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Biomedical subjects

Z C Yang

Publications and source records attributed to Z C Yang.

At least 55 records · Page 3Linked to original sources
PubMed1992

Chromosome observations of acute promyelocytic leukemia treated with all-trans retinoic acid.

Chromosome changes were observed in 8 patients with acute promyelocytic leukemia during the all-trans retinoic acid-induced differentiation course. Karyotype of patient bone marrow specimens after short-term incubation were analyzed using Giemsa-R banding. Analyses showed all 8 patients had the abnormal translocation between chromosomes 15 and 17, but when those patients were treated with all-trans retinoic acid and were in remission, the characteristic t(15;17) chromosomal abnormality disappeared. However, this aberration of chromosomes detected in 3 patients persisted during the early period of RA induction, although the patients could still achieve complete remission. However, it was found that the percentage of abnormal karyotypes declined during this early period. This phenomenon may be an important indicator for clinical remission. When one case relapsed, the t(15;17) reappeared. Thus the chromosome t(15;17) was not only useful in diagnosis, but also helpful in observing prognosis in acute promyelocytic leukemia.

Adolescent↗
PubMed1991

Prediction of retention indexes. II. Structure-retention index relationship on polar columns.

A method is described for the prediction of the retention index (I) from chemical structure, using the number of atoms in the molecule (Z), the I increment for atom addition (A) and the group retention factors (GRFs) of the functional groups and substituents. This method can predict the retention indexes of a wide range of compounds, such as acids, alcohols, amines, acid esters, aldehydes, ketones, ethers, aromatic hydrocarbons, alicyclics, heterocyclics, etc. on polar as well as non-polar columns to within 3% error. Accurate A and GRF values are essential to the prediction. These values can be obtained from homologous series, but a system of arbitrarily assigned A value and adjusted GRFs are also used. The GRFs of the substituents and functional groups depend on the polarity and polarizability of the analyte and the stationary phase and also on the molecular connectivity of the atoms, namely, primary, secondary and tertiary carbon atoms or hydrogen atoms, to which these groups are attached. Highly polar and polarizable groups can alter the A value. When the functionality of a group is masked by substitution, the analyte molecule will tend to behave chromatographically like hydrocarbons. The difficulty in predicting the I values of compounds of multi-functionality by the rule of additivity is the unknown intramolecular interaction that can alter both A and GRF values.

Alcohols↗
PubMed1991

Prediction of retention indexes. III. Silylated derivatives of polar compounds.

Polar compounds containing hydroxyl, amino and carboxyl groups, singly or in combination, can be chromatographed after the polar functional groups are silylated. The silylated derivatives of acids, alcohols, amines, diols, amino alcohols, amino acids are shown to behave chromatographically as hydrocarbons, and their retention indexes can be readily predicted from their base values. The column difference, namely, the difference between the retention indexes of the analyte on polar and non-polar columns is minimal for the silylated derivatives in comparison to that observed for the underivatized analytes. This minimal column difference is attributed to the hydrocarbon-like chromatographic characteristics of the silylated derivatives. The retention indexes of the silyl derivatives appear to correlate with the atom number Z of the analyte.

Acids↗
PubMed1991

[Effect of (-)-stepholidine on blood pressure and alpha-adrenoceptor agonists-, KCl- and CaCl2-evoked contractions of aortic strips].

Iv (-)-SPD lowered the blood pressure in anesthetized rat, the ED50 value was 5.1 +/- 2.5 mg.kg-1. In the experiments of rat and rabbit aortic strips, (-)-SPD 0.3-100.0 mumol.L-1 inhibited the contraction initiated by clonidine (alpha 2) and phenylephrine (alpha 1) and shifted the dose-response curve to the right parallely without change in maximum response. The inhibitory ratio of (-)-SPD acting on alpha 2/alpha 1 adrenergic receptors was about 7.2, and (-)-SPD thus was predominant inhibition on alpha 2 adrenergic receptors. In the experiment of aortic strips from reserpinized rabbits, the inhibition of (-)-SPD on contraction evoked by clonidine was diminished markedly. The results suggest that (-)-SPD stimulated mainly the alpha 2-adrenergic receptors of presynaptic nerve endings. Moreover (-)-SPD 1 mumol.L-1 inhibited the release of intracellular Ca2+ initiated by NE. (-)-SPD 3-30 mumol.L-1 blocked the voltage-dependent Ca2+ channel.

Animals↗
PubMed1991

Antagonistic effects of dihydropyridines and verapamil on CaCl2 and 5-HT-evoked contraction in porcine coronary artery.

In porcine coronary arterial strips, the antagonistic effects of nifedipine (Nif), nimodipine (Nim), nicardipine (Nic), felodipine (Fel), and verapamil (Ver) to CaCl2-evoked contraction in Ca(2+)-free, K(+)-depolarized solution were greater than that to 5-HT. The order of potency (pD2') was Nif (9.1) greater than Fel (8.4) greater than Nim (7.9) greater than Nic (7.8) greater than Ver (7.2) to CaCl2 and Nif (8.3) greater than Nim (7.5) greater than Fel (6.8) greater than Ver (5.6) greater than Nic (5.3) to 5-HT. Ver inhibited 2 components of 5-HT-evoked contraction in Ca(2+)-free solution, but Fel inhibited only extracellular Ca(2+)-dependent contraction, suggesting that their action modes are different.

Animals↗
PubMed1991

Changes of length of elastic fibers in rabbit lungs after smoke inhalation injury.

Pulmonary morphometry was determined in rabbit lungs after smoke inhalation. Twenty-four hours after injury, changes of the total lung volume (TLV) and the total length of all parenchymal elastic fibers (LT) were measured. Concomitant changes in arterial blood gas levels and pathomorphology of lung tissues were also studied. It was found that alveolar walls were broken and became thinner, and that alveoli were dilated. TLV was markedly increased and LT was markedly decreased as compared to normal lungs (P less than 0.05). These findings suggest that proteinases, especially elastase, released from phagocytes may play an important role in acute lung injury after smoke inhalation.

Animals↗
PubMed1990

Roles of thromboxane and its inhibitor anisodamine in burn shock.

Thromboxane (TXA2) and prostacyclin (PGI2) levels, circulatory platelet aggregate ratios (CPAR), CPK, LDH, GOT, platelet counts, blood viscosity, cortisol and urine epinephrine contents were determined in 42 burned patients who were divided into two groups: Group I control (n = 34) and Group II (n = 8) treated with TXA2 synthesis inhibitor, anisodamine. It was found that in controls, both TXA2 and the TXA2/PGI2 ratio increased significantly. There was no marked difference in PGI2 levels between the two groups. Platelet counts and CPAR decreased, while blood viscosity, CPK, LDH, GOT, cortisol and epinephrine in the controls were all significantly higher than those found in Group II patients. All these findings suggested that the changes of TXA2 and the TXA2/PGI2 ratios played an important role in the haemodynamics and haemorrheology in burn shock. The TXA2 synthesis inhibitor, anisodamine, showed beneficial effects by restoring the haemodynamic and rheological disturbances towards normal by virtue of their ability to induce vascular constriction, platelet aggregation, cellular destruction, destabilization of membranes and release of chemical mediators (including enzymes). Furthermore, at 1-3 days postburn, the levels of CPK, LDH and GOT in controls were higher than those measured at 12 h postburn, but this phenomenon was not marked in the treated group, suggesting that after resuscitation, reperfusion damage had occurred and TXA2 might be responsible for the damage. It is assumed that anisodamine could protect tissues from reperfusion damage. The findings also suggested that anisodamine could quicken the restoration of neuroendocrine disturbance initiated by shock (stress).

Adolescent↗
PubMed1990

The pathophysiology of carbon monoxide poisoning and acute respiratory failure in a sheep model with smoke inhalation injury.

A smoke inhalation model was created in 22 adult male sheep with pine smoke inhalation through an endotracheal tube for 6 min. Arterial blood gases, HbCO, HbO2 and pulmonary compliance (Cdyn) were monitored, and the morphology of the tracheobronchial tree and pulmonary parenchyma were studied by light and electron microscopy. Severe carbon monoxide poisoning with fatal levels of HbCO (greater than 50 percent) was found at the end of smoke inhalation. Acute respiratory distress, progressive hypoxemia, decreased pulmonary compliance and increased P(A-a)O2 and Qs/QT occurred after injury. Tracheobronchial blockade by pseudomembrane cast, pulmonary edema, atelectasis and necrosis of pulmonary epithelia were demonstrated pathologically. The mechanisms of CO poisoning and ARF are discussed.

Acute Disease↗
PubMed1990

[Effect of nimodipine on the contraction and the Ca influx of rat aorta].

The relaxant effect of nimodipine (Nim) on rat aorta was studied in vitro. Nim inhibited KCl-induced contraction (IC50 = 40 nmol/L) more potently than NE-induced contraction (IC50 = 20 mumol/L), but did as equipotently as KCl-induced 45Ca influx (IC50 = 30 nmol/L). There was a positive correlation between inhibiting the KCl-induced 45Ca influx and the contraction (r = 0.98). However, it inhibited the NE-induced 45Ca influx (IC50 = 60 nmol/L) more potently than the NE-induced contraction. Verapamil inhibited the 2 components of NE-induced contraction significantly, while Nim only inhibited the contraction evoked by extracellular Ca2+ influx significantly. Nim did not influence the 45Ca influx into resting cells of rat aorta. These results suggest that the relaxant effect of Nim on rat aorta may be closely related to the blockade of Ca2+ entry through both potential-dependent calcium channels (PDC) and receptor-operated calcium channels (ROC), while the action on PDC seems to play a more important role than that on ROC.

Animals↗
PubMed1990

Role of endothelin in the pathogenesis of hypertension in spontaneously hypertensive and 2 kidneys 1 clip rats.

The plasma endothelin (ET) level in spontaneously hypertensive rats (SHR) and 2K1C hypertension animal models and its vasoconstrictive effect on renal and tail arteries were studied. The results demonstrated that there was no difference in plasma ET level between the hypertensive groups SHR, 2K1C, normotensive control groups Wistar Kyot (WKY) and Sprague Dawley (SD), while the vasoconstrictive effect of ET in SHR was more dominant than in WKY. The EC50 of the renal and tail arteries in SHR (0.8912 +/- 0.1662 x 10(-8) M, 0.6103 +/- 0.0878 x 10(-8) M) was apparently lower than that in WKY (1.77 +/- 0.2991 x 10(-8) M, 1.2267 +/- 0.2502 x 10(-8) M, P less than 0.05), but no difference was found in 2K1C and SD rats. The four groups of animals exhibited no difference of such effects as response to norepine-phrine (NA). The findings suggested that the increased arteriole sensitivity to ET be an important factor in the pathogenesis of hypertension in SHR.

Animals↗
PubMed1990

[Effects of ephedrine on postsynaptic alpha-adrenoceptors and presynaptic beta-adrenoceptors in isolated guinea pig portal veins].

The effects of ephedrine (Eph) were compared with those of tyramine (Tyr) and phenylephrine (Phe) in ring segments of guinea pig portal vein in vitro. Eph (3-1000 mumol/L), Tyr (10-1000 mumol/L) and Phe (1-1000 mumol/L) all produced concentration-dependent contractile responses, which were exceedingly depressed by alpha-adrenoceptor blocker phentolamine (31 mumol/L). Pretreatment with reserpine 1 mg/(kg.d) x 2 d markedly diminished the effect of Tyr, but greatly potentiated the effects of Eph and Phe. Both Eph (1-30 mumol/L) and Tyr (10-100 mumol/L), but not Phe, significantly increased the electrical field stimulation (duration 2 ms, 3 Hz, 10 s, 50 V, 10 min intervals) evoked contractions of the portal veins. beta-Adrenoceptor blocker propranolol (0.5 mumol/L) greatly inhibited this effect of Eph, without affecting that of Tyr. It is suggested that the effect of Tyr is mainly due to its release of endogenous norepinephrine (NE) from the nerve terminals; conversely, Eph mainly bcts on postsynaptic alpha-adrenoceptors directly with some NE-releasing action which may involve the activation of presynaptic beta-adrenoceptors.

Animals↗
PubMed1989

Effects of endothelin on porcine coronary arterial strips.

Endothelin, a novel endothelium derived 21-residue vasoconstrictor peptide synthesized by Peninsula Laboratories, provoked a concentration-dependent contraction of porcine coronary arterial strips. EC50 value for endothelin was 14 +/- SD 4 nmol/L (n = 6), and significantly lower than the values for 5-hydroxytryptamine (5-HT, 0.28 +/- 0.07 mumol/L, n = 6) and 15-methyl-prostaglandin F2 alpha (15-methyl-PGF2 alpha, 4 +/- 3 mumol/L, n = 7). The maximal increase in tension caused by endothelin was 5.4 +/- 1.1 g, being much greater than that induced by 5-HT (3.7 +/- 0.8 g, P less than 0.05) and 15-methyl-PGF2 alpha (3.7 +/- 0.6 g, P less than 0.01). The changes in tension provoked by endothelin (2-20 nmol/L) were attenuated significantly after pretreated with tetrodotoxin (TTX, 30 mumol/L, P less than 0.05 or 0.01). The results suggest that endothelin is one of the most potent vasoconstrictive agents, and its action is partially related to voltage-sensitive Na+ channel in the cell membrane.

Amino Acid Sequence↗
PubMed1988

Prediction of retention indexes. I. Structure-retention index relationship on apolar columns.

A simple method is reported for predicting the retention index (RI) of a chemical compound from the number of carbon and carbon equivalent atoms in the molecule, the RI increment for atom addition and the group retention factors (GRFs) for substituents and functional groups. Atoms other than carbon such as oxygen, nitrogen, sulfur, chlorine, bromine and iodine are assigned carbon atom equivalency of approximately 1, 1, 2, 2, 3 and 4, respectively and are counted for their contribution towards RI prediction. The GRFs of substituents and functional groups are derived from the RIs of reference compounds and series of homologues. Ring structures, ring fusion, ring connection, iso- and neo-carbons, chain branching and unsaturation are also assigned GRFs. The predicted RIs of a number of alicyclic, aliphatic and aromatic hydrocarbons, primary, secondary and tertiary alcohols, phenols, aliphatic amines, aromatic amines, heterocyclics, carboxylic acids, acid esters, aldehydes, ketones, and halogenated compounds, are found to be within +/- 3% of the observed values. The structure-retention index relationship thus developed is extremely useful in the tentative identification of radioactive side products formed in tritium labeling by radiation-induced methods.

Alcohols↗
PubMed1988

Effect of smoke inhalation injury on thromboxane levels and platelet counts.

Thirteen goats with chronic lung lymph fistula suffering from smoke inhalation injury were studied for a 6-h period. All animals were found to have acute respiratory failure after injury, the arterial TXA2 (thromboxane A2) levels had increased by 5 min after injury, they peaked at 2 h, and then subsequently declined. Peripheral platelet counts decreased progressively within 2 h, then gradually recovered but were still lower than baseline values at 6 h after injury. EVLW (extravascular lung water), Q1 (lung lymph flow rate) and L/P (total lymph protein/plasma protein concentration), all increased and peaked at 2 h after injury. A negative linear correlation was observed between the TXA2 levels and the platelet counts. Furthermore, differences between the venous and arterial platelet counts were markedly increased. All these observations suggested that the increased TXA2 triggered the formation of platelet microaggregates which were then trapped in the microvasculatures of viscera such as the lung. This might be one of the causes of the decreased platelet counts in peripheral blood. Both TXA2 levels and platelet counts were closely correlated with EVLW, suggesting that TXA2 may indirectly cause the increased pulmonary microvascular permeability by promoting platelet aggregation and microaggregate formation in the pulmonary microvasculature. This may be one of the reasons for the developing pulmonary oedema in goats following smoke inhalation injury.

Animals↗