A case report of posterior spinal artery aneurysm.
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Adolescent↗
Biomedical subjects
K Hu
Publications and source records attributed to K Hu.
[Biomechanical analysis of occlusal splint therapy].
OBJECTIVE: The changes of the location and force of the condyle influenced by occlusal splint were investigated in order to know the biomechanical mechanism of occlusal splint therapy. METHODS: Auto-CAD technology, CT scanning, computer imaging analysis measurement and finite element method were separately used to comparatively analyze condylar position and its stress distribution in patients with temporomandibular joint disorders (TMD) treated with or without occlusal splint. RESULTS: Occlusal splint could lessen anterior space, in crease posterior and upper space in the temporomandibular joint (TMJ), so the condylar position move anterioinferiorly; the stress on condylar surface was lowered, mainly in anterior oblique surface or lateral side of condylar loading position; and the stress symmetry was bilaterally improved. OCCLUSION: The study suggests that regulating condylar position and improving the stress distribution is considered one of biomechanical mechanism of occlusal splint treatment.
Adult↗
[The distributional clines in P susceptibility causing by the P family transposable element in Drosophila melanogaster population of China].
An extensive survey of the P family transposable element of Drosophila melanogaster in China, from the far west as Xinjiang and Xizang (Tibet) to the east coast, covered all China was provided. Strains, sampling more than 70 localities, which were collected during 1980-1995. In the term of the PM system, the phenotypic property of it was mainly M type, including Taiwan. The molecular test determined, it was M type. There were three localities, the P activity of them were higher as Q type. They are: Dalian Peninsular. Chongming island, near Shanghai and Taizhong of Taiwan. For analyzed geographically, according to the east longitudes, grouped the country to four parts. After comparison, two dividing lines were found: 1. The East longitude of 115 degrees, it was between Area II and Area III, see Fig. 4, separating the coastal from inland. Except the P susceptibility of the northeastern three provinces was little higher, about 30.37%, the most part of the east coastal, the first line, its P susceptibility was very week. Seven strains were 0, fifteen strains were under 10%; its P activity was also low, never beyond 10%. Therefore, it was appeared neutral, its average was 7.23%. That was the major neutral property of the coastal areas. The second line of little increased P susceptibility averaged about 26.67%. Then, there was the third line was, when the line was the more westward, its P susceptibility was higher, up to 87%, closing to the highest score of middlewest part of the country. From the east coast to the west, there were three gradually increased P susceptibility lines pushing forward could be found. The E 115 degrees, it was between the lines of the second and the third. 2. Besides the East Longitude of 115 degrees, there is another natural geographic line shows its potentiality, that is the Tropic of Cancer. It divided the coastal to two parts, the localities at the south of this line, they did not show the coastal characteristic, instead of neutral or very week P susceptibility, they showed very strong P susceptibility as the inland localities strains were, They were left in the inland, Area II and their position were also there. Although the most part of the coastal areas presented the eastern property of neutral; the P susceptibility of the coastal cities located at the south of the Tropic of Cancer, that was very strong M type, which was different from that of the Tropical of Australia. At the north part of the Tropic of Capricom of Australia, there was P type.
Animals↗
Quantitative analysis of a bacteria-derived antibiotic in nematode-infected insects using HPLC-UV and TLC-UV methods.
3,5-Dihydroxy-4-isopropylstilbene (ST), an antibiotic produced by the bacterial symbiont Photorhabdus luminescens of the nematodes of the genus Heterorhabditis was determined quantitatively in nematode bacterium-infected insects using HPLC or TLC for separation and UV for quantification. Comparable and reproducible results were obtained with both HPLC-UV and TLC-UV methods. Several factors, including solvents for extraction of the antibiotic from the infected insects, eluents for TLC development and programs for HPLC operation, were investigated. Of the four solvents used, namely acetone, methanol, ethyl acetate and diethyl ether, acetone had the highest extraction efficacy, and the ST recovery rate was about 95%. ST can be easily separated from all other bacterial metabolites on a TLC plate using a mixture of chloroform-methanol (98.5:1.5) or by HPLC using acetonitrile and water as the mobile phase.
Acetone↗
Chronic endothelin receptor blockade attenuates progressive ventricular dilation and improves cardiac function in rats with myocardial infarction: possible involvement of myocardial endothelin system in ventricular remodeling.
BACKGROUND: Left ventricular dilatation after myocardial infarction is associated with impaired ventricular function and heart failure and has important implications for survival. The purpose of this study was to investigate the role of endothelin-1 (ET-1) in ventricular dilatation and the effects of chronic endothelin receptor blockade by a mixed ET(A) and ET(B) receptor blocker (bosentan) on the circulating and cardiac endothelin systems. METHODS AND RESULTS: Three hours after coronary ligation or sham operation, bosentan (100 mg x kg body wt(-1) x d(-1)) or placebo was given by gavage. Seven days and 8 weeks after surgery, hemodynamic and left ventricular volume studies were performed. Acute bosentan treatment (7 days) had no effects on hemodynamic parameters and early left ventricular dilatation. In the rats with large infarcts, chronic bosentan treatment (8 weeks) versus placebo reduced left ventricular systolic pressure (116+/-2 versus 125+/-3 mm Hg, P<.05) and arterial pressure (93+/-2 versus 103+/-3 mm Hg, P<.05), improved stroke volume index (0.69+/-0.06 versus 0.52+/-0.04 mL/kg, P<.05), and prevented in part the rightward shift of the pressure-volume curve. Chronic bosentan treatment also decreased ET-1 levels (390+/-33 versus 475+/-22 pg/g tissue, P<.05) and density of ET-1 receptors (262+/-24 versus 346+/-31 fmol/mg protein, P<.05) in left ventricular myocardium. CONCLUSIONS: In the present study, a mixed ET(A) and ET(B) receptor antagonist (bosentan) partially prevented left ventricular dilatation and improved hemodynamics, suggesting that endothelin plays a role in left ventricular remodeling after myocardial infarction. Supporting this hypothesis, we show inhibitory effects of bosentan on the peripheral and myocardial endothelin system.
Animals↗
Gene structure and chromosome localization of the G gamma c subunit of human cone G-protein (GNGT2).
Phototransduction in the vertebrate rod and cone photoreceptors is regulated by structurally homologous and yet distinct groups of signaling proteins. We have previously identified in bovine retinas a cone-specific G-protein gamma subunit (G gamma c, previously named G gamma b), which may play a key role in coupling the cone visual pigment to phosphodiesterase (O. C. Ong et al., 1995, J. Biol. Chem. 270:8495-8500). We report here the characterization of human G gamma c and its gene structure. Human G gamma c subunit shares a high degree of sequence identity with the corresponding bovine G gamma c isoform (85%) and human rod G gamma 1 (63%). The protein is specifically localized in cones, as indicated by immunohistochemical staining using anti-G gamma c antibodies. Nucleotide sequence analysis of the G gamma c gene (GNGT2) reveals a structure consisting of three exons and two introns, with the intron splice sites similar to that of the rod G gamma 1 gene (GNGT1). By using fluorescence in situ hybridization, we have further localized the human GNGT2 gene to chromosome 17q21. The elucidation of the G gamma c gene structure would facilitate the identification of genetic defects associated with cone degeneration.
Amino Acid Sequence↗
Amyloid precursor protein processing and A beta42 deposition in a transgenic mouse model of Alzheimer disease.
The PDAPP transgenic mouse, which overexpresses human amyloid precursor protein (APP717V-->F), has been shown to develop much of the pathology associated with Alzheimer disease. In this report, levels of APP and its amyloidogenic metabolites were measured in brain regions of transgenic mice between 4 and 18 months of age. While absolute levels of APP expression likely contribute to the rate of amyloid beta-peptide (Abeta) deposition, regionally specific factors also seem important, as homozygotic mice express APP levels in pathologically unaffected regions in excess of that measured in certain amyloid plaque-prone regions of heterozygotic mice. Regional levels of APP and APP-beta were nearly constant at all ages, while A beta levels dramatically and predictably increased in brain regions undergoing histochemically confirmed amyloidosis, most notably in the cortex and hippocampus. In hippocampus, A beta concentrations increase 17-fold between the ages of 4 and 8 months, and by 18 months of age are over 500-fold that at 4 months, reaching an average level in excess of 20 nmol of A beta per g of tissue. A beta1-42 constitutes the vast majority of the depositing A beta species. The similarities observed between the PDAPP mouse and human Alzheimer disease with regard to A beta42 deposition occurring in a temporally and regionally specific fashion further validate the use of the model in understanding processes related to the disease.
Age Factors↗
Remodeling of the brain post myocardial infarction: focus on central ANF.
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Animals↗
HIV-1 gp41 by a common immunological epitope induces increased levels of antibodies against human interferon-beta in HIV-1 positive individuals.
Based on our finding that a similar epitope exists between human IFN-beta (aa128-134) and HIV-1 gp41 (aa586-595), we examined 20 sera from healthy and 20 from HIV-1 infected individuals for IFN-beta antibody levels by ELISA. The levels of anti-IFN-beta antibody in sera from HIV-infected individuals were increased by about 160% in comparison with HIV-negative. We affinity-purified anti-gp41 antibodies from sera of HIV-1-infected individuals using rsgp41-sepharose column. One of three antibodies could recognize human IFN-beta in comparison with antibodies from serum of a healthy individual. A mouse antiserum to human IFN-beta recognized rsgp41 (recombinant soluble gp41 Env amino acid 539-684), while the normal mouse serum (pre-immune serum) did not bind to rspg41. These results indicate that a common immunological epitope exists between human IFN-beta and HIV-1 gp41. The sequence-similarity suggests that this common immunological epitope may be located in the region aa128-134 of human IFN-beta and the immunosuppressive domain (aa583-599) of HIV-1 gp41. The increased levels of antibodies against interferon-beta in HIV-1 positive individuals may be explained by a common immunological epitope on human IFN-beta and HIV-1 gp41.
Adult↗
[The effect of indirect trauma on the goat temporomandibular joint: a histopathologic study].
The aim of this experiment was to study the effect of indirect trauma on the goat temporomandibular joint (TMJ). Trauma to the TMJ was achieved through an impact to the right mandibular angles of 20 goats, their left TMJs were used as a controls. The animals were killed after 2 h, 1 month, 3 months and 6 months. Light microscopic observations revealed that the condyles exhibited an eburnated, eroded surface with osteophytes, the disks were thinned or perforated, and the temporal surfaces were thickened and the lining were separated. These changes were histologically similar to those of the advanced osteoarthritis. This study suggests that the indirect trauma on TMJ lead to osteoarthritis.
Animals↗
[Detection of human papillomavirus types 16, 18 DNA related sequences in bronchogenic carcinoma].
In order to study the relationship between human papillomavirus (HPV) and bronchogenic carcinoma, "high-risk" HPV 16, 18 DNA sequences were detected in samples from 50 lung cancer patients, 18 patients with benign pulmonary diseases and 4 fetal lung tissues by polymerase chain reaction (PCR) and dot-blot hybridization using biotin-labelled probes. The results showed that HPV 16, 18 DNA related sequences were found in 32% of lung cancer specimens, including 10 cases of HPV 16, 5 cases of HPV 18, 1 case of both types. 48.2% (13/27) of the squamous cell carcinomas were shown to be positive for HPV 16, 18 DNA; in addition, two adenocarcinomas and one small cell carcinoma were positive for HPV 16 DNA. No specimen from benign diseases and fetal lung tissue showed positive result. Most of HPV DNA positive cases had a history of heavy smoking. These results implicated that primary bronchogenic carcinomas may be related to HPV infection.
Carcinoma, Bronchogenic↗
Alterations of performance and oxygen utilization in chronically infarcted rat hearts.
Progressive dilatation of left ventricle has been demonstrated in hearts post-infarction. However, the relationship of performance and energy consumption in chronically infarcted heart has not been clarified. To address this problem, we measured left ventricular pressure and oxygen consumption (MVO2) during stepwise increases in left ventricular filling volume in isolated isovolumic buffer-perfused rat hearts 8 weeks after let coronary artery ligation or sham-operation. Systolic pressure-volume area (PVA) was calculated as an estimate of total mechanical energy consumed by the heart. The MVO2-PVA relation was analysed to define the economy of the contractile machinery in surviving myocardium. Structural dilatation and reduced pressure generation in infarcted hearts were indicated by a rightward shift of pressure-volume curves and a reduced maximal developed pressure of the left ventricle (80 +/- 5 v 119 +/- 4 mmHg, P < 0.01) which was obtained at substantially higher left ventricular volume compared to control hearts (0.79 +/- 0.02 v 0.39 +/- 0.01 ml, P < 0.01). The slope of the MVO2-PVA relation was significantly lower in the infarcted compared to the control groups (1.02 +/- 0.16 v 1.44 +/- 0.10 10(-5) mlO2/mmHg/ml, P < 0.05), reflecting an increased efficiency of chemomechanical energy transduction in surviving myocardium. However, at the similar MVO2 ventricular pressure development was significantly lower in infarcted hearts due to the unfavorable geometry resulting from ventricular dilatation.
Animals↗
Regional biochemical remodeling in non-infarcted tissue of rat heart post-myocardial infarction.
Changes in the capacities of ATP-synthesizing reactions were analysed in residual non-infarcted myocardium following myocardial infarction. Rats were subjected to left coronary artery ligation (MI; n = 11) or to sham operation (sham; n = 18). Two months later, hearts were excised, rinsed and buffer-perfused isovolumically. In vitro pressure-volume relationships were recorded. After separation into left and right ventricles (LV, RV) and atria (LA, RA), samples were analysed for citrate synthase, glycolytic enzymes (phosphofructokinase, glyceraldehyde-3-phosphate-dehydrogenase, lactate dehydrogenase (LDH) and its isoforms) and the creatine kinase (CK) system [total CK, CK isoenzymes (CKBB, CKMB, CKMM and CKmito) and total creatine]. In residual intact heart, citrate synthase activity and activities of most glycolytic enzymes were unchanged, but LDH activity and anaerobic LDH isoenzymes increased significantly. Total creatine kinae activity (6.5 +/- 0.2 IU/mg protein in sham LV) was decreased by chronic myocardial infarction in LV (5.4 +/- 0.3, with P < 0.05 sham v MI) but not in RV (6.2 +/- 0.2). Significant CK isoenzyme shifts occurred in both ventricles "adult" CKmito (32.5 +/- 1.4% in sham LV) was reduced in LV (22.1 +/- 2.1% with P < 0.05 sham v MI) and in RV (19.2 +/- 2.9%, with P < 0.05 sham v MI), "fetal" CKBB and CKMB increased. Total creatine content was reduced by up to 35% in both ventricles. In sham hearts atria had lower total and mitochondrial CK activity, lower total creatine content and higher CKMB and CKBB activity compared to ventricles; however, myocardial infarction induced changes directionally comparable to the changes observed in ventricles. Thus, 2 months after myocardial infarction changes of the capacities of ATP synthesizing reactions are comparable for all heart chambers, with the exception of total CK activity decreasing only in left ventricular tissue.
Animals↗
Long-term beta-blocker treatment prevents chronic creatine kinase and lactate dehydrogenase system changes in rat hearts after myocardial infarction.
OBJECTIVES: We tested the hypothesis that long-term beta-blocker treatment with bisoprolol prevents creatine kinase (CK) and lactate dehydrogenase system changes that occur after chronic myocardial infarction. BACKGROUND: The mechanism of the beneficial effect of beta-blocker therapy is still unclear. METHODS: Six groups of rats were studied. Sham operated (sham) and hearts with ligated left anterior descending coronary artery (myocardial infarction) were untreated, treated early (beginning 30 min after infarction) or treated late (beginning 14 days after infarction). After 8 weeks, hearts were isolated and buffer perfused isovolumetrically. With a left ventricular balloon, mechanical function was recorded at an end-diastolic pressure of 10 mm Hg. Biopsy samples of noninfarcted left ventricular tissue were taken. Enzyme activities were measured spectrophotometrically; isoenzymes were separated by agar gel electrophoresis; and total creatine levels were measured with high performance liquid chromatography. RESULTS: The decrease in left ventricular developed pressure in untreated hearts (120 +/- 9 vs. 104 +/- 5 mm Hg [mean +/- SE], p < 0.05, sham vs. myocardial infarction) after myocardial infarction was prevented by early treatment (118 +/- 9 vs. 113 +/- 4 mm Hg). Late treatment failed to improve mechanical function. Reduction of CK activity occurring in untreated infarcted hearts (6.4 +/- 0.3 vs. 5.1 +/- 0.3 IU/mg protein, p < 0.05, sham vs. myocardial infarction) was prevented by early beta-blocker therapy. The increase in CK isoenzyme BB and MB levels, decrease in mitochondrial CK isoenzyme levels and increase in anaerobic lactate dehydrogenase isoenzyme levels in untreated infarcted hearts did not occur during bisoprolol treatment. The decrease in total creatine levels after myocardial infarction (74.2 +/- 4.9 vs. 54.9 +/- 3.3 nmol/mg protein, p < 0.05, sham vs. myocardial infarction) was prevented by bisoprolol treatment. Early treatment was more effective than late therapy in preventing CK and lactate dehydrogenase system changes. In addition, in sham hearts, a 40% increase of creatine levels above normal levels was detected. CONCLUSIONS: Bisoprolol prevented changes in CK and lactate dehydrogenase system that occur after myocardial infarction. These observations may be related to the beneficial effects of long-term beta-blocker treatment in patients with chronic myocardial infarction.
Adrenergic beta-Antagonists↗
Antineoplastic agents; I. Three spirostanol glycosides from rhizomes of Dioscorea collettii var. hypoglauca.
By activity-guided fractionation, three known steroidal saponins, prosapogenin A of dioscin, dioscin and gracillin, were isolated from the total saponin fraction of Dioscorea coiletti var. hypoglauca as active compounds causing morphological abnormality of Pyricularia oryzae mycelia. The compounds also exhibited cytotoxic activity against the cancer cell line K562 in vitro. The structures of the compounds were elucidated on the basis of chemical evidence and IR, FAB-MS, 1H-NMR, 13C-NMR, and two-dimensional NMR (2D-NMR) analysis.
Antineoplastic Agents↗
Preservation of left ventricular mechanical function and energy metabolism in rats after myocardial infarction by the angiotensin-converting enzyme inhibitor quinapril.
We tested whether angiotensin-converting enzyme (ACE) inhibitor therapy with quinapril prevents the deterioration of mechanical function and high-energy phosphate metabolism that occurs in chronically infarcted heart. Rats were subjected to ligation of the left anterior descending coronary artery (LAD) or sham operation. Four groups were studied: sham-operated rats (n = 10), rats with myocardial infarction (MI, n = 9), sham-operated quinapril-treated rats (n = 8), and infarcted quinapril-treated (n = 13) rats. Treated rats received 6 mg/kg/day of the ACE inhibitor quinapril orally, initiated 1 h after MI or sham operation. Eight weeks after LAD ligation or sham operation, hearts were isolated and buffer-perfused isovolumically. High-energy phosphate metabolism and intracellular pH were continuously recorded with 31P-nuclear magnetic resonance (NMR) spectroscopy. Hearts were subjected to 15-min control, 30-min hypoxia (95% N2/5% CO2, and 30-min reoxygenation. Left ventricular developed pressure (LVDP) was reduced in infarcted hearts (58 +/- 10 vs. 98 +/- 9 mm Hg in sham, p < 0.05), and this reduction was partially prevented by quinapril (78 +/- 8 mm Hg). ATP content of residual intact myocardium after sham operation or MI was unchanged. Creatine phosphate was reduced in infarcted hearts (107 +/- 10 vs. 138 +/- 5% of control ATP, p < 0.05), and quinapril prevented this decrease (131 +/- 8%). Therefore, quinapril preserved both function and high-energy phosphate metabolism in the chronically infarcted heart. However, when hearts were subjected to acute hypoxia, susceptibility to acute metabolic stress was substantially increased in both quinapril-treated groups: ATP content at end-hypoxia was reduced to 31 +/- 7 and 37 +/- 6% in sham and infarcted quinapril-treated groups, whereas ATP in untreated sham and infarcted hearts was 66 +/- 6 and 66 +/- 3% of baseline values (p < 0.05 untreated vs. quinapril treated). Likewise, recovery of LVDP during reoxygenation was impaired by quinapril treatment (15 +/- 7 and 15 +/- 4 mm Hg in quinapril-treated sham and MI vs. 73 +/- 9 and 46 +/- 9 mm Hg in untreated sham and MI groups, p < 0.05 untreated vs. quinapril treated). The most likely explanation for the unexpected finding of increased susceptibility to acute metabolic stress in the quinapril-treated groups is reduced wall thickness leading to increased wall stress. The preservation of high-energy phosphate content in residual intact hearts after MI may contribute to the beneficial effects of ACE inhibitors after MI.
Adenosine Triphosphate↗
Influence of cardiac dysfunction on fast sodium current regulation by Forskolin.
There are several reports of an altered beta-adrenergic pathway in heart failure. Since the fast cardiac sodium current (INa+) is also subject to beta-receptor dependent regulation, we investigated its regulation in a model of cardiac dysfunction. Adenylyl cyclase was stimulated directly with forskolin as one step in the beta-adrenergic pathway. Twelve-week-old Wistar rats were infarcted by ligation of the left anterior descending coronary artery. Eight weeks later, the induced hemodynamic changes were evaluated. The left ventricular end-diastolic pressure (LVEDP) was used as a measure of the hemodynamic effects of the myocardial infarction. With the loose patch clamp technique, INa+ was measured in intact papillary muscles at an external sodium concentration of 150 mmol/L. Potential dependent availability was tested with pulses to 0 mV from various conditioning potentials. In animals with minor infarction (n = 7, LVEDP = 7.7 +/- 0.9 mmHg), forskolin (3 mumol/L) increased the maximal available INa+ to 109% +/- 13% of baseline values. This increase was nearly the same in the group with significant infarctions (n = 7, LVEDP = 15.7 +/- 1.6 mmHg) to 113% +/- 6%. Thus, although we previously observed a reduction of the isoproterenol induced increase of INa+ in rats with significant myocardial infarctions, this increase remains the same when adenylyl cyclase is stimulated directly. This is consistent with a direct beta-receptor down-regulation or desensitization.
Action Potentials↗
The renin-angiotensin system and coronary vasomotion.
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Angiotensin I↗