PubMed Health⌕ Search

Biomedical subjects

D Yin

Publications and source records attributed to D Yin.

At least 91 records · Page 5Linked to original sources
PubMed1998

QT dispersion in dipper- and nondipper-type hypertension.

The aim of this study was to identify the relationship of QT dispersion on 12-lead electrocardiograms and left ventricular mass index on echocardiograms associated with the circadian rhythm of blood pressure (BP). Heart rate and BP were monitored every 30 min for 48 h in 62 patients with essential hypertension using an ambulatory BP monitoring device. The patients were divided into four groups according to gender and circadian BP pattern (nocturnal BP dipper or nondipper). The patients were classified as dippers if their daytime BP decreased by at least 10% during the night and all the other subjects were classified as nondippers. Age, body mass index, and 48-h mean BP were similar among the four groups. During the night-rest period, the systolic and diastolic BP were significantly decreased in dipper-type hypertensives. The maximum QTc interval and QTc dispersion were longer in nondippers than in dippers. Left ventricular mass index (LVMI) had a tendency to increase in nondippers. The nocturnal reduction of BP significantly correlated with QTc dispersion and LVMI. The QTc dispersion significantly correlated with LVMI and interventricular septum thickness.

Adult↗
PubMed1998

[Differences in exercise blood pressure response between dipper and non-dipper elderly patients with essential hypertension].

We evaluated the circadian variation and exercise stress response patterns of blood pressure (BP) in elderly patients with essential hypertension. Ambulatory BP monitoring for 48 hours every 30 minutes, and treadmill exercise test using a Bruce protocol at PM 3 to 5 were performed in 49 untreated patients with hypertension. Mean daytime (awake), and night-time (sleeping) systolic BP (SBP) and diastolic BP (DBP) values were analyzed by reviewing the patients' diaries, and the nocturnal reduction rate (NRR) of SBP and DBP were calculated according to the following formula. NRR (%) = [(daytime mean-nighttime mean)/daytime mean] x 100. The patients were divided into two groups according to the presence (dipper, n = 25) or absence (non-dipper, n = 24) of a reduction in both SBP and DBP during the night by an average of more than 10% of the daytime BP. Mean values of SBP and DBP measured over 48 hours in the dipper and non-dipper groups were similar. Responses of SBP to dynamic exercise at 2 to 5 minutes in the non-dipper group were significantly smaller than those in the dipper group (p < 0.05). Non-dipper patients with hypertension responded to dynamic exercise stress with smaller increases in SBP than did those in the dipper group. The differences in BP responses to exercise may affect the circadian blood pressure profile in dipper and non-dipper elderly patients with essential hypertension.

Aged↗
PubMed1998

[Influence of MP infection on immunologic function in patients with chronic obstructive pulmonary disease].

The aim of this study was to detect Mycoplasma pneumoniae(MP) in sputum with chronic obstructive pulmonary disease(COPD) by using polymerase chain reaction and measured the level of sIL-2R in chronic pulmonary heart disease(CPHD) patients by Enzyme Linked Immnosorbert Assay(ELISA). At the same time, we also measured the level of the serum total IgE in CPHD patients. We determine the relationship between the sIL-2R and lymphocytes. The results showed that rate of MP infection in COPD patients was 34.59%. The rate of MP infection in CPHD patients and asthmatic patients were significantly higher than that in patients with chronic bronchitis. The level of sIL-2R in patients with CPHD who had MP infection increased significantly higher than that in CPHD patients which didn't have MP infection. There was a linear negative correlation between the level of sIL-2R and lymphocytes. The level of serum total IgE in CPHD patients with MP infection was higher than that in patients with other infection. These data suggest that MP is a common agent in COPD patients, particularly in CPHD and asthma. MP infection can impair the cellular immunity and immunotherapy combined with antibiotics may be more effective.

Adult↗
PubMed1998

[Yishen huanshuai recipe retard progression of chronic renal failure].

OBJECTIVE: To investigate the effect of Yishen Huanshuai recipe (YSHSR) on the progression of chronic renal failure (CRF). METHODS: Forty-six patients with CRF were divided into two groups: group A (self-controlled group, n = 18), whose treatment was subdivided into two stages. During the first stage, the patients treated with low protein diet and controlling blood pressure, while in the second stage, YSHSR was given. Group B(n = 28), whose treatment plan was similar with that of group A in second stage. The rate of progression of CRF was estimated by slope of the creatinine reciporcal (dl/mg) with time (month). RESULTS: Mean slope of the creatinine reciprocal with time from the group A during the first stage was -0.0104 +/- 0.0021, while during the second stage, it was -0.0034 +/- 0.0018. There was significant difference between them (P < 0.05). Mean slope from the group B was -0.0047 +/- 0.0020. There was also significant difference between that from the group B and that from the group A during the first stage (P < 0.05). CONCLUSIONS: Low protein and controlling blood pressure plus YSHSR therapy could markedly retard the rate of progression of CRF.

Adult↗
PubMed1998

[Synthesis and structure-activity relationships of novel 14 beta-side chain taxol derivatives].

In order to develop new generation of taxol-like anticancer agents with fewer side effects, improved activity, superior pharmacological properties and broad antitumor spectrum, along with structure-activity relationship study, a series of new taxol derivatives are to be synthesized starting from sinenxan A--a biosynthetic taxane. Eight new 14 beta-side chain taxol derivatives with 4-OH and 4-Ac were synthesized in 5 and 6 steps from semisynthetic taxoid intermediate 7, respectively. These included taxol derivatives modified at C-2 position with benzoate, m-Cl benzoate, valerate and phenylacetate. All target compounds together with two other 14 beta-side chain taxol derivatives were tested in a microtubule assembly assay, and in an in vitro cytotoxicity assay (KB, A2780, HCT-8 cell line). All compounds had no effect in the microtubule assembly assay at 10 mumol.L-1. Most of them showed marginal activity in the in vitro cytotoxicity. The structure-activity relationship was different from taxol derivatives. 2-Aliphatic ester displayed similar activity to 2-aromatic ester, which indicated that the aromatic group at C-2 position was not important for cytotoxicity. Comparing among themselves, 4-OH derivatives possessed stronger activity than 4-Ac.

Antineoplastic Agents, Phytogenic↗
PubMed1998

[Study on voltammetric behaviour of clozapine and its single-sweep oscillopolarography].

A sensitive reduction peak of clozapine is obtained by single-sweep oscillopolarography in 0.1 mol.L-1 H2SO4 solution. The peak potential is -0.95 V (vs. SCE). The peak current is directly proportional to the concentration of clozapine with a detection limit of 2.0 x 10(-8) mol.L-1. The voltammetric behaviour of clozapine and its mechanism of electrode reaction have been studied by linear-sweep and cyclic voltammetry and pulse polarography etc. The reduction process is irreversible with adsorptive characteristics. The number of electrons transferred n is 2. The electron transfer coefficient alpha is 0.62. Its behaviour obeys Langmuir adsorption isotherm. The adsorption coefficient beta is 1.91 x 10(6) L.mol-1. The energy of adsorption delta G0 = -35.83 kJ.mol-1. The method has been applied to the determination of clozepine in tablet and urine.

Antipsychotic Agents↗
PubMed1997

Preparation of artificial ceroid/lipofuscin by UV-oxidation of subcellular organelles.

Recent studies have consistently shown that, during oxidative damage, glycation, and other oxygen stress-related reactions, various biomolecules are converted into ceroid- and lipofuscin-like fluorescent pigments. In this study, artificial ceroid/lipofuscin was produced by exposing rat liver fractions to UV-light overnight. Thiobarbituric acid reactive substances (TBARS) were formed in increasing amounts during the early stages of the process, but decreased as the material was later converted into a polymeric structure with few remaining peroxides. In the transmission electron microscope the artificial pigment showed lamellar structures and was osmiophilic. By energy-dispersive X-ray analysis the material was found to contain Ca and Fe in the same way as natural ceroid/lipofuscin. Moreover, it exhibited ceroid/lipofuscin-like, greenish-yellowish autofluorescence when assayed by microfluorometry, with a fluorescence maximum consistently found at 430 nm when excited at 350 nm. Identical fluorescence maxima were found for each fraction of rat liver that was used as the origin of the pigments, i.e. nuclei, mitochondria, lysosomes and microsomes. Extracts with either chloroform-methanol, or sodium dodecylsulphate, showed identical complex fluorescence. When the pigments were extracted by chloroform-methanol, five fluorescent bands were obtained after thin-layer chromatographic separation. Fibroblasts were found to endocytose the material, a process that converted them into lipofuscin-loaded cells of an aged phenotype as observed by light and electron microscopy. Similar fluorescence emission spectra were obtained from cells grown at 40% O2, in order to stimulate endogenous lipofuscin-formation, and from cells exposed to artificial ceroid/lipofuscin. The described technique for creating artificial ceroid/lipofuscin is relatively easy to perform and should provide a useful new tool to study the possible influences of ceroid/lipofuscin on lysosomal and cellular functions.

Animals↗
PubMed1997

Induction of apoptosis in multi-drug resistant (MDR) human glioblastoma cells by SN-38, a metabolite of the camptothecin derivative CPT-11.

The overexpression of the multidrug resistance (mdr1) gene and its product, P-glycoprotein (P-gp), is thought to limit the successful chemotherapy of human tumors. Recent studies demonstrate that SN-38, a metabolite of the camptothecin (CPT) derivative CPT-11, has antitumor effects on several tumors, but the mechanisms responsible for its cytotoxicity remain unclear. We therefore determined whether SN-38 has cytotoxic effects on MDR human glioblastoma GB-1 cells and non-MDR human glioblastoma U87-MG cells. Furthermore, we determined what role SN-38 plays in the induction of cytotoxicity in these tumor cells. In this study, we demonstrated that SN-38 had significantly stronger antitumor effects on GB-1 and U-87MG cells than did CPT (P < 0.01 and P < 0.05, respectively). In addition, findings obtained using a DNA fragmentation assay, Hoechst 33258 staining, in situ end-labeling and cell cycle analysis demonstrated that SN-38 induced apoptosis in these tumors. Our results suggest that SN-38 has a stronger antitumor effect on malignant glioma cells regardless of MDR expression than does CPT, and therefore can be considered a new chemotherapeutic agent potentially effective in the treatment of human primary or recurrent malignant gliomas resistant to chemotherapy.

Antineoplastic Agents, Phytogenic↗
PubMed1997

Molecular dynamics simulation of unsaturated lipid bilayers at low hydration: parameterization and comparison with diffraction studies.

A potential energy function for unsaturated hydrocarbons is proposed and is shown to agree well with experiment, using molecular dynamics simulations of a water/octene interface and a dioleoyl phosphatidylcholine (DOPC) bilayer. The simulation results verify most of the assumptions used in interpreting the DOPC experiments, but suggest a few that should be reconsidered. Comparisons with recent results of a simulation of a dipalmitoyl phosphatidylcholine (DPPC) lipid bilayer show that disorder is comparable, even though the temperature, hydration level, and surface area/lipid for DOPC are lower. These observations highlight the dramatic effects of unsaturation on bilayer structure.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1997

[Circadian variation of blood pressure and heart rate in normotensive pre- and postmenopausal women].

The aim of this study was to assess the effect of menopause on circadian profile of blood pressure (BP) and heart rate (HR) in the normotensive pre- and postmenopausal women. Systolic BP (SBP), diagnostic BP (DBP) and HR were monitored every 30 min for 48 hrs using noninvasive ambulatory BP monitoring in 24 premenopausal and 40 postmenopausal women. Mean 48-hours, daytime (awake), and nighttime (sleeping) SBP, DBP and HR values were analyzed by reviewing the patients' diaries, and the nocturnal reduction rate (NRR) of SBP, DBP and HR were calculated according to the following formula. NRR (%9 = [(daytime mean-nighttime mean)/daytime mean] x 100. The study subjects were then divided into two groups according to the presence (dipper) or absence (nondipper) of a significant reduction in nocturnal BP (> 10%). Mean SBP, DBP and HR measured over 48 hours were similar between the premenopausal and the postmenopausal group. The NRR of DBP and HR in the postmenopausal group were significantly smaller than those in the premenopausal group (17.1 +/- 6.0% vs. 13.5 +/- 7.0%, 241.1 +/- 6.0% vs. 19.8 +/- 9.0%: p < 0.05). There tended to be higher prevalence of nondipper in the postmenopausal (37%) than in the premenopausal group (29%).

Adult↗
PubMed1996

Mechanisms of tolerance to rat heart allografts using posttransplant TLI. Changes in cytokine expression.

Lewis rats were rendered tolerant to ACI heart allografts using a regimen of posttransplant total lymphoid irradiation (TLI), rabbit antithymocyte or antilymphocyte globulin (RATG or RALG), and a single donor blood transfusion. All three treatment modalities were required to induce tolerance. The mechanism of the maintenance of tolerance was investigated by comparing the secretion of cytokines in the MLR, and the expression of cytokine mRNA in the allografts of tolerant and nontolerant Lewis rats. Although, the 3H-thymidine incorporation and secretion of IL-2 was frequently comparable in the MLR from tolerant and nontolerant rats, the secretion of IFN-gamma was markedly reduced in the tolerant rats. This was reflected in a markedly reduced frequency of cells expressing IFN-gamma mRNA in the allografts of tolerant as compared with nontolerant hosts. The frequency of cells expressing IL-2 and IL-10 mRNA was also reduced, but no significant difference was observed for cells with IL-4 mRNA. Spleen cells from nontolerant rats rapidly rejected ACI allografts in irradiated adoptive hosts, but spleen cells from tolerant rats did not. Evaluation of the cytokine mRNA expression at early and late time points in the allografts of adoptive hosts showed a pattern similar to that of the primary hosts. Thus, the tolerant state was associated with a maintenance or elevation of IL-4 expression and a marked reduction of IFN-gamma expression. Previous reports have shown that TLI alone induced this shift in the early recovery phase after irradiation.

Animals↗
PubMed1996

Oxidative modification of a carboxyl-terminal vicinal methionine in calmodulin by hydrogen peroxide inhibits calmodulin-dependent activation of the plasma membrane Ca-ATPase.

In order to investigate the possibility that calmodulin (CaM) may be a principal target of reactive oxygen species (ROS) produced under conditions of oxidative stress, we have examined wheat germ CaM for the presence of highly reactive sites that correlate with the loss of function. Using reversed-phase HPLC and FAB mass spectrometry after proteolytic digestion, we have identified the sites of modification by hydrogen peroxide. We find that one of the vicinal methionines (i.e., Met146 or Met147) near the C-terminus of CaM is selectively oxidized. The ability of CaM to bind and to activate the plasma membrane (PM)-Ca-ATPase from erythrocytes was measured. There is a 30-fold decrease in the calcium affinity of oxidatively modified CaM. While there is a little change in the binding constant between the carboxyl-terminal domain of calcium-saturated CaM and a peptide homologous to the autoinhibitory sequence of the PM-Ca-ATPase, we find that there is a 9-fold reduction in the affinity of the amino-terminal domain of CaM with respect to the ability to bind target peptides. The extent of oxidative modification to one of the vicinal methionines near the carboxyl-terminal domain correlates with the loss of CaM-dependent activation of the PM-Ca-ATPase. The presence of oxidatively modified CaM prevents native CaM from activating the PM-Ca-ATPase, indicating that the oxidatively modified CaM binds to the autoinhibitory sequence on the Ca-ATPase in an altered nonproductive conformation. We suggest that the functional sensitivity of CaM to the oxidation of one of the C-terminal vicinal methionines permits CAM to serve a regulatory role in modulating cellular metabolism under conditions of oxidative stress. The predominant oxidation of a methionine near the carboxyl terminal of CaM is rationalized in terms of the enhanced solvent accessibility of these vicinal methionines.

Amino Acid Sequence↗
PubMed1996

Decreased plasma membrane calcium transport activity in aging brain.

We have assessed the functional properties of both calmodulin (CaM) and the plasma membrane Ca(2+)-ATPase in brains of young, middle aged, and old Fisher 344 rats. Under optimal conditions of saturating Ca2+ and ATP, the CaM-activated Ca(2+)-ATPase activity was decreased with increasing age, particularly when CaM isolated from the brains of aged rats was used to stimulate the enzyme. In the case of CaM, structural modifications within the primary sequence of the protein from aged brains were identified. We found that during normal biological aging approximately 6 methionine residues were modified to their corresonding sulfoxide per CaM, and no other amino acids were modified. Some aspects of the age-related decline in the effectiveness of CaM as an activator of Ca(2+)-ATPase could be simulated using a range of reactive oxygen species (including hydrogen peroxide and oxoperoxynitrite) and, in the latter case, the extent of oxidative modification of specific methionine residues was directly related to their surface accessibility. The pattern of oxidative modification of the methionines in the aged CaM was less straightforward, though both in vitro oxidation of CaM and aging within the brain markedly decreased the functional properties of this important Ca(2+)-regulating protein.

Aging↗