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Biomedical subjects

K Han

Publications and source records attributed to K Han.

At least 127 records · Page 7Linked to original sources
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↗
PubMed1991

Activation and repression of transcription by the gap proteins hunchback and Krüppel in cultured Drosophila cells.

We have studied the ability of the Drosophila gap proteins Krüppel and hunchback to function as transcriptional regulators in cultured cells. Both proteins bind to specific sites in a 100-bp DNA fragment located upstream of the segment polarity gene engrailed, which also contains functional binding sites for a number of homeo box proteins. The hunchback protein is a strikingly concentration-dependent activator of transcription, capable of functioning both by itself and also synergistically with the pair-rule proteins fushi tarazu and paired. In contrast, Krüppel is a transcriptional repressor that can block transcription induced either by hunchback or by several different homeo box proteins. While repression of the homeo box protein activators requires a Krüppel-binding site on the DNA, repression of hunchback can occur efficiently in the absence of a Krüppel-binding site. We discuss the possible molecular mechanisms underlying these activities, as well as the potential significance of these results with respect to segmentation in Drosophila.

Animals↗
PubMed1990

Architectural glass injuries: a case for effective prevention.

Nine hundred and eighteen patients with glass-related injuries were studied retrospectively. Forty per cent of the injuries were due to architectural glass, which resulted in more severe injuries, required more complicated plastic/surgical repairs and needed longer treatment time. It also produced more disabilities in all age groups. These injuries can be prevented by the use of safety glass in residential buildings, a usage which should be legally enforced as in the USA.

Accident Prevention↗
PubMed1990

Induction of tumor necrosis factor by macrophage colony-stimulating factor in vivo.

The effect of human urinary colony-stimulating factor (CSF-1) on the production of tumor necrosis factor (TNF) in vivo was assessed. Purified CSF-1 was administered i.v. to rabbits 4 days prior to injection with lipopolysaccharide (LPS). TNF in the serum prepared from rabbits bled 90 min after LPS injection was measured using cytotoxicity assays employing mouse L929 cells and antirabbit TNF monoclonal antibody. The results indicated that CSF-1 was able to induce the production of TNF in vivo and had a synergistic effect with Propionibacterium acnes.

Animals↗
PubMed1989

The graded distribution of the dorsal morphogen is initiated by selective nuclear transport in Drosophila.

The maternal morphogen dorsal (dl) plays a key role in the establishment of dorsal-ventral polarity in Drosophila. We present evidence that the graded distribution of dl protein is initiated by selective nuclear transport. The dl protein is uniformly distributed throughout the cytoplasm of early embryos, but approximately 90 min after fertilization, dl protein present in ventral but not dorsal regions is selectively transported to the nucleus. Mutations in maternally active genes that regulate dl disrupt this transport process, resulting in an inactive, cytoplasmically localized form of the dl protein. Selective nuclear transport of dl protein was reproduced in tissue culture cells. The wild-type dl protein is largely restricted to the cytoplasm, while truncated proteins are predominantly localized within the nucleus. Transient cotransfection assays suggest that dl activates expression from several promoters in an apparently sequence-independent manner. We discuss the role of nuclear transport as a regulated process in gene expression and development.

Amino Acid Sequence↗
PubMed1989

Synergistic activation and repression of transcription by Drosophila homeobox proteins.

We have used a transient expression assay employing Drosophila tissue culture cells to study the potential of several Drosophila homeobox proteins to function as transcriptional regulators. A 96 bp fragment from the promoter region of the segment polarity gene engrailed, previously shown to contain five copies of a 10 bp consensus binding site for these proteins, enhanced transcription in the presence, but not the absence, of several different homeobox protein expression vectors. It is interesting that cotransfection with combinations of expression vectors encoding the homeobox proteins fushi tarazu, paired, and/or zen resulted in substantial synergistic increases in expression. In contrast, the products of the even-skipped and engrailed genes were found to repress, or quench, the activation induced by the other proteins. We discuss the implications of these results with respect to the role of homeobox genes in the control of embryonic development, and propose a "multi-switch" model whereby the activity of a target gene depends on the interactions of different homeobox proteins with multiple copies of a common binding site.

Animals↗
PubMed1989

Clinical significance of isometric bite force versus electrical activity in temporal and masseter muscles.

Bite force and activity in temporal and masseter muscles during biting and chewing were recorded in 19 control subjects and 23 subjects with symptoms and signs of functional disorders of the craniomandibular system. The entire group comprised 13 men and 29 women, 14-63 yr of age. Maximal unilateral bite force was 480 Newton (N) in control subjects and 387 N in patients, with corresponding bilateral values of 347 N and 230 N. At predetermined levels of contraction, temporalis and masseter activity were linearly related. Correlations of bite force and activity in short static contractions were significant with respect to unilateral, but not to bilateral force measurements. Only in the masseter muscle was strength of dynamic contractions during chewing significantly correlated to bite force. With the present method it was demonstrated that unilateral bite force is a simple clinical indicator of mandibular elevator strength as a whole, but inadequate to disclose asymmetric conditions. During isometric contraction, relative strength of electromyographic activity fairly accurately imaged the output of mechanical activity.

Adolescent↗
PubMed1989

Antiphlogistics in periodontology.

In 146 individuals with inflammatory periodontal disease the authors verified the therapeutical effect of Sanchelin (the mixture of sanguinarine and chelerythrine in 0.05% concentration) in gel (4% hydrogel carboxymethylcellulose) applied into pockets and in aqueous solution administered in the intrapapillar route. The effect of Sanchelin in solution was compared with the effect of 2% hydrocortison in the same way of administration. The clinical condition of periodontium and the quality of oral hygiene was evaluated by means of indexes and papillae were examined histologically. The authors demonstrated that Sanchelin in gel is an effective drug in treatment of inflammatory periodontal disease. They observed lesser effectivity when intrapapillar administration of Sanchelin in solution was used.

Anti-Inflammatory Agents↗