Search PubMed⌕ Search

Biomedical subjects

X Ma

Publications and source records attributed to X Ma.

At least 271 records · Page 15Linked to original sources
PubMed1997

[Study on measuring blood pressure and heart rate in patients taking antipsychotics].

To decrease the prevalence of orthostatic hypotension in patients taking antipsychotics 62 pchizophrenics' blood pressure and heart rate were measured at different posture. The data showed that the systolic pressure, diastolic pressure and heart rate in supine position were statistically different from those at standing position (P < 0.01). In standing position the heart rate was 41/min higher, the systolic pressure 1.32 kPa lower and the diastolic pressure 1.2 kPa higher than those in supine position. The systolic pressure of 5 cases were normal in supine position and under 12 kPa in standing position. It is concluded that the heart rate and blood pressure should be measured both in standing and supine position in patients taking antipsychotics, so as to prevent the onset of orthostatic hypotension.

Antipsychotic Agents↗
PubMed1997

[Observations on before and after employ of screw of implant denture with SEM].

The loss of screw is one of the clinic complication in MDIC implant denture cases. The purpose of this study is to find the cause of loss of screw. The authors has studied MDIC implant denture with SEM before and after employ of the screw and found that the causes of screw loss were crevice corrosion and friction pressure. Crevice corrosion may promote the loss of screw. Base the above condition, it is necessary to select Ti-alloy screw and associat with anticorrosive measure in MDIC implant denture construction.

Corrosion↗
PubMed1997

[Scalp expansion in treatment of scalp defect with skull exposure].

We repaired the scalp defect and skull exposure with scalp expansion. The technique consisted of two stages. First, expander was implaned an then N. S injected to its enough volume. The size of the expander was estimated by the formula that 1 cm2 needs 4 ml expansive volume. The incision was made at normal skin. Second flap was transferred. The expander was removed and the external skull which was necrotic severed. There were five patient with eight flaps at all, followed up for 6 months to 1 year. The hair grew. The results were satisfactory. This method not only treated the disease, but also avoided alopecia.

Adolescent↗
PubMed1997

[A positioning device for oral paralleling technique].

OBJECTIVE: To design a reliable method for standardized paralelling dental projection, for comparison of the tiny variations of alveolar bone during the treatment of the periodontal disease. METHODS AND MATERIAL: Periapical radiographs in 29 pairs of films with this device and 14 pairs of films with traditional method on dried skulls were comparatively analysed by digital subtraction. Standard deviations and angle variations of subtracted image were studied comparatively between this method and traditional paralleling technique. RESULTS: Significant difference of reproducibility between two groups was showed. The reproducibility of the successive pictures was apparently increased when projected with positioning device.

Alveolar Process↗
PubMed1997

[Effect of nitrogen, phosphorus and potassium on the growth of rhizome of Coptis chinensis Franch and its contents of berberine].

It has been found out that the normal growth of Coptis chinensis is heavily affected and both NRA in leaves and berberine contents in rhizome are very low when seedlings are short of nitrogen, phosphorus and potassium. The plants grow especially worse and most of them soon die off when nitrogen is short. The new leaves are smaller both in number and size when phosphorus and potassium are short. Few roots can grow up and easily get old in the solution short of potassium.

Berberine↗
PubMed1997

[Analysis of registration parameter of the dental radiographs for digital subtraction].

OBJECTIVE: To investigate the registration parameters in the dental radiographs for digital subtraction, to find out the significance of them and try to improve the quality control of the registration of the dental radiograph for the digital subtraction. METHOD: Sixteen projections of molar and premolar of mandible of minipigs were investigated for stability of the registration system of the dental radiographs. The rotation and the movements of the bite plans were measured with different height of edge of the bite plan. The 128 radiographs with varying parameters of the projection were digital subtracted. The noise of the subtraction photograph was compared for analyses of the relationship between subtraction noise and the projection parameters. RESULTS: The depth of the bite plan and the strength of the connect bar between the X-ray tube and the bite plans are the most significant parameters for the stability of the registration system. The thicker bar the better of the registration was. When the strength of the connected bar is increased, the depth of the bite plan is permitted not too strict. There is not significant effect for digital subtraction with other parameters in this investigation. CONCLUSION: For the best stability of the registration of dental radiographs, the connected bar with 8 mm in diameter is strong enough and the depth of the bite plan between 2.5-4 mm are adequate.

Animals↗
PubMed1997

Characteristic of facial muscle and efferent nerve on physiology and anatomy.

OBJECTIVE: To study the specialty of orbicularis oculi muscles, nerves and oris muscles, nerves and mechanism of difference of facial muscular injury in facial paralysis deeply. METHODS: The conductive velocity of the efferent nerves of orbicularis oculi and oris muscles of the health human beings and guinea pigs is measured with electromyogram (EMG) apparatus. RESULTS: The conductive velocity of orbicularis oculi nerve is quicker and oris muscles are controlled by facial nerves on both sides. Measuring the threshold of Strength-Duration (S-D) curves of the motor point of orbicularis oculi and oris muscles shows the threshold of the former is lower. Measuring the diameter of orbicularis oculi and oris nerve fibers on the guinea pigs and rabbits shows the diameter of orbicularis oculi nerve fiber is bigger. The area of secondary synapse space of orbicularis oculi motor end plate is larger than that of oris under scanning electron microscope. CONCLUSIONS: Orbicularis oculi muscles, orbicularis oculi nerves and oris muscles, oris nerves all have their own characteristic on physiology and anatomy. It elucidated the mechanism that orbicularis oculi muscle is easy to be injured.

Action Potentials↗
PubMed1997

[Determination on the electric-mate order of prosthodontic materials in artificial saliva].

Electric-mate corrosion of the different prosthodontic materials has been noticed in oral cavity. The aim of this investigation was to determine corrosion potential of prosthodontic materials, and to acquire the electric-mate order in artificial saliva. That will conduct us to select the materials of resistance corrosion. For resistance electric-mate corrosion, it's better to use same materials, or to use close materials of the electric-mate order.

Chromium Alloys↗
PubMed1997

[A comparative study on chemical constituents in different processed products of Dioscorea opposita].

The quantitative comparisons of Water-soluble extract, alcohol-soluble extract and allantoin in crude and three processed products of Dioscorea opposita is carried out by the method recorded in Pharmacopoeia and TLCS respectively. As a result, the changes of water-soluble extract and alcohol-soluble extract during the four samples are similar. It is the hightest in the processed product stir-fried with soil and lowest in the crude. But for allantoin, it is the highest in the processed product stir-fried with wheat bran and lowest in that stir-fried with no material. It is suggested that the contents between water-soluble extract, alcohol-soluble extract and allantoin are not interrelated. It shall be considered to increase the content of allantoin as a quality control index to control the quality of the processed products.

Allantoin↗
PubMed1997

[The antitumour activity of Sinopodophyllum emodi].

This paper has shown the cytocidal effects of alcohol extracts of roots and rhizomes of Sinopodophyllum emodi (Wall.) Ying on human erythroleukemia K562 cells, leukemia L1210 cells, leukemia L7712 cells in vitro, using microculture method for 24 hours. The survival rates on K562 cells in the final concentrations of 10.0, 5.0, 2.5, 1.0 micrograms/ml of the extracts of Sinopodophyllum emodi (WA11.) Ying were 44.17%, 47.63%, 64.43%, 79.57% respectively. The survival rates on L1210 and L7712 cells were 42.84%, 50.73%, 63.21%, 75.10%, and 39.76%, 46.36%, 61.42%, 75.24% respectively. LD50 of the extracts singly i.p. in mice was 76.3-60.6 mg/kg. In vivo, the growth of transplanted mouse tumours (EAC, U14 and Hc) was inhibited by the extracts of Sinopodophyllum emodi (Wall.) Ying with inhibitory rates 42.2%, 38.8%, 41.5% (14.0 mg/kg); 37.8%, 33.3%, 35.6% (7.0 mg/kg).

Animals↗
PubMed1997

[Cloning and sequencing of cDNA of E2/NS1 gene of hepatitis C virus].

Hepatitis C virus (HCV) RNA extracted from serum of a patient infected with HCV in Beijing was converted to cDNA by reverse transcription. HCV E2/NS1 gene (approximately 930 bp) was amplified by nested polymerase chain reaction and was inserted into pGEM-T plasmid vector. The 431 bp nucleotide sequence at 5' terminus of this gene was determined by dideoxy-mediated chain termination method. The result of comparison of this sequence and sequences of another 9 HCV isolates suggested that the isolate we obtained was highly homologous to HCV genotype II. There are two hypervariable regions (HVR) at the N terminus of envelope protein encoded by HCV E2/NS1 gene. Several relatively conserved amino acid residues and areas located in and out of HVR were also observed. They are concerned in maintenance of spatial conformation of HCV envelope protein, but their immune function remains to be further studied.

Amino Acid Sequence↗
PubMed1997

[Study on cleavage mechanisms of dimer (t-Bu)2NO in several solvent phases].

In this paper, we studied the cleavage products of dimer t-BuNO in aqueous and organic solutions using method of 1HNMR and UV-Vis, analyzed the reactive kinetics, put forward that dimer (t-Bu)2NO homolytically cleavaged in nonpolar organic solution, and that dimer (t-Bu)2NO homolytically and heterolyticall cleavaged in a competitive manner in polar aqueous solution.

English Abstract↗
PubMed1997

Heterogeneity of airway smooth muscle at tissue and cellular levels.

Heterogeneity of smooth muscle behavior is rapidly emerging as an important phenomenon. However, it is only recently that investigators have begun to explore its physiological and pathogenic importance. Stenmark's group recently reported the existence of four subpopulations of smooth muscle cells in pulmonary artery, and noted that only a specific group of cells was likely responsible for the hyperplasia of smooth muscle in the hypertensive artery. Our studies reported here were focused on determining whether heterogeneity of contractile properties existed in airway smooth muscle cells. Firstly, mechanical properties of muscle strips, free of cartilage and epithelium, were compared among the different generations of canine airway from trachea down to bronchial generation 6. Two distinct groups of smooth muscle were detected from these airways: (i) an extrapulmonary group, consisting of muscle strips from the trachea, and bronchial generation 1 and 2, characterized by higher maximum shortening capacity (delta Lmax) and zero-load velocity (V0) of shortening; (ii) an intrapulmonary group, containing bronchi from generation 3 to 6, with lower delta Lmax and V0. This led to the implication that smooth muscles from these two groups consisted of different types of cells. Secondly, single smooth muscle cells were isolated from trachea and bronchus (from generation 3 to 6) enzymatically, and the unloaded shortening capacity of fresh isolated cells was measured employing electrical field stimulation at room temperature. Two types of cells were identified from these preparations based on the length of muscle cells: type I, with a mean length of 110 +/- 3 microns (SE), predominated in trachea (up to 84%); type II, with a mean length of 200 +/- 9 microns (SE), accounted for 58% in bronchus. The mechanical properties of these two types of cells were also different. Type I cells shortened by 28% of their original lengths in response to maximal stimulation, while most type II cells (90% of total type II cells) shortened 16% (type IIA), and the remainder shortened 58% (type IIB). Because of the paucity of information about the orientation and arrangement of these different types of smooth muscle cells in the airway tree, it is difficult to apply these data directly for interpretation of differences in mechanical properties of smooth muscle cells obtained from strips from extrapulmonary and intrapulmonary airways. Existence of great numbers of cells with lower shortening capacity in intrapulmonary airways may be the major factor responsible for lower mechanical performance of these airway smooth muscle strips. The relatively lower mechanical performance of intrapulmonary airway smooth muscle may be of importance in preventing excessive narrowing of these airways during muscle contraction and optimizing airflow.

Animals↗
PubMed1997

Collagen synthesis by liver stellate cells is released from its normal feedback regulation by acetaldehyde-induced modification of the carboxyl-terminal propeptide of procollagen.

Acetaldehyde stimulates collagen synthesis in stellate cells and forms adducts with procollagen in the liver of alcoholics. To assess the possibility that modification of the carboxyl-terminal propeptide by acetaldehyde affects its capacity to exert a feedback inhibition of collagen synthesis after splitting from procollagen, the propeptide was prepared by gel filtration of the bacterial collagenase digests of procollagen type I (obtained from 10(9) calvaria fibroblasts of newborn rats) and reacted with either 250 mM acetaldehyde and 100 mM CNBH3 or with 170 microM acetaldehyde without reducing agents, to mimick in vivo conditions. The unmodified propeptide produced a concentration-dependent inhibition of collagen synthesis by Ito cells. By contrast, the acetaldehyde-modified propeptide produced a lesser inhibition of procollagen synthesis in the cells, associated with a greater accumulation of collagen in the media. The incubation with 170 microM acetaldehyde and, to a lesser extent, 50 mM ethanol produced collagenase-digestible adducts in stellate cells. Thus, the formation of acetaldehyde adducts with the carboxyl-terminal propeptide of procollagen may account, at least in part, for the stimulatory effect of acetaldehyde on collagen synthesis by stellate cells and may lead to collagen accumulation through a decrease of the normal feedback regulation of collagen synthesis by the propeptide.

Acetaldehyde↗
PubMed1997

[Optimum time of maternal blood sampling for prenatal diagnosis with fetal cells].

OBJECTIVE: To investigate the optimum time of maternal blood sampling for prenatal diagnosis with fetal cells. METHODS: Zinc-finger protein gene on Y-chromosome (ZFY) sequences were examined by nested polymerase chain reaction in the peripheral blood of 41 pregnant women. RESULTS: 19 pregnant women carrying male fetuses, and another 22 women found to carry female fetuses. Among the 19 pregnant women, ZFY gene were detected in 1/19 (5.3%) cases before the 6th gestational weeks, in 13/19 (68.4%) before the 11th weeks, and in 18/19 (95.0%) before the 14th weeks. The results of this study clearly demonstrated that the gender prediction obviously increased along with the gestational weeks. ZFY gene was not detected in the blood of another 22 women carrying female fetuses. The final accuracy of 97.8% (40/41) was attained in all cases. CONCLUSION: The optimum time of maternal blood sampling is at the 14th week, and the appearance of fetal cells in maternal blood was quite case-variable from the 6th to 14th weeks.

Adult↗
PubMed1996

Discordant expression of the cyclin-dependent kinases and cyclins in rat liver following acute administration of the hepatocarcinogen [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio] acetic acid (WY14,643).

Cellular proliferation is an essential aspect of chemical carcinogenesis. At the core of cell cycle regulation is a family of serine/threonine protein kinases termed cyclin-dependent kinases (cdk). Cdk activity, which directs progression through the cell cycle, is dependent upon cdk binding to the appropriate, phase-specific cyclin proteins. Alterations in hepatic cdk1, cdk2, cdk4, cdk5, and cyclin protein expression were determined in response to acute dosing of the prototypic peroxisome proliferator and hepatocarcinogen [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio] acetic acid (WY14,643). Intraperitoneal dosing of 45 mg WY14,643/kg daily for 4 days to young, male rats produced dramatic increases in hepatic protein expression of all cdk analyzed as well as cyclins B, D2, D3, and proliferating cell nuclear antigen (PCNA). The largest relative increases, 6.1-, 2.8-, 11-, 83-, and 7.9-fold, were seen with cdk1, cdk4, cyclin B, cyclin D3, and PCNA, respectively. Increases of only 1.8-, 2-, 1.6-, and 1.4-fold were noted, respectively, for cdk2, cdk5, cyclin D2, and cyclin E. Analysis of gel filtration fractions indicated that PCNA co-eluted with cdk1 from the WY14,643-treated rats as a 70-80 kDa molecular complex. In contrast, cdk4, cdk5 and D cyclins migrated as much larger complexes with an estimated MW of approximately 180-190 kDa.

Animals↗