Biomedical subjects
Publications and source records attributed to M Q Chen.
A novel dimeric abietane diterpene, hongencaotone (1), has been isolated from the roots of Salvia prionitis, and its structure was determined by spectral data interpretation and X-ray analysis. Hongencaotone (1) is the first ether-linked heterodimeric diterpene to have been isolated from the genus Salvia.
The title compound, 2,2'-(2,4,8,10-tetrathiaspiro[5.5]undecane-3,9-diylidene)bis(propanedinitrile), C(13)H(8)N(4)S(4), has been designed and synthesized for use as a potential new organic molecular electronic material. The spiro-annulated structure has twofold symmetry and is formed by two equal push-pull ethylene units, with the cycloalkylthio groups as electron donors and the cyano groups as electron acceptors. The intermolecular S.N non-bonded separation within a layer in the lattice is 3.296 (6) A, indicating a strong intermolecular interaction between the cyano groups and the S atoms, while the S atoms in two neighbouring molecules have a shortest S.S contact of 3.449 (3) A. In addition, attractive C-H.N and C-H.S interactions bridge adjacent molecules either within a layer or between layers. In short, these four types of intermolecular interactions combine to form an extended three-dimensional network in the lattice, resulting in a highly ordered array of molecular packing.
Thermostable alkaline phosphatase from Thermus sp. 3041 has been expressed in Escherichia coli, purified and crystallized. The crystals belong to space group P2(1)22(1), with unit-cell parameters a = 57.7, b = 69.9, c = 111.5 A. Diffraction data were collected to 2.54 A with a completeness of 91.1% (87.8% for the last shell), an R(merge) value of 0.105 (0.312) and an I/sigma(I) value of 9.5 (3.6).
1. Increases in cell proliferation and DNA synthesis were observed in vascular smooth muscle cells (VSMC) from old rats. These effects were significantly enhanced by noradrenaline but were inhibited by nifedipine. 2. Ginsenosides, traditional Chinese drugs, inhibited the proliferation and DNA synthesis in VSMC from old rats. Cytosolic and nuclear Ca2+ levels, as well as calmodulin activity, were clearly higher in old rats compared with young rats. 3. Both Ca2+ and calmodulin levels rose abruptly in the late G1 phase in the VSMC cell cycle in old rats. 4. The increase in inositol phosphate levels stimulated by phenylephrine in VSMC was greater in old than in young rats. 5. The platelet-derived growth factor (PDGF) gene was overexpressed in old rats. The results indicate that vascular ageing is related to enhanced proliferation of VSMC. Abnormal Ca2+ homeostasis as well as overexpression of the PDGF gene may be responsible. 6. Nifedipine and ginsenosides may inhibit VSMC proliferation with age.
The thermostable catechol 2,3-dioxygenase of Bacillus stearothermophilus has been crystallized. The crystal is probably in the space group I222 with unit-cell dimensions of a = 70.87, b = 74.60 and c = 133.69 A. A native data set has been collected with a completeness of 96% at 2.22 A resolution and an Rmerge value of 0.091.
The functional activities of blood vessels in various organs have their own characteristics, named individuality of blood vessel. One of the most outstanding characteristics is that the responses of blood vessels in various organs to the same stimulation are different, even contradictory. This physiological characteristic of the blood vessel guarantees that the blood vessel can make adjustable responses in varying parts and under different conditions to fulfil the functional tasks of circulatory system and to meet the demands of blood supply of recipient organs. The study of vascular individualization would benefit to explain the mechanism of blood vessel activities and is also important in the study of pathogenesis of vascular diseases. This paper gives a brief description on the vascular mechanisms contributing to the individualization of blood vessel.
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We previously demonstrated the presence of a long-acting antihypertensive factor (AHF) in the erythrocytes of essential hypertensive subjects (EHS). The present investigation demonstrates further that the AHF is also capable of producing a rapid and transient blood pressure lowering effect in stroke prone spontaneously hypertensive rats (from 26.8 +/- 1.7 to 20.1 +/- 1.5 kPa by 10-30 s, P < 0.001). An even more stronger antihypertensive effect could be found if the AHF prepared from normal subjects or rats was used. We also found that some hypertensive factor was present in EHS plasma, but not in normal subjects. The results of the present paper suggest that AHF deficiency and higher level of pressor substance may play an important role in the development of essential hypertension.
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The effects of antihypertensive factor (AHF) from erythrocytes of essential hypertensive human subjects on the systolic blood pressure (SBP) and diastolic blood pressure (DBP) in spontaneously hypertensive rats (SHR), renal hypertensive rats (RHR), Wistar-Kyoto rats (WKY) and Wistar rats were examined. Single intraperitoneal injection of AHF (1.6 mg/kg body weight) resulted in a significant decrease in SBP of SHR and RHR. At 10 min postinjection, AHF lowered the SBP in SHR by 34.0 mmHg. SBP recovered to the original level at 3 h. The maximal decrease of SBP in RHR by 92.5 mmHg was at 24h postadministration and the SBP did not recover until the 9th day. When AHF was administered via femoral vein (0.8 mg/kg body weight), the maximal decrease values of the SBP and the DBP were 42.8 and 48.2 mmHg in SHR at 12 min and 38.3 and 42.5 mmHg in RHR at 25 min postinjection respectively. The DBP in Wistar rats decreased considerably (from 96.7 +/- 12.9 to 83.3 +/- 11.7 mmHg) at 5 min postadministration of AHF, but no effect on DBP in WKY rats was observed. The depressor effect of AHF on SBP in RHR was dose-dependent. AHF could also antagonize the pressor effect of norepinephrine in Wistar rats.
Upon treatment of 1-aryl-4-ethoxycarbonyl-5-amino-1,2,3-triazoles (1) with excess acetic acid, acetic anhydride, acetyl chloride, benzoyl chloride, formamide, etc., fourteen new derivatives of 1 were obtained in good yields, such as, 1-H-4-ethoxycarbonyl-5-arylamino-1,2,3-triazoles (2b-d), 1-RCO-4-ethoxycarbonyl-5-arylamino-1,2,3-triazoles (3a-d), 1-aryl-4-ethoxycarbonyl-5-acetylamino-1,2,3-triazoles (4a-d) and 1-formoyl-4-ethoxycarbonyl-5-p-nitrophenylamino-1,2,3-triazole (5a), 1-benzoyl-4-ethoxycarbonyl-5-p-nitrophenylamino-1,2,3-triazoles (5b), 1-p-chlorobenzoyl-4-ethoxycarbonyl-5-p-nitrophenylamino-1,2,3-triazoles (5c). Some of them were rearrangement products. Structures of all heterocyclic compounds were identified by elemental analyses, IR, 1HNMR and MS. Inhibiting effects of some compounds on B. substilis, E. coli, E. aerogenes and S. aureus were also screened.
The effects of a partially purified antihypertensive factor (AHF) from erythrocytes of spontaneously hypertensive rats (SHR) on the blood pressure (BP) and Ca2+ influx of vascular smooth muscle (VSM) in rats were studied. The results indicated that AHF could produce a marked prolonged depressor effect and significantly inhibit the Ca2+ influx dose-dependently on both SHR and renal hypertensive rat (RHR) either in acute or in chronic experiments, but not on normotensive rats. It suggested that the inhibition of Ca2+ influx might be one of the important mechanisms for AHF as an endogenous depressor substance.
Neurogenic pulmonary edema (NPE) was induced by microinjection of kainic acid into bilateral preoptic area (POA) of the hypothalamus in rats. Sympathetic discharge of the left adrenal branch was recorded, plasma catecholamine (CA) was assayed and the physical properties of pulmonary surfactant (PS) of the lung lavage were measured. The results showed that some physical properties of PS were changed in NPE, i.e. maximal surface tension (gamma Max) decreased, minimum surface tension (gamma Min) increased, recruitment index (RI), stability index and area of hysteresis loop (H-area) decreased. After injection of kainic acid into POA, the sympathetic discharge increased by 22.8 +/- 7.20% and 32.2 +/- 8.0% respectively at 30 and 60 min after injection and paralleled by a marked elevation of plasma catecholamine (CA). The results showed that PS activity had decreased at an early stage of NPE and the change of the plasma CA level was parallel to that of sympathetic discharge. It is suggested that generation of NPE may be related to some disorder of the autonomic nervous system at the level of hypothalamus, increase of sympathetic discharge, elevation of plasma CA level and fall of PS activity.
The central mechanism of the pressor response induced by stimulation of the central ends of abdominal vagi (SCAV) was studied in 33 anesthetized cats. The results of the experiments showed that both electro-stimulation to part of the nucleus tractus solitarius (NTS) and SCAV caused similar rises of blood pressure. The microinjection of kainic acid into the NTS (40 mmol/L, 2 microliters) evoked a prolonged rise of blood pressure but did not affect the pressor response induced by SCAV. Electro-stimulation of the locus coeruleus (LC) also elicited a pressor effect. Kainic acid at blocking dose (40 mmol/L, 2 microliters bilaterally injected into the LC induced an increase followed by a decrease in blood pressure and markedly attenuated the SCAV's pressor response. Bilateral microinjections of phentolamine (4 micrograms/2 microliters), propranolol (2 micrograms/2 microliters) or 6-hydroxydopamine (6-OHDA, 8 micrograms/2 microliters) into LC had no significant effect on the pressor response, but atropine could markedly attenuate it. These results suggest that the pressor afferents in abdominal vagi do not terminate in but pass through the NTS and the neurons in the LC play an important role in the SCAV pressor reflex. Cholinergic transmission rather than catecholaminergic transmission in the LC may be involved in this pressor response.
The effect of ligustrazine (Lig) on blood pressure and Ca2+ uptake by inside-out red cell membrane vesicles (IOV) was investigated in renal hypertensive rats (RHR). After oral administration of Lig (30 mg/kg body weight/day) for 10 days, the blood pressure of RHR was not significantly changed (before vs after experiment: 147.50 +/- 2.50 vs 150.00 +/- 13.42 mmHg). The active Ca2+ uptake rate of IOVs from RHR was 5.03 +/- 1.15 nmol/ng IOV protein/min, and this was lower than that of IOVs from normotensive Wistar rats (8.95 +/- 1.08 nmol/ng IOV protein/min, P less than 0.01). In RHR, no change in IOV Ca2+ uptake capacity was observed after administration of Lig in vivo. Experiments in vitro showed that Lig markedly reduced Ca2+ uptake by IOVs from both RHR and control rats. The results indicate that the active Ca2+ transport capacity of red cell membranes is decreased in RHR and not significantly affected by oral administration of Lig; this drug, however, exerts an inhibitory effect on the transport process in vitro.
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