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Biomedical subjects

J H Hong

Publications and source records attributed to J H Hong.

At least 127 records · Page 7Linked to original sources
PubMed1991

Human placental protein methylase--I. Purification and characterization.

1. Protein methylase I (S-adenosylmethionine[:]protein-arginine N-methyltransferase; EC 2.1.1.23) which methylates protein-bound arginine residues has been purified from human term placenta 400-fold with an approximate yield of 6%. 2. When histone was used as in vitro substrate, the methylation products were found to be NG-mono-, NG, NG-di- and NG, N'G-dimethylarginine. The enzyme was found to be sensitive toward Cu2+ with Ki value of 8 x 10(-5) M. The Km value for S-adenosyl-L-methionine was 5 x 10(-6) M. 3. When this partially purified protein methylase I was incubated with isolated human placental nuclei and S-adenosyl-L-[methyl-3H]methionine, the major endogenous [methyl-3H]-labeled proteins were protein species of 23, 38, 45 and 68 kDa, the 23 kDa species being the most predominant. 4. The endogenous enzyme activity during the pregnancy increased significantly, reaching more than 4 times the initial activity at the end of term.

Chromatography, High Pressure Liquid↗
PubMed1991

Effect of timing of cyclosporine administration on recovery from renal ischemia in rats.

The effect of timing of cyclosporine administration on functional recovery from renal ischemia was studied in Sprague-Dawley rats. Animals were given cyclosporine and subjected to renal ischemia by temporarily occluding both the renal artery and vein. Our data demonstrate no significant difference in serum creatinine among rats subjected to renal ischemia, cyclosporine, or cyclosporine-vehicle cremophor EL administration, or the control group. On the other hand, renal ischemia in combination with cyclosporine resulted in rapid and marked deterioration in renal function with serum creatinine peaking on Day 2. The most significant rise was in rats that received cyclosporine 4 hr prior to induction of renal ischemia (4.7 +/- 0.5 mg/dl), followed by those that received cyclosporine 4 and 24 hr postischemia (2.8 +/- 0.5 and 3.2 +/- 0.7 mg/dl, respectively). Cyclosporine administration 24 hr prior to renal ischemia resulted in the least elevation of the serum creatinine (2.1 +/- 0.5 mg/dl) and the earliest return to the baseline value. Our data suggest that the timing of cyclosporine administration in rats subjected to renal ischemia influences the extent of renal injury and the subsequent recovery of renal function.

Animals↗
PubMed1991

Diabetes mellitus after renal transplantation in the cyclosporine era--an analysis of risk factors.

Despite mounting experimental evidence that cyclosporine inhibits pancreatic islet cell function, clinical data on posttransplant diabetes mellitus (PTDM) in renal allograft recipients in the cyclosporine era are scarce. Between June 1983 and December 1988, 39 of 337 (11.6%) cyclosporine-treated adult renal transplant recipient whose grafts survived longer than 1 year developed PTDM. Of these, 43.6% and 74.4% were diagnosed by 3 and 12 months posttransplant, respectively, and 51.3% were insulin-dependent. Incidence of PTDM was highest in blacks (19.8%) and Hispanics (21.3%) and in those with HLA-A 30 and Bw 42 antigens. Older recipients and those that received cadaveric kidneys were more likely to develop diabetes than those who received living related allografts (14% vs. 5.3%, P less than 0.05). The rate of PTDM appeared to be independent of the type of induction, immunosuppressant therapy, incidence of rejection, total steroid and cyclosporine dose, percentage of body weight gain in the first posttransplant year, and serum creatinine concentration. Actuarial 5-year, decaying from 100% at 1 year, patient and graft survival rates were 87% and 70%, respectively, in the PTDM group compared with 93% and 90%, respectively, in controls. Causes of graft failure among the diabetics included chronic rejection (6), patient death (3), noncompliance with immunosuppressants (2), and sepsis (1). The incidence of infectious complications was significantly higher in the PTDM group compared with the control group (53% vs. 16%, P less than 0.05), with all 5 deaths among the diabetics being sepsis-related.

Communicable Diseases↗
PubMed1991

The impact of ciclosporin in patients with adult polycystic kidney disease following transplantation.

In order to evaluate the impact of ciclosporin in patients with adult onset polycystic kidney disease (ADPKD) following renal transplantation, we performed a single-center study of all (n = 65) patients with this disorder since 1978, 43 of whom received CSA (PC-CSA) with the remaining 22 treated with azathioprine (PC-AZA). An additional group of 45 age- and time-matched group of non-polycystic CSA-treated patients (nonPC-CSA) were used as a separate control group. Patient and graft survivals at 1 and 5 years were similar in PC-CSA when compared to nonPC-CSA. The commonest causes of death in both groups were cardiovascular related. The incidence of posttransplant hypertension and acute rejection were also similar. Urinary tract infections (UTIs) were, however, more frequent among PC-CSA (11 and 33% pre- and posttransplant respectively) when compared to the nonPC-CSA (2 and 17% pre- and posttransplant respectively). The PC-CSA cohort showed improved 1-year patient and graft survivals when compared to PC-AZA (94 and 70% vs. 72 and 34%) with less rejection episodes (42 vs. 88%) during the first year posttransplant but a higher mean serum creatinine at the end of the first year (2.0 vs. 1.6 mg/dl, 176.6 vs. 141.3 mumol/l). Posttransplant hypertension (67 vs. 70%) and UTIs (33 vs. 33%) were, however, similar in both groups. In summary, renal transplantation in ADPKD in the CSA era is associated with equal patient and graft survivals when compared with nonpolycystic patients of comparable age, but superior results when compared with the earlier azathioprine era.

Adult↗
PubMed1991

Retrospective analysis of posttransplantation diabetes mellitus in black renal allograft recipients.

OBJECTIVE: To study the incidence, outcome, and possible etiopathogenic factors involved in posttransplantation diabetes mellitus in cyclosporine-treated black renal allograft recipients. RESEARCH DESIGN AND METHODS: One hundred thirty-eight nondiabetic black renal transplant recipients whose grafts survived greater than 1 yr were studied retrospectively. RESULTS: Twenty-eight (20.3%) patients developed posttransplantation diabetes mellitus, 46 and 75% were diagnosed by 6- and 12-mo posttransplantation, respectively, and 46% were insulin dependent. Diabetes was more frequently encountered in older recipients and recipients of cadaveric kidneys but was independent of sex, number of transplants, incidence of acute rejection, percentage of body weight gain, steroid or cyclosporine dose, and use of beta-blockers and/or diuretics. Renal function was similar in the diabetic group compared with the control group. Actuarial 5-yr graft survival was 82% in the diabetic cohort compared with 78% in the control group, with chronic rejection accounting for all graft losses within the diabetic group. CONCLUSIONS: Twenty percent of black cyclosporine-treated renal allograft recipients developed diabetes mellitus in the posttransplantation period. However, its presence did not appear to influence intermediate-term graft or patient survival.

Adult↗
PubMed1990

Prognostic factors of nasopharyngeal carcinoma: a multivariate analysis.

Between 1979 and 1985, 561 patients with nasopharyngeal carcinoma were reviewed to determine prognostic factors that may influence survival. Sex (p = 0.294) and histopathology (p = 0.677) had no correlation to the actuarial survival, whereas the site of cervical metastasis (p = 0.001) and the radiation doses to the nasopharynx and regional lymph nodes (p = 0.03) were both significant when one used univariate analyses. Cox's multivariate regression model revealed that the presence rather than the site of distant metastases was the single most important independent factor influencing the treatment outcome (p less than 0.0001). The addition of chemotherapy, on the other hand, did not show a survival benefit even when one took available confounding factors into account. There are, however, survival advantages associated with: (a) young age (less than or equal to 40 years), (b) asymptomatic status, (c) Stage I or II lesions, and (d) biopsy via nasopharynx instead of neck nodes. These favorable prognostic factors may be used for therapeutic guidance and end-result reporting.

Adolescent↗
PubMed1990

Isolation and characterization of VP-16 resistant human leukemia cell line.

VP-16 resistant cells, designated VP-16K6-1 (K6-1) were isolated from human acute lymphoblastic leukemia cell line RPMI 8402. IC50 value against VP-16 were 11-fold higher than their sensitive parental cell line. The membrane permeability of the drug was not responsible for resistance in K6-1 cells. K6-1 cells showed resistance in drug-induced DNA strand breaks (single strand breaks) determined by the alkaline sucrose gradient sedimentation method. Dot-blot analysis of RNA extracted from 2 cell lines showed that the mRNA levels of DNA topoisomerase II in K6-1 cells decreased slightly compared with that of parent cells. However, Topo II activities were similar in wild-type and K6-1 cells. In addition, K6-1 cells exhibited cross-resistance only to VM-26. These data suggest that a reduced intracellular Topo II level may contribute to drug resistance as an important factor in K6-1 cells.

DNA Replication↗
PubMed1990

Reduced DNA topoisomerase II in VP-16 resistant mouse breast cancer cell line.

VP-16 resistant cells, FvprB350 (50B-3), were isolated from mouse breast cancer cell line FM3A. 50B-3 cells showed 84-fold higher resistance than their parent cells. Reduced drug uptake was not found in resistant cells. Quantitative analysis of drug-stimulated DNA cleavage activity using 3'32P end-labeled pBR322 restriction fragments showed that VP-16 stimulated DNA-topoisomerase II cleavable complex forming activity in crude nuclear extract from 50B-3 cells was approximately one-fifth as compared with that of FM3A wild-type cells. Dot-blot analysis of RNA extracted from the two cell lines showed that mRNA levels of topoisomerase II in 50B-3 cells drastically decreased and catalytic activity was also 1/2-1/3 as compared with that of parent cells. 50B-3 cells showed cross resistance to VM-26, m-AMSA, adriamycin. These findings suggest that reduced topoisomerase II activity (cellular levels) and cleavable complex forming activity may be significant factors in the marked drug resistance.

Animals↗