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Biomedical subjects

H S Choi

Publications and source records attributed to H S Choi.

At least 163 records · Page 9Linked to original sources
PubMed1989

Heat shock induction of HSP 89 is regulated in cellular aging.

Induction of heat shock proteins (HSPs) was evaluated as a function of age of the IMR-90 human diploid fibroblasts. Heat shock (42 degrees C) markedly increased the synthesis of proteins with apparent molecular weights of 98, 89, 72, 50, 42 and 25 KDa, with HSP 89 and 72 being most prominent. This heat shock induction of HSPs was inversely correlated to the population doubling level (PDL) of the cell cultures used. For example, the synthesis rate of HSP 89 increased from a basal heat shock of young cells (PDL 18); in the old cells (PDL 51), the increase was from 1% to a maximum of 4% at 10-12 hrs after initiation of the heat shock. Western blot analysis showed that HSP 89 constituted approximately 2 and 10% of total cellular proteins in control and heat shocked (42 degrees C, 12-24 hrs) young cells; corresponding values for the old cells were 2 and 4.5%, respectively. Northern blot quantitation of the amount of mRNA hybridizable to cDNA probes of HSP 89 provided evidence that this age-dependent decrease in induction of HSP 89 in IMR-90 cells was attributable to a transcriptional/pre-translational mechanism.

Blotting, Northern↗
PubMed1989

Attenuated induction of heat shock gene expression in aging diploid fibroblasts.

We examined the effects of cellular aging on the regulation of heat shock gene expression in IMR-90 human diploid fibroblasts. Heat shock (42-43 degrees C) and canavanine (200-400 micrograms/ml) were used to evoke the heat shock response in these cells. We showed that heat shock induced the synthesis of proteins with apparent molecular weights of 98,000, 89,000, 78,000, 72,000, 64,000, 50,000 and 25,000, with heat shock protein (HSP) 89 and 72 being most prominent. Canavanine induced the synthesis of the four high molecular weight HSPs, particularly HSP 89 and HSP 78, without noticeably enhancing synthesis of the low molecular weight HSPs. We found that, while a similar series of HSPs were induced in the young and old cells, there was a marked decrease in the magnitude of this induction in the old cells. Using cells with defined population doubling levels, we observed a direct correlation of the inducibility of HSP synthesis and the replicative potential of the cells used. Analysis of the amount of translatable and hybridizable mRNA, by the methods of in vitro translation and Northern blot hybridization, demonstrated that the induction of HSPs synthesis can be accounted for by increases in their mRNA. Nuclear runoff transcription provided evidence that the decrease in inducible expression of the HSPs in aging IMR-90 cells was attributable to a transcriptional mechanism. This conclusion was substantiated by analysis of the hsp 70 promoter activity in transient expression assay of the hsp 70 promoter-chloramphenicol acetyltransferase construct. We propose that there is an age-associated dysfunction in the signaling mechanism of the heat shock response.

Autoradiography↗
PubMed1989

Infarction of intestine with massive amyloid deposition in two patients on long-term hemodialysis.

Two patients undergoing hemodialysis for 19 and 13 yr, respectively, developed intestinal infarction with extensive amyloid deposits in the muscle layer and blood vessels. In 1 patient the deposit reacted positively with antiserum to beta 2-microglobulin by immunohistochemical stain, and therefore was classified as beta 2-microglobulin in origin. The amyloid protein of the other patient remains unclassified. In patients with gastrointestinal symptoms who have been undergoing hemodialysis for long periods of time, amyloidosis of the intestine should be considered.

Amyloidosis↗
PubMed1989

Photodynamic therapy of human choriocarcinoma transplanted to the hamster cheek pouch. II. Intra-lesional photosensitization.

Photodynamic therapy (PDT) uses light-activated compounds, such as hematoporphyrins, to produce cytotoxic effects after illumination. Human choriocarcinoma cells were transplanted into the hamster cheek pouch to study PDT. The transplanted choriocarcinoma secretes human chorionic gonadotropin (hCG) in proportion to tumor volume. Red light (630 nm) from an argon-pumped dye laser (100-200 J/cm2) was used to illuminate tumors sensitized with dihematoporphyrin ether (DHE). Previous work has demonstrated complete regression (CR) of 90% of tumors (18/20) after one or two PDT sessions, while contralateral cheek pouch tumors continued to grow despite intraperitoneal DHE. Neither DHE nor laser light alone resulted in significant CRs. In this study we evaluated intratumoral injection of DHE followed in 2 hr by laser treatment. In all tumors, localization of DHE was demonstrated by induced fluorescence with ultraviolet light or He:Cd laser. After a single treatment, 14 of 38 tumors (37%) completely regressed (hCG less than mIU/ml); 4 tumors regressed grossly with low-level hCG [partial regression (PR)]. After repeat treatment there were 10 additional CRs in 19 rapidly enlarging tumors. After a third treatment 3 CRs and 3 PRs were achieved in 6 tumors. Because of large volumes, 2 of 3 progressing tumors failed to fluoresce uniformly after intratumoral DHE and were treated after intraperitoneal DHE injection; both completely responded. Overall, 29 of 38 tumors (76%) completely responded to PDT, and 7 partially responded (18%) with no gross tumor remaining in 5 of the 7. Only 5% of tumors (2/38) were non-responders. Photodynamic therapy results in gross elimination of 90% of tumors (52/58) in this model after intraperitoneal or intratumoral DHE sensitization (P less than 0.0001). DHE in chorio-carcinomas is easily detected and may enable detection of occult foci of malignancy. Choriocarcinoma transplanted into the hamster cheek pouch is highly responsive to photodynamic therapy. Clinical trials of PDT in gynecologic cancers are warranted to confirm the high response rates observed in refractory nongynecologic cancers.

Animals↗
PubMed1989

Conversion of steroids in bovine blood in vitro.

Blood samples collected from eight Braunvieh cows between the sixth and eighth month of gestation were allowed to stand with and without anticoagulant at 20 degrees C and 0 degrees C for different time periods. In these samples the degree of in vitro conversion of gestagens, androgens and estrogens was investigated. The concentrations were measured by radioimmunoassay. After 24 h at 20 degrees C, the levels of pregnenolone, progesterone, 17alpha-hydroxyprogesterone, androstenedione, dehydroepiandrosterone and estrone decreased to 62, 29, 25, 10, 34 and 44%, respectively, of the initial value and those of 17alpha, 20beta-dihydroxyprogesterone, epitestosterone and estradiol-17alpha increased to 385, 800 and 852%, respectively. The conversion was slower in clotted blood. The concentrations of testosterone and estradiol-17beta were consistent over the 24 h period. There was no marked decrease of the steroid concentration after 24 h of incubation of whole blood at 0 degrees C and of plasma at 20 degrees C. After the addition of (3)H-steroids, conversion could be demonstrated by thin-layer chromatography and autoradiography. These results demonstrate that all investigated hormones except testosterone and estradiol-17beta were metabolized by bovine blood cells.

Journal Article↗
PubMed1989

Magnetic control for the vocal cord adduction in the canine.

An entirely satisfactory and physiologic solution to adduct paralyzed vocal cord during phonation, coughing, and swallowing has not yet been achieved. The authors noticed that velopharyngeal closure takes place simultaneously with adduction of vocal cords in order to perform phonation, coughing, and swallowing. We devised a new laryngeal pacing system to adduct the paralyzed vocal cord, utilizing velopharyngeal closure under magnetic control. Two mongrel dogs were anesthetized and the interior of the larynx was exposed using a Lynch suspension laryngoscope. A small magnet wrapped by thin Silastic was inserted into the nasal side of the soft palate via a small incision. After making a vertical midline neck incision, the pharynx was dissected and the Gaussmeter probe was inserted into the retropharyngeal space. The Gaussmeter probe was connected to the Gaussmeter and finally to the pacemaker. Electrodes were inserted into the paralyzed adductor laryngeal intrinsic muscles via punctures of the cricothyroid membrane. When the pacing system operated, arbitrarily elevated soft palate to the posterior pharyngeal wall brought about an abrupt increase in magnetic force and thus obvious adduction of the paralyzed vocal cords could be seen.

Animals↗
PubMed1989

Pneumocystis carinii pneumonia in the acquired immunodeficiency syndrome: diagnosis using minilavage samples.

Over a 30-month period, we evaluated 74 patients with acquired immunodeficiency syndrome (AIDS) for suspected opportunistic pulmonary infection. All had abnormal findings on chest roentgenogram. Sixty patients (81%) were found to have Pneumocystis carinii pneumonia (PCP). We assessed the yield of various diagnostic methods, and found that bronchoalveolar lavage samples obtained by the instillation of 20 to 50 ml of normal saline (minilavage) contained detectable organisms in 51 of 53 patients (sensitivity of 96%) when the samples were embedded in plastic, cut in thick sections (1 micron), stained with toluidine blue O, and evaluated by light microscopy. In comparison, the diagnostic yield was 94% for lung biopsy, 85% for touch preparation of lung tissue, 32% for bronchial washing, and 14% for brush biopsy. It is significant that minilavage samples embedded in plastic were positive in all seven patients who did not have transbronchial lung biopsy because they were at high risk for complications. We conclude that the process of embedding minilavage samples in plastic and evaluating thick sections stained with toluidine blue O is a sensitive method of diagnosing PCP in patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1989

CT findings of the nose and paranasal sinuses in chromium intoxication.

We performed computed tomography (CT) of the nose and paranasal sinuses in 21 patients with chromium induced septal perforation or thinning. Twenty patients showed various magnitudes of septal perforation. Twelve of 20 had perforation at the mid portion of the cartilaginous nasal septum. One patient had a sheet-like thinning of septal cartilage. Sixteen patients had mucosal thinning of the nasal conchas. In most cases, unilateral involvement of the inferior concha was seen. Eleven of 21 cases showed paranasal sinus mucosal thickening and one patient had a cyst or polyp in the sinus cavity. The main finding was nodular thickening of mucosa. Septal perforation by inhalation of chromic acid was located in the cartilaginous septum and there was no destruction of the bony septum and wall of the sinuses.

Adult↗
PubMed1989

Granulocytic sarcoma presenting as a solitary nodule of skin in a patient with Waldenstrom's macroglobulinemia. An immunohistochemical and electron-microscopic study.

While he was being treated for Waldenstrom's macroglobulinemia, a 75-year-old man developed an enlarging forearm skin nodule. On biopsy, the lesion appeared to be a malignant lymphoma. The tumor cells were negative for immunoglobulins but positive for lysozyme and alpha-1-antitrypsin. Therefore, the lesion was diagnosed as histiocytic lymphoma. Nine months later, an ipsilateral axillary lymph node biopsy revealed a small focus of tumor identical to that of the skin lesion. Three months after the lymph node biopsy, the patient developed acute myeloid leukemia. A reevaluation of the electron micrographs of the skin and lymph node lesion showed primary lysosomal granules within the tumor cell cytoplasm consistent with a diagnosis of leukemic infiltrates (granulocytic sarcoma); additionally, the naphthol AS-D chloracetate esterase activity of the skin lesion was positive, supporting the diagnosis of granulocytic sarcoma. This report shows that if not suspected, granulocytic sarcoma is difficult to diagnose in nonleukemia patients.

Acute Disease↗
PubMed1988

Histiocytic medullary reticulosis: radiologic diagnosis of splenic infarction--a case report.

A case of histiocytic medullary reticulosis with splenic infaraction from a 23-year-old male is presented. Radiologic findings on selective spleen scintigraphy and abdominal CT are described. Selective spleen scintigraphy showed huge, multilobulated spleen with numerous photon-deficient areas in it and peripherally. Abdominal CT showed large peripheral band-like low density and infiltrative lesion in spleen with accompanying intraabdominal lymphadenopathy. Histoligical features were consistent with HMR in spleen and liver specimens.

Adult↗
PubMed1987

Erythropoietin rapidly alters phosphorylation of pp43, an erythroid membrane protein.

The phosphorylation of a prominent 43-kDa phosphoprotein (pp43) in the membranes of normal murine erythroid cells was reduced markedly by exposure of the membranes to highly purified erythropoietin. A virtually identical reduction of pp43 phosphorylation was seen when erythropoietin-responsive Rauscher murine erythroleukemia cell membranes were exposed to the hormone. This effect was both time-dependent, occurring within 30 min after erythropoietin exposure, and concentration-dependent. Phosphoamino acid analysis revealed that pp43 is phosphorylated on serine residues. The results provide the first evidence that rapid alterations in membrane protein phosphorylation may serve as a trans-membrane signal for erythropoietin.

Adenosine Triphosphate↗
PubMed1987

Laryngeal pacemaker using a temperature sensor in the canine.

With the use of a temperature sensor that would detect temperature changes during the respiratory cycle in the pharynx, electrical stimulation of the posterior cricoarytenoid muscle was achieved in dogs whose recurrent laryngeal nerves were artificially paralyzed. Due to the temperature difference between inspiratory and expiratory air flow, a trigger pulse was generated at the beginning of inspiration. The stimulation pulse following the trigger pulse stimulated the electrodes inserted into the posterior cricoarytenoid muscles. In all five canines, obvious abduction of the vocal folds synchronized with inspiration was observed during electrical pacing.

Animals↗
PubMed1986

5-Iodoribose 1-phosphate, an analog of ribose 1-phosphate. Enzymatic synthesis and kinetic studies with enzymes of purine, pyrimidine, and sugar phosphate metabolism.

The 5'-deoxy-5'-iodo-substituted analogs of adenosine and inosine are cytotoxic to tumor cells that have high activities of 5'-methylthioadenosine phosphorylase and purine nucleoside phosphorylase, respectively (Savarese, T.M., Chu, S-H., Chu, M.Y., and Parks, R. E., Jr. (1984) Biochem. Pharmacol. 34, 361-367). 5-Iodoribose 1-phosphate (5-IRib-1-P), the common intracellular metabolite of these 5'-iodonucleosides, has been synthesized enzymatically from 5'-deoxy-5'-iodoadenosine via adenosine deaminase from Aspergillus oryzae and human erythrocytic purine nucleoside phosphorylase. The purification and chemical properties of 5-IRib-1-P are described. The analog sugar phosphate inhibited purine nucleoside phosphorylase from human erythrocytes, phosphoglucomutase from rabbit muscle, and 5'-methylthioadenosine phosphorylase from Sarcoma 180 cells with Ki values of 26, 100, and 9 microM, respectively. Enzymes that react with 5-phosphoribosyl 1-pyrophosphate (P-Rib-PP), P-Rib-PP amidotransferase, hypoxanthine-guanine phosphoribosyltransferase, adenine phosphoribosyltransferase, and orotate phosphoribosyltransferase-orotidylate decarboxylase from extracts of Sarcoma 180 cells, were inhibited with Ki values of 49, 465, 307, and 275 microM, respectively. 5-IRib-1-P had no effect on P-Rib-PP synthetase. Since the Ki values of the analog sugar phosphate for 5'-methylthioadenosine phosphorylase and P-Rib-PP amidotransferase are much lower than the Km values of the natural substrates, Pi or P-Rib-PP which are reported to be present at nonsaturating concentrations under physiological conditions, these enzymes could be significantly inhibited by 5-IRib-1-P in intact cells.

Adenosine Deaminase↗
PubMed1986

Olfactory neuroblastoma: an immuno-electron microscopic study of S-100 protein-positive cells.

An immuno-electron microscopic study performed by a pre-embedding peroxidase-antiperoxidase (PAP) technique revealed S-100 protein reactivity in the cytoplasm and connecting processes of marginal cells of olfactory neuroblastomas. The overlapping cytoplasmic processes of S-100 immunoreactive cells completely surrounded the main membrane-bound granule-bearing tumor cells forming a continuous interface between those tumor cells and fibrous connective tissue. The S-100 immunoreactivity was also observed in the cytoplasm and processes on non-membrane-bound granule-bearing tumor cells within the tumor nodule. The tumor cell nodules and isolated tumor cells were completely surrounded by basement membrane material stainable with anti-laminin antiserum. It appears that the membrane-bound granule-bearing tumor cells of olfactory neuroblastoma are partitioned by basement membrane of S-100 protein-reactive cells and their processes. No S-100 protein-reactive cells were observed within the olfactory epithelium of the two patients with olfactory neuroblastoma. To determine a possible origin of S-100 protein-positive cells, normal olfactory epithelium from six adult patients at autopsy was studied for S-100 reactivity. There were no S-100 protein-positive cells within the normal olfactory epithelium. We discuss the evidence for considering olfactory neuroblastoma a variant of paraganglioma.

Cytoplasm↗
PubMed1985

Pancreatic choriocarcinoma presenting as inflammatory pseudocyst.

A primary pancreatic choriocarcinoma was discovered at surgery in a patient with a clinical diagnosis of pancreatic inflammatory pseudocyst. To our knowledge, this is the first example of an extragonadal choriocarcinoma reported as a primary at this site. We consider this neoplasm to be another example of a visceral choriocarcinoma arising from a primary carcinoma through a process of metaplasia. This case illustrates the inherent difficulties in the preoperative evaluation of cystic lesions of the pancreas, and the importance of recognizing endocrinologic manifestations of malignant disease.

Adult↗
PubMed1985

Immunohistochemical diagnosis of olfactory neuroblastoma.

Olfactory neuroblastoma (OLF NB) is an uncommon neurogenic tumor arising in the nasal cavity. To identify the immunohistochemical reactivity of OLF NB, we examined specimens from ten patients for the presence of neuron-specific enolase (NSE), S-100 protein (S-100) and glial fibrillary acidic protein (GFAP). Formalin-fixed paraffin sections were treated with rabbit antisera using the peroxidase-antiperoxidase (PAP) and avidin-biotin immunofluorescence methods. Results were compared with those observed in four neuroblastomas (two central and two peripheral sites), 17 medulloblastomas, four pheochromocytomas and five paragangliomas. All OLF NB were positive for NSE and S-100. NSE was uniformly distributed throughout clusters of tumor cells within tumor nodules. The S-100 reactivity was distributed in neoplastic cell nuclei and long cytoplasmic processes of cells which interconnected to form a network at the periphery of tumor cell nests. GFAP was observed only in astrocyte-like cells in one tumor. Although the S-100-positive cells in OLF NB resembled S-100-positive sustentacular cells of paraganglioma and pheochromocytoma, the network pattern was distinctive in OLF NB. The immunodiagnostic pattern of OLF NB includes the following: (a) NSE present in irregular clusters of tumor cells, (b) S-100 present in peripheral cells which form a marginal network, (c) and GFAP rarely present.

Adult↗
PubMed1985

Autonomic neuropathy associated with autoimmune disease.

Mononeuropathy multiplex and mixed sensorimotor neuropathy are known complications of systemic vasculitis and related autoimmune disorders. Autonomic dysfunction is not generally considered a neurologic complication of these diseases. We report two patients who came to neurologic attention because of autonomic dysfunction and were then discovered to have autoimmune disease. Autonomic dysfunction may be the presenting sign of autoimmune disorders, which should be considered in the differential diagnosis of acquired autonomic disturbances.

Adult↗