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Biomedical subjects

Y M Zhang

Publications and source records attributed to Y M Zhang.

At least 55 records · Page 3Linked to original sources
PubMed2000

Evaluation of the new TAMZ titanium alloy for dental cast application.

OBJECTIVE: To reveal the potential of the new titanium alloy as dental prosthodontic materials. METHODS: Dental castings of TAMZ alloy were investigated in the casting machine specially designed for titanium. A mesh pattern was used to count the castability value. The mechanical properties were measured by means of a universal testing machine. Optical micrography was done on the exposed cross-section of TAMZ alloy casting. From the surface to the inner part the Knoop hardness in reacted layer of TAMZ alloy casting was measured. The structure and elemental analyses of the reacted layer were made by SEM and element line scanning observation. RESULTS: The castability value (Cv = 98%) and the tensile test (sigma b = 850 Mpa, sigma 0.2 = 575 Mpa, delta = 7.33%) data were collected. The castings microstructure showed main alpha phase and small beta phase. Knoop hardness in the surface reacted layer was greater than that in the inner part. From the SEM and element line scanning observation, there are three different layers in the surface reacted layer of the TAMZ alloy castings, and higher level of element of O, Al, Si and Zr were found in the reacted layer while the Si permeated deeper than others. CONCLUSION: TAMZ alloy can be accepted as a material for dental alloy in prosthodontics.

Aluminum↗
PubMed2000

[Hemangioendothelioma of larynx].

OBJECTIVE: To study the biological behaviour and treatment of larynx hemangioendothelioma. METHOD: One case of larynx hemangioendothelioma was reported and the relative literatures were reviewed. RESULT: The common symptoms of the disease include hoarseness and larynx obstruction caused by the enlargement of the tumor. The biological behaviour of the larynx hemangioendothelioma is low-grade malignant and recurred, between the benign hemangiomas and malignant angiosarcomas. CONCLUSION: The treatment of the hemangioendotheliomas is enlarged removal of the tumor by Majer-Piquet' operation. Chemotherapy and radiation are not valuable.

Hemangioendothelioma↗
PubMed2000

[Determination of activity of bone alkaline phosphatase in whole serum by high performance liquid chromatography].

An analytical method has been established for the determination of bone alkaline phosphatase (BALP) activity using high performance liquid chromatography(HPLC). The stainless steel column was 22 cm x 4.6 mm i.d. packed with totally porous, spherical silica particles. A solution of methanol and 0.01 mol/L CH3COOH(30/70, V/V) adjusted to pH 4.8 was employed as the mobile phase. The flow rate was 0.8 mL/min. Chromatography was performed with ultraviolet detector at 275 nm. Linear calibration curve for BALP was measured within the range of 8-200 mg/L with correlation coefficient of 0.996. The lowest detection limit was 3 ng. The HPLC method described is simple, rapid and reliable and suitable for clinical monitoring.

Alkaline Phosphatase↗
PubMed1999

NMR study of a Lewis(X) pentasaccharide derivative: solution structure and interaction with cations.

The structure and conformation of the synthetic pentasaccharide Gal(beta 1-4){Fuc(alpha 1-3)}GlcNAc(beta 1-3)Gal(beta 1-4)Glc-beta OMe of the Lewis(X) family has been determined by NMR spectroscopy in dimethyl sulfoxide and methanol. In these solvents, the binding constants with calcium have been evaluated as 9.5 and 29.6 M-1, respectively. Study of the interaction sites has been achieved through the use of paramagnetic divalent cations and distance triangulation methods. Two regions have been found, the first one in the vicinity of the fucose unit, the second one closer to the lactose part.

Calcium↗
PubMed1999

Chromatic sensitive epilepsy: a variant of photosensitive epilepsy.

We herein report 4 Japanese children who suffered epileptic seizures while watching a popular animated TV program. They showed a photoparoxysmal response that is more frequently observed in response to rapid color (blue/red) frame changes than monochromatic ones. These patients were all considered to have photosensitive epilepsy; however, chromatic sensitivity also plays an important role in the generation of such seizures.

Adolescent↗
PubMed1999

Influences of age and gender on dose response and time course of effect of atracurium in anesthetized adult patients.

STUDY OBJECTIVE: To determine the influences of age and gender on the dose response and the time course of effect of atracurium. DESIGN: Prospective, nonrandomized, clinical comparison. SETTING: Operating room, Plastic Surgery Hospital of the Chinese Academy of Medical Sciences and Peking Union Medical College. PATIENTS: 72 adult ASA physical status I patients (38 male and 34 female), aged 15 to 59 years, scheduled for elective plastic surgery. INTERVENTIONS: Patients were divided into the three groups on the basis of age: Group 1, patients aged 15-29 years (n = 32); Group 2, patients aged 30-40 years (n = 21); and Group 3, patients aged 41-59 years (n = 19). Anesthesia was maintained with 60% nitrous oxide in oxygen, thiopental, and incremental doses of fentanyl as required. The dose-response relationship of atracurium was determined by a cumulative dose-response technique. MEASUREMENTS AND MAIN RESULTS: Neuromuscular function was assessed mechanomyographically with train-of-four stimulation at the wrist every 12 seconds and the percentage depression of first twitch (T1) response was used as the study variable. Age and gender significantly affected the dose-response relationship and time course of recovery of atracurium. Advancing age was associated with a reduced effective doses (ED50, ED90, and ED95) of atracurium and a longer duration of action. The effective doses of atracurium were greater, and its duration of action was shorter in men than in women. There were significant differences in the 50%, 90%, and 95% effective dose (ED50, ED90, and ED95) of atracurium, and clinical duration and total duration following administration of atracurium 400 micrograms/kg among the three age groups, and between men and women. CONCLUSIONS: Age and gender have significant effects on the dose response and time course of effect of atracurium. Older patients and women are more sensitive to atracurium-induced neuromuscular block than are young patients and men.

Adolescent↗
PubMed1999

Steady-state vibration somatosensory evoked potentials: physiological characteristics and tuning function.

OBJECTIVE: The steady-state somatosensory evoked potentials (S-SEPs) to vibratory stimulation were recorded to characterize their physiological properties. METHODS: Vibratory stimuli were applied to the right palmar surface in 10 normal subjects. A total of 200 responses were recorded from electrodes at 2 cm posterior to C3, Cz and C4 and 2 cm anterior to C3. All responses were Fourier analyzed and the amplitudes of the first (1F) and second (2F) harmonic components were thus obtained. The effects of modulation frequency (5-30 Hz) and stimulus intensity (0.001-0.1 Newton (N)) on S-SEPs were studied. RESULTS: The amplitudes of 1F and 2F were greatest at the electrode 2 cm posterior to C3, 1F being predominant. The mean 1F amplitudes as a function of modulation frequency showed a bimodal distribution with a trough at 14 Hz and a peak at 21 Hz. The mean 1F amplitudes showed a linear increase of up to 0.05 N and thereafter reached a plateau against the logarithmic stimulus intensity axis. CONCLUSION: Vibratory S-SEPs may originate from the primary somatosensory cortex and provide information on the fast-adapting mechanoreceptive afferents. The temporal resonance at 21 Hz places the somatosensory system between the visual and auditory systems.

Adolescent↗
PubMed1999

Combining qualitative with quantitative approaches to study contraceptive pill use.

According to large-scale studies, oral contraceptive users become pregnant at rates that exceed ideal use failure rates. It is thought that a major cause is missed pills, but current research on consistent contraceptive pill taking is characterized by inadequate measures and a failure to investigate women's thinking about their own patterns of use. The purpose of this study was to gain some understanding about women's interpretations of consistency in their own pill taking through combining qualitative with quantitative data. The study was conducted in China, where contraception is free and widely available. Five urban and five rural oral contraceptive users were followed for up to three pill-taking cycles during 1996 for a total of 759 person-days. Consistency of pill taking was measured with electronic data obtained from a new blister package made by Anderson Clinical Technologies (Elmhurst, IL). Data from these devices were reviewed and interpreted by the study participants during in-depth private interviews. The users' reasons for missing pills included disruptions in their daily routines, their husband's absence, spotting, and trouble implementing the family planning program's instructions to take one pill per day for 22 days and start the next cycle on the fifth day of menses. One user gave these reasons for two cycles but denied missing numerous pills in her third cycle. Data from a series of four questionnaires showed that most demographic, psychosocial, and service system characteristics were not related to missed pills. However, results suggested that the daily routines of rural living may make consistent use more likely and that instructions for taking the pill may be associated with prolonged pill-free intervals and skipping pills during episodes of spotting. Three of the 10 women were at increased risk of pregnancy during the study period because of their pill-taking pattern. We concluded that the combination of qualitative with quantitative data enhances understanding of contraceptive use. Women themselves offer plausible reasons for their use behaviors. Listening to women could be useful in improving programs.

Adolescent↗
PubMed1999

The influence of surgical sites on early postoperative hypoxemia in adults undergoing elective surgery.

UNLABELLED: To determine the influence of the surgical sites on early postoperative hypoxemia, we studied postoperative hypoxemia in 994 patients, ASA physical status I or II, aged 18-68 yr, scheduled for various types of elective surgery. Patients were divided into three groups on the basis of the surgical sites: Group 1 = elective superficial plastic surgery (n = 288); Group 2 = upper abdominal surgery (n = 452); and Group 3 = thoracoabdominal surgery (n = 254). Anesthesia was maintained with 1%-2% enflurane and 67% nitrous oxide in oxygen; thiopental or fentanyl was given IV as required. SpO2 levels were recorded while patients breathed room air shortly after arrival in the recovery room (0 min) and 5, 10, 15, 20, 30, 40, 50, 60, 120, and 180 min thereafter. The results showed that during the early postoperative period, the degree of arterial desaturation and the incidences of hypoxemia (SpO2 86%-90%) and severe hypoxemia (SpO2 85%) were closely related to the operative sites and were greatest for thoracoabdominal operations, less for the upper abdominal operation, and least for the peripheral surgery. The incidence of hypoxemia and severe hypoxemia in the recovery room was 7% and 0.7%, respectively, in Group 1, 38% and 3% in Group 2, and 52% and 20% in Group 3. Mild airway obstruction and hypothermia in the postanesthesia recovery unit (PAR) were the predictive factors of early postoperative hypoxemia. We conclude that during the early postoperative period, there were significant differences in SpO2 levels and incidences of hypoxemia and severe hypoxemia among the three groups. IMPLICATIONS: We found that the severity of arterial desaturation and the incidence of hypoxemia during the early postoperative period are closely related to the surgical sites and are strongest for thoracoabdominal surgery, less for upper abdominal surgery, and least for peripheral surgery.

Abdomen↗
PubMed1999

Cytogenetic abnormalities in natural killer cell lymphoma/leukaemia--is there a consistent pattern?

The group of putative natural killer cell lymphomas, also known as NK/T cell lymphomas (nasal and nasal-type) has been characterized only in recent years. Whilst a good amount of clinical information has been gathered on this group of uncommon lymphoid neoplasms, there is little information on the cytogenetic or molecular alterations. A review of the literature shows that chromosomal abnormalities are indeed commonly found in these tumours, and aberrations involving chromosome 6q are most frequent. Other non-random abnormalities include +X, i(1q), i(7q), +8, del(13q), del(17p), i(17q), and 11q23 rearrangement. It appears that deletions of the chromosome 6 at around q21-23 region is the commonest recurrent chromosomal abnormality, and fluorescence in situ hybridisation studies have confirmed the occurrence of deletions at 6q22-23 in the CD3- CD56+ tumour cells. Search for the involved genes located in this chromosome region can potentially shed light on the molecular pathogenesis of the natural killer cell neoplasms.

Chromosome Aberrations↗
PubMed1998

Activation-induced down-regulation of retinoid receptor RXRalpha expression in human T lymphocytes. Role of cell cycle regulation.

A 5.4-kilobase mRNA, the expression of which is down-regulated after treatment of human peripheral blood mononuclear cells (PBMCs) with various T cell-activating agents, was isolated using an mRNA differential display method. Nucleotide sequence analysis identified the 5' end of this RNA as human retinoid receptor RXRalpha mRNA. Here, we report the nucleotide sequence of 3.6 kilobases of this RNA, which represents the 3' end of RXRalpha mRNA, the sequence of which has not been previously described. Activated PBMCs also expressed lower levels of RXRalpha protein, and a DNA binding assay showed that the activation-induced loss of RXRalpha mRNA and protein expression correlated with the loss of DNA binding activity of this protein. We present evidence that the transition from G0/G1 to S phase of the cell cycle results in the down-regulation of RXRalpha expression and that cell cycle inhibitors, which block the cells in G1 phase, prevent this down-regulation. The decrease in the levels of RXRalpha mRNA was found to be regulated at the post-transcriptional level and involved new protein synthesis. These observations indicate that the levels of RXRalpha expression in T lymphocytes are coupled to cell cycle progression, and there is tight regulatory control of RXRalpha expression during the transition from G0/G1 to S phase of the cell cycle.

Base Sequence↗
PubMed1998

A human cadaver model for determination of pathologic fracture threshold resulting from tumorous destruction of the vertebral body.

STUDY DESIGN: Thoracic vertebrae were subjected to compressive loads after drilling of the centrum to simulate destruction from metastatic tumorous involvement. OBJECTIVE: To determine whether a threshold exists that is predictive of fractures to establish a correlation between significant variables and vertebral strength. SUMMARY OF BACKGROUND DATA: The mechanical effects of metastatic destruction of thoracic vertebral bodies and their correlation to pathologic fractures has been analyzed in few studies. In additional studies on intact vertebral strength, investigators have determined that bone mineral density and geometric factors are important. METHOD: Fifty-four cadaveric thoracic vertebrae were studied. All were examined by quantitative computed tomography. T4 and T10 served as mechanical controls to predict the intact strength of T7. The test vertebrae were drilled from the anterior cortex through to the posterior cortex before they were loaded. RESULTS: Linear correlation between the strength of T4 and T10 in each spine supported the predicted strengths of T7. Because of variation from other factors, no threshold defect size was noted beyond which failure consistently occurred. Results of linear correlation analyses showed that the best combination of parameters for predicting vertebral strength was the product of bone mineral density and the remaining intact vertebral body cross-sectional area. This vertebral strength index correlated linearly with the strength of intact and compromised T7 vertebrae (r2 = 0.52). CONCLUSIONS: The vertebral strength index can be used to predict the strength of any thoracic vertebra. When compared with an idealized vertebral strength index based on the intact vertebral cross-sectional area and normal bone mineral density, a patient's actual vertebral strength index can be used as one of the criteria for prophylactic stabilization.

Aged↗
PubMed1998

A comparative study of the dose-response and time course of action of rocuronium and vecuronium in anesthetized adult patients.

STUDY OBJECTIVES: (1) To compare the dose-response relations of rocuronium and vecuronium in healthy adult patients anesthetized with nitrous oxide-oxygen-fentanyl-thiopental; and (2) to evaluate the time-course of action of two drugs following equipotent doses. DESIGN: Prospective, randomized, clinical comparison. SETTING: Operating room, Plastic Surgery Hospital of the Chinese Academy of Medical Sciences and Peking Union Medical College. PATIENTS: 60 ASA physical status I patients, aged 17-51 years, scheduled for elective plastic surgery. INTERVENTIONS: All patients were randomly assigned to either the rocuronium or vecuronium group. General anesthesia was induced with thiopental 4 to 6 mg/kg and fentanyl 2 to 4 micrograms/kg intravenously (i.v.), and maintained with 60% nitrous oxide (N2O) in oxygen. Further increments of thiopental or fentanyl were given as required. The dose-response relations of rocuronium and vecuronium were determined by the cumulative dose-response technique. MEASUREMENTS AND MAIN RESULTS: Neuromuscular function was assessed mechanomyographically with train-of-four (TOF) stimulation at the wrist every 12 seconds. The percentage depression of first twitch (T1) was used as the study parameter. The cumulative dose-response curve of vecuronium was shifted to the left in a parallel fashion compared with that of rocuronium. As assessed by linear regression, the potency ratio of vecuronium: rocuronium was 1:7.2. There were significant differences in the ED50, ED90, and ED95 between the two drugs. After i.v. administration of equipotent doses of both drugs (2 x ED90), the duration of peak effect, clinical duration, recovery index, and total duration were not significantly different between the two drugs. CONCLUSIONS: Compared with vecuronium, rocuronium is a low-potency, nondepolarizing relaxant, and its neuromuscular blocking potency is approximately 15% that of vecuronium in adult patients anesthetized with N2O and fentanyl. Following equipotent doses, the time-course of recovery for rocuronium is similar to that of vecuronium.

Adolescent↗
PubMed1998

Intervertebral measurement of lumbar segmental motion with a new measuring device.

A new Intervertebral Motion Device (IMD) was developed in this study. Depending on its configuration, the IMD was used to measure motion in the sagittal, frontal, and transverse planes. Calibration results showed that the root-mean-square (RMS) error of the IMD was 0.092 mm in axial translation, 0.065 mm in shear translation, and 0.091 in rotation. Using the IMD, nine intact human lumbosacral spine specimens (L3-S1) were tested under a simulated physiological load on an MTS (Model 858 Bionix, MTS System Corporation Minneapolis, MN). The ranges of motion (ROMs) of intact and instrumented specimens were measured in terms of angular motion (main motion) and coupled translation in the sagittal plane, and angular motion in the transverse plane. The results demonstrated that simulated fusion with CS instrumentation at the level of L4-L5 significantly decreased the ROMs of L4-L5 for all main and coupled motions (P < 0.03). The application of CD rods had less influence on the angular ROM in L/R axial rotation compared to the angular ROMs in Flex/Ext and L/R lateral bending.

Adult↗
PubMed1998

Dose-response curve and time-course of effect of vecuronium in male and female patients.

To determine the differences between men and women in the dose-response curve and the time-course of effect of vecuronium, we studied 60 adult patients (30 male and 30 female), ASA I, age 18-51 yr, undergoing elective plastic surgery. Anaesthesia was maintained with nitrous oxide 60% in oxygen; thiopentone and incremental doses of fentanyl were given as required. Neuromuscular function was assessed mechanomyographically using the train-of-four (TOF) stimulation at the wrist every 12 s. The percentage depression of T1 was used as the study variable. The dose-response relationship of vecuronium was determined by a cumulative dose-response technique. The dose-response curve in men was shifted in a parallel fashion to the right, indicating a decrease in the sensitivity to vecuronium-induced neuromuscular block, compared with women. The ED50, ED90 and ED95 of vecuronium were 23.9 (4.7), 45.4 (11.2) and 55.7 (14.3) micrograms kg-1 in men and 18.4 (3.7), 33.5 (7.8) and 39.8 (9.6) micrograms kg-1 in women respectively. There were statistically significant differences in these values between the two groups (P < 0.01 in each instance). After a total dose of vecuronium 80 micrograms kg-1, neuromuscular block was significantly longer in women than in men. The duration of peak effect, clinical duration, and the total duration were 18.7 (7.1), 26.6 (8.8) and 50.6 (16.0) min respectively in men and 26.0 (7.2), 37.1 (11.2) and 65.9 (20.7) min in women. They differed significantly between men and women (P < 0.005 in each case).

Adolescent↗
PubMed1998

[Observation of female gametophyte development of Ginkgo biloba and its protoplast isolation and culture].

Results of observation showed that the female gametophyte of Ginkgo biloba was at the coenocytic stage from March 30ty to May 30ty. A density of 6-8 x 10(5) protoplasts/ml with a viability of 87.3% was achieved when the female gametopytes collected from May 8th to 15th were treated with 0.5% cellulase Onzuka R-10, 0.5% Pectolyase for 4-5 hours. The thin-layer liquid Murashige and Tuker medium modified by omitting ammonium ions and supplementing with glutamine 1000 mg/L, Vc 5 mg/L, benzyladenine 1.0 mg/L and naphthaleneacetic acid 3.0 mg/L was used for the protoplast culture and multiple cell colonies were obtained.

Cells, Cultured↗