Biomedical subjects

Hongmei Yu

Publications and source records attributed to Hongmei Yu.

8 recordsLinked to original sources

PubMed2005

Outcome of ethnic minorities with acute or chronic leukemia treated with hematopoietic stem-cell transplantation in the United States.

PURPOSE: We previously reported a higher risk of mortality among Hispanics after allogeneic hematopoietic stem-cell transplantation (HSCT). However, it is not known how specific post-transplantation events (acute or chronic graft-versus-host disease [GVHD], treatment-related mortality [TRM], and relapse) may explain mortality differences. The purpose of this study was to examine the relationship between ethnicity and post-transplantation events and determine their net effect on survival. PATIENTS AND METHODS: We identified 3,028 patients with acute myeloid leukemia, acute lymphoblastic leukemia, or chronic myeloid leukemia reported to the International Bone Marrow Transplant Registry between 1990 and 2000 who received an HLA-identical sibling HSCT after a myeloablative conditioning regimen in the United States. There were 2,418 white patients (80%) and 610 ethnic minority patients (20%), of whom 251 were black (8%), 122 were Asian (4%), and 237 were Hispanic (8%). Cox proportional hazards regression was used to compare outcomes between whites and ethnic minorities while adjusting for other significant clinical factors. RESULTS: No statistically significant differences in the risk of acute or chronic GVHD, TRM, or relapse were found between whites and any ethnic minority group. However, Hispanics had higher risks of treatment failure (death or relapse; relative risk [RR] = 1.30; 95% CI, 1.08 to 1.54; P = .004) and overall mortality (RR = 1.23; 95% CI, 1.03 to 1.47; P = .02). CONCLUSION: The higher risks of treatment failure and mortality among Hispanics may be the net result of modest but not statistically significant increases in both relapse and TRM and cannot be accounted for by any single transplantation-related complication. Further studies should examine the role of social, economic, and cultural factors.

Acute Disease↗

PubMed2005

Diffusion dependent cell behavior in microenvironments.

Understanding the interaction between soluble factors and cells in the cellular microenvironment is critical to understanding a wide range of diseases. Microchannel culture systems provide a tool for separating diffusion and convection based transport making possible controlled studies of the effects of soluble factors in the cellular microenvironment. In this paper we compare the proliferation kinetics of cells in traditional culture flasks to those in microfluidic channels, and explore the relationship between microchannel geometry and cell proliferation. PDMS (polydimethylsiloxane) microfluidic channels were fabricated using micromolding methods. Fall armyworm ovarian cells (Sf9) were homogeneously seeded in a series of different sized microchannels and cultured under a no flow condition. The proliferation rates of Sf9 cells in all of the microchannels were slower than in the flask culture over the first 24 h of culture. The proliferation rates in the microchannels then continuously decreased reaching 5% of that in the flasks over the next 48 h and maintained this level for 5 days. This growth inhibition was reversible and influenced only by the cell seeding density and the channel height but not the channel length or width. One possible explanation for the observed dimension-dependent cell proliferation is the accumulation of different functional molecules in the diffusion dominant microchannel environment. This study provides insights into the potential effects of the diffusion of soluble factors and related effects on cell behavior in microenvironments relevant to the emerging use of microchannel culture systems.

Animals↗

PubMed2002

[Associations of insulin resistance and pancreatic beta-cell function with plasma glucose level in type 2 diabetes].

OBJECTIVE: To investigate the influence of insulin resistance and pancreatic beta-cell function on plasma glucose level in type 2 diabetes so as to provide theoretical basis for reasonable selection of hypoglycemic agents. METHODS: The plasma non-specific insulin (NSINS), true insulin (TI) and glucose in eight-one type 2 diabetics, 38 males and 43 females, with a mean age of 53 years, were examined 0, 30, 60 and 120 minutes after they had 75 grams of instant noodles. The patients were divided into two groups according to their fasting plasma glucose (FPG): group A (FPG < 8.89 mmol/L) and group B (FPG> = 8.89 mmol/L). The insulin resistance was evaluated by HOMA-IR, the beta-cell function was evaluated by HOMA-beta formula and the formula deltaI(30)/deltaG(30) = (deltaI(30)-deltaI(0))/(deltaG(30)-deltaG(0)). The insulin area under curve (INSAUC) was evaluated by the formula INSAUC=FINS/2+INS(30)+INS(60)+INS(120)/2. RESULTS: The mean FPG was 6.23 mmol/L in group A and 12.6 mmol/L in group B. PG2H was 11.7 mmol/L in group A and 19.2 mmol/L in group B. The TI levels in group B at 0, 30, 60, 120 min during standard meal test were significantly higher than those in group A: 6.15 +/- 1.06 vs 4.77 +/- 1.06, 9.76 +/- 1.1 vs 5.88 +/- 1.1,14.68 +/- 1.11 vs 6.87 +/- 1.1 and 17.13 +/- 1.12 vs 8.0 +/- 1.1 microU/dl (all P< 0.01). The NSINS showed the same trend. The insulin resistance in group B was 1.5 times that in group A. With the insulin resistance adjusted, the beta cell function in group A was 5 to 6 times that in group B. The INSAUC in group A was 1.66 times larger than that in group B, especially the INSAUC for true insulin (2 times larger). The contribution of insulin resistance and beta cell function to PG2H was half by half in group A and 1:8 in group B. beta cell function calculated by insulin (Homa-beta) explained 41% of the plasma glucose changes in group A and 54% of the plasma glucose changes in group B. The contribution of insulin deficiency to plasma glocose was 3.3.times that of insulin resistance in group A and was 9.5 times that of insulin resistance in group B. Insulin sensitivity explained 12% of the plasma glucose changes in group A, and only 5.7% of the plasma glucose changes in group B. CONCLUSION: Diabetics with FPG greater than 8.89 mmol/L have both higher insulin resistance and poorer beta-cell function, their hyperglycemia being caused mainly by beta-cell failure, The combined use of insulin sensitizer and insulin or insulintropic agents during the initial stage of treatment is effective.

Adult↗

PubMed2002

Silicone implant in augmentation rhinoplasty.

During the past 6 years the authors have treated 406 patients with classic silicone augmentation rhinoplasty. The types and incidence of complications after subcutaneous or subfascial implantation are examined and discussed. They propose that most complications are related to the depth of the implant and the character of the tissues. To improve their operation and to prove their hypothesis, they performed subperiosteal augmentation rhinoplasty in 22 patients with satisfactory results. At the same time, they investigated the biomechanical properties of human nasal periosteum and fascia, including tensile strength, the stress-strain relationship, and stress relaxation characteristics under uniaxial tension. Although it has less failure strain, the periosteum has more tensile strength than fascia. So, in the view of biomechanics, the periosteum is thicker, tougher, and stiffer than fascia, and thus more suitable for covering silicone implants.

Adolescent↗

PubMed2002

Fluid shear stress induces the secretion of monocyte chemoattractant protein-1 in cultured human umbilical vein endothelial cells.

In this study we investigated the patterns of fluid shear stress on induction of monocyte chemoattractant protein-1 (MCP-1) secretion in cultured human umbilical vein endothelial cells (HUVECs). MCP-1 is a potent special chemoattractant, which recruits monocytes into the sub-endothelium. This process is one of the early events of atherosclerosis. We examined the pattern of fluid shear stress inducing the secretion of MCP-1 in cultured HUVECs from the view of biomechanics. In our experiments, HUVECs were subjected to controlled levels of shear stress (4, 10, 20 dyn/cm(2)) in a parallel plate flow chamber. MCP-1 in HUVECs of different periods was measured by an immunohistochemistry method and digital image analysis; MCP-1 in perfusion was measured by sandwich ELISA. The results demonstrated the increase of MCP-1 synthesis and secretion by shear stress was time- and force-dependent. The accumulated level of MCP-1 in HUVECs under lower shear stress (4 dyn/cm(2)) for 4-5 hrs was 3-fold compared with that for static cells. When the shear stress lasted to 6 hrs, the secretion of MCP-1 was reduced to normal levels and could not be increased even when the shear stress lasted for 12 hours. 10 dyn/cm(2) had less effect on the secretion of MCP-1 compared with 4 dyn/cm(2). This research provides data for understanding the mechanism of the contribution of hemodynamic forces to atherosclerosis.

Chemokine CCL2↗

PubMed2002

Effects of fluid shear stress on expression of proto-oncogenes c-fos and c-myc in cultured human umbilical vein endothelial cells.

The objective of our research was to reveal the effects of different shear stresses on the expression of proto-oncogenes c-fos and c-myc in cultured human umbilical vein endothelial cells (HUVEC). A parallel plate flow chamber was used to control the value and duration of shear stress (SS), and the expression of c-fos and c-myc protein was measured by immunocytochemistry methods and image analysis software. Some important conclusions were drawn. In the stationary state, c-fos protein levels were very low. The SS's of 4 dyn/cm(2) and 10 dyn/cm(2) induced rapid increases of c-fos protein levels, especially the SS of 10 dyn/cm(2). The levels peaked at 1.0 h. Then, c-fos protein levels began to decrease, after 2.5 h, they declined to almost basal levels. In the stationary state, the c-myc protein levels were also very low slowly increasing after the onset of shear stress. The effects of 4 dyn/cm(2) and 10 dyn/cm(2) SS on c-myc protein expression levels had no difference and apparently were less than the effect on c-fos protein levels. The c-myc protein levels peaked at 1.5 h. Subsequently, they fell to basal levels at 2.5 h. Increased expression of these proto-oncogenes mediated by shear stress may have important effects on the regulation of critical cell activities, such as proliferation and differentiation.

Blood Circulation↗

PubMed2002

[Comparison of biomechanical properties between human nasal periosteum and fascia].

There has been a lot of controversies on which layer the silastic implants should be inserted in the augmentation rhinoplasty, i.e. subperiosteal or deep subfascial. This study is to investigate the biomechanical properties of human nasal periosteum and deep fascia, including tensile strength, stress-strain and stress relaxation characters under uniaxial tension system. The periosteum is stronger in tensile strength than that of the fascia, but it is less elastic. Under a sudden increase of load, the periosteum relaxes far less than the fasia. Therefore, in view of biomechanics, the periosteum is thicker, tougher, stiffer and less relaxation than facia, thus has a better fixation effect.

Biomechanical Phenomena↗

PubMedDate not supplied

Silicone implants in augmentation rhinoplasty.

During the past six years, we have treated 406 patients with classical silicon augmentation rhinoplasty. The types and incidence of complications after subcutaneous or subfascial implantation were examined and discussed. We proposed that most complications are related to the depth of the implant and the character of the tissues. In order to improve our operation and prove our hypothesis, we performed subperiosteal augmentation rhinoplasty in 22 cases with satisfactory results. At the same time, we investigated the biomechanical properties of human nasal periosteum and fascia, including tensile strength, stress-strain relationship and stress relaxation characters under uniaxial tension. Although less elastic, the periosteum has more tensile strength than fascia. So, in the view of biomechanics, the periosteum is thicker, tougher, and stiffer than fascia, thus more suitable for covering silicon implants.

Adolescent↗