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Biomedical subjects

C H Oh

Publications and source records attributed to C H Oh.

At least 19 recordsLinked to original sources
PubMed1999

Characterization of a novel unconjugated pteridine glycoside, cyanopterin, in Synechocystis sp. PCC 6803.

A new pteridine glycoside, called cyanopterin, was isolated from Synechocystis sp. PCC 6803 and its structure was elucidated as 6-[1-(4-O-methyl-(alpha-d-glucuronyl)-(1, 6)-(beta-d-galactosyloxy]methylpterin by chemical degradation and 1H- and 13C-NMR spectroscopic means. Cyanopterin is constitutively synthesized at a relatively high intracellular concentration that is comparable to that of chlorophyll a in a molar ratio of approximately 1 to 1.6. The in vivo oxidation state of cyanopterin is primarily the fully reduced 5,6,7,8-tetrahydro form. The cellular function is unknown at present. The findings have established a model system, using Synechocystis sp. PCC 6803, for studies of the physiological functions of unconjugated pteridine glycosides found mostly in cyanobacteria.

Chromatography, High Pressure Liquid↗
PubMed1999

Synthesis and antibacterial activity of 1 beta-methylcarbapenem having a 1,3-diazabicyclo[3.3.0]octan-4-one moiety, Part II.

The synthesis of a new series of 1 beta-methylcarbapenems having a 1,3-diazabicyclo[3.3.0]octan-4-one moiety is described. Their in vitro antibacterial activities against both Gram-positive and Gram-negative bacteria are tested and the effect of substituent on the bicyclic ring was investigated. A particular compound (11 h) having aminoethyl group showed the most potent antibacterial activity.

Bacteria↗
PubMed1999

Synthesis and biological activities of C-2, N-9 substituted 6-benzylaminopurine derivatives as cyclin-dependent kinase inhibitor.

In this study, C-2, N-9 substituted 6-benzylaminopurine derivatives were synthesized and their inhibitory effects on cyclin-dependent kinase (CDK2) were evaluated. The effect of substituents at the C-2 and N-9 positions of substituted purine was investigated. Among the compounds tested, compound 7b-iii (6-benzylamino-2-thiomorpholinyl-9-isopropylpurine) was the most active inhibitor (IC50 = 0.9 microM). Compound 7b-iii showed 10-fold higher activity compared to olomoucine and almost the same activity as roscovitine. Results from structure-activity relationship studies should allow the design of more potent and selective CDK inhibitors, which may provide an effective therapy for cancer or other CDK dependent diseases.

Antineoplastic Agents↗
PubMed1999

Activation of inducible nitric oxide synthase by Taraxacum officinale in mouse peritoneal macrophages.

The objective of the current study was to determine the effect of Taraxacum officinale (TO) on the production of nitric oxide (NO). Stimulation of mouse peritoneal macrophages with TO after the treatment of recombinant interferon-gamma (rIFN-gamma) resulted in increased NO synthesis. TO had no effect on NO synthesis by itself. When TO was used in combination with rIFN-gamma, there was a marked cooperative induction of NO synthesis in a dose-dependent manner. The optimal effect of TO on NO synthesis was shown 6 h after treatment with rIFN-gamma. This increase in NO synthesis was manifested as an increased amount of inducible NO synthase (iNOS) protein. NO production was inhibited by N(G)-monomethyl-L-arginine. The increased production of NO from rIFN-gamma plus TO-stimulated cells was decreased by treatment with a protein kinase C inhibitor such as staurosporin. In addition, synergy between rIFN-gamma and TO was mainly dependent on TO-induced tumor necrosis factor-alpha (TNF-alpha) secretion. All the preparations of TO were endotoxin free. These results suggest that the capacity of TO to increase NO production from rIFN-gamma-primed mouse peritoneal macrophages is the result of TO-induced TNF-alpha secretion.

Animals↗
PubMed1999

A study of the solar effect on actinic keratoses by quantification of elastic fibres using an image analysis system.

It is widely accepted that elastotic changes of the skin are primarily an indicator of cumulative sun exposure of the dermis and are a characteristic finding of actinic keratoses. To date, there have been few reports that measure the amount of elastic tissue objectively and quantitatively, especially in actinic keratoses. The computerized image analysis method has proved useful recently in determining the area of elastic fibres. Using this method, we objectively quantified the elastotic tissue in actinic keratoses and evaluated the relationship between the degree of dermal elastosis, epidermal atypia and histological types of actinic keratoses. Of the 28 actinic keratoses studied, the average percentage area of the elastic fibre was 40.48 +/- 14.48 (mean +/- SD) percentile. There was a 3.65-fold increase in the amount of elastic fibre in actinic keratoses compared with that of seborrhoeic keratoses occurring on the face (p < 0.00001). In addition, the more severe the atypia, the greater the area of elastic fibres in a representative section of the dermis. In conclusion, we observed that on quantitative assessment of elastic tissue in actinic keratoses, the percentage area of the elastic fibres in a representative section of the dermis ranges from 34.86 to 46.11%. This result may provide information for use in histological diagnosis of actinic keratoses and evidence for the possible role of sunlight in the pathogenesis of actinic keratosis.

Adult↗
PubMed1999

Quantitative image analysis of hair follicles in alopecia areata.

We took biopsies from similar sites on the scalps of normal controls, normal looking and hair loss areas of patients with alopecia areata. The specimens were sectioned serially and horizontally. We measured morphological parameters, such as the diameter of the hair shaft, the thickness of the inner root sheath, the diameter of the outer root sheath, the irregularity of the outer root sheath and the ratio between the diameters of the hair shaft and the outer root sheath, using a computerized image analysis system. There were significant differences in 5 parameters between hair loss areas and normal controls. The proportions of vellus and telogen hair were significantly higher in the areata areas than in the controls. The 5 morphological parameters and most quantitative-measured parameters of normal-looking areas from patients with alopecia values intermediate between the other groups.

Adolescent↗
PubMed1999

Prospective evaluation of perinatal risk factors for cerebral palsy and delayed development in high risk infants.

Prematurity, intrauterine infection and perinatal brain injury have been reported to be significant risk factors of cerebral palsy (CP). We examined the perinatal predictors of cerebral palsy and delayed development (DD) in 184 high risk infants. Thirty-five infants were diagnosed as cerebral palsy and delayed development at 12 months corrected age. Antenatal, intrapartum, and neonatal factors were prospectively evaluated in 2 groups of high risk infants compared with controls; Group A (n = 79), infants weighing less than 2,000 g; Group B (n = 43), infants weighing 2,000 g or more. In univariate analysis, there were no significant antenatal and intrapartum factors associated with cerebral palsy and delayed development in either group. We found that significant postnatal risk factors of CP in group A included sepsis (p = 0.008), BPD (bronchopulmonary dysplasia) (p = 0.028), IVH (intraventricular hemorrhage) (p = 0.042), ventriculomegaly (VM) (p = 0.001) and a longer duration of mechanical ventilation (p = 0.001); while in group B, sepsis (p = 0.047) and neonatal seizure (p = 0.027) were significant risk factors. In multivariate analysis, sepsis in group B was a moderate risk factor of CP (OR (odds ratio) 1.47; 95% CI (confidence interval) 1.02-2.13). In conclusion, neonatal sepsis may contribute to the development of cerebral palsy and delayed development. We suggest that high risk infants who have sepsis should be carefully followed for cerebral palsy and delayed development. The prevention of cerebral palsy may be feasible by decreasing neonatal risk factors such as sepsis during the neonatal period.

Cerebral Palsy↗
PubMed1998

Suppression of adventitious formation of 8-oxoguanine(TMS)4 from guanine during trimethylsilylation.

GC/MS quantitation of 8-oxoguanine derived from DNA may yield artificially high values when trimethylsilylation is used as the technique to form a volatile derivative. Significant quantities of the tetrakis trimethylsilyl-derivative of 8-oxoguanine may be formed from guanine during the derivatization reaction at elevated temperatures. We have screened eight antioxidants in an attempt to identify a substance that will reduce the spurious formation of this product. Whereas several compounds were active, N-phenyl-1-naphthylamine was the most effective agent. Moreover, this compound was sufficiently basic to act as a catalyst for the derivatization reaction. Our data, which are based on the use of an isotopically labeled internal standard, show that the level of the tetrakis trimethylsilyl derivative of 8-oxoguanine remained constant as a function of derivatization heating time when N-phenyl-1-naphthylamine was added to a reaction in which guanine was present. In contrast, the level in control samples increased linearly with reaction time indicating formation of 8-oxoGua during derivatization. The level of 8-oxoguanine was measured in both a synthetic oligodeoxynucleotide containing a single 8-oxo-2'-deoxyguanosine moiety and commercially available calf thymus DNA using this technique.

1-Naphthylamine↗
PubMed1998

Clinical significance of intrahepatic biliary stricture in efficacy of hepatic resection for intrahepatic stones.

In the Far East, hepatic resection is the definitive treatment for complicated intrahepatic stones (IHS). However, many investigators have reported that the associated intrahepatic biliary stricture is the main cause of treatment failure. A retrospective comparative study was undertaken to clarify the long-term efficacy of hepatic resection for treatment of IHS and to investigate the clinical significance of intrahepatic biliary stricture in treatment failure after hepatic resection performed in 44 patients with symptomatic IHS. The patients were divided into two study groups: group A, with intrahepatic biliary stricture (n = 28) and group B, without stricture (n = 16). Residual or recurrent stones, recurrence of intrahepatic biliary stricture, late cholangitis, and final outcomes were analyzed and compared statistically between the two groups. The patients were followed up for a median duration of 65 months after hepatectomy. The overall incidence of residual or recurrent stones was 36% and 11%, respectively, in groups A and B. The initial treatment failure rate was 50% in group A and 31% in group B. Intrahepatic biliary stricture recurred in 46% of patients in group A, while none of the group B patients had biliary stricture recurrence (P = 0.001). More than two-thirds of the restrictures in group A were identified at the primary site. The incidence of late cholangitis was higher in group A (54%) than in group B (6%) (P = 0. 002). Three-quarters of the patients with cholangitis in group A had severe cholangitis, that was recurrent, and related to stones and strictures (n = 11). They and 2 asymptomatic patients in group B required secondary procedures done at a median of 12 months after hepatectomy. Final outcomes after hepatectomy with or without secondary management were good in 80%, fair in 16%, and poor in 4% of our 44 patients. Most recurrent cholangitis after hepatectomy in patients with IHS was related to recurrent intrahepatic ductal strictures. Therefore, to be effective, hepatic resection should include the strictured duct. However, with hepatectomy alone it is difficult to clear the IHS or relieve the ductal strictures completely, particularly in patients with bilateral IHS, so perioperative team approaches that include both radiologic and cholangioscopic interventions should be combined for the effective management of IHS.

Bile Ducts, Intrahepatic↗
PubMed1998

Multiple pigmented basal cell carcinomas.

Basal cell carcinoma is the most common of all skin cancers and the most prevalent one among Caucasians. Rarely, these tumors are seen in other races. We report a 77-year-old Korean woman who presented with multiple darkly pigmented enlarging nodules on her scalp, face, trunk, and extremities. The patient had first noted a 6-mm pigmented lesion on her left eyebrow 10 years previously. Since then, other lesions had appeared in many locations on her body. She had been otherwise healthy and without a history of exposure to arsenic or radiation. There was no family history of skin cancer, xeroderma pigmentosum, or basal cell nevus syndrome. On physical examination, multiple darkly pigmented dome-shaped papules and nodules were present on her scalp, face, right forearm, lower abdomen, and inguinal areas. They ranged in size from 0.5 mm to 2 cm. The larger ones showed central ulceration. Multiple biopsy specimens from different sites showed pigmented basal cell carcinomas. Clinically, there was no evidence of nevus sebaceus, xeroderma pigmentosum, basal cell nevus syndrome, or immunodeficiency. Clinical workup including chest radiography, abdominal ultrasound, bone scan, and brain computerized axial tomography scan did not demonstrate primary or secondary tumors. The results of serologic and hematologic tests were also within normal limits. This is an unusual case report of multiple pigmented basal cell carcinomas in an Asian woman without any predisposing risk factors.

Aged↗
PubMed1997

Effects of ultraviolet light on the tension of isolated human cavernosal smooth muscle from non-diabetic and diabetic impotent men.

The effects of ultraviolet (UV) light (310 nm) on human cavernosal smooth muscles were investigated. Cavernosal strips were obtained from men during penile prosthetic surgery. When the cavernosal strips were irradiated with UV light in an organ bath, after precontraction by norepinephrine (100 nM) for 10, 20, 40 and 90 s at intervals of 3 min, the contracted cavernosal smooth muscles from the impotent men without vascular risk factors (controls) showed relaxation depending on the duration of irradiation. However, the relaxation was not found when the strips were pretreated with methylene blue (10 microM) or their epithelia were denuded. The relaxation response of the cavernosal strips from the patients with diabetogenic impotence was significantly reduced compared with that of the controls. Photorelaxation of human cavernosal strips therefore seems to be dependent on endothelium.

Adult↗
PubMed1997

Weight loss following transected gastric bypass with proximal Roux-en-Y.

BACKGROUND: Cross-sectional analysis was performed to study the trend in weight loss following surgery. METHODS: Among 194 patients involved in the study during the period 1990-1995, 86.6% were female and 87.1% were white. Median values for the initial cohort of 194 patients were as follows: age 32.5 years; height 163.8cm; preoperative weight 122.81 kg. Of these patients 67%, 30%, and 3% of the patients were categorized as morbidly obese, super obese, and obese respectively. They all underwent gastric bypass surgery. RESULTS: Follow-up rates were 67.9% at 1 year, 55.8% at 2 years, 62.8% at 3 years, and 70.0% at 4 years postoperation. Median BMI was reduced from 45.18 to 28.40, and median percentage loss of excess weight was 68.5% after 1 year. After 2, 3, and 4 years, median BMI values were 27.69, 28.63, and 29.40, and median percentages of excess weight loss were 71.18%, 69.28%, and 57.49%, respectively. Although the analysis at 4 years indicates that some patients experience slight weight gain, the increase was not significant and further analysis will be performed when more data points are available. CONCLUSION: Postoperative weight loss has been satisfactory.

Adult↗
PubMed1996

Synthesis and antibacterial activity of 1-beta-methylcarbapenem having a 1,3-diazabicyclo[3.3.0]octan-4-one moiety.

The synthesis of new series of 1-beta-methylcarbapenems having a 1,3-diazabicyclo[3,3,0]octan-4-one moiety is described. Their in vitro antibacterial activities against both Gram-positive and Gram negative bacteria are reported and the effect of the substituent on the bicyclic ring was investigated and was in agreement with findings from our previous studies.

Anti-Bacterial Agents↗
PubMed1996

Disseminated cutaneous epithelioid hemangioma.

Epithelioid vascular tumors are a heterogeneous group characterized by epithelioid-appearing endothelial cells. Included are benign vascular tumors (epithelioid hemangioma), borderline tumors (epithelioid hemangioendothelioma), and malignant tumors (epithelioid angiosarcoma). We describe a case of multiple epithelioid hemangiomas.

Aged↗