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Biomedical subjects

H Cai

Publications and source records attributed to H Cai.

At least 127 records · Page 7Linked to original sources
PubMed1997

[Significance and changes of plasma endothelin in patients undergone upper abdominal surgery].

We observed the changes of plasma endothelin, hemodynamic and electrocardiogram in twelve patients undergone upper abdominal surgery under epidural anesthesia. The results showed that mean artery pressure, heart rate, cardiac output, cardiac index, systemic vascular resistance, maximum left atrial pressure, maximum ascendant speed of artery systolic pressure and mean ascendant speed of artery systolic pressure were all significantly lower during intraab-dominal exploration than that of preanesthesia (P < 0.01). Mean artery pressure and systemic vascualr resistance kept low levels to the end of operation. Plasma endothelin was significantly higher at 1 hour after skin resection than that of preanesthesia (P < 0.01) and was apparently negative related with cardiac output(CO) and cardiac index(CI) during exploration(CO r = -0.9221; CI r = -0.8768), two patients' with myocardial ischemia were specially higher. We conclude that plasma endothelin is closely related with cardiac function and myocardial ischemia during operation.

Abdomen↗
PubMed1997

[A study of multi-channel visual evoked potentials in exotropic children without amblyopia].

OBJECTIVE: To investigate the clinical significance of multi-channel visual evoked potentials (VEPs) in constant exotropic children without amblyopia and the mechanism of exotropia. METHODS: With 14 active cup electrodes, and full and half field stimulation, the checkerboard pattern was reversed and the VEPs were recorded in control and experimental groups. RESULTS: With full field stimulation, the latent period 1 (LP1) of binocular VEPs was not longer and the amplitude N1-P1 (AN1P1) not higher respectively than those of monocular VEPs in experimental group. These properties were different from those of control group. The AN1P1 of non-dominant eye was decreased, and the LP1 of dominant and non-dominant eye was longer in experimental group than that of the control group. There were no significant differences in comparing LP1 and AN1P1 between nasal-retina and temporal-retina of experimental group. CONCLUSIONS: VEPs can provide a scientific basis for abnormal binocular vision in constant exotropia. Although the visual acuity of constant exotropic children is normal, their VEPs are abnormal. Therefore, there might be dysfunction in primary visual cortex. With half field stimulation, there is no suppression of temporal-retina in monocular VEPs of constant exotropic children.

Adolescent↗
PubMed1997

[Studies on the ganoderic acid, a new constituents from the fruiting body of Ganoderma lucidum (Fr.) Karst].

Three compounds have been isolated from the dichloromethane soluble fraction of the fruiting body of Ganoderma lucidum (Fr.) Karst. On basis of spectral analyses (UV, IR, MS, 1HNMR, 13CNMR and 2D-NMR), they were identified as 3, 7-dioxo-lanosta-8, 24(E)-dien-26-oic acid (I), 7 beta-15 alpha-dihydroxy-3, 11, 23-trioxo-5 alpha-lanost-8-en-26-oic acid (II) and 3 beta, 7 beta, 15 alpha-trihydroxy-11, 23-dioxo-5 alpha-lanosta-8-en-26-oic acid (III). Compound I is a new compound named ganoderic acid DM.

Drugs, Chinese Herbal↗
PubMed1997

[Effect of sodium iron chlorophyllin (SIC) on CFU-E and CFU-GM yields of normal and anemic animal models].

OBJECTIVE: To observe the effect of sodium iron chlorophyllin (SIC) on hematopoiesis and its therapeutic efficacy in anemic mice. METHODS: The effects of SIC on CFU-E and CFU-GM yields of normal and anemic animal models were studied. RESULTS AND CONCLUSIONS: (1) SIC significantly enhanced the CFU-E and CFU-GM yields of mouse bone marrow. (2) SIC also increased the percentage of reticulocyte in mouse. (3) In hemolytic anemia mice induced by i.p. N-acetphenylhydrazine, SIC markedly prevented the decrease of RBC and Hb. (4) In hemorrhagic anemia rats induced by bleedletting, SIC accelerated the normalization of RBC, Hb and elevated the serum iron level and transferrin saturation.

Anemia↗
PubMed1997

[Determination of liensinine in plasma by high performance liquid chromatography].

A sensitive method of high performance liquid chromatography (HPLC) for determination of liensinine in plasma is reported. An Ultrasphere Si column, 250 mm x 4.6 mm i.d. with dichloromethaneisopropyl alcohol-diethylamine (75:25:0.2, V/V) as mobile phase at a flow-rate of 1.0 mL/min and UV-detector at 282 nm were used. Neferine was served as the internal standard. Liensinine in plasma was extracted with diethyl ether three times after adding ammonia-ammonium chloride buffer (pH 10). Liensinine was completely separated from nefrine. The retention times of liensinine and neferine were 8.5 and 5.0 minutes, respectively. The calibration line of liensinine was linear in the range of 0.0625-5.0 mg/L (r = 0.9996). The mean recovery was 93.6% with RSD of 1.9%. The precision of intra-day and inter-day for liensinine was in the range of 1.4%-4.1% and the detectable limit was 0.025 mg/L based on a signal-to-noise ratio of 3. The results showed that the method was simple and sensitive.

Chromatography, High Pressure Liquid↗
PubMed1997

[Determination of prostaglandinum E1 by fluorescence extinction method].

In this paper, we have studied the fluorescence extinction effect of methyl alcohol by prostaglandinum E1 (PG E1) and found the linear relation between the fluorescence extinction intensity and prostaglandinum E1 concentration. Its linear equation is deltaF = 0.222c + 9.33 x 10(-2)(deltaF: fluorescence extinction value; c: PG E1 concentration microg/mL), correlation coeficient r = 0.99930. The results derived from fluorescence extinction method correspond to the results from violet spectrophotometric method.

Alprostadil↗
PubMed1997

[Effects of glycyrrhisin on myocardial ischemia/reperfusion injury of rabbits].

The content of MDA and the activity of creatine phosphokinase (CPK) together with the ultrastructural changes in myocardial tissue were analysed to observe the effects of glycyrrhisin on myocardial ischemia/reperfusion injury in rabbits. The results showed that glycyrrhisin could remarkably reduced the level of MDA and the activity of CPK in myocardial tissue (P < 0.01), and mitigated significantly the myocrdial ultrastructural injury in comparison with ischemia/reperfusion group. It was considered that glycyrrhisin exerted obvious protective effects on myocardial injury induced by ischemia/reperfusion.

Animals↗
PubMed1997

[Activation of L-Arg: no pathway in canine brain by the damage from complete cerebral ischemia-reperfusion].

To ascertain whether complete cerebral ischemia-reperfusion activate L-Arg: NO pathway in canine brain, we anestherized nine adult dogs with ketamine and fentayle and randomly divided into two groups. Four dogs were nonischemic control group. Five dogs were complete cerebral ischemia-reperfusion group, they underwent a 18-minute cardiac arrest, and were resusciatation by standard CPR, supported by intensive care for 8 hours. At the end of each experiment, the parietal cortex was assayed for content of Nitrite and NADPH-positive neurons. Compared with the control group, the contents of Nitrite and NADPH-positive neurons of coxtex in complete cerebral ischemia-reperfusion group increased significantly (P < 0.01). The results suggest that complete cerebral ischemia-reperfusion activate the L-Arg: NO pathway in canine brain, and NO may play an important role in cerebral ischemia-reperfusion injury.

Animals↗
PubMed1996

Amlodipine, a Ca2+ channel antagonist, modifies cerebral blood flow autoregulation in hypertensive rats.

We measured the cerebral blood flow at rest and during hemorrhagic hypotension in 7 rats of each group using laser-Doppler flowmetry. Simultaneously, the absolute baseline cerebral blood flow values in the parietal cortex were quantified with the hydrogen clearance method. Baseline mean arterial pressure was significantly lowered, by 29 mm Hg, in the amlodipine-treated group, while the baseline cerebral blood flow was 36 +/- 4 ml/100 g/min (mean +/- S.D.) which was almost the same as the 40 +/- 5 in the control group. The lower limits of the cerebral blood flow autoregulation, defined as the mean arterial pressure at which the cerebral blood flow decreased by 10% of the baseline value, were shifted to a lower level of 107 +/- 9 mm Hg in the treated group compared with 133 +/- 5 mm Hg in the control (P < 0.001). The results demonstrated that, in hypertensive rats with amlodipine treatment, cerebral perfusion was preserved at a lower blood pressure level, which is advantageous under hypotensive conditions.

Amlodipine↗
PubMed1996

cDNA cloning of a chick homologue of human ATPase complex subunit 4, quantitative tissue distribution and tertiary structure comparison of the ATPase domain to RecA.

The ocular lens consists of a single layer of epithelial cells on its anterior surface and underlying fiber cells, which are derived from the epithelial cells by differentiation and make up the bulk of the lens. Because lens cells are segregated by age and stage of differentiation, we are using this tissue to study the role of the proteasome in differentiation. The purpose of this study is to corroborate the ATPase function of chick subunit 4 (cS4) and assess the levels of the mRNA in the differentiating lens relative to other tissues. We have generated a computer model of the tertiary structure of the ATPase domain of the cS4 of the ATPase complex that regulates the 20S proteasome. The predicted polypeptide from the cloned cDNA of cS4 (440 residues) had a calculated molecular mass of 49,182 and is 98 and 73% identical to human and yeast S4 protein sequences, respectively. A computer search for comparison with known proteins in GenBank showed that the cS4 protein sequence has a conserved region of about 200 amino acid residues including an ATP/GTP binding site and a mitochondrial energy transfer proteins signature sequence. Based on secondary structure, the computer-generated model of the ATPase domain is comparable to that of RecA, with a root mean square deviation of 0.851 from the RecA triad. mRNA in the 14-day-old chick embryo lens is derived primarily (90%) from differentiating cells. The level of cS4 mRNA determined by quantitative RT/PCR in this differentiating tissue was comparable to the cS4 mRNA levels in chick liver, heart, and brain.

Adenosine Triphosphatases↗
PubMed1996

Preclinical pharmacology of the natural product anticancer agent bryostatin 1, an activator of protein kinase C.

Bryostatin 1, a natural product anticancer agent isolated from a marine bryozoan, has been shown in tissue culture to activate protein kinase C. This agent has recently undergone Phase I testing in humans given either as a bolus i.v. injection or a continuous infusion. To understand how bryostatin 1 might be used best as an anticancer agent, a study of the pharmacokinetics, tissue distribution, metabolism, and elimination of bryostatin 1 in mice was undertaken, using [C26-3H]-labeled bryostatin 1. Following i.v. administration, the plasma disappearance curve for bryostatin 1 could be described by a two-compartment model, with half-lives of 1.05 and 22.97 h, respectively. In contrast, the plasma disappearance curve for bryostatin 1 administered i.p. was better described by a first order absorption one-compartment model, with an absorption half-life of 0.81 h and an elimination half-life of 28.76 h, respectively. The majority of radioactivity in plasma was associated with the intact drug for up to 24 h after dosing. In the first 12 h after i.v administration, urinary excretion represented the major pathway of elimination, with 23.0 +/- 1.9% (mean +/- SD) of the administered dose excreted. Within 72 h after i.v. administration, approximately equal amounts of radioactivity (40%) were excreted in feces compared to urine. Bryostatin 1 was widely distributed in many organs but concentrated in the lung, liver, gastrointestinal tract, and fatty tissue. The concentration in the gastrointestinal tract, along with the fecal excretion, suggests the possibility of enterohepatic circulation of this drug. In summary, this study demonstrates that bryostatin 1 is relatively stable in vivo, widely distributed but concentrated in some major tissues, and rapidly excreted first through urine and at later times through the feces. The data from this animal study should be useful in the design of future human trials with this anticancer drug.

Animals↗
PubMed1996

Single-fibre laser Doppler flowmetry and electromyography for evaluating microcirculation in forearm muscle during static and continuous handgrip contractions.

A technique is described for intramuscular measurement of muscle blood flow in the forearm, by using a 0.5-mm thin optical single-fibre for laser Doppler flowmetry (LDF) inserted percutaneously. Continuous recordings were performed of the brachioradial muscle during an 11-min series of alternating 1-min periods of increased static contraction and rest determined by an electronic handgrip forcemeter and surface electromyography (EMG) of the muscle. Stepwise increased handgrip contractions were performed at 10%, 20%, 30%, 40% and 50% maximal voluntary contraction (MVC). This was followed by a similar series of continuous contractions. Finally, an endurance test was performed with a handgrip force of 50% MVC maintained for as long as possible. A group of ten healthy men of different ages was studied. Signal processing was done on line by computer. Successive increases in rootmean square (rms)-EMG and a fall in the mean power frequency (MPF) of the EMG spectrum occurred during the series of static contractions, which evoked perceived local fatigue in the forearm. Muscle blood flow recorded simultaneously showed no change from resting level during contractions at 10%, 20% and 30% MVC, while at 40% and 50% MVC mean increases of 150% and 200% were recorded. Blood flows measured during the rest periods showed large variability with no significant changes. This was also found after continuous contractions of the same intensities. The endurance time was 1.2-3.5 min (mean 2.4 min). Muscle blood flow showed mean increases of 214%, 256% and 229% of resting level each minute of the maintained contraction. Nevertheless, EMG signs of local fatigue developed, such as a rise in rms-EMG and a fall in MPF, and the subject experienced local fatigue. To conclude, this technique of percutaneous, continuous LDF recorded, at high sensitivity, the microcirculation at different fluxes and EMG-defined muscle activity.

Adult↗
PubMed1996

Optical aspects of a fibre-optic sensor for respiratory rate monitoring.

A new sensor for respiratory rate monitoring is described. The sensor uses an optical fibre that detects the evaporated humidity from the mouth and/or nose at each exhalation. The condensed humidity substantially alters the coupling of light from the optical fibre to the surrounding medium, which can be monitored by a photo-detector. The sensing principle is evaluated using ray-tracing simulation and scattering measurements.

Computer Simulation↗
PubMed1996

Laser Doppler flowmetry: characteristics of a modified single-fibre technique.

The single-fibre percutaneous laser Doppler technique has been used in previous studies of intramuscular blood flow. This method facilitates studies of blood flow in deep tissue volumes and minimises the tissue trauma. The technique has been further developed with the aim of improving the signal quality. This has been accomplished by modifying the geometry of the fibre tip. By melting the fibre core material, lenses of different shapes are formed. Flat, spherical and 'pear'-type tips have been manufactured and are evaluated theoretically and experimentally. The paraxial theory cannot accurately predict the position of zones of highest irradiance. Therefore, a ray-tracing program has been developed in the C language, by means of which some of the optical properties of the modified fibre tips can be simulated. Iso-irradiance graphs and beam profiles are calculated for the three different fibre tips. Measured and calculated irradiance curves are used for evaluation of the properties of the ray-tracing model. The three types of fibre tips are also evaluated and compared in flow models. The sphere and pear-type probes show a higher flow sensitivity than the flat-end type. These improvements in flow sensitivity are interpreted as being related to the larger, strongly irradiated tissue volumes in front of the fibres. Intramuscular measurements with the pear-type probe show high sensitivities to induced blood flow changes.

Evaluation Studies as Topic↗
PubMed1996

Synthesis and evaluation of deglycobleomycin A2 analogues containing a tertiary N-methyl amide and simple ester replacement for the L-histidine secondary amide: direct functional characterization of the requirement for secondary amide metal complexation.

The synthesis and comparative examination of 3-5, analogues of deglycobleomycin A2 (2) which address the inferred importance of the L-histidine secondary amide directly, are detailed. The agent 3 lacks only the L-histidine beta-hydroxy group of deglycobleomycin A2 and the corresponding agents 4 and 5 incorporate a tertiary N-methyl amide and simple ester in place of the L-histidine secondary amide. The DNA cleavage properties of 3 proved essentially indistinguishable from those of deglycobleomycin A2 (2) confirming that the distinctions between bleomycin A2 (1) and deglycobleomycin (2) are due to the removal of the disaccharide and not the introduction of the L-histidine free beta-hydroxy group. The agents 4 and 5 containing a tertiary N-methyl amide and ester in place of the L-histidine secondary amide were found to cleave duplex DNA but to do so in a nonsequence selective fashion with a substantially reduced efficiency and a diminished double to single strand cleavage ratio that are only slightly greater than that of free iron itself. These latter observations establish the functional requirement for the L-histidine secondary amide and are consistent with the proposals that the L-histidine deprotonated secondary amide is required for functional metal chelation and activity.

Amides↗
PubMed1996

Synthesis and evaluation of potential N pi and N sigma metal chelation sites within the beta-hydroxy-L-histidine subunit of bleomycin A2: functional characterization of imidazole N pi metal complexation.

The synthesis and evaluation of 4 and 5, fully functionalized deglycobleomycin A2 (2) analogues incorporating an oxazole and a pyrrole in place of the beta-hydroxy-L-histidine imidazole, are detailed. The oxazole agent is only capable of Npi metal complexation through a form related to the N1-H imidazole tautomer of bleomycin A2 (1) while the pyrrole agent may potentially mimic the Nsigma metal complexation capabilities of the imidazole N3-H tautomer. Metal complexes (Fe-II, Fe-III) of 4 and 5 were found to cleave duplex DNA in the presence of O2 (Fe-II) or H2O2 (Fe-III). The oxazole agent 4 which is incapable of Nsigma metal chelation was found to behave analogous to, albeit slightly less effectively than, deglycobleomycin A2 resulting in the characteristic 5'-GC/5'-GT sequence selective cleavage of duplex DNA directly confirming that imidazole/oxazole Npi metal chelation is sufficient for functional reactivity. Importantly, the effective substitution of the oxazole O-1 for the histidine N-1 further illustrates that this group does not require deprotonation upon metal complexation, oxygen activation, or the ensuing oxidation reactions, that the functional bleomycin A2 tautomer is the imidazole N'-H tautomer, and that the imidazole N'-H functionality is not contributing to the polynucleotide recognition through H-bonding to the phosphate backbone or nucleotide bases. In contrast, the pyrrole agent 5 which is incapable of Npi metal chelation, but possesses the capabilities of functioning as a Nsigma metal donor was also found to cleave duplex DNA, but does so in a nonsequence selective fashion with a significantly reduced efficiency and a diminished double to single strand cleavage ratio both only slightly above that of background iron itself. These observations are analogous to those made with 3 which lacks the imidazole altogether and further support the observations that Nsigma coordination, not Npi coordination, of the imidazole is required for the functional activity of bleomycin A2.

Antimetabolites, Antineoplastic↗
PubMed1996

Demonstration and definition of the noncovalent binding selectivity of agents related to CC-1065 by an affinity cleavage agent: noncovalent binding coincidental with alkylation.

A study of the DNA cleavage efficiency and selectivity of CDPI3-EDTA (4), an affinity cleavage agent based on the structure of CC-1065, is described. The studies with 4 provide direct evidence of AT-rich noncovalent binding coincidental with all DNA alkylation sites observed with (+)- or ent-(-)-CC-1065.

Alkylation↗