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Z Liang

Publications and source records attributed to Z Liang.

At least 109 records · Page 6Linked to original sources
PubMed1997

Evaluating a possible pharmacokinetic interaction between remifentanil and esmolol in the rat.

Remifentanil (Ultiva) is a novel, ultra-short-acting opioid which has recently been approved for use as an analgesic during induction and maintenance of general anesthesia. Esmolol is a short-acting beta-blocker used during surgical procedures to reduce heart rate and blood pressure. Both drugs are metabolized by nonspecific esterases in the blood and other tissues and may be administered concomitantly during surgery. The goal of this study was to determine if coadministration of esmolol significantly alters the pharmacokinetics of remifentanil in the rat. Two groups of rats were dosed with remifentanil [25 micrograms/kg/min (n = 8)] and remifentanil plus esmolol [25 and 200 mg/kg/min (n = 7)] for 20 min. Cardiovascular measurements were collected continuously over the course of the study. Serial blood samples (12) were collected over 25 min into test tubes containing 0.5 mL of acetonitrile. Blood samples were extracted (liquid-liquid) with methylene chloride and then analyzed by a validated GC-MS assay. Compartmental data analysis was performed using PCNONLIN. The mean(+/- SD) for Cl and t1/2 observed in treatment I were 390(+/- 98) mL/min/kg and 0.69(+/- 0.27) min and in treatment II were 421(+/- 164) mL/min/kg and 0.56(+/- 0.22) min, respectively. Comparison of clearance, volume of distribution, and terminal half-life between the two groups showed that coadministration of esmolol had no significant (p < 0.05) effect on the pharmacokinetics of remifentanil in the rat.

Adrenergic beta-Antagonists↗
PubMed1997

The pharmacokinetics and electroencephalogram response of remifentanil alone and in combination with esmolol in the rat.

PURPOSE: The goal of this study was to determine if the co-administration of esmolol (ES), a short acting cardioselective beta-blocker, significantly alters the pharmacokinetics and/or pharmacodynamics of remifentanil (REMI), an ultra short-acting opioid, in the rat. METHODS: Sprague-Dawley rats (N = 8, Wt. = 325 +/- 15 g) were surgically implanted with stainless steel cerebrocortical EEG electrodes three days before the study. Each rat was dosed with REMI (15 micrograms/kg/min), and REMI & ES (15 micrograms/kg/min and 600 micrograms/kg/min) for 21 minutes in a random crossover design. Six serial blood samples were collected over 25 minutes into test-tubes containing 0.5 ml acetonitrile. Blood samples were extracted with methylene chloride and analyzed by a validated GC-MS assay. EEG was captured and subjected to power spectral analysis (0.1-50 Hz) for spectral edge (97%). RESULTS: No significant differences (p < 0.05) were found in clearance (REMI = 287 + 73 ml/min/leg vs. REMI & ES = 289 +/- 148 ml/min kg) or Vd (REMI = 286 +/- 49 ml/kg vs REMI & ES = 248 + 40 ml/kg). A linked sigmoid Emax PK-PD model was used and the pharmacodynamic parameters were not statistically different. Mean Emax and EC50 after REMI were 18.0 +/- 6.0 Hz and 32 +/- 12 ng/ml; and after REMI + ES were 19 + 4.8 Hz and 26 + 8.6 ng/ml. CONCLUSIONS: At the doses tested, there is no pharmacokinetic or pharmacodynamic interaction between remifentanil and esmolol in the rat.

Adrenergic beta-Antagonists↗
PubMed1997

Single-and dual-energy CT with monochromatic synchrotron x-rays.

We explored the potential for clinical research of computed tomography (CT) with monochromatic x-rays using the preclinical multiple energy computed tomography (MECT) system at the National Synchrotron Light Source. MECT has a fixed, horizontal fan beam with a subject apparatus rotating about a vertical axis; it will be used for imaging the human head and neck. Two CdWO4-photodiode array detectors with different spatial resolutions were used. A 10.5 cm diameter acrylic phantom was imaged with MECT at 43 keV and with a conventional CT (CCT) at 80 kVp: spatial resolution approximately equal to 6.5 line pairs (lp)/cm for both; slice height, 2.6 mm for MECT against 3.0 mm for CCT; surface dose, 3.1 cGy for MECT against 2.0 cGy for CCT. The resultant image noise was 1.5 HU for MECT against 3 HU for CCT. Computer simulations of the same images with more precisely matched spatial resolution, slice height and dose indicated an image-noise ratio of 1.4:1.0 for CCT against MECT. A 13.5 cm diameter acrylic phantom imaged with MECT at approximately 0.1 keV above the iodine K edge and with CCT showed, for a 240 micrograms I ml-1 solution, an image contrast of 26 HU for MECT and 13 and 9 HU for the 80 and 100 kVp CCT, respectively. The corresponding numbers from computer simulation of the same images were 26, 12, and 9 HU, respectively. MECT's potential for use in clinical research is discussed.

Acrylates↗
PubMed1997

Validation of the central-ray approximation for attenuated depth-dependent convolution in quantitative SPECT reconstruction.

In order to model photon attenuation and detector resolution variation as a depth-dependent convolution for efficient reconstruction of quantitative SPECT, a central-ray approximation is necessary. This work investigates the impact of the approximation upon reconstruction accuracy and computational efficiency. A patient chest CT image was acquired and converted into an object-specific attenuation map. From a segmentation of the map, an emission thorax phantom was constructed with a cardiac insert. To generate a system-specific resolution-variant kernal, a point source was measured at several depths from the surface of a low-energy, high-resolution, parallel-hole collimator of a SPECT system. Projections of parallel-beam geometry were simulated from the phantom, the map, and the kernel on an elliptical orbit. Reconstruction was performed by the ML-EM algorithm with and without the central-ray approximation. The approximation cuts down dramatically (more than 100 fold) the computing time with a negligible loss (less than 1%) of reconstruction accuracy.

Algorithms↗
PubMed1997

Benefits of angular expression to reconstruction algorithms for collimators with spatially varying focal lengths.

Fan-beam collimators with spatially varying focal lengths are used in single photon emission computed tomography (SPECT) to improve the imaging sensitivity and to reduce the reconstruction artifacts resulting from the truncation of projection data. An angular representation of the detector coordinates for the projection data is adopted to investigate several aspects of the reconstruction problem for this type of collimation. A rebinning reconstruction algorithm is derived. We prove a conjecture posed by Zeng and Gullberg and obtain a simplified form of their backprojection filtering algorithm. Some computer simulations are presented to investigate the performance of the rebinning algorithm.

Algorithms↗
PubMed1997

[The relationship between female infertility and genital inflammation of Chlamydia trachomatis].

To address the relationship between female infertility and genital inflammation of chlamydia trachomatis (CT), we took samples from the cervix and fallopian tube of 147 cases of female infertility and investigated the rate of CT infection by using polymerase chain reaction (PCR) assay. 60 cases of normal pregnant women were chosen as controls. The results showed that in the infertile group the CT positive rates for fallopian tubes and cervices were 15.66% and 22.45% respectively, whereas in the control group the tubal positive rate was 3.33%. There was significant difference between the two groups in tubal positive rate (P < 0.05). Youngsters and workers were the high risk population of genital infection of CT. These results indicate that genital infection of CT is an important factor causing infertility; in that disease, the tubal infection of CT is even more important. Besides the damage to tubal mucosa and smooth muscle, CT infection causes tubal adhesion and obstruction. As a result it impairs the function of the fimbriae and leads to infertility.

Adult↗
PubMed1997

[Effects of spinal cord extract on neurite growth of GABAergic and dynergic neurons of spinal cord in vitro].

We use the crude extract from human fetal spinal cord to study the effect of endogenous substances of the spinal cord on neurite growth of E 12-15 mouse GABAergic and DNYergic neurons of the spinal cord in vitro. The results indicated that the crude extract had no effect on GABAergic neurons but had markedly neurite-promoting effect on DNYergic neurons when the protein concentration of the crude extract was 250 micrograms/ml. It suggests that there are endogenous substances in the crude extract of the human fetal spinal cord, which can promote neurite growth of spinal cord neurons and this effect is neuron type specific at particular embryonic age.

Animals↗
PubMed1997

[The stress reaction induced by intensive noise exposure in rats].

To study the effects of sustained intensive noise on rats, fifty SD male rats were randomly divided into: control group and 1 d, 3 d, 7 d and 14 d noise exposure groups (120 dBSPL, broadband noise, 2 h daily). The results showed that after noise exposure, the ACTH level and the corticosterone level in serum increased, but the content of DA in diencephalon decreased, the weight of adrenal gland increased, while that of thymus and spleen decreased. Change of weight of adrenal gland and thymus became maximum after 7d-exposure. The ACTH level in serum and the content of DA in diencephalon decreased and the later reached the lowest value and the weight of adrenal gland and thymus returned to normal level after 14 d exposure. It indicated that the acute response began to decrease after 7d-exposure, and the response turned into a chronic inhibitory state after 14d-exposure.

Adrenal Glands↗
PubMed1997

[Effect of noise in submarine compartment on signal discrimination and arithmetic performance].

To study the effects of noise level in submarine compartment on signal discrimination and arithmetic performance, experiments were carried out on 13 subjects. The results showed that as noise level raised from moderate (73 dBA) to higher levels (85-92 dBA), work efficiency showed a progressive decrease, but when noise level reached 96 dBA the decrease in efficiency reached a steady state. The results indicated that impairment of efficiency apparently occurred at a level of 85 dBA and that the interference effect of noise was more pronounced on task performance with mental strain.

Auditory Perception↗
PubMed1997

[The antibechic, expectorant and antiasthmatic actions of Cynanchum komarovii].

The water and ethanol extracts of Lao Gua Tou (Cynanchum komarovii) is effective on relieving cough caused by the irritation of ammonnia water in mice. The extract can increase the secretion of repiratory tract and promote expectoration, also alleviate asthma induced by histamine and acetylcholing chloride in guinea pigs.

Animals↗
PubMed1997

[Hot-point mutations of viral C gene during hepatitis B virus infection].

To investigate the relationship of the HBV C gene mutations with the disease progress, the hotpoint mutations of pre- C stop28 and C region L97 were examined with restrictio-fragment-length-polymorphism (RFLP) technique in 91 hepatitis patients with diverse clinical features and HBe status. Both mutations were almost not seen in acute hepatitis B and chronic asymptomatic virus carriers; rarely in chronic persistent hepatitis and frequently in chronic active hepatitis (CAH) and active liver cirrhosis (ALC), accounting for 80% and 78% in CAH and ALC respectively. The pre-C mutant was mixed with wild strain in 11 of 31 patients who were HBeAg-positive CAH and ALC; on the other hand, the wild strain also coexisted with variant in anti-HBe-positive cases. So did the L97 in both HBeAg- and anti- HBe-positive cases. Possibly, both the mutant and the wild strain are usually in a relatively growth and decline status. So, the hot-point mutations of HBV C gene were closely related with the disease activity.

Adult↗
PubMed1997

Expression of the spinach betaine aldehyde dehydrogenase (BADH) gene in transgenic tobacco plants.

Plasmid pLS9 contains a 1.5-kb of spinach cDNA including its complete open reading frame. The 1.5-kb BADH cDNA was cut from pLS9 using restriction enzyme and was inserted into the expression cassette of plasmid pYH between the CaMV 35S promoter and polyA signal sequence. The 35S-BADH cDNA-polyA fragment of pYH was cloned into a polylinker cloning site of the binary vector pBin19. The resulting plasmid pBinBADH-S was transferred to Agrobacterium tumefacies LBA4404. The tobacco plants were transformed with strain LBA4404 containing pBinBADH-S, and more than ninety kanamycin-resistant transformants were selected. Polymerase chain reaction (PCR) detection showed that more than 60% of the transformed tobacco plants contained the foreign BADH gene. The Western blot analysis, BADH enzymatic assay, specific stain for BADH activity, and the test for salt tolerance showed that BADH gene was normally expressed in the transgenic tobacco plants. The BADH enzymes also presented in chloroplasts and cytosol of the transgenic plants. The transgenic tobacco plants having strong expression of BADH gene had strong ability to tolerate high salt stress.

Aldehyde Dehydrogenase↗
PubMed1997

[Effects of herpes simplex virus thymidine kinase gene transduction and prodrug on ovarian cancer cell].

OBJECTIVE: To evaluate the efficacy of gene therapy with the herpes simplex virus thymidine kinase (HSV-TK) gene transference followed by ganciclovir (GCV) therapy in ovarian cancer. METHODS: HSV-TK gene was inserted into the hind III site of pLNSX vector and recombinant plasmid (pLNS/HSV-TK) was constracted. Then, the recombinant plasmid was transfered into PA317 packaged cell and the producer cell line of recombinant retrovirus vector pLNS/HSV-TK was established. The cytotoxicity efficacy of HSV-TK/GCV system to AO cell line was evaluated by microcucture tetrajolium test (MTT) method. RESULTS: The recombinant retroviral vector pLNS/HSK-TK can transfer HSV-SK gene into the genome of AO cell line and make it sensitive to GCV. The growth inhibitory rate of AO cell line transfered by pLNS/HSV-TK was 98.0% in the medium containing 400 mumol GVC. CONCLUSION: The ovarian cancer cell line transfered by HSV-TK gene regressed rapidly in response to the GCV therapy.

Antiviral Agents↗
PubMed1996

In vivo MR imaging and spectroscopy using hyperpolarized 129Xe.

Hyperpolarized 129Xe has been used to obtain gas phase images of mouse lung in vivo, showing distinct ventilation variation as a function of the breathing cycle. Spectra of 129Xe in the thorax show complex structure in both the gas phase (-4 to 3 ppm) and tissue-dissolved (190-205 ppm) regions. The alveolar gas peak shows correlated intensity and frequency oscillations, both attributable to changes in lung volume during breathing. The two major dissolved peaks near 195-200 ppm are attributed to lung parenchyma and to blood; they reach maximum intensity in 5-10 s and decay with an apparent T1 of 30 s. Another peak at 190 ppm takes 20-30 s to reach maximum; this must represent other well-vascularized tissue (e.g., heart and other muscles) in the thorax. The maximum integrated area of the tissue components reaches 30-80% of the maximum alveolar gas area, indicating that imaging at tissue frequencies can be achieved.

Animals↗
PubMed1996

Determination of remifentanil, an ultra-short-acting opioid anesthetic, in rat blood by high performance liquid chromatography with ultraviolet detection.

Remifentanil is an ultra-short-acting opioid under evaluation for use during surgical procedures which require opioid analgesia or anesthesia. It has an N-substituted methyl propanoate ester group which is highly susceptible to clevage by blood and tissue esterases as well as to chemical hydrolysis. A selective and specific high performance liquid chromatography method was developed to quantitate remifentanil in rat blood. A liquid-liquid extraction method using n-butyl chloride was used to separate interfering endogenous products from the compound of interest. Reverse phase chromatography with ultraviolet (lambda 210 nm) detection was used to quantitate the eluate. The calibration curves were found to be linear in the range 2.5-250 ng ml-1. Intra-day assay variability was 15% or less for all standards evaluated. The method was applied to blood samples collected from a short-term infusion study in rats. Good recovery, linearity, accuracy and precision were achieved with the assay.

Analgesics, Opioid↗
PubMed1996

The inversion of the exponential Radon transform for quantitative brain SPECT.

The mathematical derivation for the inversion of the exponential Radon transform is presented and the implementation of the inversion is detailed. The inversion can be verified and implemented by the readers for practical applications, such as for quantitative reconstruction of brain SPECT (single-photon emission computed tomography).

Brain↗