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Biomedical subjects

S M Kang

Publications and source records attributed to S M Kang.

68 records · Page 4Linked to original sources
PubMed1991

Transcriptional regulation of cytokine genes in nontransformed T cells. Apparent constitutive signals in run-on assays can be caused by repeat sequences.

Cytokines are immunoregulatory proteins that are secreted by T lymphocytes and other cells upon activation. A controversy exists as to whether the induction of cytokine production is mediated at the transcriptional level by the initiation of RNA synthesis or at the post-transcriptional level by the enhancement of mRNA stability. We show that in a nontransformed T cell clone the induction of all of the cytokines that are analyzed in this report is mediated transcriptionally. We also found that a constitutive signal was seen in resting cells when the probes used in the nuclear run-on assay contained some potential cross-hybridizing sequences, for example a poly (A) tract in a cDNA probe. This observation could explain the constitutive signals seen in other studies that claim cytokine production is regulated by differential mRNA stability.

Animals↗
PubMed1990

[Burns caused by electrocautery during surgery].

A 19-year-old male suffering from crushed injury on the neck and anterior upper chest with suspected laceration of the trachea underwent emergent operation for surgical restoration of the trachea. First and second degrees of electric burns over the neck and upper back regions(4%) were accidentally caused by electrocautery during surgery. Short circuit due to over-wetting of the sheet and EKG leads may be responsible for this avoidable accident.

Adult↗
PubMed1989

Increased Proteolysis of Senescing Rice Leaves in the Presence of NaCl and KCl.

NaCl and KCl enhanced the degradation of chlorophylls and proteins in detached rice (Oryza sativa) leaves in a concentration-dependent manner. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) accounted for 73 to 80% of the protein lost by day 4 in the light. NaCl at 50 millimolar increased proteolysis by 21% over the control in 4 days, but the addition of cycloheximide reduced the increase to about one-half. Cycloheximide alone had no effect on proteolytic activity during this period. Leaf segments taken from 10-day-old seedlings contained the highest proteolytic activity. Both NaCl and KCl increased the activity of Rubisco-degrading endoproteinases (the amount of ninhydrin-positive compounds measured from HCl-hydrolyzates of trichloroacetic acid-soluble supernatant), but decreased the activity of hemoglobin- and Rubisco-degrading exoproteinases (the amount of ninhydrin-positive compounds measured directly from trichloroacetic acid-soluble supernatant). Efflux of amino acids from senescing leaf segments into the incubation media increased 7- and 12-fold in the presence of KCl and NaCl, respectively. The increased efflux resulted in a negative correlation between salt concentration and amino acid content of leaf segments at the later stage of senescence. It is concluded that, in addition to the induction of new proteinase synthesis, the increased efflux of protein hydrolyzates may play a significant role in increasing proteolysis of salt-treated leaves, especially at the later stages of senescence.

Journal Article↗
PubMed1989

An efficient and site-specific gene trimming method.

Trimming a DNA strand into a precisely determined fragment can be carried out efficiently by an improved method involving a site-specific trim-primer and a single-stranded DNA template which is generated from a multifunctional vector, pTZ18R, and linearized by using an Eco RI-pTZ18R splinter. A complementary DNA strand is synthesized by DNA polymerase I (Klenow), and the 3'-end of the template upstream from the annealed primer is trimmed by subsequent T4 DNA polymerase reaction. An ATG translation initiator codon or a termination codon can be incorporated into the trim-primer, providing versatility to this single-stranded DNA-initiated gene trimming method that can be applied to subcloning and expression of any DNA fragment with known terminal sequences.

Biotechnology↗
PubMed1989

Inhibition of phytoagglutinin potency of Korean vicia unijuga by human urine.

Human urines are often examined for individual identification in medicolegal field, therefore, authors attempted to classify the urines by inhibition of agglutination potency of phytoagglutinin Korean vicia unijuga which is known as a panphytoagglutinin to human red blood cells, and demonstrated that some individuals excrete urine which has ability to interfere with the agglutination potency of vicia extracts. The inhibiting substance appears to be either a protein or a glycoprotein, for it can be eliminated by boiling the urine sample. This substance is not present in human serum, semen and saliva. Presence or absence of the inhibiting substance in the urine has no relation to the individual's blood type and a sample urine spot test yielded a high rate of inhibitory property.

Hemagglutination↗
PubMed1983

Synthesis of 3,6-bis(aminoalkoxy)acridines and their effect on the immune System.

A series of 3,6-bis(aminoalkoxy)acridines (2) was prepared and shown to have a protective antiviral effect against an interferon-sensitive virus (Columbia SK) and to partially restore an antibody response to a T-cell-dependent antigen in leukemic immunosuppressed mice. The presence of circulating interferon and the stimulation of natural killer cell activity in mice was observed for 21.

Acridines↗
PubMed1982

Characteristics and Activity Changes of Proteolytic Enzymes in Apple Leaves during Autumnal Senescence.

At least four different proteinases are present in senescing apple leaves (Malus domestica Borkh. cv. Golden Delicious) as determined by their pH optima, substrate specificity, and their reactivity to proteinase inhibitors. An enzyme active at pH 4.5 to 5.0 appears to be a sulfhydryl-dependent (iodoacetamide and phenylmercuric acetate-sensitive) endoproteinase, and degradation of the large subunit of ribulose bisphosphate carboxylase was observed only with this enzyme. It is tentatively concluded that this endoproteinase is responsible for the breakdown of ribulose bisphosphate carboxylase in vivo. However, the presence of more than one endoproteinase in apple leaves is suggested by the broad range of pH optima of the SH-dependent enzyme. Another enzyme active at pH 6.0 appears to be a carboxypeptidase, and was sensitive to phenylmethylsulfonylfluoride. This enzyme showed a strong hydrolytic activity against carbobenzoxyphenylalanylalanine. A sulfhydryl-dependent aminopeptidase and a second hydroxyl-dependent carboxypeptidase were active at pH 7.5Total autolytic activity (the sulfhydryl-dependent endoproteinase) as measured by the disappearance of proteins decreased during the period of protein decline. Evidence is presented that the measured proteinase activity can be dependent on assay methods and substrates. While the disappearance of protein measures most of endo-type activity, the ninhydrin assay appears to measure exo-type activity preferentially.

Journal Article↗
PubMed1980

Isolation and partial characterization of an Acid endoprotease present in dormant apple shoot bark.

A major protease present in dormant bark tissues of the apple (Malus domestica Borkh. cv. "Golden Delicious") was partially purified by hemoglobin-coupled Sepharose column chromatography. The protease active at pH 4.6 and at temperatures of 30 to 50 C was found to be sulfhydryl-dependent. Phenylmercuric acetate inhibited the enzyme approximately 50% at 2 millimolar, whereas phenylmethylsulfonyl fluoride inhibited less than 30% even at 10 millimolar. Substrate specificity and the separation of the enzyme reaction products indicated that the enzyme is likely to be an endoprotease. We suggest that the storage proteins in apple bark tissue undergo some modification prior to their eventual hydrolysis to amino acids, which requires a multi-enzyme system(s). Evidence is presented that the apple bark protein extracts enzymically release ninhydrin-positive compounds upon storage at 5 C. It is concluded that the activation of the sulfhydryl-dependent acid endoprotease is associated with the rapid metabolism of storage proteins which accompanies bud break upon regrowth.

Journal Article↗
PubMedDate not supplied

Subclavian arteritis and pseudoaneurysm formation secondary to stent infection.

Technically uncomplicated percutaneous angioplasty and stent placement of a left subclavian artery stenosis was performed in a 56-year-old man for treatment of subclavian steal syndrome and vertebrobasilar insufficiency. Six days later the patient was readmitted with Staphylococcus aureus bacteremia and stigmata of septic emboli isolated to the ipsilateral hand. Nine days later he had computed tomography (CT) evidence of a contrast-enhancing phlegmon surrounding the stent. Despite clinical improvement and resolution of bacteremia on intravenous antibiotic therapy, the phlegmon progressed, and at day 21 a pseudoaneurysm was angiographically confirmed. The patient underwent surgical removal of the stented arterial segment and successful autogenous arterial reconstruction. The possible contributory factors leading to stent infection were prolonged right femoral artery access and an infected left arm venous access. Although the role of prophylactic antibiotics remains to be defined, it may be important in cases where the vascular access sheath remains in place for a prolonged period of time.

Aneurysm, False↗
PubMedDate not supplied

Expression of p53 and vascular endothelial growth factor associated with tumor angiogenesis and prognosis in gastric cancer.

Recently, it has been reported that p53 tumor suppressor gene plays an important role in controlling tumor angiogenesis by regulating expression of vascular endothelial growth factor (VEGF), which is a well-characterized angiogenic inducer. In this study, we investigated these antigens' expression together with microvessel density, and investigated their clinical importance. One hundred twenty specimens resected from patients with gastric carcinoma were investigated using immunohistochemical methods. p53 and VEGF expression was observed in 42 and 35% tumors, respectively. p53 and VEGF staining status was coincided in 72% tumors, and a significant correlation was found between p53 and VEGF status. The microvessel density, determined by immunostaining for factor VIII-related antigen, was significantly higher in p53-positive or VEGF-positive tumors. According to prognosis, patients with p53-positive tumors had significantly worse survival than those with p53-negative tumors. There was also a significant worse survival in the patients with VEGF-positive tumors than those with VEGF-negative tumors. Moreover, the 5-year survival rate was lowest in the patients with p53-positive and VEGF-positive tumors, while it was highest in the patients with p53-negative and VEGF-negative tumors. In conclusion, both p53 and VEGF significantly correlated with tumor vascularity and prognosis in patients with gastric carcinoma.

Adult↗
PubMedDate not supplied

Expression of thrombospondin-1 inversely correlated with tumor vascularity and hematogenous metastasis in colon cancer.

Solid tumors require neovascularization for growth and metastasis. Angiogenesis depends on the local balance between various molecules that induce and inhibit neovascularization. Thrombospondin-1 (TSP-1) is thought to be an antiangiogenic factor. In this study, we examined the correlation between expression of TSP-1 and tumor vascularity, and determined its prognostic significance in colon cancer. Microvessel density, determined by immunostaining for factor VIII-related antigen, was significantly higher in tumors that were TSP-1-negative. TSP-1 expression was inversely correlated with prognosis. Patients with TSP-1-negative tumors had a significantly worse prognosis than did those with TSP-1-positive tumors. Frequency of hepatic recurrence was significantly higher in patients with tumors that were TSP-1-negative. In conclusion, TSP-1 is an important negative-regulator of tumor angiogenesis, and TSP-1 may be useful for predicting recurrence in patients with colon cancer.

Adenocarcinoma↗