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Biomedical subjects

S M Chung

Publications and source records attributed to S M Chung.

At least 19 recordsLinked to original sources
PubMed1992

Effects of vanadate on vascular contractility and membrane potential in the rabbit aorta.

Isolated rabbit aortic ring with intact endothelial cell preparations precontracted with NE (10(-7) M) were relaxed by vanadate in a dose dependent manner (from 0.2 to 2 mM). Application of vanadate and ACh during the tonic phase of high K+(100 mM)-induced contraction showed a slight relaxation in contrast to that in NE-induced contraction, but sodium nitroprusside (10 microM) more effectively relaxed the aortic ring preparations in high K+ contraction than that of vanadate. Vanadate-induced relaxation in NE-contracted aortic rings was reversed by application of BaCl2 (50 microM) or glibenclamide (10 microM). Furthermore, Vanadate hyperpolarized membrane potential of smooth muscle cells in endothelium-intact aortic strips and this effect was abolished by application of glibenclamide. The above results suggest that vanadate release EDHF (Endothelium-Derived Hyperpolarizing Factor), in addition to EDRF (Endothelium-Derived Relaxing Factor) from endothelial cell. This EDHF hyperpolarize the smooth muscle cell membrane potential via opening of the ATP-sensitive K+ channel and close a voltage dependent Ca++ channel. So it is suggested that the vanadate-induced relaxation of rabbit thoracic aortic rings may be due to the combined effects of EDRF and EDHF.

Animals↗
PubMed1992

Bilateral internuclear ophthalmoplegia in a patient with Wernicke's encephalopathy.

The most common cause of bilateral internuclear ophthalmoplegia is multiple sclerosis. Wernicke's encephalopathy has been reported as a cause of unilateral internuclear ophthalmoplegia but not of bilateral internuclear ophthalmoplegia. In this report, we present the case of a patient with a history of alcohol abuse and acute onset of bilateral internuclear ophthalmoplegia whose clinical course and diagnostic studies are most consistent with a diagnosis of Wernicke's encephalopathy.

Adult↗
PubMed1991

Management of the hearing-impaired adults in Singapore.

A preliminary study to investigate that the pure-tone air-conduction hearing threshold level which is not an accurate index of amplification need profile applies to the hearing-impaired population in Singapore. Results obtained from a sample of twenty users of monaural amplification indicate that the hearing-impaired patients showed a significant reduction in communication difficulties with their hearing aids and are overall satisfied with their monaural amplification despite certain problems with background noise, regardless of the severity of their hearing losses.

Adult↗
PubMed1990

Characterization of a cathepsin L-like enzyme secreted from human pancreatic cancer cell line HPC-YP.

Spent culture medium from the human pancreatic carcinoma cell line HPC-YP, which can propagate in a protein-free, chemically defined medium without any other supplements, was analyzed for the presence of the cysteine protease, cathepsin L. The secreted form of cathepsin L was distinguished from the lysosomal form by its increased stability at alkaline pH, by its strong thermostability, and by its larger molecular size. HPC-YP cathepsin L was still stable at pH 7.4 and at 56 degrees C after 60-min preincubation. The molecular weight of this enzyme was estimated to be 68,000, compared with a molecular weight of 29,000 for normal liver cathepsin L. By Western blot analysis, HPC-YP enzyme was found to be composed of two components, one with a molecular weight of 37,000 and the other of 31,000. This result suggests that HPC-YP enzyme in the spent medium may be a complex of the proenzyme (in the case of liver proenzyme; Mr 39,000) and the mature enzyme (in the case of liver mature enzyme; Mr 29,000). Interestingly, an intrinsic inhibitor was also separated from the spent medium by gel filtration. The molecular weight of this inhibitor was estimated to be approximately 13,000. The cathepsin L of HPC-YP proved more resistant toward leupeptin than did liver cathepsin L. On the other hand, the former was more sensitive than the latter toward the diazomethane inhibitors, Z-Phe-Phe-CHN2 and Z-Phe-Ala-CHN2. These results indicate that cathepsin L secreted from cancer cell lines may play a role in the destruction of basal lamina, invasion of tissue, and formation of metastasis.

Blotting, Western↗
PubMed1990

Variant cathepsin L activity from gastric cancer tissue.

Cathepsin L activity was partially purified by S-Sepharose FF chromatography, concanavalin-A Sepharose chromatography, phenyl-Superose column chromatography, Mono S column chromatography, and TSK G3000SWXL column chromatography from gastric cancer tissue. The optimal pH of cathepsin L from gastric cancer tissue was 7.4, and the activity was retained even at alkaline pH. Heat stability tests showed that cathepsin L from gastric cancer tissue was heat stable; that is, 65% activity was retained after incubation at 56 degrees C for 60 min. The molecular weight of cathepsin L from gastric cancer tissue was estimated as 115 kD by gel filtration or 110 kD by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme showed a different affinity for wheat germ agglutinin-Sepharose than cathepsin L from gastric normal mucosa. These results suggest that cathepsin L from gastric cancer tissue may play an important role in gastric cancer invasion through the destruction of the surrounding extracellular matrix by its proteolytic activity.

Cathepsin L↗
PubMed1990

[Protease activities in gastric and colon cancer tissues].

Activities of cathepsin B, cathepsin L, and plasminogen activators (urinary type plasminogen activator and tissue type plasminogen activator) were assayed in homogenates of cancer tissue, normal tissue closely surrounding the cancer tissue, and normal tissue distant from the cancer tissue from 30 patients undergoing surgery for gastric cancers and 10 patients undergoing surgery for colon cancers. Activities of those proteases were also assayed in homogenates of adenoma tissue from 10 patients undergoing polypectomy for colon polyps. In the gastric cancer tissue homogenates, the activities of cathepsin B, cathepsin L and tissue type plasminogen activator were significantly higher than in normal tissues. By contrast, the activities of urinary type plasminogen activator of gastric cancer tissues were significantly lower than normal tissues. In the colon cancer tissue homogenates, the activities of cathepsin, B, cathepsin L, and urinary type plasminogen activator were significantly higher than in normal tissues. On the other hand, the activities of tissue type plasminogen activator of cancer tissues were significantly lower than normal tissues. But there were no significant differences in the activities of plasminogen activators between the cancer tissues and adenoma tissues. These results suggest that cathepsin B and cathepsin L play an important role in gastric and colon cancer proliferation and evolution, although the roles of plasminogen activators in gastric and colon cancer proliferation and evolution and in the colon adenoma-carcinoma sequence are still unknown.

Cathepsin B↗
PubMed1989

Variant cathepsin B activity secreted from human pancreatic cancer cell lines into protein-free chemically defined medium.

Cathepsin B activity was found in serum-free spent media of human pancreatic cancer cell lines, Panc-1 and MiaPaca. Cathepsin B activity was partially purified by gel filtration on TSK G3000SW, Con-A Sepharose chromatography, Phenyl-Superose column chromatography, and Mono S column chromatography. The optimal pH of cathepsin B was 7.4, and the activity was retained even at alkaline pH. Heat stability test showed that the enzyme was heat stable; that is, 50% activity was retained after incubation at 56 degrees C for 60 min. These results suggest that cathepsin B secreted from human pancreatic cancer cell is a variant type and may play an important role in pancreatic cancer invasion or metastasis through destruction of the surrounding extracellular matrix by its proteolytic activity.

Cathepsin B↗
PubMed1989

Characterization of variant gamma-glutamyl transpeptidase produced by pancreatocholangiocarcinoma cell lines in a protein-free, chemically defined medium.

Four pancreatocholangiocarcinoma cell lines (HPC-Y1, HPC-YT, MIA PaCa-2, and HChol-Y1) were established to propagate in a protein-free, chemically defined medium. High gamma-glutamyl transpeptidase (GGTP) activities were showed in their spent media (designated as the secreted (GGTP). Their GGTP activities in the spent media were 125, 85, 110, and 153 IU/L/mg of lyophilized spent media, whereas GGTP activities extracted from their cancer cell lines with bromelain were 105, 37, 86, and 112 IU/L/1 x 10(6) cells, respectively. The chemical characteristics of the GGTPs in the spent media from these cell lines resembled one of the GGTPs, sialic acid-rich GGTP, extracted from normal human pancreas with bromelain treatment as follows: the GGTPs secreted from the cancer cell lines bound to an anion exchange column moved fast on electrophoresis and then showed decreased electrophoretic mobility with neuraminidase treatment, showed a high affinity for concanavalin A and lentil lectin columns, and had an acidic isoelectric point. However, the elution patterns of erythroagglutinating phytohemagglutinin (E-PHA) column chromatography and thermostability tests demonstrated clear differences between the carcinoma GGTPs both in the spent media and cell lines and the sialic acid-rich GGTP of normal pancreas, namely the carcinoma GGTPs treated with neuraminidase showed affinity to E-PHA columns, and, in addition, the GGTPs in the spent media showed an apparent heat resistance at 56 degrees C. These findings indicate that the carcinoma GGTPs have a different oligosaccharide structure from that in normal pancreatic GGTPs.

Adenoma, Bile Duct↗
PubMed1978

The histological characteristics of congenital coxa vara: a case report of a five year old boy.

In a 51/2 year old boy with unilateral coxa vara who died of unrelated causes histological sections were made of the proximal femora and pelvic growth plates. The proximal femora were also perfused to study the pattern of arterial supply. Evidence of active endochondral ossification was not detectable in growth plates of the affected right femur, the clinically and roentgenographically normal left femur and the pelvis, including a Salter Type II fissure fracture. The endochondral ossification defect found in growth plates of the proximal right femur and pelvis was associated with a reduction in the number and caliber of intraosseous arteries supplying the metaphyseal sides of the growth plates in the proximal femur and those supplying the subchondral region and extraosseous medial ascending cervical arteries on the surface of the femoral neck. This deficiency in endochondral ossification resembles a form of dwarfism associated with a coxa vara and a generalized growth plate disorder.

Cartilage, Articular↗
PubMed1978

Fractures of the odontoid process in young children.

We reviewed eleven patients less than seven years old with fractures of the odontoid process in an effort to establish a more standard form of treatment for the injury and to determine what complications, if any, occur as a result of fractures of the odontoid process in pediatric patients. Our study showed that children with odontoid fractures that are recognized and treated promptly usually do well. The fracture can usually be reduced by passive manipulation or by the "hanging head technique". Support in the reduced position for two to three months in a Minerva jacket or halo cast should be long enough to permit healing. Our study suggests that fractures of the odontoid process in young patients almost always heal.

Age Factors↗
PubMed1977

Thanatophoric dwarfism. Two case reports and survey of the literature.

Thanatophoric dwarfism is a severe form of short-limbed dwarfism in which cardiorespiratory failure uniformly results in death in the neonatal period. Its radiographic features include markedly flattened vertebral bodies with a typical U-shaped deformity, a flat squat pelvis, and short, bowed extremities with flaring and irregularity of the metaphyses. These characteristic features distinguish this entity from the two other most commonly confused congenital short-limbed forms of dwarism--achondroplasia and achondrogenesis. The distinctions are discussed in the text.

Achondroplasia↗
PubMed1976

Congenital dislocation of the hip--diagnostic screening and treatment. A comparative study of two populations of infants and children.

To understand why congenital dislocated hip (CDH) was diagnosed late (mean age: nine months) in children admitted to the Children's Hospital of Philadelphia (CHOP), 714 consecutive CHOP admissions, aged zero to two years, and 947 consecutive newborns delivered at the Hospital, University of Pennsylvania (HUP) were examined for CDH. The expected frequency of CDH was found at HUP. At CHOP, the children had a higher incidence of CDH, many with associated congenital anomalies, their hips were more difficult to examine, the hospital records contained few references to hip examinations. Had these children's hips been formally examined at birth, the delay in diagnosis might have been eliminated and treatment might have been easier and more successful.

Age Factors↗
PubMed1976

Shear strength of the human femoral capital epiphyseal plate.

After the determination of the shear strength and modes of failure of the capital femoral epiphyseal plates in twenty-five pairs of hips obtained post mortem from children five days to fifteen years and ten months old, with the plate intact on one side and with the perichondrial fibrocartilaginous complex removed on the other, the gross and microscopic morphology was studied. The shear strength of the human epiphyseal plate varied with age and was greatly dependent on the surrounding perichondrial complex in infancy and early childhood, but less so in adolescence. When this complex was excised, the strength of the epiphyseal plate was diminished, especially in specimens from younger children. The forces necessary to cause slipping were found to be within the physiological range of the force that would be generated in overweight children, suggesting that purely mechanical factors may play a major role in the etiology of slipped capital femoral epiphysis.

Adolescent↗
PubMed1976

Surgery of the clavicle in Sprengle's deformity.

Surgery for Sprengel's deformity can produce less lowering of the scapula than desired and occasionally can result in an injury to the brachial plexus or brachial artery. The method used to produce better correction and to avoid complications was a softening of a clavicle by the morcellization technique of Robinson et al. We feel that the procedure is a simple one which helps to improve the degree of correction and to avoid neurovascular complications. The procedure should be combined with the Woodward correction for Sprengel's deformity.

Child↗
PubMed1976

Long-term results in the treatment of femoral-shaft fractures in young children by immediate spica immobilization.

Manual traction reduction without anesthesia and immediate immobilization in a spica cast were used to treat eighty-five children ranging in age from birth to ten years old who had closed femoral-shaft fractures and no associated injuries. Up to two centimeters of overriding, 30 degrees of anterior angulation, and 15 degrees of medial angulation were accepted. Any angulation in excess of these amounts, or lateral or posterior angulation, was corrected by wedging the cast at the fracture site. Further telescoping of the fracture fragments in the case was attributed to the child pressing the foot against the bottom of the cast and was prevented by removing the sole of the cast. Of the seventy-five children examined two to eighteen years after fracture, none had any residual skeletal deformity or joint stiffness. The length discrepancies of the fractured limbs ranged from 1.7 centimeters of shortening to 0.9 centimeter of overgrowth.

Casts, Surgical↗
PubMed1976

The arterial supply of the developing proximal end of the human femur.

By means of perfusion studies, an analysis was made of the arterial supply to the proximal end of the femur in 150 specimens from autopsied fetuses and children, aged from twenty-six weeks of gestation to fourteen years and eight months old. All died of diseases which did not involve the hip joint. Two anastomotic rings were found: an extracapsular one formed by the medial and lateral femoral circumflex arteries, and a subsynovial intra-articular ring at the articular cartilage-neck junction. The intra-articular rings in males were discontinuous more often than in females. A three-plane analysis of totally-cleared specimens demonstrated that the epiphyseal plate constituted an absolute barrier to blood flow between the epiphysis and metaphysis in all but two of the 124 barium sulphate-perfused specimens examined. A smaller number of ascending cervical arteries crossed the anterior and medial surfaces of the mid-neck in the specimens from three to ten-year-old white children than in those from newborn to two-year-old white and black children. This finding may be important for the etiology of Legg-Perthes disease. No differences with respect to age, sex, or race were found in the arteries of the ligamentum teres.

Adolescent↗