Biomedical subjects

H Ma

Publications and source records attributed to H Ma.

At least 73 records · Page 4Linked to original sources

PubMed2001

[Analysis and experimental study of reasons for breakage in the bone fracture plate during internal fixation].

Bone fracture plate has been in clinical use for internal fixation of fracture, however, during healing, the steel plate breaks occasionally. This paper applied the static strength theory to imitate the pressed down combination out of shape that was borne by single limb of human body standing. Fracture was made on low limbs of the fresh dead body, fixed with a bone fracture plate. Strain measure was made on a bone fracture plate. Additionally, fatigue experiment and four-point bending experiment were carried out on a bone fracture plate. The reason for a breakage in the bone fracture plate was analyzed with static strength theory and low period fatigue theory.

Bone Plates↗

PubMed2001

Effects of peripheral blood mononuclear cells from idiopathic nephrotic children on cultured rat glomerular epithelial and mesangial cells.

OBJECTIVE: To investigate the effect of immune cell from idiopathic nephrotic children on extracellular matrix (ECM) synthesis by cultured rat glomerular epithelial cell (GEC) and on the proliferation of mesangial cell (GMC). METHODS: Twenty-eight children with idiopathic nephrotic syndrome and 15 age-matched healthy children were randomly selected and divided into 4 groups: Group 1, untreated nephrotic children; Group 2, glucocorticoid treated nephrotic children; Group 3, children undergoing glucocorticoid treatment with negative proteinuria; and Group 4, normal control. The peripheral blood mononuclear cells (PBMC) were collected from these children and PBMC conditioned medium (PBMC-CM) were prepared. The PBMC-CM was co-cultured with GEC and GMC respectively. The concentrations of collagen, laminin, collagen III and collagen IV in the GEC and PBMC-CM co-culture medium were investigated. The GMC proliferation was measured by the 3H-thymidin incorporation method. RESULTS: The 3H-proline incorporation coefficients of the GEC treated with the PBMC-CM of the 4 groups were 0.93, 1.24, 1.23, and 1.11, respectively. The laminin inhibitory coefficients of the 4 groups were 0.95, 1.02, 1.01, and 1.04, respectively. The inhibitory coefficients of collagen III were 0.97, 1.00, 0.99, and 1.01, respectively, for the 4 groups. All these parameters showed a significant difference between Group 1 and the other 3 groups (P < 0.05). However, there was no significant difference in the inhibitory coefficient of collagen IV between each two of the 4 groups (1.04, 1.05, 1.04, 1.08, P > 0.05). The 3H-thymidine incorporation coefficients of GMC responsive to PBMC-CM were 1.21, 1.53, 1.50, and 1.10, respectively, and no significant difference was found between the 4 groups (P > 0.05). CONCLUSION: The results suggested that the circulating immune cells from idiopathic nephrotic children have a direct effect on some ECM component synthesis in cultured rat GEC; the bio-activity of immune cells could be neutralized by administering glucocorticoid; and the circulating immune cells of nephrotic children have no direct effect on GMC proliferation.

Animals↗

PubMed2001

[Experimental research of viscoelasticity of C2-T1 cervical vertebra].

This is a research on the characteristics of stress relaxation and creep of cervical vertebra (c2-t1) of fresh body (18 cases). The effect of stress relaxation and creep of cervical vertebra was detected by simulating front and back routes operation. Reduced curve and data in the constant strain and stress were obtained. By using regression analysis method the reduced relaxation and creep functions were acquired. The experimental result showed the decrease of viscoelasticity in simulating operation conditions.

Adult↗

PubMed2001

[Association of vascular endothelial growth factor expression with angiogenesis and tumor cell proliferation in human lung cancer].

OBJECTIVE: To evaluate the expression of vascular endothelial growth factor (VEGF) and the relation with angiogenesis and tumor cell proliferation in human lung cancer. METHODS: Expression of VEGF, angiogenesis, tumor cell proliferation in 63 cases of human lung cancer were examined immunohistochemically. Anti-VEGF(165)-Ab3 was used for VEGF expression, a monoclonal antibody directed against CD(34) to identify intratumoral microvessel density (iMVD) and the proliferating cell nuclear antigen (PCNA) as a marker of proliferating tumor cells. RESULTS: Positive staining for VEGF was obtained in 32 of the 63 cases (50.8%), iMVD varied from 4 to 138.7 (M = 36)/x 400 and the proportion of PCNA positive cells varied from 0 to 92% (M = 25.03%). iMVD in high-grade VEGF tumors was significantly higher than that in VEGF-negative tumors and low-grade VEGF tumors. PCNA labeling proliferation index in small cell lung cancer was higher than that in non-small cell lung cancer. iMVD significantly increased with increasing VEGF expression. CONCLUSION: There is VEGF expression in lung cancer. VEGF expression is significantly associated with iMVD, but there is no association between iMVD or VEGF expression and PCNA expression. There is no association between VEGF expression and histological classification and clinical stages.

Adult↗

PubMed2001

[The role of insulin-like growth factor-I gene expression abnormality in pathogenesis of diabetic peripheral neuropathy].

OBJECTIVE: To explore the role of insulin-like growth factor-I (IGF-I) gene expression abnormality in neurotrophic causes of diabetic peripheral neuropathy. METHODS: Diabetes was induced in Sprague Dawley rats by alloxan. Various parameters were measured as follows: IGF-I mRNA by reverse-transcriptase polymerase chain reaction (RT-PCR), IGF-I peptide by enzyme-linked immunosorbent assay (ELISA), electrophysiological parameters of nerves by evoked electromyogram, morphometric evaluation of sciatic nerve under light microscope and transmission electron microscope. RESULTS: During the early diabetic stage, IGF-I mRNA (0.430 +/- 0.031 vs 0.370 +/- 0.016 +/- 0.280 +/- 0.010, P < 0.01, < 0.001) and IGF-I peptide contents [(0.430 +/- 0.031) ng/mg vs (30.06 +/- 3.60 +/- 23.71 +/- 2.70) ng/mg, P < 0. 01, < 0.001] in sciatic nerve tissue reduced in diabetic rats with hyperglycemia and varied with severity of diabetes. These parameters were further down regulated in diabetic rats with less duration of diabetes and non-diabetic control rats [IGF-I mRNA 0.320 +/- 0.021 - 0.230 +/- 0.060; IGF-I peptide (28.8 +/- 3.30 - 19.51 +/- 1.80) ng/mg]. They also correlated with nerve functional (sensory nerve conduction velocity: r = 0.714, P < 0.001, amplitude of evoked potentials: r = 0.716, P < 0.001, respectively) and structural abnormality (axonal size r = 0.81, P < 0.001) of the sciatic nerve. No difference was found in the above parameters between diabetic rats with euglycemia and non-diabetic control group. CONCLUSION: IGF-I gene expression in tissues was down-regulated from the early diabetic stage and the down-regulation varied with the severity and duration of diabetic state. The decrement in IGF-I level might contribute to the initiation and development of diabetic neuropathy via autocrine or paracrine pathway.

Animals↗

PubMed2001

[An epidemiological study on the risk factors of irritable bowel syndrome in Zhanjiang, Guangdong province].

OBJECTIVE: To assess the risk factors in the pathogenicity of irritable bouel syndrome(IBS) in Zhanjiang city. METHODS: Two hundred and seven IBS patients were randomly selected and compared with "healthy" people diagnosed in the same hospital during the same period. Roles of major risk factors to IBS were studied through using a case-control study. RESULTS: Family history of hysteria or mental disease and vegetorsis was closely related to IBS, with ORs 3 and 4 respectively. There was alse close relationship between IBS and psychic trauma, often taking antibiotics, tension at work and eating sweet potato or cassava, with ORs between 1 and 2. CONCLUSION: Our investigation suggested that the six major risk factors mentioned above played important roles in the progression of IBS in Zhanjiang city.

Case-Control Studies↗

PubMed2001

[1.4 kb 5' flanking region of class I patatin directs tuber-specific gus expression in potato (Solanum tuberosum L.)].

Binary vectors pPATIs (with partial signal sequence) and pPATI (without signal sequence) were constructed by fusing 1.4 kb 5' flanking regions of Class I patatin gene with GUS. Transient GUS expression was observed in in vitro tuber slices bombarded with pPATI. These constructs were then introduced into potato (cv. Desiree) via Agrobacterium tumefaciens transformation. Transgenic potato plants were confirmed by X-Gluc staining and PCR. Using in vitro tuberization system, GUS activities were assayed by fluorescence. It was shown that, in plants transformed with PATI-GUS, GUS specific activities were about 10-20 fold higher in tubers than in stems. Increased sucrose concentration could not induce PATI-GUS expression, but light enhanced PATI-GUS expression in cultured shoots.

Carboxylic Ester Hydrolases↗

PubMed2001

[The effect of radix pseudostellariae from 8 habitats on spleen-deficiency and immunologic function].

75% ethanol extracts of Radix Pseudostellariae could improve spleen-deficiency and immunologic function from Yixing(Jiangsu), Tuorong (Fujian), Guangde(Anhui), Zhonggou(Shandong), Linmu(Shandong), Shanghai, Langxi(Anhui) and Xuanzhou (Anhui). They could decrease spleen-deficienly ratio, increase body weight, anus temperature, thymus and spleen indexes, and prolong swimming time in 15 degrees C water and survival time under anoxic circumstances on resperpine-induced mice. They could also inhibit delayed hypersensitivity induced by prednisolone on mice. Radix Pseudostellariae from Xuanzhou was most effective on spleen-deficiency mice.

Animals↗

PubMed2001

[Determination of salvianolic acid B in the radix of Salvia miltiorrhiza Bge. by HPLC].

OBJECTIVE: To develop an HPLC method for determining salvianolic acid B in radix of Salvia miltiorrhiza. METHOD: The sample was extracted with 75% methanol. ODS column was used with methanol-5% acetic acid solution (35:65) as mobile phase. Detection wavelength was 281 nm. RESULT: Salvianolic acid B was separated well. Good linearity of salvianolic acid B was obtained (r = 0.9997) within the range of 0.17-1.7 micrograms. The average recovery was 98.9%. Repeatability was good, and RSD was 1.82%. CONCLUSION: This method can be used for quality control of radix of Salvia miltiorrhiza.

Benzofurans↗

PubMed2001

[New applications of FTIR micro-spectroscopy in the field of forensic science].

The new applications of FTIR micro-spectroscopy in the field of forensic science are presented, and the process and results of infrared spectra measurements of many kinds of samples, such as paint, fiber, dye, plastic, rubber, ink and drug have been discussed in detail, including two real cases. Various sampling accessories (Diamond cell, Attenuated total reflection and Micro manipulator system) and different determination modes (transmission and reflectance) are used according to the properties of samples.

Coloring Agents↗

PubMed2001

[Monte Carlo simulation of FCS in a laser gradient field].

Fluorescence correlation spectroscopy (FCS) is a powerful tool for probing biological process inside living cells. It measures fluorescence fluctuations of small number of molecules and derive information on molecular kinetics and reactions. We have developed a Monte Carlo model to simulate Browning motion of Rayleigh particles in a laser gradient field. The simulation reveals relations between laser field strength and measured parameters from FCS, such as diffusion coefficient and number density of the particles. The simulated results agree qualitatively to the experimental results obtained using fluorescent spheres. Empirical relations from the simulation are also discussed.

Computer Simulation↗

PubMed2001

[Spontaneous renal subcapsular or perinephric haematoma].

OBJECTIVE: To improve the diagnosis and treatment of spontaneous renal subcapsular and perinephric haematoma. METHODS: Seventeen cases of spontaneous renal subcapsular or perinephric haematoma were analyzed retrospectively. For imaging diagnosis, we used ultrasonography, computerized tomography (CT) and angiography. Thirteen cases were subjected to nephrectomy and one case was to renal biopsy, whereas the remaining 3 cases were treated conservatively. RESULTS: After follow up for 6-108 months, 3 patients died and 14 patients survived. CONCLUSIONS: For diagnosis, imaging examinations are very valuable. For treatment, most of patients with perinephric haematoma should be operated on.

Adult↗

PubMed2001

[The influence of antidepressive therapy on short-term prognosis in elderly patients with unstable angina and depression].

OBJECTIVE: To observe the influence of antidepressive therapy on short-term prognosis in elderly unstable angina pectoris patients with depression. METHODS: 76 unstable angina pectoris patients were random into a therapy group (38) and control group (38). Patients in the therapy group were treated with psychotherapy and administration of antidepressant Fluoxetine (Prozac Eli Lilly, USA) 20mg once a day on the basis of regular cardiac medicine therapy for 12 weeks, Patients in the control group were only treated with regular cardiac medicine therapy. RESULTS: Myocardial ischaemia in the therapy group was significantly improved. The recurrence rate of angina pectoris and incidence ratio of acute myocardial infarction in the therapy group were low. There was significant difference in comparison with the control group (P < 0.05). CONCLUSION: Antidepression can significantly improve the short-term prognosis in elderly unstable angina pectoris patients.

Aged↗

PubMed2000

Characterization of Epstein-Barr virus-infected B cells in patients with posttransplantation lymphoproliferative disease: disappearance after rituximab therapy does not predict clinical response.

Post-transplantation lymphoproliferative disease (PTLD) is associated with Epstein-Barr virus (EBV). Quantitative and qualitative differences in EBV in peripheral blood mononuclear cells (PBMCs) of PTLD patients and healthy controls were characterized. A quantitative competitive polymerase chain reaction (QC-PCR) technique confirmed previous reports that EBV load in PBMCs is increased in patients with PTLD in comparison with healthy seropositive controls (18 539 vs 335 per 10(6) PBMCs, P =.0002). The average frequency of EBV-infected cells was also increased (271 vs 9 per 10(6) PBMCs, P =.008). The distribution in numbers of viral genome copies per cell was assessed by means of QC-PCR at dilutions of PBMCs. There was no difference between PTLD patients and healthy controls. Similarly, no differences in the patterns of viral gene expression were detected between patients and controls. Finally, the impact of therapy on viral load was analyzed. Patients with a past history of PTLD who were disease-free (after chemotherapy or withdrawal of immunosuppression) at the time of testing showed viral loads that overlapped with those of healthy seropositive controls. Patients treated with rituximab showed an almost immediate and dramatic decline in viral loads. This decline occurred even in patients whose PTLD progressed during therapy. These results suggest that the increased EBV load in PBMCs of PTLD patients can be accounted for by an increase in the number of infected B cells in the blood. However, in terms of viral copy number per cell and pattern of viral gene expression, these B cells are similar to those found in healthy controls. Disappearance of viral load with rituximab therapy confirms the localization of viral genomes in PBMCs to B cells. However, the lack of relationship between the change in viral load and clinical response highlights the difference between EBV-infected PBMCs and neoplastic cells in PTLD.

Adult↗

PubMed2000

Stabilization of the GDP-bound conformation of Gialpha by a peptide derived from the G-protein regulatory motif of AGS3.

The G-protein regulatory (GPR) motif in AGS3 was recently identified as a region for protein binding to heterotrimeric G-protein alpha subunits. To define the properties of this approximately 20-amino acid motif, we designed a GPR consensus peptide and determined its influence on the activation state of G-protein and receptor coupling to G-protein. The GPR peptide sequence (28 amino acids) encompassed the consensus sequence defined by the four GPR motifs conserved in the family of AGS3 proteins. The GPR consensus peptide effectively prevented the binding of AGS3 to Gialpha1,2 in protein interaction assays, inhibited guanosine 5'-O-(3-thiotriphosphate) binding to Gialpha, and stabilized the GDP-bound conformation of Gialpha. The GPR peptide had little effect on nucleotide binding to Goalpha and brain G-protein indicating selective regulation of Gialpha. Thus, the GPR peptide functions as a guanine nucleotide dissociation inhibitor for Gialpha. The GPR consensus peptide also blocked receptor coupling to Gialphabetagamma indicating that although the AGS3-GPR peptide stabilized the GDP-bound conformation of Gialpha, this conformation of Gialpha(GDP) was not recognized by a G-protein coupled receptor. The AGS3-GPR motif presents an opportunity for selective control of Gialpha- and Gbetagamma-regulated effector systems, and the GPR motif allows for alternative modes of signal input to G-protein signaling systems.

Amino Acid Motifs↗

PubMed2000

Search for lepton flavor violation in K+ decays into a charged pion and two leptons.

A search for lepton flavor violating decays, K+ --> mu+ mu+ pi-, K+ --> e+ e+ pi-, K+ --> pi+ e+ mu-, K+ --> mu+ e+ pi-, and pi0 --> e+ mu-, was performed using the data collected in Experiment E865 at the Brookhaven Alternating Gradient Synchrotron. No signal was found in any of the decay modes. At the 90% confidence level, the branching ratios are less than 3.0x10(-9), 6.4x10(-10), 5. 2x10(-10), 5.0x10(-10), and 3.4x10(-9), respectively.

Journal Article↗

PubMed2000

Human 3alpha-hydroxysteroid dehydrogenase isoforms (AKR1C1-AKR1C4) of the aldo-keto reductase superfamily: functional plasticity and tissue distribution reveals roles in the inactivation and formation of male and female sex hormones.

The kinetic parameters, steroid substrate specificity and identities of reaction products were determined for four homogeneous recombinant human 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD) isoforms of the aldo-keto reductase (AKR) superfamily. The enzymes correspond to type 1 3alpha-HSD (AKR1C4), type 2 3alpha(17beta)-HSD (AKR1C3), type 3 3alpha-HSD (AKR1C2) and 20alpha(3alpha)-HSD (AKR1C1), and share at least 84% amino acid sequence identity. All enzymes acted as NAD(P)(H)-dependent 3-, 17- and 20-ketosteroid reductases and as 3alpha-, 17beta- and 20alpha-hydroxysteroid oxidases. The functional plasticity of these isoforms highlights their ability to modulate the levels of active androgens, oestrogens and progestins. Salient features were that AKR1C4 was the most catalytically efficient, with k(cat)/K(m) values for substrates that exceeded those obtained with other isoforms by 10-30-fold. In the reduction direction, all isoforms inactivated 5alpha-dihydrotestosterone (17beta-hydroxy-5alpha-androstan-3-one; 5alpha-DHT) to yield 5alpha-androstane-3alpha,17beta-diol (3alpha-androstanediol). However, only AKR1C3 reduced Delta(4)-androstene-3,17-dione to produce significant amounts of testosterone. All isoforms reduced oestrone to 17beta-oestradiol, and progesterone to 20alpha-hydroxy-pregn-4-ene-3,20-dione (20alpha-hydroxyprogesterone). In the oxidation direction, only AKR1C2 converted 3alpha-androstanediol to the active hormone 5alpha-DHT. AKR1C3 and AKR1C4 oxidized testosterone to Delta(4)-androstene-3,17-dione. All isoforms oxidized 17beta-oestradiol to oestrone, and 20alpha-hydroxyprogesterone to progesterone. Discrete tissue distribution of these AKR1C enzymes was observed using isoform-specific reverse transcriptase-PCR. AKR1C4 was virtually liver-specific and its high k(cat)/K(m) allows this enzyme to form 5alpha/5beta-tetrahydrosteroids robustly. AKR1C3 was most prominent in the prostate and mammary glands. The ability of AKR1C3 to interconvert testosterone with Delta(4)-androstene-3,17-dione, but to inactivate 5alpha-DHT, is consistent with this enzyme eliminating active androgens from the prostate. In the mammary gland, AKR1C3 will convert Delta(4)-androstene-3,17-dione to testosterone (a substrate aromatizable to 17beta-oestradiol), oestrone to 17beta-oestradiol, and progesterone to 20alpha-hydroxyprogesterone, and this concerted reductive activity may yield a pro-oesterogenic state. AKR1C3 is also the dominant form in the uterus and is responsible for the synthesis of 3alpha-androstanediol which has been implicated as a parturition hormone. The major isoforms in the brain, capable of synthesizing anxiolytic steroids, are AKR1C1 and AKR1C2. These studies are in stark contrast with those in rat where only a single AKR with positional- and stereo-specificity for 3alpha-hydroxysteroids exists.

3-Hydroxysteroid Dehydrogenases↗

PubMed2000

Improved limit on the rate of the decay K+ --> pi(+)&mgr;(+)e(-)

We report results of a search for the lepton-family number violating decay K+-->pi(+)&mgr;(+)e(-) from data collected by experiment E865 in 1996 at the Alternating Gradient Synchroton of Brookhaven National Laboratory. We place an upper limit on the branching ratio at 3.9x10(-11) ( 90% C.L.). Together with results based on data collected in 1995 and an earlier experiment, E777, this result establishes a combined 90% confidence level upper limit on the branching ratio at 2.8x10(-11). We also report a new upper limit on the branching ratio for pi(0)-->&mgr;(+)e(-) of 3.8x10(-10) ( 90% C. L.).

Journal Article↗