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Y Cho

Publications and source records attributed to Y Cho.

At least 19 recordsLinked to original sources
PubMed1991

HLA matching: univariate and multivariate analyses of UNOS Registry data.

1. Black transplant recipients showed little or no matching effect when HLA-A, B, and DR antigens matched. This may have been due in part to differences in serologically defined antigens found in Black populations. 2. There was a statistically significant (p less than 0.001 for best vs worst match) matching effect in White transplant recipients that occurred at 3 months following grafting and continued through 3 years follow-up. These patients had better graft survival for both 5 and 6, compared to 3 and 4, or as compared to 0-, 1-, and 2-match transplants; the corollary groups for mismatched transplants were also significantly different. At 3 years, there was a 20% difference in graft survival from the best- to the worst-matched transplants. Earlier this difference was 7-10% but significantly different. 3. When the HLA Class I parent antigens as defined in the Materials and Methods section were eliminated, there was an increase in graft survival for the best-matched transplants. This was postulated to occur because of better matching obtained by matching the well-defined HLA specificities. 4. With hierarchy matching, possibly there was a stronger effect of matching HLA Class II antigens at 3 months; however, this effect was quickly lost at 1 and 3 years, and data that support early graft survival advantages by matching Class II antigens were inconclusive. Most importantly, there was a threshold matching effect that showed transplant recipients with 4 or more HLA matches or 2 or less mismatches had significantly better short- and long-term outcome than the poorer-matched groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

UCLA and UNOS Registries. Overview.

The subjects of this study were transplant recipients entered in the UCLA Registry file since 1984 and in the UNOS Registry since 1987. [table: see text] 5. Based on the data above, we conclude that the near 20% loss rate in the first year can be roughly allocated as follows: death 3%, technical 3%, agonal kidney damage 6%, and histocompatibility differences 7%. 6. The quality of HLA typing was assessed by examining the frequencies of the various specificities reported for cadaver donors in 8 yearly periods from 1984 to 1991. The A and B loci specificities were remarkably constant. The DR specificities were still undergoing stabilization. 7. No urine output on the first day, which occurred in approximately 10% of the first cadaver-donor transplants, resulted in about a 20 percentage point lower graft survival rate at 1 year. 8. Anuria on the first day increased with cold ischemia time, donor age, cerebral vascular accident donors, and retransplant recipients. 9. Graft survival with anuria on the first day and: [table: see text] 10. When dialysis was required during the first week, there was an approximate 15 percentage point decrease in 1-year graft survival in 25% of the patients. 11. One rejection in the first hospitalization period resulted in 67% 1-year graft survival. More than 1 rejection led to 57% 1-year graft survival. 12. Serum creatinine at discharge was an accurate indicator of subsequent graft survival. Approximately a 7 percentage point drop in 1-year graft survival was noted with each unit of serum creatinine above 2.0 mg/dl.

Adolescent↗
PubMed1991

A report from the UNOS Scientific Renal Transplant Registry.

The UNOS Kidney Transplant Registry is now fully operational. Aside from scientific reports from UCLA, analysis of the same data base from investigators who initiate projects through UNOS central in Richmond, as well as from HICFA and USRDS, can be anticipated. Plans are underway to simplify the reporting process. With the large number of accumulated cases, it should be possible to analyze many factors in the future. Presently, histocompatibility differences in living related vs cadaver donors and degrees of HLA mismatching among recipients of cadaveric kidneys are major factors. Immunization by transplant rejection is the second most important factor.

Graft Survival↗
PubMed1990

Uptake of glutamate and cysteine in C-6 glioma cells and in cultured astrocytes.

The uptake of glutamate in rat glioma C-6 cells and cultured astrocytes derived from rat cerebral hemispheres was found to be mediated by a Na(+)-dependent and a Na(+)-independent system. The Na(+)-dependent system was inhibited by aspartate and was consistent with the commonly occurring system designated system X-AG. The Na(+)-independent system was inhibited by cystine and was consistent with system x-c described in various types of cells in the periphery. It was also found that quisqualate selectively and competitively interfered with the Na(+)-independent glutamate uptake. In C-6 cells, the glutamate uptake via systems X-AG and x-c accounted for approximately 35% and 55% of the total uptake, respectively, at 0.05 mM glutamate. In cultured astrocytes, the glutamate uptake via system X-AG was very potent, whereas the uptake via system xc- was relatively weak and its contribution to the total uptake of glutamate seemed almost negligible. However, in both C-6 cells and astrocytes, system xc- was necessary for the uptake of cystine, another substrate of system xc-. Cystine in the culture medium was an essential precursor of glutathione, and the inhibition of the cystine uptake by excess glutamate as a competitor led to a severe deficiency in glutathione, followed by cell degeneration.

Amino Acids↗
PubMed1989

Endothelial attachment and plasmalemmal apposition in the transcellular movement of intravascular leukemic cells entering the myeloid parenchyma.

The plasmalemmal relationship between metastases-forming leukemia cells and myeloid sinus endothelium during the transmural passage of the leukemia cells has been studied in rat bone marrow. After the myeloid vascular system was freed from normal circulating blood cells, the bone marrow was perfused with a suspension of leukemia cells derived from an ascites tumor. The bone marrow was then fixed by perfusion with double aldehyde with and without the addition of tannic acid. Leukemia cells were seen adhering to the adluminal aspect of the sinus endothelium and in all stages of endothelial penetration. The penetration of the sinus wall was independent of endothelial junctions; i.e., the transmural passage into the myeloid parenchyma was transcellular. At these sites, there were restricted areas of close plasmalemmal appositions of the two cell types where the intraplasmalemmal space was reduced to 2.3 nm. This space was interrupted by electron densities of 5 nm diameter and spaced 9 nm center to center. These close plasmalemmal appositions extended over distances ranging from 150 nm to 200 nm. It is suggested on the basis of the structural similarity that these heptalaminar complexes of close plasmalemmal apposition represent the structural equivalent of gap junctions and may be sites of intercellular communication requisite for transmural passage. When tannic acid was added to the fixative, there were extended areas of apparent fusion of the plasmalemmas of the two cell types, at the sites both of adhesion and of endothelial penetration. This fusion was limited to the outer leaflets of the two plasmalemmas, resulting in a single pentalaminar complex. These pentalaminar complexes extended over decidedly longer distances than the presumed gap junctions seen in the nontannic-acid-fixed material. The tannic acid material did not show the heptalaminar gap junction type of plasmalemmal apposition. It is believed likely that the tannic-acid-induced pentalaminar complexes may incorporate the smaller heptalaminar ones. The factors underlying the plasmalemmal configurational differences between the tannic acid and non-tannic-acid material remain undetermined.

Animals↗
PubMed1989

The UNOS Scientific Renal Transplant Registry.

1. After 2 years of data collection and compiling, the UNOS Scientific Renal Transplant Registry was analyzed for the first time. One-year graft survival rates were 89% for first parent donor transplants (257), 76% for first cadaver (7,049), 65% for second cadaver (1,072), and 57% for multiple retransplant recipients (221). 2. The side-by-side comparison of the UNOS and UCLA registries revealed a remarkable similarity between results from the 2 databases. The concordance between the registries makes us confident in the validity of the UNOS data and also suggests that centers submitting data to the voluntary UCLA Registry are representative of the national experience. 3. Eighty-nine recipients of 6-antigen matched first cadaver transplants were identified in the UNOS Registry with 88% graft survival at 1 year. This result is comparable to that obtained from surveys that identified 224 recipients with 90% graft survival at 1 year. These results underscore the importance of sharing cadaver kidneys to achieve perfectly matched transplants. 4. Blood transfusions improved graft survival by 5% at 1 year. More than one-quarter of the first cadaver transplant recipients were nontransfused. 5. The first follow-up report after discharge of the transplant recipient was requested at 6 months by UNOS. This delay in reporting transplant outcome resulted in a serious lag between the time a transplant was performed and its availability for analysis. The UCLA Registry collects a report at 3 months and had more recent transplants available for analysis.

Databases, Bibliographic↗
PubMed1988

Clinical transplants 1988. Overview.

1. The 3-month actual graft survival of 6-antigen matched transplants in the UNOS program was 96% compared to 85% in control kidneys which were not shipped (p = 0.004). Actuarial graft survival at 1 year was 89% for the 6-antigen matched kidneys and 78% for the controls (p = 0.02). 2. Several individual centers reported 1-year graft survival rates of 85-95% (in the first half of this volume). Various immunosuppressive protocols and attention to patient care resulted in high 10-year survival of 53% in 1 instance (Leuven). 3. The 1-year graft survival peaked at about 77% for transplants performed in 1985, 1986, and 1987. 4. Among transplants performed since 1984, HLA matching of cadaver donor transplants showed a 13% difference at 1 year between the best and worst A,B,DR matches, which expanded in 3 years to an 18% difference. 5. The center effect, which produces about a 13% difference in 1-year graft survival for cadaver donors, decreased to 0 in HLA-identical transplants. Thus, when the donor and recipient were histocompatible, all centers were able to achieve superior results. The results of the 6-antigen Match Study appear to validate this conclusion. 6. Preformed antibody is associated with a 9% decrease in graft survival for greater than 50% PRA in first grafts and 4% in second grafts. For peak antibodies, the difference was 7% for first grafts and 11% for second grafts. 7. Platelet flow cytometry in 23 patients with a positive flow cytometry crossmatch to T cells furnished a further refinement in grouping the patients. All 11 patients with a negative platelet crossmatch had functioning grafts at 1 month whereas only 5 of 12 patients with a positive platelet crossmatch had a functional graft at 1 month (p = 0.003). 8. The duration of first graft effect on the second graft has diminished considerably as immunosuppression improved. Patients whose first graft survived more than a year and who had a high 1-year graft survival of the second graft lost their second graft at an accelerated rate after the first year. At the end of 4 years, their survival was the same as that of the responder patients who had rejected their first grafts within 3 months. 9. False positive crossmatches, especially in "highly" sensitized patients were identified by the use of DTT. Transplants into 69 patients who were positive by the standard test but negative after DTT had a 94% 1-month function rate.(ABSTRACT TRUNCATED AT 400 WORDS)

Cadaver↗
PubMed1987

Kinetic analysis of new formation, internalization, and turnover of bristle coated pits of the myeloid sinuses.

The rate of new formation of bristle coated pits (BCP) of the myeloid sinuses, their internalization, and turnover was determined by labeling of BCP with bovine albumin adsorbed to colloidal gold (Au) at low temperatures (0 degrees C to 4 degrees C), followed by endothelial activation with balanced saline at 38 degrees C to 40 degrees C for graded periods of time. New formation of BCP was practically instantaneous, occurring within 28 seconds, a time span which includes the in situ assembly of the coating protein clathrin as well as of the material effecting the binding of the ligand. Almost the entire population of BCP was turned over in 6 minutes, a time period which encompasses the initial formation of the plasmalemmal bristle coated binding site to the internalization of BCP. The number of BCP varied within a narrow range indicating a substantial degree of physiological constancy resulting from a quantitative parallelism between internalization and new formation of bristle coated binding sites. The number of BCP is markedly reduced in the prolonged (greater than 12 minutes) absence of endocytosable material. The reduction in the number of BCP is reversible. The binding to BCP at low temperatures (0 degrees C to 4 degrees C) of a series of proteinaceous substances adsorbed to Au was examined for the following Au complexes: bovine albumin/Au, rat albumin/Au, IgG/Au, orosomucoid/Au, ovalbumin/Au, fetuin/Au, transferrin/Au, insulin/Au, low density lipoprotein/Au, alpha 2 macroglobulin/Au, and Au stabilized by polyethylene glycol. All these Au complexes bound to BCP although there were differences in the degree of affinity as judged by the number of BCP labeled and by the number of Au/complex particles present in the labeled BCP. Au stabilized by polyethylene glycol did not bind to BCP. Under the condition of these experiments, bovine albumin/Au had the highest degree of affinity for BCP and was therefore selected for the kinetic studies.

Adsorption↗
PubMed1986

In vivo exocytosis of lysosomes by the endothelium of the venous sinuses of bone marrow and liver: visualization at normal and low body temperature.

We have visualized the exocytosis of lysosomes into the peripheral circulation by the phagocytic endothelia of the venous sinuses of liver and bone marrow of rats. Perfusion fixation at normal body temperature produced images of the earliest stages of lysosomal exocytosis. After fixation at low body temperatures (7-12 degrees C), advanced stages of this process became evident, showing extrusion of lysosomes and their contents into the circulation. It is postulated that this form of exocytosis has escaped structural detection because of its rapidity and relative infrequency as compared to merocrine secretory exocytosis, and that fixation at low body temperatures arrests or slows down these exocytic events in sufficient measure for ultrastructural visualization. The possibility that this lysosomal exocytosis contributes to the presence of lysosomal enzymes detected in the peripheral blood should be considered. In addition, it is likely that lysosomal degradation products may be discharged by exocytosis into the circulation.

Animals↗
PubMed1986

Internal structure of the postcapillary high-endothelial venules of rodent lymph nodes and Peyer's patches and the transendothelial lymphocyte passage.

Scanning electron microscopy (SEM) shows that the postcapillary high-endothelial venules of lymph nodes and Peyer's patches consist of two segments each with a different surface relief: a proximal segment with a cobblestone surface pattern and a distal segment of interlacing cytoplasmic plates. Both segments have deep adluminal crevices in which lymphocytes are lodged. The internal structural configuration of this endothelium has been examined by transmission electron microscopy (TEM) of serial sections of lymph nodes and Peyer's patches of mice, rats, and guinea pigs. The serial sections revealed that the endothelial cell bodies and their cytoplasmic extensions were disposed in a direction generally lateral to the luminal surface and intruded into the intercellular spaces of similarly disposed neighboring endothelial cells, resulting in a complex interlacing cellular pattern. Lymphocytes penetrated the endothelial cell body and secondarily followed an intracellular pathway through which they entered the extravascular compartment. At the exposed surfaces of the adluminal venule wall, recirculating lymphocytes were seen in SEM images to enter the endothelium by penetrating the endothelial cell body. The mode of migration of lymphocytes lodged in the endothelial crevices could be determined by SEM and has been examined by TEM of serial sections. At these locations as at the exposed surfaces, lymphocytes also entered the venule by penetrating the endothelial cell body. At both sites this transcellular pathway was followed by lymphocyte entry into the intercellular spaces from which they migrated into the extravascular compartment.

Animals↗
PubMed1985

A new punctum plug.

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Equipment and Supplies↗
PubMed1985

Acid-labile interferon produced in human peripheral leukocytes by induction with Sendai virus.

An acid-labile interferon-alpha (IFN-alpha) exists in IFN produced in human peripheral leukocytes with Sendai virus. This activity was found in fractions of molecular weights about 100 000 (100K), 58K and 44K. The IFN activity in the 100K fraction was neutralized with anti-HuIFN-alpha serum alone, but activity in the 58K and 44K fractions was neutralized only by a mixture of anti-HuIFN-alpha and anti-HuIFN-beta sera.

Animals↗
PubMed1985

[Inhibition of virus multiplication by immunoactive peptides].

In the present study we show that peritoneal macrophages obtained from the mice treated with the immunoactive peptides inhibit the multiplication of Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), but not that of vesicular stomatitis virus (VSV), and that the intraperitoneal administration of the peptides suppresses the infection with HSV-1 in mice.

Adjuvants, Immunologic↗