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Biomedical subjects

J Hong

Publications and source records attributed to J Hong.

232 records · Page 13Linked to original sources
PubMed1977

Reduction of error rates in the microlymphocytotoxicity test.

The overall error rate of the microlymphocytotoxicity test has been reduced from 1.08% in 1971 to approximately 0.35%, based on comparisons of 882 replicate test pairs (different bleedings) and on family studies, with 0.11% attributable to "reading" errors. This reduction was attributed to automation for lymphocyte adding, better incubation temperature control, better technical preparation of cells and stronger, more monospecific sera. Three types of errors contribute to the overall error rate: random, sera-related (affected by strength and specificity), and lymphocyte-related (possible B-cell reactivity and donor/lymphocyte physiological condition). Strongly skewed error distributions, which seem to be lymphocyte-related, occurred in less than 4% of the test pairs.

Cytotoxicity Tests, Immunologic↗
PubMedDate not supplied

On the mechanism of growth of cells (Bacillus amyloliquefaciens) in the mixed aqueous two-phase system.

The growth of Bacillus amyloliquefaciens in the aqueous two-phase system, made up of polyethylene glycol, dextran, and water, was investigated. Generally, Bacillus partitions in the dextran phase, but the magnitude of the separation depends largely on the overall composition of polymers in the phase system. The kinetics of growth of Bacillus amyloliquefaciens was studied in the polyethylene glycol-rich continuous phase, dextran-rich dispersed phase, and in the mixed phase. From the kinetic data it appears that increasing the overall polymer composition causes the cells to adsorp at the interface. On the other hand, partition measurements indicate that increasing polymer concentrations make the cell partitioning more one-sided. This anomaly is explained by studying the interfacial adsorption of cells via dynamic surface tension measurements.

Adsorption↗
PubMedDate not supplied

Theoretical analysis of the effect of cell recycling on recombinant cell fermentation processes.

A cell recycle system is studied for two-stage continuous fermentation. Cell recycle around the second stage provides higher cell concentrations than processes without recycle and a longer residence time of the cell, which is necessary for inducible products, especially in recombinant cell fermentation. Residence time distribution of the cell in the fermentor is important for the optimization of inducible products. The residence time distributions are studied for the cases with and without significant cell growth in the second stage. With cell growth in the second stage, three cases are considered. These are the cases of (1) zero residence time for two daughter cells after the cell division, (2) zero residence time of one daughter cell after the cell division and inherited residence time for the other daughter cell from the mother cell after the cell division, and (3) two daughter cells having the residence time of the mother cell after the cell division.

Cell Cycle↗
PubMedDate not supplied

Stimulated muscle force assessment of the sternocleidomastoid muscle in humans.

The aim of this study was to configure a force assessment device and determine potential testing protocols for quantitative evaluation of human neck muscles. The study design consisted of non-randomized control trials, with repeated measures; data from 12 normal subjects were obtained. Several apparatuses were designed, constructed and tested, i.e. single or short trains of supramaximal stimuli were used to activate sternocleidomastoid muscles in a seated position with strain gauges (6.2% variability with double-pulse stimulations) or in supine positions with load cells (5.2% variability with similar activation). Using a final configuration, maximum elicited peak forces were 1742 +/- 323 g for single-pulse and 3976 +/- 484 g for double-pulse stimulations (n = 12). There were no significant differences in maximum recorded peak torques between sessions per individual. Yet, detectable muscle activities were simultaneously recorded in the contralateral sternocleidomastoid muscles. This non-invasive, quantitative assessment approach has novel value for determining treatment efficacy, disease progression, and/or approach has novel value for determining determining treatment efficacy, disease progression, and/or relative distribution of muscle strength in patients with abnormal neck muscle function.

Electric Stimulation↗
PubMedDate not supplied

The effect of diastolic stiffness on ventricular function after partial ventriculectomy: a finite element simulation.

Partial ventriculectomy (PV) has been proposed by Batista and colleagues to improve cardiac function in patients with dilated cardiomyopathy (DCM); however, results have been mixed. We tested the hypothesis that preoperative diastolic function affects the stroke volume/end-diastolic pressure (Starling) relationship after PV. A previously described finite element simulation of DCM and PV was used. Diastole and end systole were represented by separate elastic finite element models with different unloaded shapes and nonlinear material properties. Left ventricular (LV) end-systolic elastance (E(ES)), diastolic compliance (DC), and Starling relationships were calculated. DC was varied by changing Ogden material property alpha(i) from 12 (compliant) to 20 (stiff). PV was simulated at 20% LV mass reduction. The slope of the Starling relationship increased from 1.82 to 1.21 as alpha(i) increased from 12 to 20. Partial ventriculectomy increased the Starling relationship in each case from 1.34 to 1.01 respectively. However, the net result in each case is a decrement in the Starling relationship with resection, and the smallest decrement was associated with the highest diastolic stiffness (alpha(i) = 20). Partial ventriculectomy depressed the Starling relationship for all values of diastolic compliance. It is expected that patients with a higher diastolic stiffness should do better.

Cardiomyopathy, Dilated↗
PubMedDate not supplied

Differential effects of estradiol and its analogs on cyclin D1 and CDK4 expression in estrogen receptor positive MCF-7 and estrogen receptor-transfected MCF-10AEwt5 cells.

Estradiol stimulates the growth of a majority of human breast tumors containing the estrogen receptors (ERs), proteins that mediates estrogen function. Opposing effects of estradiol have been found in cells expressing endogenous ER and those containing a transfected ER. To understand the role of estradiol structure in diverse estrogenic responses related to cell cycle regulation, we evaluated the effects of estradiol and its analogs on cell cycle progression, and the expression of cyclin D1 and the cyclin dependent kinase 4 (CDK4) in ER-positive MCF-7 and ER-transfected MCF-10AEwt5 cells. Four analogs of estradiol, with a re-positioned or a deleted hydroxyl group, were used. Our results show that estradiol and all of the analogs facilitated cell cycle progression of MCF-7 cells. In contrast, only estradiol inhibited the cell cycle progression of MCF-10AEwt5 cells significantly. Western blot analysis revealed that cyclin D1 protein increased to the maximal level by 6 h after the initiation of cell cycle from G1 phase of MCF-7 cells. The least effective analog in inducing cyclin D1 was 3-hydroxyestratriene. However, this analog was most effective at inducing CDK4, contributing to its efficacy in facilitating MCF-7 cell cycle. In contrast to MCF-7 cells, the level of cyclin D1 protein was not influenced significantly by estradiol or its analogs in MCF-10AEwt5 cells. Sucrose gradient sedimentation analysis of ER from MCF-7 cells showed that the major peak of [3H]-estradiol bound to ER could be displaced by a 10-fold excess of unlabelled estradiol or any of the analogs. In contrast, several analogs were less effective than unlabelled estradiol in competitive displacement of [3H]-estradiol bound to ER from MCF-10AEwt5 cells. These data indicate that the induction of cyclin D1 is an important part of the growth stimulatory effects of estrogens in MCF-7 cells, but it may not be involved in growth inhibition of MCF-10AEwt5 cells. Our results also show that estrogenic compounds interact with ER from MCF-10AEwt5 cells with altered ligand binding affinity, possibly due to the absence or dysfunction of certain transcription factors or ER-associated proteins that co-regulate ER function.

Breast Neoplasms↗
PubMedDate not supplied

Vascular access surgery for maintenance hemodialysis. Variables in hospital stay.

Access surgery in support of maintenance hemodialysis is a major factor contributing to prolonged hospitalization in the hemodialysis patient population. In surveying 140 consecutive patients admitted for access surgery, average length of stay was 14 days, independent of race or underlying cause of renal disease. Extended length of stay was most commonly encountered in older patients admitted for thrombosed fistulae or grafts. Postoperative fever, the need for repeated femoral catheterization, delay in access revision or placement due to infection, and the need for adequate social service support resulted in prolonged hospitalization. Understanding and preventing factors that prolong hospitalization may allow the minimization of length of stay in the future and improve quality of life for the end-stage renal disease patient, while also decreasing the cost of care.

Adult↗
PubMedDate not supplied

Long-term outcome of one haploidentical live related donor transplantation in children.

UNLABELLED: We report on 69 children, 6 months to 18 years old, who received a one-haploidentical live related donor transplantation from 11/72 through 4/89. Thirty patients were maternal and 22 were paternal recipients; 23 were Black, 27 Caucasian, 17 Hispanic, and 1 each Oriental and Arabic. The original diagnoses in these patients were aplastic/dysplastic kidneys 13%, obstructive uropathy 30%, focal segmental glomerulosclerosis (FSGS) 23% and lupus nephritis 10%. RESULTS: 1-, 5-, 10- and 15-year actuarial patient and graft survivals were 98, 84, 84, 84% and 94, 70, 41, 30% respectively. Actual 5-year graft survival of paternal recipients was better than maternal recipients (p less than 0.05). No differences were noted comparing actuarial graft survival between Blacks, Caucasians and Hispanics. 1/16 FSGS and 1/7 lupus nephritis patients had recurrence of their original disease. Posttransplant therapy in 37 patients consisted of azathioprine and prednisone while 32 patients received ciclosporin A (CSA) and prednisone. At transplantation, CSA and prednisone patients were younger, i.e., 10.7 years (range 0.5-18) compared to 13.3 years (range 4-18) and (p less than 0.03) in azathioprine and prednisone patients. The 5-year actuarial graft survival of azathioprine and prednisone patients was 57% compared to 76% in CSA and prednisone patients. 16/32 CSA and prednisone patients had their prednisone discontinued for a mean duration of 18 months (3-54 months). Ten of these 16 patients were prepubertal and had their growth hormone levels measured. All had an adequate level (greater than or equal to 10 ng/ml) poststimulation. Five of the 10 patients were less than 6 years of age and exhibited accelerated growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Profiling clinically important metabolites in human urine by capillary electrophoresis and electrochemical detection.

Clinically important metabolic markers, including alditols, carbohydrates, and amino acids, were profiled directly in urine by capillary electrophoresis with electrochemical (EC) detection via oxidation at a copper electrode. CE in strongly basic buffers was found to provide an effective means with which to achieve the separation of these compounds with the buffer pH being the most important factor governing the separation. EC detection at a copper electrode provided a convenient means for detecting all of these species with sensitivity usually down to the femtomole level. Most important, both the CE separation and EC detection were performed directly on the urine samples without extensive sample cleanup and with no analyte derivatization required. Specific compounds that were able to be identified and quantitated included glucose, galactose, creatinine, and uric acid. All were found to be present at normal levels in urine samples from healthy subjects.

Electrochemistry↗