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Biomedical subjects

C Zhou

Publications and source records attributed to C Zhou.

At least 109 records · Page 6Linked to original sources
PubMed1999

Decoding information by following parameter modulation with parameter adaptive control.

It has been proposed to realize secure communication using chaotic synchronization via transmission of a binary message encoded by parameter modulation in the chaotic system. This paper considers the use of parameter adaptive control techniques to extract the message, based on the assumptions that we know the equation form of the chaotic system in the transmitter but do not have access to the precise values of the parameters which are kept secret as a secure set. In the case in which a synchronizing system can be constructed using parameter adaptive control by the transmitted signal and the synchronization is robust to parameter mismatches, the parameter modulation can be revealed and the message decoded without resorting to exact parameter values in the secure set. A practical local Lyapunov function method for designing parameter adaptive control rules based on originally synchronized systems is presented.

Journal Article↗
PubMed1999

Robustness of supersensitivity to small signals in nonlinear dynamical systems.

Nonlinear dynamical systems possessing an invariant subspace can display interesting dynamical behavior, such as on-off intermittency and bubbling. This Rapid Communication shows that a class of such systems has amazing features of (1) supersensitivity to small input signals and (2) robustness of the supersensitivity in the presence of noise. These features make the systems very promising as small signal detectors.

Journal Article↗
PubMed1999

Extracting messages masked by chaotic signals of time-delay systems.

We show how to extract messages masked by a chaotic signal of a time-delay system with very high dimensions and many positive Lyapunov exponents. Using a special embedding coordinate, the infinite-dimensional phase space of the time-delay system is projected onto a special three-dimensional space, which enables us to identify the time delay of the system from the transmitted signal and reconstruct the chaotic dynamics to unmask the hidden message successfully. The message extraction procedure is illustrated by simulations with the Mackey-Glass time-delay system for two types of masking schemes and different kinds of messages.

Journal Article↗
PubMed1999

Amplification of weak signals and stochastic resonance via on-off intermittency with symmetry breaking.

Nonlinear dynamical systems possessing reflection symmetry have an invariant subspace in the phase space. The dynamics within the invariant subspace can be random or chaotic. As a system parameter changes, the motion transverse to the invariant subspace can lose stability, leading to on-off intermittency. Under certain conditions, the bursting behavior is symmetry breaking. We demonstrate the possibility of observing multiplicative noise(chaos)-induced amplification of weak signal and stochastic resonance via on-off intermittency with symmetry breaking in a general class of symmetrical systems. Differences of this mechanism of stochastic resonance to that in noisy bistable or threshold systems are discussed.

Journal Article↗
PubMed1999

Renal protective effects of blocking the intrarenal renin-angiotensin system.

It has been well demonstrated that angiotensin-converting enzyme inhibitors (ACEIs) can retard the progression of renal failure and kidney sclerosis in patients and animal models with glomerular diseases. The aim of this study was to observe the influences of ACEI on intrarenal Ang II and TGFbeta1 local formation and their relation to renal protective effects. Experimental glomerulosclerosis with nephrotic syndrome was induced in unilateral nephrectomized rats with repeated injections of adriamycin. Rats were randomly divided into three groups: 1) a sham-operated control group (n=8); 2) an NS group treated with ACEI (benazepril 4 mg/kg/d) (n=10), and 3) an NS group not treated (n=10). After 8 wk, serum, urine and renal tissue were collected for study. ACE activity and Ang II concentration in renal tissue were measured by colorimetry and radioimmunoassay, respectively. Immunohistochemistry staining was employed for transforming growth factor-beta1 (TGFbeta1) and extracellular matrix (ECM) examination. TGFbeta1 mRNA was assessed by in situ hybridization. Compared with those of non-treated nephropathy rats, ACE activity (13.39+/-5.02 vs. 49.13+/-12.92 U/ml, p< 0.01) and Ang II (402.61+/-80.22 vs. 751.63+/-137.45 pg/mg/pr p < 0.01) in renal tissue were significantly inhibited in the rats treated with ACEI. At the same time, proteinuria was significantly reduced (155.06+/-103.56 vs. 421.11+/-148.45 mg/24 h, p < 0.01) and renal function improved (Scr 76.3+/-33.1 vs. 107.1+/-71.0, p < 0.05), concomitant with a reduction in the glomerular sclerosis index (30.6+/-19.5 vs. 120.3+/-61.9, p < 0.01) and a reduction in ECM accumulation such as Col IV, III, LN and FN (29.2+/-9.8 vs. 76.8+/-12.4; 29.5+/-12.4 vs. 85.9+/-11.5; 26.0+/-5.1 vs. 69.6+/-1.73; 32.4+/-12.4 vs. 70.5+/-13.5; p< 0.01 in all cases). In the ACEI treated group, these histologic benefits coincided with a reduced expression of TGFbeta1 in both tubular cells and sclerosed glomeruli in protein as well as mRNA level. These findings provide further evidence that ACEI (benazepril) can prevent the progression of renal damage in both the function and morphologic changes which associated with a down-regulation of intrarenal Ang II level through the relative inhibition of renal ACE activity. The blocking of the intrarenal renin angiotensin system (RAS) might contribute to the inhibition of TGFbeta1 local formation and the TGFbeta1-mediated ECM accumulation that are related to the renal protective effects of ACEI.

Angiotensin II↗
PubMed1999

A transgenic animal model of osmotic cataract. Part 1: over-expression of bovine Na+/myo-inositol cotransporter in lens fibers.

PURPOSE: Intracellular osmotic stress is believed to be linked to the advancement of diabetic cataract. Although the accumulation of organic osmolytes (myo-inositol, sorbitol, taurine) is thought to protect the lens by maintaining osmotic homeostasis, the physiologic implication of osmotic imbalance (i.e., hyperosmotic stress caused by intracellular over-accumulation of organic osmolytes) on diabetic cataract formation is not clearly understood. Studies from this laboratory have identified several osmotic compensatory mechanisms thought to afford the lens epithelium, but not the lens fibers, protection from water stress during intervals of osmotic crisis. This model is founded on the supposition that the fibers of the lens are comparatively more susceptible to damage by osmotic insult than is the lens epithelium. To test this premise, several transgenic mouse lines were developed that over-express the bovine sodium/myo-inositol cotransporter (bSMIT) gene in lens fiber cells. METHODS: Of the several transgenic mouse lines generated, two, MLR14 and MLR21, were analyzed in detail. Transgenic mRNA expression was analyzed in adult and embryonic transgenic mice by a coupled reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridization on embryonic tissue sections, respectively. Intralenticular myo-inositol content from individual mouse lenses was quantified by anion exchange chromatography and pulsed electrochemical detection. Ocular histology of embryonic day 15.5 (E15.5) embryos from both transgenic (TG) families was analyzed and compared to their respective nontransgenic (NTG) littermates. RESULTS: Both RT-PCR and in situ hybridization determined that transgene expression was higher in line MLR21 than in line MLR14. Consistent with this, intralenticular myo-inositol from MLR21 TG mice was markedly higher compared with NTG littermates or MLR14 TG mice. Histologic analysis of E15.5 MLR21 TG embryos disclosed a marked swelling in the differentiating fibers of the bow region and subcapsular fibers of the central zone, whereas the lens epithelium appeared morphologically normal. The lenticular changes, initiated early during lens development in TG MLR21 embryos, result in severe bilateral nuclear cataracts readily observable in neonates under normal rearing and dietary conditions. In contrast, TG MLR14 pups reared under standard conditions produced no lens opacity. CONCLUSIONS: Lens fiber swelling and related cataractous outgrowth positively correlated to the degree of lens bSMIT gene expression and intralenticular myo-inositol content. The affected (i.e., swollen) lens fibers appeared to be unable to cope with the water stress generated by the transgene-induced over-accumulation of myo-inositol and, as a result of this inability to osmoregulate, suffered osmotic damage due to water influx.

Animals↗
PubMed1999

[Gene expression profiles in squamous esophageal cancer tissues and adjacent almost normal tissues].

OBJECTIVE: To describe an esophageal cancer-specific expression profile and to identify genes that showed altered expression in squamous esophageal cancer tissues and their adjacent almost normal tissues. METHODS: The cDNA probes were synthesized from polyA(+)RNA of cancer and adjacent almost normal tissues and were differentially hybridized with two identical Atlas human cDNA expression arrays membranes containing 588 known genes. RESULTS: Autoradiographic analysis showed that of the 588 genes analyzed, 61 were found up-regulated in cancer, including cdc25B, Notch1, MMP, MET etc, and 22 down regulated in cancer, including cytokeratin4, BAD, IL-1 RECEPTOR ANTAGONIST, IL-6, etc. Expression levels of genes that associated with the regulation of cell proliferation, apoptosis, differentiation and metastasis altered most. CONCLUSION: The results for the first time provide an esophageal cancer-specific expression profile, showing that complex alterations of gene expression underlie the development of malignant phenotype of esophageal cancer cells. In addition, this line of research can lead to the identification of EC-specific genes which may be helpful for the development of diagnostic and prognostic biomarkers or therapeutic targets. The differential hybridization technique of Atlas Human cDNA expression array can be a useful method for describing the expression profiles of a tissue of cell interested.

DNA, Complementary↗
PubMed1999

Relationship between ventral stream for object vision and dorsal stream for spatial vision: an fMRI + ERP study.

Recent imaging studies indicated the existence of two visual pathways in humans: a ventral stream for object and form vision and a dorsal stream for spatial and motion vision. The present study was motivated by a stimulating question: Supposing shape and motion are processed separately in the two pathways, how do the respective cortical areas respond to the stimuli of "forms defined by motion"? fMRI and ERP recordings were combined in order to measure the spatiotemporal activation pattern in the two pathways responding to forms defined by motion, which were produced solely by coherent movement of random dots against a background of dynamic or static random dots. The fMRI data indicated that the stimuli of forms defined by motion indeed activated both dorsal MT/V5 and ventral GTi/GF. Furthermore, the RV curves resulting from fMRI-seeded dipole modeling indicated that each pair of dipoles located at MT/V5 or GTi/GF reached the same best-fit point; a single pair of free dipoles located near the fMRI foci of MT/V5 and GTi/GF could be identified at the corresponding best-fit point; and the source waveforms resulting from fixed dipole modeling also showed simultaneous activation of MT/V5 and GTi/GF dipoles in the time interval around the best-fit point. The present results, therefore, suggest that MT/V5 and GTi/GF appear to be activated in parallel and simultaneously responding to forms defined by motion. Such findings raise interesting issues about the hierarchical organization and the functional specialization in the two pathways.

Adult↗
PubMed1999

A double blind observation for therapeutic effects of the tong luo kai bi tablets on rheumatoid arthritis.

The therapeutic effects of the Tong Luo Kai Bi Tablets [symbol: see text] in 120 patients with rheumatoid arthritis were observed in this clinical trial by the randomized double blind method. Both the observed group and the control group each had 60 patients. In the observed group treated with the Tong Luo Kai Bi Tablets, 1 case (1.7%) was cured clinically, 27 cases (45.0%) improved markedly, 26 cases (43.3%) improved, with a total effective rate of 90.0%. In the control group treated with Rheumatic Semen Strychni Tablets [symbol: see text], no case was cured, 16 cases (26.7%) improved markedly, 33 cases (55.0%) improved, with a total effective rate of 81.7%. Statistical data showed the Tong Luo Kai Bi Tablets had much better therapeutic effectiveness clinically than the Rheumatic Semen Strychni Tablets (P < 0.05).

Adult↗
PubMed1999

[The evaluation of 156 cycles of intracytoplasmic sperm injection in the management of male infertility and idiopathic infertility].

OBJECTIVE: The aim of this study was to examine, retrospectively, the efficacy of intracytoplasmic sperm injection (ICSI) in the treatment of male infertility and idiopathic infertility. METHODS: From November 1995 to January 1998, 140 couples (156 cycles) received ICSI because of severe male factor infertility or idiopathic infertility in our assisted reproductive technology center. The treatment cycles were divided into two groups, group I included 74 cycles done before May 1997, group II included 82 cycles done after May 1997. Mature oocytes were selected for microinjection. RESULTS: No differences were observed between the two groups in the number of mature oocyte and the total cleavage rate. Oocyte survival rate, normal fertilization rate, embryos of good morphology rate and clinical pregnancy rate were significantly higher in group II than that in group I. CONCLUSION: ICSI procedure does affect the quality of embryos. With the improvement of ICSI technique, ICSI should be the treatment of choice for male infertility and idiopathic infertility.

Adult↗
PubMed1999

[Dual color fluorescent in-situ hybridization detects sex chromosome mosaicism in human embryos].

OBJECTIVE: Using dual color fluorescent in-situ hybridization (FISH) to detect sex chromosome mosaicism in human embryos and perform preimplantation gender diagnosis. METHODS: Three abnormal fertilized embryos and 18 normal fertilized embryos which were not suitable for embryo transfer and cryopreservation were analyzed by dual color fluorescent in-situ hybridization. RESULTS: Mosaicism analysis was performed on 14 normal fertilized embryos, which had more than two cells. Nine embryos had sex chromosome mosaicism. XO in male and female embryos cells were 12% and 14% respectively. CONCLUSION: Identification of sex by FISH analysis of a single cleavage cell is accurate, and sex chromosome mosaicism will not affect preimplantation gender diagnosis.

Embryo Transfer↗
PubMed1999

[The supporting effects of the pedicle of the subdermal vascular network flap in the rat].

OBJECTIVE: To investigate the role of the pedicle in the survival of the subdermal vascular network skin flap. METHODS: The subdermal vascular network skin flap was created on the back of the rat in the experimental group. The subdermal vascular network skin graft was made at the same position of the rat in the control group. The ratio of length to width of the flap was 4:1. The observation was carried out with naked eyes and instrument. Hair growing on the flap was one of the most important indexes of the observation. RESULTS: It was observed in 116 animals that the proximal 25 percent of the flap possessed regular colour and well-growing hair. CONCLUSION: The pedicle of the subdermal vascular network skin flap in the rat can supply 25 percent of the whole flap.

Animals↗
PubMed1999

[The effects of blocking intrarenal renin-angiotensin system on the expression of transforming growth factor-beta1 mRNA and extracellular matrix components].

OBJECTIVE: To explore the possible mechanism of benazepril in diminishing the progression of the renal diseases. METHODS: Experimental glomerulosclerosis in rats was induced by adriamycin. The treated group was given benazepril (4 mg x kg(-1) x d(-1)). Intrarenal angiotensin converting enzyme (ACE) activity and angiotensin II (AngII) concentration were measured with colorimetry and radioimmunoassay respectively. Immunohistochemistry staining was employed for transforming growth factor beta1 (TGF beta1) and extracellular matrix (ECM) examination. To observe the expression of TGFbeta1 mRNA in the kidney, in situ hybridization was performed. RESULTS: In the rats treated with benazeapril, ACE activity and Ang II concentration in renal tissue were significantly inhibited. In the meantime, expression of TGFbeta1 mRNA and TGFbeta1 protein were down-regulated, accompanied by decreasing accumulation of ECM (compared with the untreated rats, P < 0.01). CONCLUSION: Benazepril plays an important role in down-regulating the expression of TGFbeta1 and decreasing the accumulation of ECM by blocking intrarenal renin-angiotensin system.

Angiotensin II↗
PubMed1999

[Investigation on interaction between Streptococcus sanguis and Porphyromonas gingivalis in specific pathogen-free rats].

OBJECTIVE: To examine whether endogenous S. sanguis could prevent, or reduce the colonization of the virulent P. gingivalis strain. METHODS: First, 10 specific pathogen-free Wistar rats were divided into 2 groups. Doxycycline was administered in the drinking water for 7 days. Successful implantation of the endogenous strain of S. sanguis, isolated from one of the rats before doxycycline administration, and P. gingivalis 381 within 14 days of observation were demonstrated in the rats of each group respectively. Then, 30 SPF rats were divided into 6 groups. Doxycycline was administered in the drinking water for 7 days to all the rats. Afterwards, the rats in group A and B were inoculated orally once a day for 5 days with P. gingivalis, the rats in group C and E were inoculated orally once a day for 5 days with S. sanguis. Then, the rats in group A were inoculated for 5 days with S. sanguis, and rats in group C and D were inoculated for 5 days with P. gingivalis. The rats in group F served as negative control. After inoculation, the levels of S. sanguis and P. gingivalis in the mouths of the rats were determined after 12, 24, 36 hours, 7 days and 14 days. RESULTS: Both pre-colonization of S. sanguis and superinfection with S. sanguis did reduce the level of P. gingivalis in experimental rats. However, the reduction only maintained quite short time, about 36 hours. It was not caused by the decreased level of S. sanguis after 36 hours because the level of S. sanguis kept stable during the observation period of 14 days. CONCLUSION: That S. sanguis function as the effector strain requires the successful implantation of S. sanguis as well as S. sanguis producing antagonistic action efficiently in vivo.

Animals↗
PubMed1999

[Study on the separation of Co2+ from Cu2+, Cd2+, Mn2+, Zn2+ and Fe3+ by extraction chromatography].

In this paper, extraction chromatography by which Co2+ can be separated from Cu2+, Cd2+, Mn2+, Zn2+, Fe3+ is developed. The chromatographic column was 17 mm i.d. x 520 mm, containing polymers synthesized by styrene, divinylbenzene and P204 (volume fraction was 40%), with particle size of 100-200 mesh. The effects of transformation of P204 from the H(+)-form to the Na(+)-form by NaAc solution, the eluent acidity, and eluent composition were investigated. The results indicated that this extraction chromatographic method is good to separate Co2+ from Cu2+, Cd2+, Mn2+, Zn2+ and Fe3+, and the condition of separation is simple and convenient. When the P204 is transformed from the H(+)-form to the Na(+)-form by pH 4.0 NaAc (0.5 mol/L), and the column is eluted with pH 2.5 ClCHCOOH-ClCHCOONa (0.1 mol/L), the separation can be completed effectively.

English Abstract↗
PubMed1999

[The effect of partial middle turbinectomy upon the frontal sinus].

OBJECTIVE: To investigate the effect of partial middle turbinectomy under endoscopy upon the frontal sinus. METHOD: A retrospective analysis of 87 patients undergone endoscopic sinus surgery was made. RESULT: Among 55 sinusitis patients (no frontal sinus) suffered Fess, 29 cases had partial middle turbinectomy and 7 cases were found postoperative frontal sinusitis. In other 26 cases without partial middle turbinectomy, 5 cases were found frontal sinusitis. No significant difference between two groups was found (P > 0.05). In 32 nonsinutis patients no postoperative frontal sisusitis was found. CONCLUSION: The partial middle turbinectomy has no effect on the incidence of frontal sinusitis.

Adult↗