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Biomedical subjects

C Park

Publications and source records attributed to C Park.

At least 217 records · Page 12Linked to original sources
PubMed1993

Polymorphism in BoLA-DRB3 exon 2 correlates with resistance to persistent lymphocytosis caused by bovine leukemia virus.

The relationship between polymorphism of the bovine lymphocyte Ag (BoLA)-DRB3 gene and resistance and susceptibility to persistent lymphocytosis (PL) caused by bovine leukemia virus (BLV) was investigated. Exon 2 of the BoLA-DRB3 gene was cloned from animals with BoLA haplotypes previously found to be associated with resistance and susceptibility to PL. Sequence analysis revealed the presence of the amino acids Glu-Arg (ER) at putative Ag binding residues 70 and 71 only in BoLA haplotypes associated with resistance to PL. This correlation was confirmed in a case control study (n = 26) using an allele-specific polymerase chain reaction for the detection of ER at residues 70-71. These results provide a molecular basis for Ir gene control of resistance and susceptibility to PL and suggest that the cellular immune response is important in preventing the in vivo spread of BLV infection.

Alleles↗
PubMed1993

Fluorescence properties of the three tyrosine residues in the ribose-binding protein.

Three tyrosine residues but no tryptophan exist in the ribose-binding protein (RBP) of Escherichia coli. In order to assess the contribution of each tyrosine to the fluorescence properties, mutants were constructed by site-directed mutagenesis to replace tyrosines at 32, 115, and 261 by phenylalanines. The mutant proteins were functional as confirmed by in vivo tactic response and by their ability to bind to ribose. The fluorescence emission spectra of the native proteins purified from the various tyrosine mutants were measured from emission scans with a peak at 303 nm. The tyrosines, at positions 32, 115, and 261, contribute 10.0, 69.6, and 23.4%, respectively, to the total intensity of fluorescence. In completely unfolded polypeptide, these tyrosines have almost the same intensities of fluorescence, indicating that the fluorescence from tyrosines at 32 and 261 are considerably quenched in the folded, native protein.

Carrier Proteins↗
PubMed1993

Design superiority of palindromic DNA sites for site-specific recognition of proteins: tests using protein stitchery.

Using protein stitchery with appropriate attachment of cysteines linking to either C or N termini of the basic region of the v-Jun leucine zipper gene-regulatory protein, we constructed three dimers--pCC, pCN, and pNN. All three bind specifically to the appropriately rearranged DNA recognition sites for v-Jun: ATGAcgTCAT, ATGAcgATGA, and TCATcgTCAT, respectively (Kd, approximately 4 nM at 4 degrees C). Results of DNase I footprinting provide strong support for bent recognition helices in leucine zipper protein-DNA complexes. Comparison of the results for pCC and pNN with those for pCN shows the design superiority of palindromic sequences for protein recognition.

Amino Acid Sequence↗
PubMed1993

Nonvisualization of suppressed thyroid tissue on Tl-201 scintigraphy.

Tl-201 scintigraphy has been used to visualize thyroid tissue that is suppressed by an autonomously functioning thyroid nodule. Reports have indicated that the sensitivity of this technique rivals that obtained by I-123 scanning after thyroid-stimulating hormone stimulation. We report a case of triiodothyronine toxicosis caused by an autonomously functioning thyroid nodule in which the suppressed thyroid tissue was not visualized on Tl-201 scintigraphy. The suppressed tissue was readily identified with ultrasound imaging, which demonstrates the utility of this technique in differentiating between thyroid suppression and agenesis.

Adult↗
PubMed1993

Superior oblique lengthening procedure with silicone expander in rabbits.

Using a rabbit model, we assessed the postoperative status and histopathologic findings of superior oblique tenotomy with silicone expander procedure. In the control group we marked and cut the superior oblique, and in the experimental group we inserted a silicone 240 retinal band 4 mm in length along the edges of incision. At the postoperative weeks 1,3,5 and 7, we randomly chose five rabbits and made a histopathologic examination after hematoxylin-eosin and Masson's trichrome stain. The distance between the incised edges was various in the control group, but constant in the experimental group. With time inflammation decreased and fibrosis of the superior oblique increased. Foreign body reaction occurred around the suture material in both groups., but not around the silicone expander. At 5 weeks atrophy of the superior oblique was observed in both groups. From the above results, we concluded that the superior oblique lengthening procedure using silicone expander is a useful surgical method for weakening the superior oblique muscle.

Animals↗
PubMed1993

Liver involvement in multiple myeloma proven by peritoneoscopy--a case report.

Liver involvement in multiple myeloma has been known to be common in autopsied series. However, since its clinical significance is uncertain yet, invasive procedure confirming plasma cell infiltration of the liver has been rarely performed. We report a case with multiple myeloma which had plasma cell infiltration of a liver. A peritoneoscopic biopsy of the liver for the purpose of disclosing the nature of the aggravating liver function in a carrier of the hepatitis B virus showed infiltration of lymphoreticular cell which were identified later as lambda-light chain producing primitive plasma cells by immunohistochemical stain.

Adult↗
PubMed1993

[Appearance of hallucinations and one-and-a-half syndrome after resection of a cavernous angioma located in the fourth ventricle floor].

A patient is described who simultaneously suffered from hallucinations and one-and-a-half syndrome following surgical resection of a cavernous angioma located on the fourth ventricle floor. A 30-year-old male was admitted having a 10 year history of progressive weakness and hypesthesia of the right extremities. Neurological examination revealed right hemiparesis and hemihypesthesia. A computerized tomography (CT) scan showed a well circumscribed mixed-density area at the left portion of the pontine tegmentum. Magnetic resonance imaging (MRI) indicated a mixed intensity core surrounded by hypointense regions on T2-weighted images. A red mulberry-like tumor was found, during surgical procedures, on the mid-and left-portion of the fourth ventricle floor. The tumor was totally resected and the histological diagnosis was cavernous angioma. Visual hallucinations occurred several times following surgery, being subsequently described as images of moving worms, a dump truck next to the bed, and a bed falling from the ceiling. The patient soon understood these objects were not real. He simultaneously exhibited left lateral gaze palsy associated with left internuclear ophthalmoplegia i.e., one-and-a-half syndrome. Three months after surgery the visual hallucinations disappeared but the one-and-a-half syndrome was incompletely resolved. According to the neurological signs and the MRI results, the lesion site was considered to extend from the left lower pons to the midbrain. Previously reported operations of cavernous angioma of the fourth ventricle floor are also described.

Adult↗
PubMed1992

Protein stitchery: design of a protein for selective binding to a specific DNA sequence.

We present a general strategy for designing proteins to recognize DNA sequences and illustrate this with an example based on the "Y-shaped scissors grip" model for leucine-zipper gene-regulatory proteins. The designed protein is formed from two copies, in tandem, of the basic (DNA binding) region of v-Jun. These copies are coupled through a tripeptide to yield a "dimer" expected to recognize the sequence TCATCGATGA (the v-Jun-v-Jun homodimer recognizes ATGACTCAT). We synthesized the protein and oligonucleotides containing the proposed binding sites and used gel-retardation assays and DNase I footprinting to establish that the dimer binds specifically to the DNA sequence TCATCGATGA but does not bind to the wild-type DNA sequences, nor to oligonucleotides in which the recognition half-site is modified by single-base changes. These results also provide strong support for the Y-shaped scissors grip model for binding of leucine-zipper proteins.

Amino Acid Sequence↗
PubMed1992

Treatment of postcataract fibrinous membranes with tissue plasminogen activator.

PURPOSE: The purpose of this study is to investigate the efficacy and toxicity of tissue plasminogen activator (tPA) in treatment of postcataract fibrinous membranes. METHODS: The authors injected 25 micrograms of tPA into the anterior chamber of 52 pseudophakic eyes with moderate to severe fibrinous membranes that developed after cataract surgery. RESULTS: Intraocular tPA injection resulted in complete fibrinolysis in 47 of 52 eyes (90%) and partial fibrinolysis in 5 of 52 eyes (10%). In cases of complete fibrinolysis, resolution of the fibrinous membrane occurred within 30 minutes in 22 of 47 eyes (47%) and within 1 hour in 25 of 47 eyes (53%). No evidence of toxicity was observed as measured by slit-lamp biomicroscopy, intraocular pressure, and corneal endothelial cell density, size, and morphology. Complications of tPA administration included periorbital pain (4 eyes), anterior chamber hemorrhage (4 eyes), and anterior chamber turbidity (3 eyes). CONCLUSION: The authors believe that intraocular tPA is effective and safe in the treatment of postcataract fibrinous membranes.

Adult↗
PubMed1992

Arterial supply of the anterior ear.

Twenty cadaver auricles were injected with a latex solution to define the arterial supply of the anteroauricular surface. Two arterial networks exist, the network of the triangular fossa-scapha and the network of the concha. Both eventually communicate on the anthelix. The triangular fossa-scapha network originates from one subbranch of the upper auricular branch of the superficial temporal artery and from branches of the posterior auricular artery that come through the earlobe and triangular fossa and over the helical margin. The conchal network is provided by two to four perforators that come from the posterior auricular artery, piercing the conchal floor. Auricular branches of the superficial temporal artery in the preauricular region and their communications with the posterior auricular artery also were confirmed. We believe that a greater understanding of the detailed arterial anatomy in this area allows one to develop safely a variety of surgical techniques for reconstruction of the ear.

Arteries↗
PubMed1992

Involvement of SecB, a chaperone, in the export of ribose-binding protein.

Ribose-binding protein (RBP) is an exported protein of Escherichia coli that functions in the periplasm. The export of RBP involves the secretion machinery of the cell, consisting of a cytoplasmic protein, SecA, and the integral membrane translocation complex, including SecE and SecY. SecB protein, a chaperone known to mediate the export of some periplasmic and outer membrane proteins, was previously reported not to be involved in RBP translocation even though small amounts of in vitro complexes between SecB and RBP have been detected. In our investigation, it was shown that a dependence on SecB could be demonstrated under conditions in which export was compromised. Species of RBP which carry two mutations, one in the leader that blocks export and a second in the mature protein which partially suppresses the export defect, were shown to be affected by SecB for efficient translocation. Five different changes which suppress the effect of the signal sequence mutation -17LP are all located in the N domain of the tertiary structure of RBP. All species of RBP show similar interaction with SecB. Furthermore, a leaky mutation, -14AE, generated by site-specific mutagenesis causes reduced export in the absence of SecB. These results indicate that SecB can interact with RBP during secretion, although it is not absolutely required under normal circumstances.

Bacterial Proteins↗
PubMed1992

Subacute necrotizing lymphadenitis--a collective clinicopathological and immunohistochemical study.

Subacute necrotizing lymphadenitis (SNL) is a well documented and unique clinicopathologic entity, although its etiology and pathogenesis have not been clearly established. Microscopically, cortical and paracortical necrotizing lesions with karyorrhexis, abundant nuclear debris and infiltration of large mononuclear cells are characteristic. This study analyzed the common clinical and pathological features of 118 patients with SNL and the nature of the mononuclear cells. Patients were generally young women and revealed cervical lymphadenopathy with tenderness, fever, leukopenia and elevation of the erythrocyte sedimentation rate. Features of the adjacent uninvolved area in the lymph node included a starry sky pattern, follicle centers, sinus histiocytosis or aggregation of foamy histicoytes. There was an inverse relationship between the extent of necrosis and of histocytic infiltration but not between the extent of necrosis and the duration from the onset of symptoms to the diagnosis. Immunohistochemically the infiltrated mononuclear cells of the affected foci were T lymphocytes and histiocytes. The clinical, histological and immunohistochemical features suggest that SNL represents a hypersensitivity reaction to certain infectious agent without forming granuloma.

Adolescent↗
PubMed1992

DNA flow cytometry in pheochromocytoma and paraganglioma.

Flow cytometric DNA analysis was performed on 19 adrenal pheochromocytomas and 6 extra-adrenal paragangliomas in parallel with clinical and histopathological review to determine the usefulness of this technique to predict biologic behavior of these tumors. In pheochromocytomas and paragangliomas, tetraploidy or near-tetraploidy occurred in 32% and 33% and aneuploidy in 10% and none respectively. A case of malignant pheochromocytoma had diploid DNA content. Occurrence of aneuploidy or tetraploidy is frequent in clinically benign tumors in conjunction with a marked degree of nuclear atypia and cannot be a predictor of malignancy.

Adolescent↗
PubMed1991

Mutations that affect the folding of ribose-binding protein selected as suppressors of a defect in export in Escherichia coli.

It has been proposed (Randall, L. L., and Hardy, S. J. S. (1986) Cell 46, 921-928) that export of protein involves a kinetic partitioning between the pathway that leads to productive export and the pathway that leads to the folding of polypeptides into a stable conformation that is incompatible with export. As predicted from this model, a decrease in the rate of export of maltose-binding protein to the periplasmic space in Escherichia coli resulting from a defect in the leader sequence was able to be partially overcome by a mutation that slowed the folding of the precursor, thereby increasing the time in which the polypeptide was competent for export. (Liu, G., Topping, T. B., Cover, W. H., and Randall, L. L. (1988) J. Biol. Chem. 263, 14790-14793). Here we describe mutations of the gene encoding ribose-binding protein that were selected as suppressors of a defect in export of that protein and that alter the folding pathway. We propose that selection of such suppressors may provide a general method to obtain mutations that affect the folding properties of any protein that can be expressed and exported in E. coli.

Biological Transport↗
PubMed1991

Contaminant reduction by ventilation in a confined space model--toxic concentrations versus oxygen deficiency.

Airborne contaminants can create hazardous conditions in confined spaces (CS) across a broad range of concentrations, e.g., from relatively low, potentially toxic levels (ppm) to much higher levels (%) causing oxygen deficiency. This study investigated ventilation characteristics for isobutylene (IBE) at relatively low concentrations, simulating toxic levels. Experimental data were compared to results from previous studies of oxygen deficiency. Data were obtained at several locations in a cubical CS model, with several variable test parameters: ventilation mode (exhaust and supply), volume flow rate ("air changes" per hour), and ventilation inlet/outlet elevation (% of model height). Findings indicated similar ventilation characteristics, in general, for simulated toxic (IBE) levels compared to oxygen deficiency. Both IBE and O2 deficiency data have shown that supply ventilation is typically more effective than exhaust and that CS locations aligned with supply outlets experience much more rapid contaminant reduction than do other locations. The data suggest that highly accurate predictions of ventilation characteristics cannot be expected for all cases with widely different contaminants and concentrations. Findings from this study indicate that ventilation guidelines for one range of contaminant concentration (e.g., causing oxygen deficiency) can be extended reasonably to encompass a broader range of concentration (e.g., to include toxic or flammable atmospheres).

Air Pollutants, Occupational↗
PubMed1991

Total palmar resurfacing with scapular free flap in a 26-year contracted hand.

The scapular free flap offers a large-sized and well-vascularized coverage for variable defects. It is not regarded, however, as a favorite tool for palmar resurfacing because of its bulky and rigid nature. A 28-year-old man had sustained a contact dermal injury at the age of 2 years that resulted in a severely deformed hand. The total palmar defect was resurfaced by surgical intervention with a scapular free flap. After secondary procedures, the final result was promising. The present report focuses on the secondary procedures, which make a more functional and aesthetically pleasing hand after coverage with the scapular flap. Also, our result suggests that even finger joints contracted for 26 years can recover motion if they have not been directly damaged.

Adult↗