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Biomedical subjects

K Han

Publications and source records attributed to K Han.

At least 109 records · Page 6Linked to original sources
PubMed1994

Implantation of PNS graft inhibits the induction of neuronal nitric oxide synthase and enhances the survival of spinal motoneurons following root avulsion.

In a spinal root injury model, our previous studies have shown that induction of nitric oxide synthase (NOS) appears only in spinal motoneurons of the root-avulsed segment in which significant motoneuron loss occurs but not in those of the distal root-axotomized segment (root axotomy 5-10 mm from the spinal cord) in which most motoneurons survive the injury. One hypothesis for the different response of motoneurons to root avulsion and distal root axotomy is that neurotrophic factors produced by the remaining peripheral nervous system (PNS) component are available for the distally axotomized motoneurons but are not available following avulsion. This hypothesis is tested in the present study by implantation of a PNS graft following the root avulsion. Results of the present study show that implantation of a PNS graft significantly enhances the survival of motoneurons following avulsion. Expression of NOS due to avulsion injury is completely inhibited in all motoneurons that regrow into the PNS graft. These results indicate that induction of NOS in avulsed motoneurons may result from the deprivation of neurotrophic factors produced by the PNS component, and the survival promoting effects of neurotrophic factors may be achieved by modifying certain cellular molecules such as NOS.

Amino Acid Oxidoreductases↗
PubMed1994

Comparison of chromosome aberrations in leiomyoma and leiomyosarcoma using FISH on archival tissues.

Fluorescence in situ hybridization (FISH) with chromosome-specific probes was used to study cytogenetic changes in five cases of leiomyosarcoma (LMS) and nine cases of uterine leiomyoma (LM). Biotinylated DNA probes for the centromeric regions of chromosomes 1, 6, 8, 9, 17, and 18, painting probes for chromosomes 1 and 22, and the cosmid probe for chromosome region 21q22.3 were used on nuclei isolated from paraffin blocks. Four of five LMS cases revealed major chromosomal aberrations, while the only case with minor clonal aberrations was subsequently found not to be a typical LMS. The most common numerical aberrations found in the LMS cases were extra copies of chromosome 8 (three of five cases), loss of chromosome 1 (three of five cases), and loss of chromosome 6 (two of five cases). One of two LMS cases studied with a chromosome 1 painting probe demonstrated translocations of chromosome 1. In contrast to LMS, only five of nine uterine LM cases had abnormal clones, and these were smaller than those in LMS. Two LM cases showed 9% tetrasomy 8 with 17 or 20% monosomy 6, and three other cases had monosomy 6 clones in 18-34% of cells. These results indicate that typical LMS is characterized by multiple chromosomal aberrations affecting most of the cells, whereas borderline LMS and LM have fewer affected chromosomes and less clonal involvement.

Adult↗
PubMed1994

Quantifying chromosome changes and lineage involvement in myelodysplastic syndrome (MDS) using fluorescent in situ hybridization (FISH).

A simplified technique for fluorescent in situ hybridization (FISH) was used to investigate the prevalence of chromosomally abnormal clones in 13 cases of myelodysplastic syndrome (MDS). Biotinylated centromeric probes for chromosomes 7, 8, 12 and X, as well as painting probes for chromosomes 7 and 11, were applied to air-dried bone marrow smears stored from 6 to 23 months. Nine of the cases had been previously karyotyped, and five of these demonstrated normal karyotypes which were confirmed by FISH. The remaining four cases showed different chromosome changes. One case of sideroblastic anemia with chronic lymphocytic leukemia showed minor clones with either monosomy 12 (12% of cells) or tetraploidy (15% of cells) by FISH, whereas metaphase cytogenetics had demonstrated trisomy 12 in 20% of cells, with no evidence of tetraploidy. Another case which had been previously karyotyped was found to have a t(7;11) in 90% of cells while only 10% of cells were shown by FISH to contain this translocation. Monosomy 7 was demonstrated by FISH in a case of refractory anemia (RA), while trisomy 8 was found in a case of RA with excess blasts in transformation (RAEB-T), and in both of these cases the aneuploid clone was present in eosinophils as well as in erythroid and granulocytic precursors but not in lymphocytes or histiocytes, thereby demonstrating the value of FISH for identifying the affected cell lineage.

Aged↗
PubMed1993

Detection of aneuploidy and possible deletion in paraffin-embedded rhabdomyosarcoma cells with FISH.

Conventional cytogenetic studies of solid tumors are limited by the difficulty of culturing tumor cells, while in situ hybridization using paraffin sections of interphase cells results in too many truncated cells. To solve these problems, fluorescent in situ hybridization (FISH) technique was used on free nuclei isolated from formalin-fixed paraffin-embedded embryonal rhabdomyosarcoma (RMS) tissue using our modification of Hedley's method for isolation of nuclei. Biotinylated DNA probes for the centromeric regions of chromosomes 6, 8, 11, 12, 17, and 18, painting probes for chromosomes 8 and 11, and a cosmid probe for the HER-2/neu oncogene, were used. The centromeric probes worked well, demonstrating two copies of chromosomes 6, 17, and 18, but three copies of chromosome 11 in 52.9% of nuclei. Four copies of chromosome 8 were observed in 57.1% of nuclei and five or more in 17.1%. Chromosome 12 demonstrated 21.8% trisomy and 62.2% tetrasomy. Painting probes for chromosome 11 also worked well and matched the results of the centromeric probes, with no suggestion of structural aberration. However, the results of the painting probe for chromosome 8 yielded fluorescent areas of different sizes, suggesting that some of the extra chromosomes 8 could be deleted. The cosmid probe for the HER-2/neu oncogene also worked well, and revealed two signals in each nucleus without evidence of amplification. This study illustrates the successful use of a new technique for studying chromosomal aberration in paraffin-embedded solid tumors. The importance of this technique is that it has not been previously possible to use painting probes or cosmid probes on paraffin tissue sections. Use of this procedure will broaden the type of retrospective studies that can be performed to include detection of deletions or translocations.

Aged↗
PubMed1993

Prediction of common folding structures of homologous RNAs.

We have developed an algorithm and a computer program for simultaneously folding homologous RNA sequences. Given an alignment of M homologous sequences of length N, the program performs phylogenetic comparative analysis and predicts a common secondary structure conserved in the sequences. When the structure is not uniquely determined, it infers multiple structures which appear most plausible. This method is superior to energy minimization methods in the sense that it is not sensitive to point mutation of a sequence. It is also superior to usual phylogenetic comparative methods in that it does not require manual scrutiny for covariation or secondary structures. The most plausible 1-5 structures are produced in O(MN2 + N3) time and O(N2) space, which are the same requirements as those of widely used dynamic programs based on energy minimization for folding a single sequence. This is the first algorithm probably practical both in terms of time and space for finding secondary structures of homologous RNA sequences. The algorithm has been implemented in C on a Sun SparcStation, and has been verified by testing on tRNAs, 5S rRNAs, 16S rRNAs, TAR RNAs of human immunodeficiency virus type 1 (HIV-1), and RRE RNAs of HIV-1. We have also applied the program to cis-acting packaging sequences of HIV-1, for which no generally accepted structures yet exist, and propose potentially stable structures. Simulation of the program with random sequences with the same base composition and the same degree of similarity as the above sequences shows that structures common to homologous sequences are very unlikely to occur by chance in random sequences.

Algorithms↗
PubMed1993

Use of fluorescence in situ hybridization for retrospective detection of aneuploidy in multiple myeloma.

In malignancies with a low mitotic index such as multiple myeloma (MM), conventional cytogenetic studies may not be informative. This study's purpose was to assess specific numerical chromosomal aberrations in non-dividing MM cells by fluorescence in situ hybridization (FISH) of DNA chromosome probes on bone marrow smears. Old air-dried bone marrow smears from 18 MM patients were probed with alpha satellite DNA sequences for chromosomes 7, X, and Y, and a whole painting probe for chromosome 11. Plasma cells were identified by their morphologic characteristics so that counts of fluorescent signals in the nuclei of MM cells could be differentiated from those of normal marrow cells. Numerical chromosome aberrations were found in 66.7% of the cases (12 of 18), including 5 cases of trisomy 7, 2 cases of tetraploidy, 2 cases of monosomy X in females, 2 cases of disomy X in males, and 1 case of nullisomy Y. In addition, 2 of the 7 cases probed with chromosome 11 paint demonstrated 3 signals in about 15% of the cells. This study illustrates the advantages of FISH for interphase analysis of chromosome aberrations in slowly dividing cells, as well as the ability to use old slides for retrospective studies.

Adult↗
PubMed1993

Functional domains of the Drosophila Engrailed protein.

We have studied the transcriptional activity of the Drosophila homeodomain protein Engrailed (En) by using a transient expression assay employing Schneider L2 cells. En was found to very strongly repress promoters activated by a variety of different activator proteins. However, unlike another Drosophila homeodomain-containing repressor, Even-skipped (Eve), En was unable to repress the activity of several basal promoters in the absence of activator expression. These findings indicate that En is a specific repressor of activated transcription, and suggest that En may repress transcription by a different mechanism than Eve, perhaps by interfering with interactions between transcriptional activators and the general transcription machinery. By analyzing the properties of a variety of En mutants, we identified a minimal repression domain composed of 55 residues, which can function when fused to a heterologous DNA binding domain. Like repression domains identified in the Drosophila repressors Eve and Krüppel, the En repression domain is rich in alanine residues (26%), but unlike these other domains, is moderately charged (six arginine and three glutamic acid residues). Separate regions of En that may in some circumstances function in transcriptional activation were also identified.

Amino Acid Sequence↗
PubMed1993

Tripartite frontalis muscle flap transposition for blepharoptosis.

Transposition of frontalis muscle to the tarsus is an effective technique for correction of blepharoptosis with poor levator function. This is refined by division of the frontalis muscle flap into three strips, which are sutured separately to the upper tarsal border. Thirty-six patients with blepharoptosis (54 eyelids) had tripartite frontalis muscle flap procedures. The ptosis was congenital in 33 patients. Forty-eight eyelids had poor levator function. Six had fair levator function. The frontalis action ranged from 8 to 14 mm. The average of follow-up evaluation was 32 months. The postoperative results were evaluated by Berke's criteria, various sensation tests of the forehead, and presence of forehead wrinkles. The tripartite frontalis muscle flap provided an even distribution of upward pull on the tarsus without tenting the lid margin. Ptosis on superior and primary gaze, an intrinsic complication of maximal levator resection or frontalis suspension, was not observed after this procedure. Lagophthalmos was transitory, usually disappearing within 3 months. Lid lag was mild-to-moderate. Mild hypesthesia of the forehead returned completely to normal in all patients, followed more than 24 months. Slight lowering of the medial portion of the eyebrow and incomplete wrinkling of the forehead on upward gaze were mild cosmetic defects after correction in 4 patients with unilateral ptosis. The tripartite frontalis flap technique is recommended for patients with bilateral congenital ptosis and fair-to-poor levator function, and for unilateral ptosis, if either contralateral brow lift or bilateral frontalis transposition is appropriate.

Adolescent↗
PubMed1993

Transcriptional repression by the Drosophila even-skipped protein: definition of a minimal repression domain.

We have used a transient expression assay employing Drosophila tissue culture cells to study the transcriptional repression activity of the homeo domain protein Even-skipped (Eve). Eve was found to repress all promoters that contained Eve-binding sites, including both TATA-containing and TATA-lacking minimal promoters, as well as promoters activated by several different classes of activator proteins. These findings suggest that the general transcription machinery can be a target of Eve. By analyzing properties of a variety of Eve mutants and chimeric fusion proteins, we have identified several features important for efficient repression. In addition to the DNA-binding domain, a potent repressor requires a repression domain, which can be as small as 27 residues. The minimal 57-residue Eve repression domain, as well as several others studied here, were all found to be proline rich and to contain a high percentage of hydrophobic residues. An intriguing feature of the strong repressors was that their DNA-binding activities, measured by gel retention assays with nuclear extracts, were significantly less than those of derivatives inactive in repression.

Amino Acid Sequence↗
PubMed1993

[A study of the reasonable vertical thickness of stabilization splint]

It was proved in this study through the measurement and calculation of the shape and size of dentition and jaws and the position of the hinge axes that the thickness of stabilization splint was difficult to be confirmed within free way space, it was therefore suggested that attention should be paid on forming a flat and smooth occlusal plane during the design and manufacture of splint, so that the points to a flat plane contact relation could be presented between the split and the tops of working cusps. Guidance effect on inclines must be eliminated. The thickness of splint should depend upon the height of cusp and the overbite degree of the patient, so that free way space wasn't absolutely inviolable in the set of stabilization splint.

Journal Article↗
PubMed1993

Use of FISH to detect chromosomal translocations and deletions. Analysis of chromosome rearrangement in synovial sarcoma cells from paraffin-embedded specimens.

Retrospective cytogenetic analysis was performed on paraffin-embedded cells from five cases of synovial sarcoma to evaluate the frequency of the X;18 translocation characteristic of this tumor. Fluorescent in situ hybridization with DNA probes for the centromeres of chromosomes X and 18 was used with whole chromosome painting probes for X and 18. Translocation was inferred when there were only two X and 18 centromere signals but three painting probe signals of unequal size. On this basis it was possible to identify the t(X;18) in three cases. The fourth case was found to have extra copies of chromosome 18 without translocation, while the fifth case, the only one with a questionable diagnosis, had a normal chromosome pattern with a minor clone showing a translocated 18 but a normal X. Thus this study demonstrates the feasibility and value of using fluorescent in situ hybridization to detect chromosome rearrangements in archival tumor specimens.

Adolescent↗
PubMed1992

Cellular autophagy in proximal tubules of early diabetic rats following insulin treatment and islet transplantation.

The influence of insulin treatment (group 1) and allogenic islet transplantation (group 2) on renal cellular autophagy were evaluated in adult Lewis rats in the early phase of streptozotocin-induced diabetes mellitus--a condition in which autophagy is inhibited and renal mass is increased. Three days after insulin treatment or islet transplantation (IT), the right kidney was resected and cortical tubular tissue was examined by quantitative electron microscopy. In group 1, the volume and numerical densities of autophagic vacuoles (AVs) increased by 70% and 80% respectively in the proximal tubular cells compared with saline-injected controls. The additive effect of unilateral nephrectomy (Ux) on cellular autophagy was investigated 1 or 2 days after Ux. Compared with the resected right kidney, the volume and numerical densities of AVs in the remnant left kidney decreased by 49% and 43% in the insulin-treated rats, and by 43% and 39% in the saline-injected diabetic animals. In group 2, the volume and numerical densities of AVs increased by 45% and 44% in parenchyma regressing from diabetic hypertrophy after IT, compared with sham-operated controls. After Ux, the volume and numerical densities of AVs decreased by 49% and 43% in IT rats, and by 41% and 53% in the still diabetic sham-operated animals. The data show that inhibition of cellular autophagy in the proximal tubules of the early diabetic kidney can be reversed by insulin replacement, despite the fact that insulin per se inhibits cellular autophagy in the nondiabetic kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Epizootiology of fascioliasis in Montana.

During 1989-1990, the United States Department of Agriculture (USDA) meat inspection records were used to determine the distribution and incidence of liver flukes (Fasciola hepatica and Fascioloides magna) in Montana cattle. Of the cows and bulls slaughtered in USDA-inspected packing plants during a 12 month time period, 17.24% had livers that were condemned because of liver flukes. This was a 12% increase over USDA liver condemnations reported for 1973. Infected animals have been reported from 26 counties in Montana, mostly located in the south-central and western half of the state. Forty-nine percent of the 2.4 million cattle in Montana are raised in these counties. Lymnaeid snail species that may serve as intermediate hosts for Fasciola hepatica were found in most of the counties where liver flukes were reported. The principal vectors believed to be responsible for the transmission of Fasciola hepatica in Montana are species of the genus Fossaria. Stagnicola montanensis and Lymnaea stagnalis, which may serve as intermediate hosts for this parasite have also been collected. A known intermediate host for Fascioloides magna, Stagnicola caperata, was also found in several locations.

Abattoirs↗