Biomedical subjects

Y Diao

Publications and source records attributed to Y Diao.

16 recordsLinked to original sources

PubMed1998

[Solid-phase microextraction of dichlorvos from white spirits].

DDVP was isolated from white spirits using Solid-Phase Microextraction (SPME) technique, and determined by wide-bore capillary gas chromatography (GC) coupling a flame ionization detector. This method had an excellent linearity among 0.5-12 mg/L. Correlation coefficient and minimum detectable concentration were 0.9983 and 0.05 mg/L respectively. This method enables the extraction, the enrichment and the injection to integrate into a single step, and it was free-solvent in whole process. SPME is an advanced technique for the extraction and analysis of the samples.

Alcoholic Beverages↗

PubMed1998

A possible basic cortical microcircuit called "cascaded inhibition." Results from cortical network models and recording experiments from striate simple cells.

The robust behavior, the degree of response linearity, and the aspect of contrast gain control in visual cortical simple cells are (amongst others) the result of the interplay between excitatory and inhibitory afferent and intracortical connections. The goal of this study was to suggest a simple intracortical connection pattern, which could also play a role in other cortical substructures, in order to generically obtain these desired effects within large physiological parameter ranges. To this end we explored the degree of linearity of spatial summation in visual simple cells experimentally and in different models based on half-wave rectifying cells ("push-pull models"). Visual cortical push-pull connection schemes originated from antagonistic motor-control models. Thus, this model class is widely applicable but normally requires a rather specific design. On the other hand we showed that a more generic version of a push-pull model, the so-called cascaded inhibitory intracortical connection scheme, which we implemented in a biologically realistic simulation, naturally explains much of the experimental data. We investigated the influence of the afferent and intracortical connection structure on the measured linearity of spatial summation in simple cells. The analysis made use of the relative modulation measure, which is easy to apply but is limited to moving sinusoidal grating stimuli. We introduced two basic push-pull models, where the order of threshold nonlinearity and linear summation is reversed. Very little difference is observed with the relative modulation measure for these models. Alterative models, like half-wave squaring models, were also briefly discussed. Of all model parameters, the ratio of excitation to inhibition in the simple cell exerts the most crucial influence on the relative modulation. Linearity deteriorates as soon as excitatory and inhibitory inputs are imbalanced and the relative modulation drops. This prediction was tested experimentally by extracellular recordings from cat area 17 simple cells and we found that about 62% showed a significant deviation from linear behavior. The problem that individual basic push-pull models are hard to distinguish experimentally led us to suggest a different solution. In order to generically account for the observed behavior (e.g., imbalance of excitation versus inhibition), we suggested a rather generic version of a push-pull model where it no longer mattered about (the hard-to-distinguish) fine differences in connectivity. Thus, we introduced a new class of biophysically realistic models ("cascaded inhibition"). This model class requires very little connection specificity and is therefore highly robust against parameter variations. Up to 25 cells are connected to each target cell. Thereby a highly interconnected network is generated, which also leads to disinhibition at some parts of an individual receptive field. We showed that the performance of these models simulates the degree of linearity and its variability in recal simple cells with comparatively high accuracy. This behavior can be explained by the self-regulating properties of a cascaded inhibitory connection scheme by which the balance between excitation and inhibition at a given cell is improved by the joint network effects. The virtues and the generic design of this connection pattern, therefore, allow to speculate that it is used also in other parts of the cortex.

Animals↗

PubMed1998

Distribution of endotoxins in tissues and circulation and its effects following hemorrhagic shock.

OBJECTIVE: To systemically investigate 1) distribution of endogenous endotoxin (ET) in tissues and circulation; 2) its relationship with shock duration and organ damage; and 3) its possible mechanism after hemorrhagic shock. METHODS: To further elucidate the intrinsic relationship between endogenous endotoxin translocation and hemorrhagic shock, the present study systematically investigated the distribution of endogenous ET into the liver, lungs, kidneys and circulation, and the relationship between ET levels and the corresponding organ dysfunction with limulus amebocyte lysate (LAL) chromogenic assay following hemorrhagic shock in rats. RESULTS: It was found that ET levels in hepatic homogenate markedly increased (P = 0.09) 1.5 hours following shock compared with that in the sham group. After resuscitation, ET levels in hepatic, pulmonary and renal tissues were all significantly elevated. The levels kept increasing with the prolonged experimental time, and reached as high as 3.88 +/- 0.95 EU (endotoxin unit)/g in the livers, 2.53 +/- 1.46 EU/g in the lungs and 2.51 +/- 0.89 EU/g in the kidneys 12 hours after shock. ET levels in plasma reached a peak of 1.13 +/- 0.42 EU/ml at 1 hour following resuscitation, then rapidly decreased to the sham levels 3 hours following resuscitation. There was a close relationship between endotoxin translocation and shock duration. Correlation analysis further indicated that the changes in glutamic-pyruvic transaminase (GPT), blood urea nitrogen (BUN) in plasma and angiotensin I-converting exzyme (ACE) in pulmonary homogenate were significantly and positively correlated with the ET levels in the liver, kidneys and lungs after hemorrhagic shock. CONCLUSIONS: Hemorrhagic shock can induce obvious endogenous ET translocation, which is closely related to the shock duration. Although only transient endotoxemia occurs after hemorrhagic shock, ET can massively accumulate in tissues (liver, lungs and kidneys), and may play an important role in the development of shock.

Animals↗

PubMed1998

[Ovarian follicular maldevelopment in infertile women].

OBJECTIVE: To study the manifestation and outcome of ovarian follicular maldevelopment (FM) in infertile women. METHODS: Among 296 infertile women, 80 cases with FM were taken as study group and 20 with normal ovulation as control. Serial B-ultrasonography, cervical mucus scoring, serum estradiol (E2) assay and laparoscopy, endometrium histology were monitored in both groups. RESULTS: The incidence of FM in infertile women was 27.0%, B-ultrasonography showed many small and obscure outlined follicles in the ovarian. The maximum and mean cervical mucus socres in FM group were < 9 and 7.3 +/- 1.8, significantly lower than those in control (> 10, 13.2 +/- 1.8) (P < 0.01). So were the midcycle serum E2 levels (300 +/- 100 pmol/L vs 900 +/- 400 pmol/L, P < 0.001). No stigma was found in two-third of FM patients and no corpus luteum in about one-third. Proliferative endometrium was shown in 34.0% of the FM group. CONCLUSION: (1) FM with an incidence of 27.0% might be an important cause of infertility. (2) FM results finally in follicular atresia or multiple immature luteinized follicles.

Adult↗

PubMed1997

Expression of TNF alpha, IL-1 beta, IL-6 mRNA, release of TNF alpha in vital organs and their relationship with endotoxin translocation following hemorrhagic shock.

This study was designed to systematically investigate expression of TNF alpha, IL-1 beta, Il-6 mRNA in the liver, lungs and kidneys, release of TNF alpha in the above tissues, their relationship with hepatic, pulmonary and renal dysfunction, and distribution of endogenous endotoxin in tissues after hemorrhagic shock in mice and rats, with reverse-transcription-polymerase chain reaction, ELISA, etc, to elucidate the kinetics of expression and release of major cytokines in vital organs, their role and mechanism of production in shock. The results were: 1. expression of TNF alpha, IL-1 beta, IL-6 mRNA in vital organs successively increased after hemorrhagic shock and resuscitation, and TNF alpha expression was the first to appear followed by IL-1 beta. Though expression of IL-6 mRNA appeared late, it persisted longer; 2. TNF alpha levels in the liver, lungs and kidneys were all elevated but to different degrees after shock and resuscitation. At 3 hours after resuscitation, TNF alpha levels in the three above tissues were still significantly high, while plasma TNF alpha levels were already decreased to control levels; 3. hepatic, pulmonary and renal functions were damaged to different degrees after hemorrhagic shock, with hepatic dysfunction being the most severe; 4. endotoxin levels in the liver, lungs and kidneys were markedly increased after shock and resuscitation, and paralleled the expression of cytokine genes. In addition, there was significant correlation between changes in endotoxin level in tissues and TNF alpha release in tissues during early shock. It is suggested that expression and release of cytokines in vital organs might play an important role in local organ damage after hemorrhagic shock, and production of cytokines is related to endotoxin translocation.

Animals↗

PubMed1997

Effect of hemorrhagic shock on endotoxin-induced TNF production and its molecular mechanism in rats.

The present study was designed to investigate the production of tumor necrosis factor alpha (TNF alpha) induced by low-dose (1 microgram/kg) lipopolysaccharide (LPS) and its cellular source after hemorrhagic shock (HS) in rats, and to further analyze the mechanism for increased sensitivity to LPS through looking at expression of lipopolysaccharide-binding protein (LBP) mRNA in the liver, lungs and kidneys. It was found in vivo that plasma TNF alpha levels in the HS + LPS group were 20-fold higher than that in the HS group (P < 0.01), and 2.7-fold higher than that in the LPS group (P < 0.05). It was shown in vitro that the capacity of peripheral white blood cells to produce TNF alpha in response to LPS stimulation was significantly decreased by 126% (P < 0.01) and 57% (P < 0.05) compared with pre-shock levels and the sham group respectively at the end of resuscitation following shock, and was still markedly decreased 3 hours after resuscitation, while the capacity of Kupffer cells was significantly increased by 110% compared with the sham group (P < 0.01) after shock and resuscitation. Results from RT-PCR showed that expression of LBP mRNA in the liver, lungs and kidneys was increased after shock and resuscitation. It is suggested that hemorrhagic shock could significantly enhance endotoxin-induced TNF alpha production, which might be due to up-regulation of LBP expression in tissues after shock, and tissue macrophages might be the main source of cytokine production.

Acute-Phase Proteins↗

PubMed1997

[Increased sensitivity to endotoxin and its molecular mechanism after hemorrhagic shock].

OBJECTIVE: To study the increasing sensitivity to endotoxin induced by hemorrhagic shock and its mechanism. METHODS: Routine biochemical assay, reverse transcription-polymerase chain reaction. (RT-PCR) and cell in situ hybridization were used to investigate the effects of low-level endotoxin under hemorrhagic shock and its possible mechanism. RESULTS: In rabbits, blood pressure levels were significantly decreased, and plasma lactate and beta-glucuronidase (beta-G) levels increased in hemorrhagic shock (HS) + LPS group, all of which were significantly different from those in the LPS or HS group. All of the animals in the HS + LPS group were dead while those in the LPS or HS group survived 24 hours after shock. The results of RT-PCR showed that expression of lipopolysaccharide-binding protein (LBP) mRNA in the liver, lungs and kidneys was increased in rats after shock and resuscitation. The expression of CD144 mRNA in the peritoneal macrophages in mice was also enhanced after hemorrhagic shock and subsequent resuscitation showed by cell in situ hybridization. CONCLUSION: Hemorrhagic shock can significantly increase the sensitivity to endotoxin possibly because of up-regulation of LBP/CD14 after shock.

Acute-Phase Proteins↗

PubMed1996

Orientational and directional selectivities of visual neurons in the superior colliculus of the cat.

Based on quantitative analyses of the response characteristics of visual neurons in the superior colliculus to moving optical bar stimuli, it is demonstrated for the first time that the visual neurons in superior colliculus of the cat have, to some extent, orientational selectivity. The significance of this selectivity is discussed in reference to its morphological substrate and physiological functions. In addition, both the directional and orientational selectivities in the superior colliculus are relatively weak when compared with those in the primary visual cortex, and the majority of the neurons prefer upward or downward motion in the visual field.

Animals↗

PubMed1994

Quantification of directional and orientational selectivities of visual neurons to moving stimuli.

Directional and orientational components usually coexist and are mixed in the cell's overall responses when moving optical stimuli are used to study the response characteristics of visual neurons. While these two properties were quantified with all the previous methods for data analysis, their effects could not be efficiently separated from each other, and thus the analyses were imperfect. In this paper, theoretical evidence and examples are provided to show the defects of the old methods. In order to separate the two components completely, we propose to apply optimal regression analysis with the sine-cosine function series as the fundamental variables. Based on this separation, we defined the orientational selectivity as variation of response strength with orientation and performed integration and averaging to quantify the two properties [cf. Eqs. (5) and (6)]. The present method has the advantages of completeness and accuracy, and can detect some details which would have been missed by other methods. An explanation of the intrinsic implications of the method and our comprehension of directional and orientational selectivities and preferred direction and orientation are also given.

Algorithms↗

PubMed1993

[Highperformance liquid chromatographic assay for lomefloxacin in plasma and its pharmacokinetics in healthy volunteers].

A sensitive and simplified high performance liquid chromatographic procedure has been developed for quantification of lomefloxacin in human plasma. The recovery of lomefloxacin was 95 to 102%. The relative standard deviation was 2.1 to 7.8%. The calibration curve was linear in the range from 0.125 micrograms/ml to 5.012 micrograms/ml with r = 0.9998. The detection limit of the method is 25 ng/ml. The plasma drug concentration-time course after medication conformed to a 1-compartment open model with a first order absorption. Mean t1/2 value was 5.5 h.

Anti-Infective Agents↗

PubMed1993

Pharmacokinetics of sustained-release tablets of metoprolol in Chinese.

Single and repeated oral doses pharmacokinetic studies of metoprolol sustained-release tablets (Sino-Swed Pharmaceutical Co Ltd) were performed on 12 Chinese healthy subjects in an open randomized crossover manner, using metoprolol tablets from Sweden Astra International Pharmaceutical Co Ltd as control. Drug concentrations in plasma were assayed by gas chromatography-electron-capture detector method. The percent of drug absorbed in vivo at 1, 2, 4, 6, 8 h correlated well with the amount of drug released in vitro at corresponding time (P > 0.05). Pharmacokinetic parameters in Chinese after metoprolol tablets were comparable to the reported data in foreigners.

Administration, Oral↗

PubMed1993

Pharmacokinetics and relative bioavailability of lomefloxacin preparations in 10 healthy Chinese volunteers.

The pharmacokinetics of lomefloxacin tablet and capsule were determined following a single oral dose of 400 mg given to each of 10 Chinese healthy male volunteers in an open, randomized crossover study. Drug concentrations in plasma were assayed by HPLC method. The peak levels in plasma averaged 6.0 +/- 1.3 and 5.9 +/- 1.0 micrograms.ml-1 at 1.3 +/- 0.4 and 1.2 +/- 0.4 h, and the areas under the drug concentration curves were 43 +/- 15 and 44 +/- 13 h.micrograms.ml-1 for lomefloxacin tablet and capsule, respectively. The concentration-time courses after medication conformed to a 1-compartment open model with a first order absorption. Pharmacokinetic parameters after tablet did not differ significantly from the corresponding values after capsule. The bioavailability of tablet was comparable to that of capsule.

Adult↗

PubMed1992

[Determination of ofloxacin in human plasma and studies of its pharmacokinetics using HPLC method].

Ofloxacin is a new broad-spectrum oral bactericidal antimicrobial agent. Its primary effect is the inhibition of bacterial DNA gyrase. This paper describes the development of a simple method for its determination using HPLC with UV detection. We used a Waters liquid chromatograph equipped with a Model 490 E multi-wavelength detector, a Model 510 pump and a U6K injector. The separation was performed on a Spherisorb C18 column (200 mm x 4.6 mm ID, 5 microns) with a mobile phase of methanol-0.01 mol/L phosphate buffer-0.5 mol/L tetrabutylammonium bromide (35:65:4, pH 2.50). The flow-rate was 1.0 ml/min and detection was at 294 nm. A specimen (0.2 ml) was spiked with the internal standard (norfloxacin) and deproteinized by adding 1.0 ml methanol. The precipitated mixture was shaken and then centrifuged at 3000 x g for 10 min, the supernatant was evaporated at 75 degrees C under a nitrogen stream. The residue was taken up with 0.4 ml of the mobile phase and 50 microliters aliquots were injected into the system. The minimal detectable concentration in plasma is 20 ng/ml. There is a linear relationship between the peak area ratio over the range of 0.5-4.0 micrograms/ml with r = 0.9999. The method has been applied to assay ofloxacin concentration in human plasma. The pharmacokinetic characteristics were studied.

Biological Availability↗

PubMed1992

Pharmacokinetics and relative bioavailability of ofloxacin tablets in 12 healthy volunteers.

Single oral dose of tablet A (Daiichi Pharmaceutical Co Ltd, Japan) and B (Jining Pharmaceutical Factory, Shandong, China) of 300 mg ofloxacin (Ofl) were given to 12 Chinese healthy male volunteers in an open, randomized crossover study. Drug concentrations in serum and urine were assayed by HPLC and partial least squares spectrophotometric method, respectively. The serum concentration-time course after medication conformed to a 2-compartment open model with a first order absorption. Pharmacokinetic parameters after tablet B did not differ significantly from the corresponding values after tablet A. The bioavailability of tablet B was comparable to that of tablet A.

Adult↗

PubMed1991

[Development and pharmacokinetic study of miocamycin sustained-release tablet remaining--floating in stomach].

A novel sustained-release tablet of miocamycin was developed based on the hydrodynamically balanced controlled drug delivery system (HBS). It was prepared to contain fast-release and sustained-release granules. The gamma-scintiphotographic study after oral ingestion showed that MOM-HBS remained in human stomach for more than 7 hours, much longer than the conventional tablet (3-4 h). The in vitro release characteristics showed basically first-order kinetics (Kr = 0.1619 h-1). The serum concentration-time course of MOM-HBS exhibited typical sustained-release characteristics. Moreover, The percentage of drug released in vitro versus the percentage of drug released in vivo of MOM-HBS indicated excellent linearity. Its relative bioavailability was increased greatly compared with MOM dry syrup produced in Japan.

Adult↗

PubMed1990

A case of hemolytic disease of the newborn caused by anti-Hro and anti-e.

A Chinese woman of blood group B, D- and her husband of blood group AB, CCDee were examined. The woman had not been transfused before. Their first two babies died. Anti-Hro and anti-e were found in the mother's serum. During her third pregnancy, the titer of antibodies went up quickly, approximately one titer per month. After 36 weeks of pregnancy, the baby was delivered by Caesarean section. The cord blood Hb was 88 g/L, his red blood cell count 2.7 x 10(12)/L, and total bilirubin 114.6 mol/L. The baby was of blood group AB, and CDe-D-genotype. Exchange transfusion was begun 2.5 hours after birth. O, ccDEE washed red cells together with group AB plasma were used. Two days later, 70 ml washed O, ccDEE concentrated red cells were administered. The baby is alive and in good health.

Erythroblastosis, Fetal↗