Biomedical subjects

D Chen

Publications and source records attributed to D Chen.

At least 235 records · Page 13Linked to original sources

PubMed2000

A SXRF method for determining the relative concentration of trace elements in plasma protein affected by cisplatin.

This article presents an analytical method for the determination of the relative concentrations of trace elements in plasma protein by gel chromatography combined with SXRF (synchrotron radiation X-ray fluorescence). The fraction of plasma protein of male Kunming mice (body weight 24.2 +/- 0.3 g), treated with a cisplatin i.p. injection at a dose of 10 mg/kg, was obtained by the separation of a Sephadex G-50 column (buffered with ammonium acetate, pH 5.7). The SXRF experiments were performed at the Beijing Electron Positron Collider synchrotron radiation facility. The elements (Pt, S, Ca, Fe, Ni, Cu, Zn, Se, Br, and Sr) in the fraction of the plasma proteins (>22 kDa) were assayed using highly sensitive SXRF. The relative concentrations of elements were calculated by a normalization of Compton scattering intensity around 22 keV, after the normalization for the collection time of the X-ray spectrum and the counting of the ion chamber, and subtracting the contribution of the polycarbonate film for the supporting sample. The determination could prove that the element Pt in plasma was bound with macromolecular protein. Cu and S were present in the fraction of the protein in mice treated with cisplatin increase, and their ratios of treated/control were 1.66 +/- 0.06 and 1.78 +/- 0.33, respectively; Zn decreased to a ratio of 0.78 +/- 0.09. Our results are in agreement with others that cisplatin exposure leads to a marked loss of kidney copper and a moderate rise in kidney zinc. However, this article primarily describes one of the analytical methods used; it does not emphasize the results of the effect of cisplatin on trace elements in plasma protein.

Animals↗

PubMed2000

Human olfactory communication of emotion.

Nonhuman animals communicate their emotional states through changes in body odor. The study reported here suggests that this may be the same for humans. We collected underarm odors on gauze pads from 25 young women and men on two different occasions. On one occasion the donors were induced to feel happy by viewing an excerpt from a funny movie whereas on the other, separated by a day, they were induced to feel afraid by watching an excerpt from a frightening movie. One week later, 40 women and 37 men were asked to smell several different bottles, some of which contained underarm odor pads collected during the happy movie, some contained underarm odor pads collected during the frightening movie, whereas others contained unused pads (control odor). Each odor was identified on two separate tasks that involved identifying the odor from among three odors and identifying it again from among six odors. Data were the number of women and men who identified an odor correctly on both tasks. When asked to select which bottles contained "the odor of people when they are happy," women chose the correct bottles for both tasks significantly more often than chance. Men chose the bottle which contained the body odors collected when women (but not men) viewed the happy movie more often than would be expected by chance. When asked to select which bottles contained "the odor of people when they are afraid," women and men both chose the bottle that contained the body odors collected when men (but not women) viewed the frightening movie more often than would be expected by chance. The finding suggests that there is information in human body odors indicative of emotional state. This finding introduces new complexity in how humans perceive and interact.

Adult↗

PubMed2000

The gastrointestinal system and bowel management following spinal cord injury.

Gastrointestinal system changes following spinal cord injury (SCI) are generally less obvious than other body system changes. These alterations in function and the response to management, however, may have profound implications on the social, emotional, and physical well-being of the individual with SCI. This article reviews changes in gastrointestinal function following SCI and discusses current issues related to the management of the neurogenic bowel.

Digestive System↗

PubMed2000

Sarcoidosis of the scalp: a case series and review of the literature.

Sarcoidosis of the scalp is a rare manifestation of cutaneous sarcoidosis. We report 4 cases, all in African-American women with systemic sarcoidosis. A review of the English-language literature reveals only 24 reported cases, most in African-American women with systemic involvement and other cutaneous lesions. Scalp sarcoidosis may exhibit variable morphologies and therefore must be kept in the differential diagnosis of plaques or nodules of the scalp as well as both cicatricial and noncicatricial alopecia.

Adult↗

PubMed2000

Internal fixation of cervical trauma following corpectomy and reconstruction. The effects of posterior element injury.

Although biomechanical data indicates that anterior fixation alone in unstable cervical injuries may not provide adequate stability, reports of clinical series indicate general success with this method of treatment. The specific contribution of posterior column injury to overall stability following reconstruction has not been evaluated. This study examined the biomechanical stability of anterior and/or posterior plate fixation following anterior corpectomy and reconstruction for unstable cervical injuries with varying degrees of posterior element injury. The C4-C6 motion segments of ten fresh frozen bovine cervical spines were used. After mounting, nondestructive mechanical testing in axial compression, torsion, flexion, extension, and lateral bending was done as an intact control. A C5 corpectomy with reconstruction using a synthetic bone graft was performed and the posterior ligaments sectioned at the C5-C6 level. Each specimen was sequentially instrumented with anterior and posterior plating alone and in combination and each construct was mechanically retested. The specimens were then further destabilized by bilateral facetectomies at C5-C6 and again tested with the same instrumentation combinations. In comparison to the controls, the spines with a C5 corpectomy/bone graft and posterior ligament rupture with anterior plating demonstrated significantly increased stiffness in flexion, extension, and lateral bending; posterior plating increased stiffness in only flexion and lateral bending. In axial compression and torsion, anterior or posterior plating demonstrated stiffness similar to the controls. Further destabilization by facetectomy significantly decreased stiffness of the instrumented construct (less than control) in torsion with anterior or posterior plate fixation alone. Combined plating showed increased stability compared to controls in all loading conditions for both patterns of instability. Anterior plating alone was able to restore the stability of the cervical spines with posterior ligamentous injury after corpectomy, but it failed to do so with the addition of bilateral facetectomies. For the unstable cervical spine with significant bilateral loss of posterior bony contact, anterior or posterior plating alone may not provide sufficient stabilization in the absence of any additional external immobilization. Combined plating should be considered, which may obviate the need for external immobilization.

Analysis of Variance↗

PubMed2000

[A randomized controlled study of ligustrazine in combination with propranolol for prevention of recurrent esophageal varices bleeding].

OBJECTIVE: To assess the efficacy of Ligustrazine in combination with propranolol in the prevention of recurrent esophageal varices bleeding following liver cirrhosis, and its act mechanism. METHODS: A prospective controlled study was conducted on 74 patients, in whom 38 belonged to treatment group, and 36 to control group. By detecting the portal system hemodynamics in patients with portal hypertension and esophageal varices using color Doppler ultrasound technique, the therapeutic efficacy and safety were investigated. Meanwhile the blood pressure, heart rate, hepatic and renal function were dynamically observed. RESULTS: After four weeks administration of the drugs, the flow of portal vein and splenic vein, the diameter of portal vein and splenic vein in the treatment group were significantly decreased with the values of 1152.36A387.46 ml/min, 529.35A326.31 ml/min, 1.36A0.28 cm, and 0.94A0.19 cm, respectively. No adverse effect was observed on the system circulation and the liver function. In the follow-up period of two years, the rebleeding rate and mortality rate in the placebo group were higher than that in the treatment group, but patients with liver cirrhosis Grade C in the two groups were not significant different. CONCLUSION: Low dose ligustrazine plus propranolol is a safe and effective therapy in preventing recurrent esophageal varices bleeding, and worth further trial.

Adult↗

PubMed2000

[Physical properties of apatite bone cement].

Some properties of the apatite bone cement which is composed of alpha-tricalcium phosphate and hydroxyapatite for use as a biomaterial were investigated. The powder of cement was synthesized from calcium phosphate, calcium carbonate and dicalcium phosphate by solid reaction. Several kinds of citric acid solutions were used for hardening. When the liquid for hardening was 30% (w/w) citric acid solution, the setting time was about six minutes, the compressive strength of hardened bodies was 24.96 MPa, and the solubility was about 1.4 wt%. The compressive strength was increased by the addition of Na or K salt. Especially, when copolymer of acrylic acid/itaconic acid was added to the liquied, the strength was increased about three times, but the setting time was significantly shortened. The results of this study indicate that the apatite bone cement is a potentially highly useful biomaterial for dental and medical applications.

Apatites↗

PubMed2000

Activation of estrogen receptor alpha by S118 phosphorylation involves a ligand-dependent interaction with TFIIH and participation of CDK7.

Phosphorylation of the estrogen receptor alpha (ERalpha) N-terminal transcription activation function AF1 at serine 118 (S118) modulates its activity. We show here that human ERalpha is phosphorylated by the TFIIH cyclin-dependent kinase in a ligand-dependent manner. Furthermore, the efficient phosphorylation of S118 requires a ligand-regulated interaction of TFIIH with AF2, the activation function located in the ligand binding domain (LBD) of ERalpha. This interaction involves (1) the integrity of helix 12 of the LBD/AF2 and (2) p62 and XPD, two subunits of the core TFIIH. These findings are suggestive of a novel mechanism by which nuclear receptor activity can be regulated by ligand-dependent recruitment of modifying activities, such as kinases.

Amino Acid Motifs↗

PubMed2000

Co-operation between protein-acetylating and protein-methylating co-activators in transcriptional activation.

Nuclear hormone receptors (NRs) activate transcription by binding to specific enhancer elements associated with target genes. Transcriptional activation is accomplished with the help of complexes of co-activator proteins that bind to NRs. p160 co-activators, a family of three related 160 kDa proteins, serve as primary co-activators by binding directly to NRs and recruiting additional secondary co-activators. Some of these (CBP/p300 and p/CAF) can acetylate histones and other proteins in the transcription complex, thus helping to modify chromatin structure and form an active transcription initiation complex. We recently discovered co-activator-associated arginine methyltransferase 1 (CARM1), which binds to p160 co-activators and thereby enhances transcriptional activation by NRs on transiently transfected reporter genes. CARM1 also methylates specific arginine residues in the N-terminal tail of histone H3 in vitro. A related arginine-specific protein methyltransferase, PRMT1, also binds p160 co-activators and enhances NR function. PRMT1 methylates histone H4 in vitro. The enhancement of NR function by CARM1, PRMT1 and p300 depends on their interactions with p160 co-activators. In the presence of p160 co-activators, some pairs of these three secondary co-activators provide a highly synergistic enhancement of NR function on transiently transfected reporter genes. We have also observed an enhancement of NR function on stably integrated reporter genes by these co-activators. We propose that the synergy of co-activator function between p300, CARM1 and PRMT1 is due to their different but complementary protein modification activities.

Acetylation↗

PubMed2000

Pediatric falls: is height a predictor of injury and outcome?

Falls account for a significant proportion of pediatric injuries and deaths. A retrospective review of pediatric patients (age 0-14 years) was performed to determine whether patterns of injuries and outcomes could be predicted on the basis of the height of the fall. In addition we evaluated the triage criterion "fall greater than 15 feet" for transport of patients to a trauma center. Patients were stratified by the height of the fall: greater than or less than 15 feet. The end points for analysis were the associated injuries and survival. Patients who fell less than 15 feet had a higher incidence of intracranial injuries (and fewer extremity fractures than patients who fell more than 15 feet). Skull fractures were the most frequent injury and were associated with an increase in intracranial injuries in both subgroups. In conclusion low-level falls are associated with significant intracranial injuries. The evaluation of patients sustaining low-level falls should not be limited on the basis of the height of the fall. Using falls of greater than 15 feet as a triage criterion for transport to a trauma center needs to be prospectively evaluated to ensure that critically injured patients are triaged appropriately.

Accidental Falls↗

PubMed2000

An antigenic threshold for maintaining human immunodeficiency virus type 1-specific cytotoxic T lymphocytes.

BACKGROUND: Using the lymphocytic choriomeningitis virus (LCMV) model in mice, a number of studies show that memory cytotoxic T-lymphocyte (CTL) responses are maintained in the presence of continuous antigenic stimulation. Yet, other groups found that memory CTL specific for LCMV could last for a lifetime in mice without viral antigens. Thus, the extent to which an antigen is required for the maintenance of virus-specific CTL remains controversial. In humans, very few studies have been conducted to investigate the relationship between the quantity of antigen and the magnitude of CTL responses. MATERIALS AND METHODS: We quantified CTL precursors (CTLp) using a limiting-dilution analysis (LDA) and CTL effectors (CTLe) using a new Major Histocompatibility Complex (MHC) class I tetramer technology in six long-term nonprogressors (LTNPs) with human immunodeficiency virus type-1 (HIV-1) infection, as well as in eight patients whose viral loads were well suppressed by antiretroviral therapy. The viremia levels in these patients were measured using an reverse transcription polymerase chain reaction (RT-PCR) assay. The proviral DNA load in peripheral blood mononuclear cell (PBMC) was also measured by PCR in four LTNPs. RESULTS: The LTNPs had high levels of HIV-1-specific memory CTLp and CTLe, while maintaining a low plasma viral load. Despite also having low viral loads, patients whose plasma viremia was well-suppressed by effective therapy had low levels of CTLe. CONCLUSIONS: Our findings suggest that a complex, rather than a monotonic, relationship exists between CTL levels and HIV-1 viremia, including what appears to be an antigenic threshold for the maintenance of CTL at a measurable level. Under conditions of "antigen excess,", CTLe levels correlate inversely with viral load. On the other hand, under conditions that are "antigen limited," the correlation appears to be direct.

Adult↗

PubMed2000

The feasibility of a porcine model of acute coronary occlusion and reperfusion using off-pump coronary artery bypass grafting.

We developed an open-chest porcine model of acute coronary occlusion and surgical reperfusion, and attempted to prevent intra-operative ischaemic ventricular fibrillation (VF) by a Retrograde Intracoronary Glyceryl trinitrate (RIG) infusion into the occluded vessel. Five Yorkshire pigs (weight 50 +/- 1.1 kg), randomized into 3 groups, underwent median sternotomy under general anaesthesia. One pig (Group 1, control) underwent sternotomy and pericardiotomy only. Four pigs underwent acute left anterior descending (LAD) coronary occlusion. Two pigs were not reperfused (Group 2). Two pigs underwent surgical reperfusion (Group 3) via left internal mammary artery (LIMA) grafting to the LAD using the Off-Pump Coronary Artery Bypass (OPCAB) technique. Ischaemic injury was assessed using 7-lead electrocardiography (ECG) and transthoracic/epimyocardial echocardiography (ECHO). Group 1: transient intraoperative hypotension and VF occurred. Successful resuscitation and 10-week survival (until sacrifice) with normal left ventricular (LV) function was achieved. Group 2: there were ECG and ECHO evidence of acute LV ischaemic dysfunction in both pigs. The surviving pig had persistent anterior hypokinesis at 8 1/2 months. The other died intra-operatively following progressive ischaemic LV dysfunction despite resuscitative attempts. Group 3: the surviving pig had normal LV function at 8 months. Initial anterior LV akinesis normalized within 7 days. The other developed post-occlusion haemodynamic instability and died intra-operatively despite reperfusion. In this porcine model, acute LAD artery occlusion modified by the novel RIG infusion technique, followed by surgical reperfusion (OPCAB) is feasible. This model would facilitate further development of OPCAB surgical expertise and understanding of the pathophysiology of ischaemia-reperfusion injury.

Animals↗

PubMed2000

[Measure of vibration protection effect of driver's corset and analysis of its biomechanical effect].

The purpose of this study was to evaluate the vibration protection and biomechanical effect of driver's corset. The frequencies of vertfical and horizontal vibrations were measured at low back of driver. The vehicle driven was ISUZU truck (loading capacity 8 tons). Vibration of the driver's lumbar back was measured real time with wear corset and without wear corset when the truck loaded with 6 tons was driven at the spead of ten, thirty and sixty kilometers an hour on the asphalt road. The results showed: 1. Vibration frequencies at driver's low back was under 10 Hz. It is a low frequency vibration. 2. The value of vertical vibration was higher than the value of horizontal (back and forth) vibration. 3. The vibration value of wear corset was higher than un-wear corset. These indicate the driver's corset is effective for protecting lumbar spine by means of change in the biomechanical characteristics and the resonace requencies of lumbar spine. So the driver's corset is one of the good methods for preventing the back pain of drivers.

Automobile Driving↗

PubMed2000

[Effects of insulin-like growth factor-I and insulin-like growth factor binding-protein 1 on development of ovarian follicles during superovulation cycle].

OBJECTIVE: To investigate the effects of insulin-like growth factor I (IGF-I) and insulin-like growth factor binding-protein 1 (IGFBP-1) on development of ovarian follicles during gonadotropin stimulation in in-vitro fertilization (IVF) program. METHODS: Enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay were used to determine the levels of IGF-I, IGFBP-1 and estradiol (E2) in serum and follicular fluid obtained during oocyte pick-up (OPU) in 32 IVF-embryo transfer cycles. RESULTS: (1) Serum IGFBP-1 levels increased with growth of follicles [(3.5 +/- 1.0) micrograms/L during OPU, (2.1 +/- 0.5) micrograms/L before stimulation, P < 0.05]; follicular fluid (FF) IGFBP-1 levels were significantly higher than those of matched serum levels [(77.7 +/- 26.7) micrograms/L, (3.5 +/- 1.0) micrograms/L respectively P < 0.001]; Serum IGFBP-1 levels were positively correlated with developing of follicle numbers (r = 0.48, P < 0.05). (2) There were no significant changes of serum IGF-I levels before and after superovulation, neither was there between serum and follicle fluid [(103.7 +/- 39.2) micrograms/L, (105.9 +/- 36.8) micrograms/L, (108.9 +/- 19.1) micrograms/L respectively P > 0.05]. Significant positive correlation was found between serum IGFBP-1 and serum E2[(3.5 +/- 1.0) micrograms/L, (3,293 +/- 1,361) pmol/L, r = 0.41, P < 0.05). CONCLUSIONS: During superovulation serum total IGF-I levels do not change. However changes of serum IGFBP-1 levels may play a complementary role in regulation of follicular development by altering free IGF-I levels.

Adult↗

PubMed2000

[Quantitative study on the expression of mRNA for TGF-beta and collagenase (MMP-1), tissue metalloproteinase inhibitor-1 (TIMP-1) in hypertrophic scar].

OBJECTIVE: To investigate the expression of mRNA for TGF-beta, MMP-1 and TIMP-1 and their effects on the formation of hypertrophic scar (HTS). METHODS: In situ hybridization and image analysis were used in this study. RESULTS: The expressions of mRNA for TGF-beta and TIMP-1 in HTS was greatly increased compared with those of normal skin. The average integral optical density of mRNA for TGF-beta and TIMP-1 increased by 8 and 7 folds (P < 0.001) related to normal skin and the expression of them showed highly positive correlation. CONCLUSIONS: The findings suggest that TGF-beta promotes the expression of TIMP-1 and may be a possible factor for hypertrophic scar formation.

Adolescent↗

PubMed2000

[Combined treatment of pseudohermaphroditism].

OBJECTIVE: To diagnose and treat female pseudohermaphroditism caused by 21-hydroxylase deficiencies. METHODS: Four female patients with 21-hydroxylase deficiencies have received combined treatment of reconstructive surgery and supplementary glucocorticoid in our hospital since 1990. RESULTS: The patients obtained a female external genitalia through the operation. Various symptoms resulted from 21-hydroxylase deficiency were improved with glucocorticoid therapy. CONCLUSION: A satisfying result can be achieved for pseudohermaphroditism by combination of surgery and medicine.

Adolescent↗

PubMed2000

[Effects of temperature, relative humidity and pH on germination of chalkbrood fungus, Ascosphaera apis spore].

Studies on the effects of environmental temperature, relative humidity and pH-value on the germination of Ascosphaera apis spore at the stages of activation, enlargement and germ-tube production showed that the germination was found to be independent of temperature within the range of 15-40 degrees C was and 25-40 degrees C, respectively at the stage of activation and enlargement, but closely correlated with the temperature within the range of 25-37 degrees C at the stage of germ-tube production, with the optimum range of 31-35 degrees C. Relative humidity below 80% inhibited spore germination. pH value within the range of 5-7.8 did not affect the spore germination significantly, but pH < 5 reduced the enlargement and germ-tube production drastically. The results indicated that A. apis is a highly specialized pathogen for the life in honeybee larvae.

Humidity↗

PubMed2000

[Analysis of the relevant morphological characteristics observed in intracytoplasmic sperm injection].

OBJECTIVE: To analyze the morphological characteristics of oocyte, sperm and blastomere-stage embryo and correlate with intracytoplasmic sperm injection (ICSI) embryo score. METHODS: ICSIs were done in M II oocytes harvested after superovulation with long-protocol gonadotropin releasing homone agonist. Various morphological characteristics of oocyte, sperm and blastomere-stage embryo were identified and correlated with the embryo score. RESULTS: Forty-three ICSI cycles were completed. Twelve out of 31 male factor infertile couples and 2 out of 12 with fertilization failure during previous standard in vitro fertilization-embryo transfer cycles achieved clinical pregnancy, resulting in a pregnancy rate of 38.7% and 16.7% per transfer respectively. Severe teratospermia and abnormal cytoplasm of the oocytes, such as cytoplasmic central dark granulas, inclusions, had significantly low embryo score (P < 0.01). The size of perivitelline space had no influence on the result. The oocytes without oolemma elasticity during ICSI process had a lower oocyte survival rate compared with those with oolemma elasticity (P < 0.01). The clinical pregnancy rate per transfer between transferred embryo with average score higher and lower than 3 was significantly different (52% vs 10%, P < 0.001). CONCLUSION: Some morphological characteristics of gamates correlate with the embryo quality and clinical pregnancy rate. They can be used to assess and improve the clinical management during ICSI.

Adult↗