabled by severe osteoporosis.

Adult↗
PubMed1985

Immunologic evidence of a bone morphogenetic protein in the milieu intérieur.

Eighteen different groups of proteins have been identified in the organic matrix of bone. To date, seven have been identified in circulating blood. Several plasma proteins are found to accumulate in bone matrix. Two bone, carboxyglutamic acid rich proteins (BGP or osteocalcin) and bone morphogenetic protein (BMP) are measured by RIA in serum in the range of ng/ml. Of all matrix groups, the least abundant is BMP. Acting as a paracrine or local hormone, BMP induces perivascular connective tissue cells of bone marrow to differentiate into cartilage and bone. Neither the mechanism of action or target cells, nor the mode of transport of BMP in serum are known, but the immunologic activity demonstrates higher serum BMP RIA levels in growing children and patients with Paget's Disease than in normal adults. Serum BMP is remarkably low in postmenopausal women with severe osteoporosis; serum anti-BMP antibody is correspondingly high. Although these observations are preliminary and based on a relatively small number of patients, the data suggest a working hypothesis that BMP and anti-BMP are bone tissue-specific parameters of normal and pathological bone physiology. The possibility of diagnosis of osteoporosis in the prefracture stage, and the prospects of evidence of an autoimmune response to the products of bone resorption, derived from the serum BMP anti-BMP ratio, warrant special investigation.

Adult↗
PubMed1984

Purification of bovine bone morphogenetic protein by hydroxyapatite chromatography.

Bovine bone morphogenetic protein (bBMP) induces differentiation of mesenchymal-type cells into cartilage and bone. bBMP has an apparent Mr of 18,500 +/- 500 and represents less than 0.001% of the wet weight of bone tissue. A Mr 34,000 protein resembling osteonectin is separated by extraction with Triton X-100. A Mr 24,000 protein and about half of a Mr 22,000 protein are disassociated from bBMP by precipitation in 1.5 M guanidine hydrochloride. Aggregates of bBMP and a Mr 14,000 protein are insoluble in aqueous media; the bBMP becomes soluble when the Mr 14,000 protein is disassociated in 6 M urea and removed from the solution by ultrafiltration. Three separate molecular species with apparent Mrs 18,500, 17,500, and 17,000 are eluted at 0.10, 0.15, and 0.20 M phosphate ion concentrations, respectively, from a hydroxy-apatite column. The Mr 18,500 protein has the amino acid composition of acidic polylpeptide and includes four half-cystine residues; the pI is 4.9-5.1. The Mr 22,000 component is a chromoprotein resembling ferritin. The NH2-terminal amino acid sequence of the Mr 17,500 protein simulates histone H2B. The Mr 17,000 protein may possess calmodulin activity. Aggregates of the Mr 18,500 and other proteins induce formation of large deposits of bone; the Mr 18,500 protein alone is rapidly absorbed and induces formation of small deposits. None of the other proteins induces bone formation.

Amino Acid Sequence↗
PubMed1983

Human bone morphogenetic protein (hBMP).

Human bone morphogenetic protein (hBMP) was chemically extracted from demineralized gelatinized cortical bone matrix by means of a CaCl2 X urea inorganic-organic solvent mixture, differential precipitation in guanidine hydrochloride, and preparative gel electrophoresis. hBMP is isolated in quantities of 1 mg/kg of wet weight of fresh bone, and has the amino-acid composition of an acidic polypeptide. The mol wt is 17 to 18 k-Da (kilodaltons). Implants of the isolated 17-kDa protein are very rapidly adsorbed and produce a smaller volume of bone than protein fractions consisting of 24-, 17-, and 14-kDa proteins. Since the isolated 24- and 14-kDA components lack hBMP activity, the kinetics of the bone morphogenetic processes including the function of other proteins as carrier molecules, await investigation.

Adult↗