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Biomedical subjects

C Liang

Publications and source records attributed to C Liang.

At least 145 records · Page 8Linked to original sources
PubMed1994

Analysis of an origin of DNA amplification in Sciara coprophila by a novel three-dimensional gel method.

The replication origin region for DNA amplification in Sciara coprophila DNA puff II/9A was analyzed with a novel three-dimensional (3D) gel method. Our 3D gel method involves running a neutral/neutral 2D gel and then cutting out vertical gel slices from the area containing replication intermediates, rotating these slices 90 degrees to form the third dimension, and running an alkaline gel for each of the slices. Therefore, replication intermediates are separated into forks and bubbles and then are resolved into parental and nascent strands. We used this technique to determine the size of forks and bubbles and to confirm the location of the major initiation region previously mapped by 2D gels to a 1-kb region. Furthermore, our 3D gel analyses suggest that only one initiation event in the origin region occurs on a single DNA molecule and that the fork arc in the composite fork-plus-bubble pattern in neutral/neutral 2D gels does not result from broken bubbles.

Animals↗
PubMed1993

Developmental progression of DNA puffs in Sciara coprophila: amplification and transcription.

DNA amplification for two major DNA puffs (II/2B and II/9A) of the fungus fly Sciara coprophila increases steeply from 17 to 19 days after hatching (18 degrees C), resulting in almost 20-fold more DNA at these loci in mature larval salivary glands than in adult tissues. At 19 days after hatching when gene amplification reaches a plateau, there is a burst in the amount of mRNA encoded by these two DNA puffs. Expansion of the two puffs coincides with the increase in transcription rather than reinitiation of DNA replication. In contrast, an RNA puff (III/9B) undergoes no DNA amplification, and the burst in RNA produced by this locus occurs slightly later, at 20 days after hatching. The progression of cytological puffing and associated molecular events of DNA amplification and transcription correlate with features of the external phenotype of the larvae, especially the number of pigment granules in the eyespots that are the anlage to the adult eyes. The sequential and coordinated regulation of DNA puff replication and transcription is discussed.

Animals↗
PubMed1993

Replication initiates at a confined region during DNA amplification in Sciara DNA puff II/9A.

Two independent two-dimensional (2D) gel methods were used to map an origin of replication that is developmentally regulated by the steroid hormone ecdysone, namely an origin for DNA puff amplification in the fungus fly Sciara coprophila. Initiation of replication was found to occur within a small region of no larger than 6 kb by use of the neutral/neutral 2D gel method. Neutral/alkaline 2D gel analyses support the results of the neutral/neutral 2D gels and further define within the origin region an approximately 1-kb area where the majority of replication initiates. This is the first example of an origin of replication in multicellular eukaryotes that has been mapped by 2D gels to such a small defined region. Moreover, replication can be seen by the neutral/alkaline 2D gel method to proceed bidirectionally outward from this replication origin region. These data are consistent with an onion-skin mechanism whereby multiple rounds of DNA replication initiate at a specific origin of replication for Sciara DNA puff amplification.

Animals↗
PubMed1993

[Effects of different acupuncture manipulation on plasma estradiol, testosterone and cortisol in patients with kidney deficiency].

Observation was made on the effect of different acupuncture manipulation on plasma estradiol (E2), testosterone (T), E2/T and cortisol (C) in 78 patients with kidney deficiency. The results showed that the level of E2 and T in women was lowered by both reinforcing manipulation (RFM) and reducing manipulation (RDM). E2/T index was lowered by RDM but not by RFM, and there was significance (P < 0.05) between the RDM group and RDM group in E2/T, but no significance between the man's groups. The level of C was decreased by RDM but not by RFM. The results suggest that the different manipulation effects are different on the level of sex hormones in women and the C content in patients with kidney deficiency.

Acupuncture Therapy↗
PubMed1993

[Experimental research of acupuncture manipulation of reinforcing and reducing by lifting and thrusting needle on the animal].

The experiment were performed on model rabbits injected with large dosage of Dexamethasone (DXM) for 5 days. Reinforcing manipulation (RIM), reducing manipulation (RDM), and electric stimulation (ES) were respectively used to puncture Zusanli (ST 36) points for 5 days to observe the change on temperature, body weight, corticosterone assay, testosterone assay, and the amplitude of the plethysmogram. The result showed that there was a similar syndrome of the kidney deficiency after injecting DXM. The body weight was increased in the DXM control group, decreased in the RDM group and had no significant influence in the other groups. The body weights between the reinforcing manipulation and the reducing manipulation groups had obvious difference. But the other indices of observation had no significant influence among the different groups. So there wasn't significant difference on most of observed signs among the RIM group, the RDM group and ES group. The study of acupuncture manipulation will have yet to be further done.

Acupuncture Therapy↗
PubMed1992

The chirality of ground DNA knots and links.

The chirality of ground DNA knots and links is described and characterized in terms of color symmetry groups (CSG), i.e. color symmetry groups I and II, which correspond to topochirality (topological chirality) and topoachirality (topological achirality) which bear an uncanny resemblance to point groups I (proper) and point groups II (improper) used for testing geochirality (geometrical chirality) and geoachirality (geometrical achirality), respectively. By regarding these two crossing modes in mirror images as white and black vertices, DNA knots and links with minimal crossings can be mapped to vertex-bicolored graphs under a working hypothesis that DNA knots and links exist in ground states with minimal energy m0. The color symmetry group of a vertex-bicolored graph G is defined as the set of all permutations and permutation asymmetrizations of the vertices of G that preserve its topology (connectivity), where asymmetrization, denoted as (a), is the operation of changing vertices' colors, and a permutation followed by an (a) is a permutation asymmetrization. The color symmetry groups I contains only permutations, whereas color symmetry groups II comprise permutation asymmetrizations as well as permutations. Four DNA knots and links in nature are analyzed and tabulated consisely. In addition, the well-known figure-of-eight knot and Borromean rings are discussed in much the same way.

DNA↗
PubMed1992

Physical properties of the Escherichia coli transcription termination factor rho. 2. Quaternary structure of the rho hexamer.

Under approximately physiological conditions, the transcription termination factor rho from Escherichia coli is a hexamer of planar hexagonal geometry [Geiselmann, J., Yager, T. D., Gill, S. C., Calmettes, P., & von Hippel, P. H. (1992) Biochemistry (preceding paper in this issue)]. Here we describe studies that further define the quaternary structure of this hexamer. We use a combination of chemical cross-linking and treatment with mild denaturants to show that the fundamental unit within the rho hexamer is a dimer stabilized by an isologous (or pseudoisologous) bonding interface. Three identical dimers of rho interact via a second type of isologous bonding interface to yield a hexamer with C3 or D3 symmetry. Cross-linking and denaturation experiments definitely rule out C6 and C2 symmetry for the rho hexamer. Data from fluorescence quenching, lifetime, and energy transfer experiments also argue against C2 symmetry. The simplest symmetry assignment that is not contradicted by any experimental data is D3; thus we conclude that the rho hexamer has D3 symmetry. We also consider the positioning of the binding sites for RNA and ATP relative to the coordinate reference frame of the D3 hexamer. Fluorescence energy transfer data are presented and integrated with data from the literature to arrive at a self-consistent model for the quaternary structure of the rho hexamer.

Adenosine Triphosphate↗
PubMed1992

[The effect of acupuncture on rabbits with fever caused by endotoxin].

Forty-eight rabbits were used to investigate the effect of puncturing GV14, LI11 on the change of temperature and the level of plasma endotoxin. The animals were divided into 5 groups: reinforcing manipulation, reducing manipulation, electroacupuncture, endotoxin-control, N.S.-control group. The result shows that there is no influence on the fever caused by endotoxin and the level of plasma endotoxin in the treatments by the different acupuncture techniques.

Acupuncture Therapy↗
PubMed1992

[The influence of different acupuncture manipulations on the plethysmogram of the patient with kidney deficiency].

In order to prove the specific property between the tonifying manipulation (TM) and reducing manipulation (RM), and search further for the key in improving the effect of manipulation, the influence of to on two different manipulations. The plethysmogram in the same body-condition (kidney-deficiency) One was TM with slow-trusting and quick lefting; the other was RM with the converse movement. Randomized block design, cross-over design and single-blind design were used. The result showed that the TM increased the amplitude of the plethysmogram obviously, whereas the RM had no significant influence on it. There was significant difference not only between the TM group and the central group, but also between the TM group and RM group (P less than 0.01 or P less than 0.05). The difference between the RM group and the control group was not significant (P greater than 0.05). Meanwhile, it was recommended that "mind concentration" on acupuncture manipulation is important. In conclusion, the experiment demonstrated the experimental evidence for explaining the mechanism of TM and RM. It was suggested that acupuncture manipulations are worthy to pay attention so as to improve clinical effect.

Acupuncture Therapy↗
PubMed1991

Inhibition of digestive proteinases of stored grain Coleoptera by oryzacystatin, a cysteine proteinase inhibitor from rice seed.

Electrophoresis of midgut extracts from the rice weevil, Sitophilus oryzae, and the red flour beetle, Tribolium castaneum, in polyacrylamide gels containing sodium dodecyl sulfate and gelatin revealed there was one major proteinase (apparent molecular mass = 40,000) in the rice weevil and two major proteinases (apparent molecular masses = 20,000 and 17,000) in the red flour beetle. The pH optima using [3H]casein as substrate were about pH 6.8 for the rice weevil and pH 5.2 for the red flour beetle. Use of specific inhibitors, including L-trans-epoxysuccinyl-leucylamino-(4- guanidino)-butane (E-64), p-chloromercuriphenylsulfonic acid (PCMS), and oryzacystatin, indicated that nearly all of the proteinase activity against casein was contributed by cysteine proteinases. The estimated IC50 values for oryzacystatin were 2 x 10(-6) M and 4 x 10(-7) M when tested against midgut extracts from T. castaneum and S. oryzae, respectively.

Animals↗
PubMed1990

[Diagnosis value of lateral pharyngeal roentgenography in snoring disease].

In this paper, X-ray findings of the lateral pharynx before uvulopalatopharyngoplasty in 14 cases of snoring disease were studied. The results are as follows. There is less than 5 mm in anterior-posterior airway of pharyngeal cavity (13 cases), and 8 mm (1 case), in diameter. Minimum 2 mm, average 4.4 mm. There is less than 25 mm length of uvula (7 cases), 28-35 mm (7 cases). Minimum 22 mm, average length is 27.9 mm. Shape of uvula is thick and long (12 cases), thick and short 1 case, thin and long 1 case. The etiology, abnormal X-ray finding and X-ray examination of the lateral pharynx, etc. in snoring disease have been discussed.

Adult↗
PubMed1982

Insulin infusion in conscious dogs. Effects on systemic and coronary hemodynamics, regional blood flows, and plasma catecholamines.

Cardiovascular actions of insulin were studied by intravenous infusions of insulin (4 and 8 mU/kg per min) in normal conscious dogs. This resulted in increases in cardiac output, heart rate, and left ventricular derivative of pressure with respect to time (dP/dt) and dP/dt/P, as blood glucose was reduced. The inotropic and chronotropic effects of insulin were not related to hypoglycemia, as they persisted even when blood glucose was restored to control values or when it was prevented from falling by a simultaneous infusion of glucose. These cardiac effects were accompanied by increases in plasma catecholamines, and were abolished by propranolol pretreatment. Both plasma epinephrine and norepinephrine increased during insulin hypoglycemia, but only norepinephrine increased during insulin infusion when euglycemia was maintained. Mean arterial blood pressure did not change significantly during insulin hypoglycemia, but rose if euglycemia was maintained, probably due to the selective increase in norepinephrine in the latter condition. A pressor response also occurred in propranolol-pretreated dogs during insulin hypoglycemia, but was abolished when the animals also had been pretreated with phentolamine, indicating that the vasoconstrictor action of insulin was mediated via alpha adrenergic receptors. Insulin infusion increased left ventricular work and myocardial blood flow in dogs with and without hypoglycemia. Myocardial blood flow, however, did not change significantly during insulin infusion in dogs pretreated with propranolol. As propranolol also diminished the inotropic response, it appears that the increase in myocardial blood flow caused by insulin in the normal dog is causally related to the increased myocardial metabolic demand. Insulin also produced vasomotor effects on other vascular beds. In skeletal muscle, blood flow was increased under all study conditions, except during insulin hypoglycemia after propranolol-pretreatment when unopposed alpha-mediated vasoconstriction was present. The persistent increase in flow during both alpha and beta adrenergic blockade suggests that insulin has a direct dilator effect on skeletal muscle vasculature. In the adrenal gland, flow was increased except during euglycemia, when no rise in plasma epinephrine was observed, suggesting coupling between adrenal flow and catecholamine release. In the splanchnic bed, flow was decreased during euglycemia, when plasma norepinephrine rose, and during beta adrenergic blockade with propranolol, when unopposed alpha-mediated vasoconstriction also predominated. A similar pattern was found in the kidney, except that renal blood flow also fell after combined alpha and beta adrenergic blockade. The results show that the vasomotor effects on regional flows are mediated both via adrenergic mechanisms, and in the case of skeletal muscle and kidney, via mechanisms unrelated to sympathetic stimulation.

Adrenergic beta-Antagonists↗
PubMed1981

The effect of verapamil on mechanical performance of acutely ischemic and reperfused myocardium in the conscious dog.

The effect of verapamil, an inhibitor of transmembrane calcium flux, was studied in intact conscious dogs with myocardial ischemia produced by inflating a balloon cuff implanted on the left anterior descending coronary artery. Six dogs received a continuous infusion of verapamil (10 microgram/kg per min) beginning prior to coronary occlusion, and six received normal saline infusions. Systolic ejection shortening (SES) was measured from subendocardial ultrasonic crystals implanted in the central ischemic zone (IZ) and border zone (BZ), and in a nonischemic control zone (CZ). Hearts were paced at a constant heart rate with periodic introduction of closely coupled extrasystoles. SES was measured both for normally paced beats and during postextrasystolic potentiation (PESP). Regional myocardial blood flow was measured by injecting radioactive microspheres before, during, and after coronary occlusion. There were no significant differences between verapamil-treated dogs and saline control dogs in mean aortic pressure, heart rate, left ventricular end-diastolic pressure or dP/dt, cardiac output, or regional myocardial blood flow in IZ, BZ, or CZ. Differences in mechanical performance between two groups were noted, however. In the IZ, SES was abolished completely for normally paced beats in both groups but was significantly preserved for PESP beats in the verapamil-treated animals. In the BZ, SES was significantly reduced for normally paced beats only in the saline controls, and PESP responses were preserved to a significantly greater degree in the verapamil-treated animals. These results indicate that verapamil pretreatment exerts beneficial effects upon mechanical performance of ischemic myocardium. Since no changes in systemic hemodynamics or regional myocardial blood flow were observed, the effect may be due to the calcium-antagonistic properties of the agent.

Acute Disease↗