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Biomedical subjects

K Y Tu

Publications and source records attributed to K Y Tu.

11 recordsLinked to original sources
PubMed1995

Protective effect of vitamin E on lymphocyte growth capacity during incubation in vitro.

Vitamin E, an essential lipid-soluble micronutrient, plays an important role in the immune system and serves as an immunostimulant in geriatric subjects. Using an in vitro incubation to simulate aging processes, we find that vitamin E mitigates loss of growth capacity in lymphocytes. Vitamin E presence during in vitro incubation did not affect significantly the level of peroxidation, the effects of exogenous IL-2, PGE2, or indomethacin, nor levels of IL-2 production. Thus, the preservative effect on lymphocyte growth by vitamin E is not due primarily to its antioxidant function or to interleukin-2 or prostaglandin effects. The decreased growth capacity generated by in vitro incubation is accompanied by a variety of cellular alterations, including decreased CD5 surface antigen, enhanced suppression by adherent cells, and impaired communication between lymphocytes and adherent cells. The decrease in CD5 surface antigen correlates inversely with the cell density required for maximal cell proliferation, and the diminished CD5 levels were unaltered by vitamin E presence during the aging process. In contrast, protection of T-cell proliferative capacity by vitamin E in vitro correlates with diminished suppression by adherent cells and normalized interaction between lymphocytes and adherent cells.

Adult↗
PubMed1995

Human lymphocytes incubated in vitro share multiple characteristics with geriatric-derived lymphocytes: a potential in vitro model for aging?

Aging involves a complicated set of parallel reactions that result in multiple cellular and organismic changes and may eventuate in chronic illness. In the immune system, several alterations that correlate with age have been established. In the present study, we report the results of incubating lymphocytes in vitro in whole blood and, employing measures known to be age-dependent, compare these cells 'aged' in vitro with cells from geriatric patients aged in vivo. Cells from blood aged in vivo and incubated in vitro share a number of common characteristics that include decreased growth capacity, shifted growth patterns, increased suppression by adherent cells, decrease in CD5 surface antigen, similar responses to addition of exogenous IL-1, IL-2, PGE2, or indomethacin, and similar production of PGE2. Differences found between in vivo aging and in vitro incubation are IL-2 plasma levels and IL-2 production by activated cells monitored in conditioned minimal medium. Based on these observations, this in vitro system provides a simple method to generate cells that exhibit a very significant subset, but not all, of the characteristics associated with in vivo aging in lymphocytes.

Adult↗
PubMed1995

Glycerol-3-phosphate dehydrogenase activity in human lymphocytes: effects of insulin, obesity and weight loss.

Insulin exposure stimulates an increase in glycerol-3-phosphate dehydrogenase (G3PDH) activity in isolated human lymphocytes that correlates to an increase in G3PDH mRNA and requires new protein synthesis. Synthetic diacylglycerol or phorbol ester can mimic the effect of insulin on G3PDH activity, suggesting that protein kinase C may be involved in regulation of G3PDH levels. In addition, lithium chloride, an inositol phosphate phosphatase inhibitor, and calcium uptake inhibitors can abolish insulin stimulation of G3PDH activity. For obese subjects in whom insulin resistance in vitro can be demonstrated, the extent of insulin stimulation of G3PDH activity is decreased compared to normal weight individuals, and treatment by a very low calorie diet restores insulin stimulation of G3PDH activity. Thus, insulin stimulation of G3PDH activity is dependent upon the metabolic state of the subject from whom the cells are obtained.

Diet, Reducing↗
PubMed1994

Glucose and insulin responses in isolated human lymphocytes reflect in vivo status: effects of VLCD treatment.

Human lymphocyte growth response to mitogen was examined in vitro under different conditions to monitor aspects of carbohydrate utilization in three groups: obese nondiabetic, obese/NIDDM, and normal-weight individuals. Although lymphocyte growth capacity in minimal medium for these three groups was found to be similar at a glucose concentration of 72 micrograms/ml in the absence of insulin or glycerol, differences in mitogen-stimulated growth were observed at lower glucose concentrations or in the presence of insulin or glycerol. Interestingly, these metabolic alterations in lymphocytes can be normalized by treating obese and obese/NIDDM subjects with a very low calorie diet (VLCD) regimen. The results of this study indicate that lymphocyte culture in a defined medium may provide a mechanism to examine different metabolic states and to evaluate treatment regimens (diet, exercise, etc.) for obese and NIDDM subjects.

Blood Glucose↗
PubMed1992

Effects of discectomy on the stress distribution in the lumbar spine.

The change of the stress distribution of the lumbar spine after discectomy was analysed by the three-dimensional finite element method. It was shown that the stress level in the posterior element was higher, but that in the anterior element was lower than before disc excision. The most significant change of the stress distribution was found in the trabecular bone of the vertebral body. It is considered that in discectomy the normal disc tissue should be preserved as much as possible to maintain good function of the spine.

Biomechanical Phenomena↗
PubMed1991

Lumbar intervertebral disc prosthesis. An experimental study.

To provide a more effective treatment and improve the outcome of surgical treatment of lumbar intervertebral disc protrusion, the values of lumbar intervertebral disc prosthesis (LIDP) were investigated. LIDP was specially designed and made of silicone rubber. The properties of material mechanics were investigated by compressive test and damage test of LIDP specimens. The biocompatibilities of LIDP were observed experimentally in monkeys. The surgical applicabilities were studied by in vitro experiments of fresh human lumbar spine. The results showed that LIDP has the advantages of good biomechanical applicability, biocompatibility and surgical applicability. LIDP is able to maintain the intervertebral space, stress balance and stability of the lumbar spine. after lumbar intervertebral disc excision, the replacement of LIDP could restore the functions of the lumbar spine and improve the curative results of disc excision.

Adult↗
PubMed1990

Effect of partial discectomy on the stability of the lumbar spine. A study of kinematics.

The effect on the stability of the lumbar motion segment, as affected by partial discectomy, was investigated using three-dimensional motion measurement technique. Eight functional spinal units from fresh cadaver lumbar spines were potted and clinically relevant loads applied through a special loading frame attached rigidly to the top vertebra of the specimen. Partial discectomy was performed on the right side of the specimen. The three-dimensional motions of each lumbar motion segment, before and after partial discectomy, were recorded. The results showed that partial discectomy significantly affects the stability of lumbar spinal motion segments. The clinical relevance of this finding is discussed.

Adult↗
PubMed1988

Treatment of longitudinal injuries in avascular area of meniscus in dogs by trephination.

A study promoting the healing of longitudinal injuries in an avascular area of the meniscus in 21 male dogs is reported. One horizontal hole from the peripheral vasculature to one of the artificial longitudinal injuries to both medial menisci of the knee in each dog was made with a needlelike trephine. The knee joints were not immobilized and the samples were taken 2, 4, 8, 12, and 24 weeks, respectively, after the operation. [3H]Thymidine was injected into the joint cavity 72 h before the sample was taken. Healed lengths were measured, and pathologic examinations and autoradiography were performed. The results showed that all of the injuries treated with trephination were partly or totally healed whereas those in controls were not healed at all, suggesting that trephination may be the procedure of choice for clinic orthopedists dealing with such injuries. By the 8th week, the healed length stopped increasing, the scar tissue began to mature, and the DNA synthesis of the fibroblasts in the granulation tissue and the fibrochondrocytes in the trephined meniscus reduced. It is thought that the fibrochondrocyte of the meniscus and the fibroblast in the granulation might be capable of obtaining the thymidine directly from the synovia of knee joint for their DNA metabolism. Multiplication of the fibrochondrocyte in the injured meniscus was also found.

Animals↗