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Y W Cho

Publications and source records attributed to Y W Cho.

At least 37 records · Page 2Linked to original sources
PubMed1999

Transplant risks.

1. Changes in serum creatinine is a potentially useful predictor of chronic rejection. Patients with 2 10% increases in creatinine values in 3 consecutive years between 1-5 years had 4 times the risk of chronic rejection graft loss than patients with stable creatinine. 2. Formation of HLA antibody may correlate with graft rejection since losing a kidney increased the risk of broad sensitization 5-fold and losing multiple kidneys increased the risk ten-fold. 3. Sensitization increased the risk of acute and chronic rejection while pregnancies decreased the risk of acute and chronic rejection suggesting that pregnancy may result in "beneficial" sensitization. 4. HLA matching was the most potent factor decreasing the risk of acute rejection 2-fold and chronic rejection by 62%. 5. The incidence of acute and chronic rejection have both decreased significantly since 1994.

Acute Disease↗
PubMed1998

Thioltransferase from Arabidopsis thaliana seed: purification to homogeneity and characterization.

Thioltransferase is a general GSH-disulfide reductase of importance for redox regulation. The protein thioltransferase has been purified to apparent homogeneity on SDS-PAGE from the Arabidopsis thaliana seed. The purification procedures included DEAE-cellulose ion exchange chromatography, Sephadex G-75 gel filtration, Q-Sepharose ion exchange chromatography, and DEAE-Sephadex A-25 ion exchange chromatography. The enzyme has a molecular mass of 22 kDa and a pI of 4.8, and it is heatstable. The protein had broad specificities for substrates ranging from low-molecular disulfides (S-sulfocysteine and cystine) to protein disulfides (trypsin and insulin). However, it could not reduce the disulfide linkages of ribonuclease A and bovine serum albumin. It could utilize non-disulfide substrates such as dehydroascorbic acid and alloxan. The protein can reduce the disulfide bond in 2-hydroxyethyl disulfide with an optimum pH of 8.5. Its activity was greatly activated by monothiol compounds such as reduced glutathione and L-cysteine.

Arabidopsis↗
PubMed1998

Effects of changes in the criteria for nationally shared kidney transplants for HLA-matched patients.

BACKGROUND: Nine years ago, a prospective trial began in all U.S. transplant centers to determine whether the results of renal transplantation would improve with the nationwide shipment of kidneys from cadaveric donors to HLA-matched patients. Since then, the stringency of criteria for HLA matching have been liberalized twice, from sharing only those kidneys that matched at all six HLA-A, -B, -DR antigens, to sharing phenotypically HLA-matched kidneys, and most recently to sharing zero HLA-mismatched kidneys. METHODS: Data reported to the United Network for Organ Sharing Scientific Renal Transplant Registry from October 1987 to December 1996 were analyzed to examine the transplant results of nationally shared HLA-matched kidneys and the effects of changes to the HLA matching criteria on graft survival and the distribution of HLA-matched kidneys. RESULTS: The overall 1-year graft survival rate of 5102 HLA-matched transplants was 88% compared with 81% for 58,207 recipients of kidneys with at least one HLA mismatch (P < 0.001). HLA-matched kidneys had a projected 12-year graft half-life, 50% higher than the 8-year half-life of mismatched grafts (P < 0.01). After the first change in the match criteria in August 1990, 1365 phenotypically matched kidneys with fewer than six HLA antigens identified had an 89% 1-year graft survival rate compared with 84% for 466 six antigen-matched kidneys transplanted before the change. After March 1995, 1067 zero HLA-mismatched kidneys that were not phenotypically identical nor six antigen matched, had a 1-year graft survival rate of 88%. Graft survival has not decreased as a result of these changes in the criteria for national sharing, despite an increase in the percentage of matched transplants from 2.5% during the six antigen-match era to 15.5% during the zero antigen-mismatch era. CONCLUSIONS: Changes to the United Network for Organ Sharing policy for national sharing of HLA-matched kidneys have increased the number of patients, and especially minority patients, who can benefit by receiving a well-matched graft without compromising the high graft survival rates provided by an HLA-matched kidney.

Cadaver↗
PubMed1998

Transplantation of kidneys from donors whose hearts have stopped beating.

BACKGROUND: Attempts have recently been made to expand the number of cadaveric kidneys available for transplantation by using kidneys from donors without heartbeats in addition to those from brain-dead donors with beating hearts. We studied the efficacy of transplanting kidneys from donors without heartbeats on the basis of aggregate results from the Kidney Transplant Registry of the United Network for Organ Sharing. METHODS: We compared the early function and survival rates of 229 kidney grafts from donors without heartbeats with those of 8718 grafts from cadaveric donors with heartbeats. All transplantations were performed at 64 U.S. transplantation centers. Cox proportional-hazards analysis was used to evaluate 10 major risk factors for graft failure. RESULTS: The survival rate at one year was 83 percent for kidney grafts from donors without heartbeats, as compared with 86 percent for grafts from donors with heartbeats (P=0.26). Among the kidneys from donors without heartbeats, the survival rate at one year was 89 percent for grafts from donors who had died of trauma, as compared with 78 percent for grafts from donors who had died of other causes (P=0.04). The survival rates were high for grafts from donors without heartbeats despite the poorer early function of these grafts; 48 percent of the recipients required dialysis within the first week after transplantation, as compared with 22 percent of the recipients of grafts from donors with heartbeats. The primary-failure rate for kidneys from donors without heartbeats was 4 percent, as compared with 1 percent for kidneys from donors with heartbeats. CONCLUSIONS: Transplantation of kidneys from donors whose hearts have stopped beating, especially those who have died of trauma, is often successful, and the use of kidneys from such donors could increase the overall supply of cadaveric kidney transplants.

Brain Death↗
PubMed1998

Expanded criteria donors.

These analyses of the UNOS Scientific Renal Transplant Registry data from 1994-1997 showed: 1. There was no significant difference in graft survival between en-bloc and solitary transplants from donors aged 3-4. 2. Double renal allografts should be considered as an alternative to discarding both kidneys when donors are regarded as unsuitable for single kidney transplantation. 3. Prolonged donor HTN had a statistically significant deleterious effect in the multivariate analysis (RR 1.2, p = 0.05 for duration > 10 yrs). 4. A donor history of diabetes, cigarette smoking, or cancer failed to show any significant deleterious effects on graft survival in the multivariate analysis. 5. Matching donors and recipients for HCV genotype may minimize the risk of superinfection when using kidneys from HCV-positive donors (RR 1.4, p = 0.02 for the D+/R- mismatch). 6. Hepatitis B core antibody-positive donors did not pose a significant risk in the multivariate analysis. 7. A high proportion of donors were CMV positive and transplanting kidneys from CMV-positive donors resulted in a significantly but not substantially poorer graft outcome. The highest risk (RR 1.2, p = 0.003) was observed in transplants to CMV-negative recipients. 8. Kidneys from NHBDs who died of trauma survived as well as those from conventional brain-dead donors. NHBDs promise to be an important source for expanding the cadaver donor pool.

Adolescent↗
PubMed1997

Significance of the donor age effect on kidney transplants.

The shortage of cadaveric donor kidneys for transplantation has forced a re-evaluation of the limits on donor age acceptability. However, as more kidneys from older donors have been transplanted, a significantly lower graft survival has been noted among their recipients. The impact of utilizing older donor kidneys and the relative importance of donor age with respect to other factors has not been clarified. A total of 43,172 cadaver donor transplants reported to the UNOS Scientific Renal Transplant Registry between 1987 and 1995 were the subjects of this study. Cox regression analysis was utilized to assess the joint effects on graft survival of donor age and HLA mismatch, recipient sex, race, age, original disease, donor death cause, cold ischemia time, and transplant year. Increased first day anuria, dialysis requirement, and discharge serum creatinine were noted with increasing donor age. Moreover, long-term graft and patient survival diminished as donor age increased. The 5-yr graft survival of zero HLA-A,B,DR mismatched kidneys fell steadily from 81% when the donor was aged 21-30 to 39% when the donor was over age 60. The reported causes of kidney transplant failure were remarkably similar for old and young donors. The best transplant results were obtained with zero HLA-A,B,DR mismatched transplants from young donors and the worst with older donor kidneys, regardless of HLA compatibility. We calculated that up to 21% of kidney failures resulted from insufficient renal mass due to age and were incorrectly attributed to chronic rejection.

Adolescent↗
PubMed1997

Strategy for eliminating the kidney shortage.

1. We anticipate that the number of kidneys from conventional heart beating donors who are under age 55 will remain stable at about 8,000/year. A natural increase of donors over age 55 and living donors is expected to increase the total transplants from about 12,000 today to 14,000 in 8 years. 2. We propose a 4-year acceleration phase, during which older cadaver donors, related and unrelated living donors will be increased to a maximum of 4,000 in the 4th year. This acceleration is a temporary one, and will be reduced to zero over 4 subsequent years. 3. An increase in NHBD will be encouraged at a rate of 700/year, so that at the end of 14 years, they would constitute about 10,000 cadaver donor kidneys. As can be seen in Figure 1, at this rate, NHBD kidneys will first replace the accelerated effort, then replace the living donors and eventually the older heart beating donors. With the abundance of kidneys, it is likely that many patients who are not listed today would be encouraged to become transplant candidates. Moreover, patients needing retransplants will increase. However, once this capacity is developed, any increases in new transplant candidates could be accommodated. Thus in 14 years, there will be about 18,000 kidneys available each year. Approximately 60% will be NHBD and 40% heart beating donors, with no living donors and no older donors and no need of pig donors. We will be in transplant nirvana.

Cadaver↗
PubMed1997

Spousal and other living renal donor transplants.

Aside from HLA identical sibling donors, spousal donor transplants are the best living donors because their 3-year graft survival is comparable to that of all other living donors--with the exception of HLA identical siblings. Interestingly, the 14.5 year half-life of spousal donor kidneys was superior to the 10.8 year half-life of other living donor transplants. Better quality kidneys is the principal explanation for higher spousal donor graft survival rates when compared with cadaver donors. This was evident from the 2% anuria rate in the first post-operative day for spouse donor compared with 10% of cadaver donor transplants. Moreover, the requirement for dialysis was 6% for spouse donor grafts compared with 22% of cadaver donor transplants. The damage is not attributable to cold ischemia time but rather to agonal events and shock prior to kidney harvesting. In a survey of 176 spousal renal transplant donors, 175 of 176 said they would advise others to donate a kidney to a spouse--and only one donor advised against it. Of the "yes" responses, 28% provided additional comments enthusiastically recommending it. About 47% reported improvements in the marital relationship, 29% in the sexual relationship, and 25% described improved relations with their children. The fact that the donor reaps many direct personal benefits should make spousal donation the first consideration for living-donation (after the HLA-identical sibling donor).

Adolescent↗
PubMed1997

Impact of new variables reported to the UNOS registry.

1. Donor age is now a predominant factor influencing graft outcome. 2. A new finding here is that recipient peripheral vascular disease, PVD is also a major factor. This factor was independent of whether the patient had diabetes or not. Presensitization, as shown by a high PRA is additive to PVD. 3. Hypertension in the donor was important only when a history of more than 10 years was noted in the older donors over age 50. 4. Angina and cardiovascular disease in the patient resulted in a slightly higher death rate, but was only of importance in patients over age 50. 5. Cadaver donor pretreatment was of importance only in donors over age 30. 6. White patients with private insurance had a slightly higher graft survival rate than those on Medicare or Medicaid. Black patients with private insurance had almost the same graft survival as White patients with private insurance. The lowest graft survival was noted for Black patients on Medicaid.

Adolescent↗
PubMed1996

Cytomegalovirus antibody status and renal transplantation: 1987-1994.

We examined graft and patient survival rates of 47,146 patients in the United Network for Organ Sharing registry following transplants between donors and recipients who were cytomegalovirus (CMV) antibody negative and positive. CMV positivity increased with age to about 80% in patients over 60. Seropositivity was seen in 80% of Asians, 71% of African Americans, and 56% of Caucasians. In all age groups, females had a slightly higher incidence of positivity than males. Transplants involving CMV-positive donors resulted in lower graft survival rates than those with CMV-negative donors. This occurred regardless of whether the recipient was CMV negative or positive. The greatest effect was on patient survival rate, which, in turn, adversely affected graft survival rate. The CMV-positive-donor effect was primarily noted in (1) Caucasian recipients, (2) patients with HLA-A,B,DR mismatches, and (3) patients older than 15 years of age. In contrast, CMV-positive donors were not a risk factor for African American and Hispanic patients, CMV-positive Asian patients, patients younger than 16 years of age, and patients with no HLA-A,B,DR antigen mismatches. In conclusion, a kidney from a CMV-positive donor is a risk factor for certain patients and currently yields about a 4% overall lower graft survival rate at 3 years than a kidney from a CMV-negative donor.

Adolescent↗
PubMed1996

Patient death after renal transplantation--an analysis of its role in graft outcome.

Whether patient deaths among renal transplant recipients should be counted as transplant failures when they occur while the transplant is still functioning is a controversial issue. Analyses of more than 45,000 first cadaver transplants reported to the UNOS Scientific Renal Transplant Registry between October 1987 and March 1995 showed that deaths among transplant recipients were strongly associated with the patient's age and presence of insulin-dependent diabetes. Other factors associated with poor early graft function were also associated with a significantly increased risk of death. Deaths within the first 5 years increased from 9% of recipients aged 2-15 to 30% of those over age 45 (P < 0.001). Deaths with a functioning graft occurred in 2% of the youngest patients and 13% in the older age group (P < 0.001). Among diabetics, 32% died within 5 years (12% with a functioning graft) compared with 10% (6% with graft function) of patients with glomerulonephritis (P < 0.001). When the transplanted kidney failed to function immediately or the patient required dialysis during the first week after transplant, 30% of patients died within 5 years compared with 20% when the graft functioned (P < 0.001). There was no difference in the percentage of deaths with a functioning graft. We conclude that deaths among renal transplant recipients follow an expected pattern in which the likelihood of death increases with age and diabetes.

Adolescent↗
PubMed1996

Organ Procurement Organization and transplant center effects on cadaver renal transplant outcomes.

1. A majority of transplant centers had significant improvements in cadaver donor kidney graft survival rates since 1991. A 10% or greater increase in one-year graft survival rates was reported by 36 of 128 large transplant centers. 2. When transplants were grouped according to the organ procurement agency that procured the kidney, large variations in one-year graft survival rates among 65 OPOs were noted. The "OPO effect" was of a magnitude similar to that of the "center effect" when analyzed separately. 3. Fourteen OPOs with the lowest graft survival rates procured a significantly higher fraction of kidneys from older, hypertensive or Black donors and donors whose deaths were not from motor vehicle accidents. Transplants were more often given to Black recipients, and kidneys were less frequently shared compared with 15 OPOs with the highest graft survival rates. 4. Significantly higher proportions of non-Black donors and recipients, patients with no activity limitation at the time of listing, patients working fulltime at the time of transplantation, and patients on dialysis less than one year were more frequently transplanted at 21 centers with excellent one-year graft survival rates compared with centers in groups with poorer results. 5. Increased numbers of mismatched HLA-B,DR antigens were detrimental to graft survival at centers with good or fair one-year graft survival rates, but had a minimal effect at centers with excellent results. 6. The OPO effect on graft survival rates was significantly associated with the center effect. Kidneys procured by OPOs associated with low graft survival rates and transplanted at centers with low graft survival rates resulted in the worst graft outcome. Interestingly, kidneys procured by OPOs associated with high graft survival rates, but transplanted by centers with low graft survival rates had better outcomes than kidneys from OPOs with lower graft survival rates. 7. Based on univariate analyses, the center and OPO effects ranked third and fifth among 16 significant factors. However, after adjusting for these 16 potentially confounding variables using a multivariate Cox regression model, the differences between the best and worst center and OPO groups were the fourth and eleventh most detrimental risk factors on graft outcome, respectively.

Adolescent↗
PubMed1996

Risk rate and long-term kidney transplant survival.

The findings from the UNOS Scientific Renal Transplant Registry are summarized in the following table. We've also provided our opinions on ways to influence the risk factors in the Discussion section. [table: see text]

Adolescent↗
PubMed1995

Lithium-induced inhibition of Na-K ATPase and Ca ATPase activities in rat brain synaptosome.

To explore the action mechanism of lithium in the brain, the author investigated the effects of lithium on Na-K ATPase and Ca ATPase in rat brain synaptosomes prepared from forebrains by the method of Booth and Clark. The activities of Na-K ATPase and Ca ATPase were assayed by the level of inorganic phosphate liberated from the hydrolysis of ATP. Lithium at the optimum therapeutic concentration of 1 mM decreased the activity of Na-K ATPase from the control value of 19.08 +/- 0.29 to 18.27 +/- 0.10 micromoles Pi/mg protein/h and also reduced the activity of Ca ATPase from 6.38 +/- 0.12 to 5.64 +/- 0.12 micromoles Pi/mg protein/h. The decreased activity of Na-K ATPase will decrease the rate of Ca2+ efflux, probably via an Na-Ca exchange mechanism and will increase the rate of Ca2+ entry by the depolarization of nerve terminals. The reduced activity of Ca ATPase will result in the decreased efflux of Ca2+. As a Conclusion, it can be speculated that lithium elevates the intrasynaptosomal Ca2+ concentration via inhibition of the activities of Na-K ATPase and Ca ATPase, and this increased [Ca2+]i will cause the release of neurotransmitters and neurological effects of lithium.

Animals↗
PubMed1995

New variables reported to the UNOS registry and their impact on cadaveric renal transplant outcomes - a preliminary study.

Several new factors collected by UNOS since 1994 were examined with regard to their effects on early graft function and 6-month graft survival in this study. Medicare patients had a lower 6-month graft survival rate than private insurance patients, though the difference was not statistically significant. Medicaid patients had a significantly lower graft survival rate than private insurance patients (p=0.04). Blacks had the same graft survival as Whites when they had comparable coverage. Both Blacks and Whites had higher graft survival with private insurance and lower survival with government funding. Non-heartbeating cadaver-donor kidneys yielded a lower graft survival rate than heartbeating donors (p=0.03). Experience with non-heartbeating donors is just beginning with only 89 kidneys compared with 8,766 heartbeating donor kidneys. Kidneys from donors with hypertension resulted in lower graft survival rates than those from donors without hypertension (p=0.01). In these preliminary studies, donor history of diabetes, smoking, alcohol dependency, I.V. drug use and cancer did not have a significant impact on graft survival. Patients who had a high body mass index (>26) had a lower 6-month graft survival rate (p=0.009). Patients who received kidneys from cadaver donors with a low body mass index (<20) had a lower 6-month graft survival rate (p=0.02). When the recipient was more than 30 kg heavier than the donor, a lower 6-month graft survival rate was obtained (p=0.007). When the weight ratio was greater than 2.0, again a lower survival was noted (p<0.001). A recipient-to-donor height ratio of more than 1.25 resulted in an 80% 6-month graft survival which was significantly less than the 87% survival rate among those with a ratio less than 1.25 (p<0.001). This cut-off was found to identify patients with the lowest 6-month survival rate, suggesting that donor-recipient pairs with a height ratio above 1.25 should not be transplanted. A 6-month graft survival rate of 90% was reported with a SMI of 16-20, where SMI = weight of recipient divided by the square of the donor height. From this preliminary study, the SMI appears to be the best predictor of high graft survival since 1,450 patients were in this category with a 90% survival at 6 months.

Adult↗