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Biomedical subjects

J Hong

Publications and source records attributed to J Hong.

At least 199 records · Page 11Linked to original sources
PubMed1990

Effect of Mg nutriture on the dynamics of administered 25Mg exchange in vivo in the rat.

The effect of Mg nutriture on Mg exchange and interorgan distribution was studied in adult rats ten days after a single I.P. dose of (25)Mg ( approximately 5 mg). First the effects of level of Mg intake (0.25, 0.05, or 0.01% Mg) on standard measures of Mg nutriture were studied for 62d to fully document the Mg status of the adult rats. The Mg-deficient diet led to a reduction in plasma, erythrocyte and urine Mg concentration but the only tissues affected were kidney and bone; no outward signs of deficiency were observed. At this point, the 4 remaining rats from each diet group received a single dose of (25)Mg and were killed 10d later. Unlike measures of total Mg content, Mg restriction was observed to significantly alter the distribution of isotope within the soft tissue compartment. The proportion of retained isotope accumulated by soft tissues other than skeletal muscle increased. Because this was not true for skeletal muscle, exogenous (25)Mg label was diverted to more metabolically active tissues during Mg restriction. The apparent Mg exchangeable pool (MgEP) size, determined by in vivo stable isotope dilution, reflected this difference in skeletal muscle (25)Mg accumulation; MgEP size was 39% lower in Mg restricted (0.01% Mg) compared to control (0.05% Mg) rats. The pool of exchangeable Mg in bone was also reduced by Mg restriction but, unlike the soft tissue compartment, the reduction in bone exchangeable Mg was quantitatively similar to the reduction in total Mg content.

Journal Article↗
PubMed1990

HLA-identical renal transplants: impact of cyclosporine on intermediate-term survival and renal function.

Seventy-two and 34 consecutive HLA-identical sibling renal transplant recipients were treated with azathioprine/prednisone (AZA; follow-up, 5.0 years) and cyclosporine/prednisone (CSA; mean follow-up, 2.9 years), respectively. Both groups were similar in age, sex, race, and number of transplants, but there were more diabetics in the CSA group (34% v 8%). Actual patient survival at 1 year and actuarial patient survival at 5 years were 100% and 96%, respectively in the CSA group compared with an actual patient survival of 91% and 82% at 1 and 5 years, respectively, in the AZA group. Actual graft survival at 1 year improved from 85% in the AZA group to 97% in the CSA-treated recipients (P less than 0.05). Mean serum creatinine at 5 years remained stable in the AZA group at a mean of 123 mumol/L (1.4 mg/dL) compared with a progressive increase in this parameter to a mean of 212 mumol/L (2.4 mg/dL) after the same time interval in the CSA patients. Furthermore, the slopes of the serum creatinine against time were significantly different between the two groups (P less than 0.01). Mean daily CSA dose averaged 4 mg/kg 12 months following transplantation, with a decrease to 2.4 mg/kg by the fifth year. Causes of death in the AZA group were cardiovascular (eight), sepsis (three), cancer (one); and in the CSA group, Kaposi's sarcoma (one). Causes of graft failure in the AZA group were immunological (six), sepsis (three), technical (two), recurrence of disease (one), and patient death with a functioning graft (five). Technical (one), noncompliance (two), recurrence of disease (one), and patient death with a functioning kidney (one) caused graft failure in the CSA group. No difference in posttransplantation serum cholesterol or incidence of new onset diabetes was observed between the two groups, but hypertension was significantly more frequent (51% v 21%, P less than 0.01) when CSA was used. In conclusion, intermediate-term results of CSA-treated HLA-identical transplant recipients showed improved patient and graft survival with less complications apart from hypertension. However, the slow, but relentless, increase in serum creatinine in the CSA-treated patients compared with those treated with AZA is of concern.

Actuarial Analysis↗
PubMed1990

Beneficial effect of thalidomide and ciclosporin combination in heterotopic cardiac transplantation in rats.

The effect of thalidomide on the prevention of early rejection was studied in heterotopic cardiac transplants between ACI (donors) and Lewis (recipients) rats, in combination with subtherapeutic doses of ciclosporin. Although allografts treated solely with thalidomide (5 mg/kg/day intraperitoneally) survived longer than controls (9.4 +/- 2.7 and 6.3 +/- 0.6 days, respectively, p less than 0.001), the survival rates of animals treated with low dose ciclosporin (1.25 mg/kg/day intraperitoneally) plus thalidomide (1.25, 2.5 and 5 mg/kg/day) were significantly better at 21 days (70, 88.9 and 88.9%, respectively), compared to 55.6% in those treated with ciclosporin (1.25 mg/kg/day) alone. Graft survival rates at 90 days were not significantly different in the thalidomide-ciclosporin combination groups (60, 77.8 and 55.6%, respectively) compared to the ciclosporin group alone (55.6%). We conclude that thalidomide is effective in preventing early rejection of rat cardiac allograft when combined with subtherapeutic doses of ciclosporin, thus avoiding the dose-dependent side effects of ciclosporin in the early posttransplant period.

Animals↗
PubMed1989

9;22 translocation and bcr rearrangements in chronic myelocytic leukemia patients among atomic bomb survivors.

To elucidate the mechanism of leukemia induced by radiation, we studied both chromosome abnormalities and bcr rearrangements of seven CML patients with a history of atomic bomb exposure and 14 CML patients without the exposure. All patients, irrespective of radiation exposure, had 9;22 translocation and rearrangement of the bcr gene in the leukemic cells. Further analysis of breakpoints within the bcr gene demonstrated no distinct difference between the exposed and the non-exposed groups. The present study suggests that formation of the chimeric bcr-abl gene and its genetic products may play an important role in the development of leukemia in either radiation-induced or de novo CML.

Adult↗
PubMed1989

[c-myc gene amplification and N-ras transforming gene in two cases of acute myelocytic leukemia with double minute chromosomes].

We report two leukemia patients with double minutes (DMs) chromosomes. Both patients were diagnosed as having acute myelocytic leukemia (AML) FAB M2. Cytogenetic analysis showed normal chromosome karyotype with 1-53 DMs chromosomes in the first patient, and complex chromosome aberrations including deletion of chromosome 8 at 8q24 region and 1-84 DMs chromosomes in the second patient who had a history of extensive radiotherapy for laryngeal cancer 8 years prior to the development of leukemia. Analysis of DNA from the two patients revealed that oncogene of c-myc was amplified about 5 to 10 folds in the leukemic cells. The other fourteen oncogene of c-myc was c-myb, c-abl and N-myc, showed no increases of gene content. Furthermore, a transforming gene, N-ras was detected in the first patient by in vivo selection assay method. This is the second report on AML patients with c-myc gene amplification and DMs chromosomes.

Aged↗
PubMed1988

Axillary and subclavian vein stenosis: percutaneous angioplasty.

Twenty-nine percutaneous balloon dilations of the axillary and subclavian veins were performed in 19 patients. Stenoses occurred in typical locations of anatomic narrowing or at sites of previous trauma. The initial success rate was 76%, with a 1-year patency rate of 35% and a 2-year patency rate of 6%. Angioplasty can be performed on an outpatient basis with a very low rate of significant complications and can be repeated numerous times to keep a vein patent for many years. This procedure is especially valuable in dialysis patients who have limited access sites.

Angioplasty, Balloon↗
PubMed1988

Dentate granule cells are essential for kainic acid-induced wet dog shakes but not for seizures.

The purpose of this study was to determine the role that dentate granule cells play in wet dog shakes (WDS), behavioral seizures, and hippocampal cell loss caused by systemic administration of kainic acid (KA). Rats were given bilateral injections of colchicine (COL) into the hippocampal formation to selectively lesion dentate granule cells. Two weeks later, they were injected subcutaneously with KA and were observed for WDS and seizures. Seizures were terminated with pentobarbital 2.5 hr after KA injection, and the rats were killed 48 hr later. The integrity of hippocampal cell populations and projections to the hippocampal formation from entorhinal cortex was assessed with radioimmunoassay and immunostaining for methionine-enkephalin (ME) and dynorphin (DYN) A, as well as with Timm and Nissl staining. Results indicate that COL injections eliminated KA-induced WDS, did not affect the latency to onset of seizures, and potentiated KA-induced cell loss in the CA3 region of hippocampus. COL lesions eliminated ME and DYN immunostaining of granule cells, but not ME immunostaining of entorhinal afferents to the dentate gyrus or Ammon's horn. These findings indicate that granule cells are an essential neuronal link in the expression of KA-induced WDS, but that seizures propagate along other pathways in the limbic system.

Animals↗
PubMed1987

Unpredictable cold-immobilization stress effects on voluntary ethanol consumption in rats.

The effects of exposure to a schedule of unpredictable cold-immobilization stress on voluntary ethanol consumption were examined. Following testing for ethanol preference, rats were divided into high, medium and low ethanol consuming groups on the basis of daily ethanol intake (g/kg/day) and exposed to immobilization stress over an 18 day period. Voluntary ethanol consumption was monitored during the stress period and for an additional 36 days post-stress. Results indicated a differential effect of stress on ethanol intake in that low ethanol consuming rats increased their ethanol intake during the stress period and maintained this increase throughout the entire post-stress period as compared to non-stressed controls. High ethanol consuming groups demonstrated a small (marginally significant) decrease in ethanol intake during the stress period as compared to baseline levels. No change in ethanol intake was observed for the medium ethanol consuming groups. The results suggest that unpredictable immobilization stress has a differential effect on ethanol intake depending upon pre-stress levels of ethanol consumption.

Alcohol Drinking↗
PubMed1987

The role of percutaneous angioplasty in the management of chronic hemodialysis fistulas.

One hundred forty-one dilatations of stenotic lesions in dialysis access fistulas were performed. The initial success rate was 82%. The one-year patency rate was 45%, with a 2-year patency rate of 24%. Best results were obtained with a discrete stenosis at a graft-to-vein anastomosis. The procedure can be done on an outpatient basis and, although long-term results are poor, in appropriate patients multiple dilatations can be performed to keep a fistula functioning for many years.

Aneurysm↗
PubMed1987

In vivo potentiation of cyclosporine immunosuppression by calcium antagonists.

We have shown that the addition of verapamil, a calcium channel blocking agent, or trifluoperazine, a phenothiazine, to a regiment using the immunosuppressive agent Cs significantly enhances heterotopic cardiac allograft survival in an ACI to Lewis transplant model. This work verifies previous in vitro work from our laboratory and offers a potential therapeutic strategy to decrease the dose of Cs needed for effective immunosuppression while perhaps lessening its dose-related side effects.

Animals↗
PubMed1987

Enzymatic mechanisms in the metabolic activation of N-nitrosodialkylamines.

The metabolism of several N-nitrosodialkylamines was studied using rat liver microsomes and purified cytochrome P450 isozymes in a reconstituted monooxygenase system. With purified acetone/ethanol-inducible cytochrome P450 (P450ac), high N-nitrosodimethylamine (NDMA) demethylase activity was observed. Cytochrome b5 was also involved in NDMA metabolism by decreasing the Km of NDMA demethylase. A close relationship between the demethylation and denitrosation of this substrate was observed. P450ac was also active in the metabolism of N-nitrosoethylmethylamine (NEMA), but was less active than phenobarbital-inducible cytochrome P450 (P450b) in the metabolism of N-nitrosobutylmethylamine (NBMA), especially in catalysing the debutylation reaction. Similar substrate specificity was demonstrated with liver microsomes from rats treated with other inducers. With different P450 isozymes and microsomes, a close relationship between metabolism and activation of nitrosamines to mutagens to V79 cells was demonstrated. DNA alkylation by NDMA in vitro was correlated with the rate of metabolism of these compounds, whereas DNA alkylation in vivo was more complex and was dose-dependent. The work demonstrates the importance of knowledge of the substrate specificity of cytochrome P450 isozymes in understanding the mechanisms of the metabolic activation of nitrosamines.

Animals↗
PubMed1986

Behavioral effects of centrally administered dynorphin and [D-ala2-D-leu] enkephalin (DADLE) in rats.

Dynorphin and [D-ala2-D-leu]enkephalin (DADLE) were administered directly into the cerebrolateral ventricles of rats and effects on various indices of sensorimotor function and retention of a passive avoidance task were measured. Dynorphin markedly suppressed exploratory motor activity and decreased responsiveness to an acoustic stimulus. Although increases in latency to respond to a noxious thermal stimulus were seen in rats after dynorphin, these changes were always associated with alterations in motor capacity. Injection of dynorphin immediately after a passive avoidance training trial had no significant effect on retention 1 week later. The physiological effects of DADLE were clearly different than those of dynorphin. DADLE produced a biphasic decrease followed by an increase in motor activity and an increased acoustic startle reactivity. DADLE had no effect on reactivity to a noxious thermal stimulus. Posttrial administration of DADLE significantly impaired retention of a step-through passive avoidance task 1 week after training. These data indicate different neurobiological roles for kappa and delta opiate receptors in the central nervous system.

Acoustic Stimulation↗