Biomedical subjects

S J Koh

Publications and source records attributed to S J Koh.

7 recordsLinked to original sources

PubMed1995

Ornithine decarboxylase and tyrosine kinase activity in juvenile polyps of childhood.

Juvenile polyps (JP) are the most common colonic tumor in children. Although considered benign, malignant transformation has been reported in JP. Ornithine decarboxylase (ODC) and tyrosine kinase (TyK) enzymes are markers for a rapid cell proliferation index. DNA aneuploidy score and p53 gene expression are late malignant changes seen in patients with colon cancer. In this study, we investigated ODC and TyK activities as well as DNA aneuploidy score and p53 expression in juvenile polyps compared with the adjacent normal colonic mucosa. Results showed that ODC was significantly increased in JP compared with the adjacent normal colonic mucosa. TyK activity was increased in 3/5 polyps and decreased in 2/5 polyps compared with the mucosa. Mean TyK activity was higher in JP compared with normal mucosa but did not reach significance (707 and 632 pmol/mg pmol, respectively). Moreover, changes in phosphorylization of TyK proteins was also observed in JP but not in normal mucosa. JP had a normal DNA aneuploidy score and showed no expression of p53 gene. We conclude that JP do not express p53 gene and aneuploidy but had higher activity of ODC and TyK enzymes, suggesting a higher stage of cell proliferation.

Adolescent↗

PubMed1995

Does endothelin play a role in the pathogenesis of early diabetic nephropathy?

Endothelin-1 (ET-1) causes dramatic vasoconstriction and reduction of renal blood flow, with a decreased glomerular filtration rate (GFR). Early diabetic nephropathy is characterized by elevation of GFR and the formation of intrarenal microaneurysms. However, the mechanisms are unclear. To elucidate the pathophysiologic significance of urinary ET-1 in early diabetic nephropathy, the 24-h urinary excretion of ET-1 in 12 normal subjects and 20 patients with newly diagnosed type 2 diabetes mellitus were determined by a highly sensitive radioimmunoassay. The 24-h urinary ET-1 excretion in patients with diabetes mellitus (14.2 +/- 3.1 pmol, mean +/- SEM) was significantly lower (p < 0.05) than that of normal subjects (25.0 +/- 3.7 pmol). This decrease in urinary excretion of ET-1 in patients with recent-onset diabetes mellitus suggests a possible role of ET-1 in the pathogenesis of early diabetic nephropathy.

Adult↗

PubMed1986

Cancer of the large bowel in children.

We present the morphologic and clinical features of large bowel carcinoma in 22 patients seen over 18 years at St. Jude Children's Research Hospital. We saw 18 cases of mucinous adenocarcinoma, three of well differentiated adenocarcinoma, and one case of poorly differentiated adenocarcinoma. The patients ranged in age from 9 to 19 years with a median age of 15. There were 12 female and ten male patients; 12 were black and ten were white. Eighteen patients had Dukes' stage C disease, with median survival of seven months and one patient alive 12 months after diagnosis. Three patients had Dukes's stage B disease, with two patients surviving 16 months each and one presently alive seven months after diagnosis. Only one patient had Dukes' stage A disease and is alive 121 months after diagnosis. Large bowel carcinoma in children is predominantly mucinous adenocarcinoma and occurs in the adolescent age group. Tumor distribution is fairly even throughout the large bowel, and all subtypes of the tumor are positive for carcinoembryonic antigen (CEA) on immunohistologic study. Active tumor and tumor regrowth are always accompanied by high serum levels of CEA. The tumor has no predilection for sex, but is significantly more frequent in blacks (P less than .05). Discovery of the tumor in an early stage improves the prognosis.

Adenocarcinoma, Mucinous↗

PubMed1985

Glioblastoma in children.

Both morphologic and clinical features of 72 consecutive cases of brain tumors, collected over 9 years at Le Bonheur Children's Medical Center, were reviewed. We identified 11 cases as glioblastoma, representing 16% of all intracranial neoplasm and 26% of glial tumors. The patients ranged in age from 1 to 15 years with the median age of 10 years. There were 4 females and 7 males; 2 blacks and 9 whites. The median survival was 9 months. The tumor was observed in both cerebrum and cerebellum. Sexual predominance was not appreciable, although there was male excess. The tumor was significantly more frequent in whites than blacks (p less than 0.05). Similar racial predominance was noted in the other, more common brain tumors in children such as astrocytoma and medulloblastoma.

Adolescent↗

PubMed1984

Venous aneurysm.

A 19-month-old girl had a congenital aneurysm of the neck vein. We attribute the pathogenesis of venous aneurysm to a defective vascular wall. The treatment of choice is simple surgical excision.

Aneurysm↗

PubMed1980

Malignant "histiocytic" lymphoma in childhood.

Forty-one cases of childhood "histiocytic" lymphoma were studied morphologically and immunologically to determine whether this tumor type is composed of true histiocytic cells. Lysozyme and alpha-1-antichymotrypsin were used as markers for histiocytes, and cytoplasmic immunoglobulins were used as markers for B cells. Both indirect immunofluorescence and immunoperoxidase methods were used for functional characterization of tumor cells. Eight different subgroups were identified in the series, and only one case was proved to be true histiocytic lymphoma. When survival was evaluated for different subgroups, excluding convoluted lymphocytic, unclassified, and true histiocytic lymphomas, mixed follicular cell lymphoma had the most favorable prognosis; six of seven patients survived for at least one year. Immunoblastic lymphoma, by contrast, had an unfavorable prognosis; none of four patients were alive one year after diagnosis. The difference is statistically significant (P < 0.05) by chi-square analysis. Other groups of lymphoma (large cleaved, large noncleaved, and small noncleaved) had an intermediae prognosis (three of five, six of nine, and five of nine patients surviving at one year). Our results indicate that "histiocytic" lymphoma is a morphologically heterogeneous group of neoplasms, mostly not related to true histiocytes, and that morphologic subclassification may be useful in predicting prognosis.

Child↗

PubMed1980

Antimyosin and antirhabdomyoblast sera: their use for the diagnosis of childhood rhabdomyosarcoma.

Antisera against myosin of human normal skeletal muscle and against rhabdomyoblasts of autopsy-proved rhabdomyosarcoma were raised in white rabbits, purified, and assessed for their usefulness in the diagnosis of childhood rhabdomyosarcoma. The specificity of the antisera was tested by both immunofluorescence and immunoperoxidase methods in seven cases of autopsy-proved rhabdomyosarcoma, five of malignant lymphoma, three of neuroblastoma, and two of Ewing's sarcoma. Antimyosin serum tested positive for all cases of rhabdomyosarcoma and negative for other types of tumor. Antirhabdomyoblast serum was positive in all cases of rhabdomyosarcoma and cross-reacted with cases of neuroblastoma and Ewing's tumor, although the intensity of staining was much decreased. Our results indicate that antimyosin serum is specific for childhood rhabdomyosarcoma and can be used to differentiate this from other childhood "round cell" tumors.

Adolescent↗