Search PubMed⌕ Search

Biomedical subjects

C Hu

Publications and source records attributed to C Hu.

At least 73 records · Page 4Linked to original sources
PubMed2000

[Impact of high temperature on testicular growth and development of valuable silkworm Antheraea yamamai(Lepidoptera: Saturiidae)].

The results indicated that high temperature had a significant impact on the growth and development of testis in Japanese oak silkworm Antheraea yamamai. The testicular size of the 3rd and 4th instar larvae increased within the range from 20 to 29 degrees C, and slightly decreased at 32 degrees C. While in the 5th instar, it decreased within the range from 20 to 26 degrees C, with the biggest size at 20 degrees C. The testis was almost hard to grow and develop because the larvae could not survive at 29 to 32 degrees C. When the mature larvae were treated at 32 degrees C at the beginning of coconing or at the 1st or 6th day of pupating, the growth of testicular size and spermatogenesis were significantly arrested, and the sperm number and the content of soluble protein in the testis markedly decreased. When the male moth of the 1st day was treated at 32 degrees C, the activity of the sperms in the testis obviously decreased, in contrast to the treatment at 20 degrees C. It is concluded that for the egg raising of the silkworm, its mature larvae, puape in cocoons and male moths should not be exposed to 32 degrees C from cocooning to adult stage. The proper temperature for rearing 3rd, 4th and 5th instar larvae was discussed.

Animals↗
PubMed2000

[The nuclear hardness and associated factors of age-related cataract].

OBJECTIVE: To determine the nuclear hardness and associated factors of age-related cataract. METHODS: Forty-seven eyes of 47 patients with age-related cataract aged > 50 years were studied. The opacity of lenses was assessed and classified by the LOCS II pre-operatively. The lens nucleus obtained during extracapsular cataract extraction (ECCE) was measured. By means of a fine conical probe and dynamometer, the resistance to penetration of different lens layers was transferred to an electric signal and recorded by a function recorder. The hardness to the penetration of different lens layers was calculated. Multivariate regression analysis was applied to the parameters including age, color of the nucleus, duration of symptoms and other factors. RESULTS: The mean force required to penetrate the lens was (0.51 +/- 0.29) Newtons (N) for grade I, (1.41 +/- 0.35) N for grade II and (1.95 +/- 0.42) N for grade III; it increased to (2.96 +/- 0.62) N for grade IV. The hardest part of the lens was located at the nucleus center. Multivariate analysis of the data showed that 85% of the variation in hardness could be explained in terms of color and opacity. The patients with myopia and diabetics had an increased incidence of grading IV nuclear sclerosis. Regression analysis revealed a positive correlation between nucleus color and weight (r = 0.4565), diameter (r = 0.5263), thickness (r = 0.5552) and hardness (r = 0.8969), P < 0.001. There was a weak positive correlation between age and the weight of nucleus (r = 0.3239, P < 0.05). CONCLUSIONS: The results indicate that the color can be used more reliably to predict physical characteristics of lens nucleus, the preoperative knowledge of which would help the surgeon in planning small-incision surgery including phacoemulsification.

Age Factors↗
PubMed2000

[Production of intergeneric somatic hybrid plants via protoplast electrofusion in citrus].

Leaf derived protoplasts of Sour orange (Citrus aurantium L.) were fused electrically with embryogenic protoplasts of Microcitrus papuana Swingle. Plants were regenerated from the fusion products, which were characteristic with three types of leaf morphology. Most of the plants were identical to Sour orange (namely, Leaf-parent-type plant) and two plants had large and thick leaves whereas one plant had bifoliate and trifoliate leaves. Chromosome examination showed that these plants were diploid with 18 chromosomes (2n = 2x = 18). RAPD analysis was employed to verify the hybrid characteristics of the plants in the first two types. Four 10-mer arbitrary primers with polymorphism were chosen. Band pattern of the plants was similar with the leaf parent (Sour orange) for the primer OPAA-17. Band pattern of the plants was similar with either Sour orange or M. papuana for OPA-08. As for OPA-07 and OPA-04 three kinds of band profiles were detected. Results of RAPD marker, together with chromosome determination, indicated that all of the analyzed plants were intergeneric diploid somatic hybrids between Sour orange and M. papuana.

Cell Fusion↗
PubMed2000

A comparative evaluation of Humphrey perimetry and the multi-channel pattern visual evoked potentials.

PURPOSES: To compare the multi-channel pattern visual evoked potentials to Humphrey perimetry in the assessment of central visual function in primary open angle glaucoma. METHODS: The multi-channel checkerboard reversal PVEPs waves to full-field and half-field stimulus of 25 normal persons and 74 patients with primary open angle glaucoma were recorded and analyzed, All patients were examined using Humphrey Field Analyzer. The area of visual field corresponding to the area of retina stimulated during multi-channel PVEPs testing were analysed, straight-line correlation and regression analyses of the various multi-channel PVEPs parameters and the total dB losses were performed. RESULTS: The multi-channel PVEPs demonstrated a low detection rate compared with Humphrey perimetry in the early glaucoma, absolute latency and field loss were correlated in the late stage of glaucoma, and absolute amplitude and field loss were not correlated. CONCLUSIONS: In relation to signalling "early" loss the multi-channel PVEPs was inferior to Humphrey perimetry, in late loss of primary open angle glaucoma, multi-channel PVEPs can provide a valuable, objective complement to Humphrey perimetry.

Adolescent↗
PubMed1999

Proniosomes: a novel drug carrier preparation.

A procedure is described for producing a dry product which may be hydrated immediately before use to yield aqueous niosome dispersions similar to those produced by more cumbersome conventional methods. These 'proniosomes' minimize problems of niosome physical stability such as aggregation, fusion and leaking, and provide additional convenience in transportation, distribution, storage, and dosing. This report describes the preparation of dispersions of proniosome-derived niosomes, comparison of these niosomes to conventional niosomes, and optimization of proniosome formulations. In addition, conventional and proniosome-derived niosomes are compared in terms of their morphology, particle size, particle size distribution, and drug release performance in synthetic gastric or intestinal fluid. In all comparisons, proniosome-derived niosomes are as good or better than conventional niosomes.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Decolorization and biodegradability of photocatalytic treated azo dyes and wool textile wastewater.

The photodegradation and biodegradability have been investigated for four non-biodegradable commercial azo dyes, Reactive YellowKD-3G, Reactive Red 15, Reactive Red 24, Cationic Blue X-GRL, an indicator. Methyl Orange, and one industrial wool textile wastewater, using TiO2 suspensions irradiated with a medium pressure mercury lamp. The color removal of dyes solution and dyeing wastewater reached to above 90% within 20-30 min. of photocatalytic treatment. Biochemical oxygen demand (BOD) was found to increase, while chemical oxygen demand (COD), total organic carbon (TOC) decreased, so that the ratio of BOD5/COD of the wastewater increased from original zero up to 0.75. The result implies that photocatalytic oxidation enhanced the biodegradability of the dye-containing wastewater and therefore relationship between decolorization and biodegradability exists. When the color disappeared completely, the wastewater biodegraded normally and could be discharged for further treatment. The experimental results demonstrate that it is possible to combine photocatalysis with conventional biological treatment for the remedy of wastewater containing generally non-biodegradable azo dyes.

Azo Compounds↗
PubMed1999

On the use of survival analysis techniques to estimate medical care costs.

Measurement of treatment costs is important in the evaluation of medical interventions. Accurate cost estimation is problematic, when cost records are incomplete. Methods from the survival analysis literature have been proposed for estimating costs using available data. In this article, we clarify assumptions necessary for validity of these techniques. We demonstrate how assumptions needed for valid survival analysis may be violated when these methods are applied to cost estimation. Our observations are confirmed through simulations and empirical data analysis. We conclude that survival analysis approaches are not generally appropriate for the analysis of medical costs and review several valid alternatives.

Costs and Cost Analysis↗
PubMed1999

Capability of serum to convert streptomycin to cytotoxin in patients with aminoglycoside-induced hearing loss.

Individual variations in sensitivity to the ototoxic effects of aminoglycoside antibiotics are well documented. Our research demonstrates that there is an apparent difference in serum from patients who are resistant or susceptible to aminoglycoside ototoxicity. In the first study, the cytotoxicity of sera from patients with and without hearing loss after various time periods following the discontinuation of aminoglycoside treatment was assayed using the isolated outer hair cell toxicity assay. The results indicate that sera from patients with hearing loss were significantly more toxic than sera from patients with normal hearing or minimal hearing loss. This toxicity may persist for up to 1 year after discontinuation of aminoglycoside therapy. In a second study, sera were obtained from patients who had received aminoglycoside therapy several years previously. None of these sera was toxic to isolated outer hair cells in vitro. Streptomycin was then incubated with the sera or a protein fraction isolated from sera, and the incubation mixtures were tested for toxicity. The percentage of damaged outer hair cells was significantly higher when streptomycin had been treated with sera or a serum protein fraction from patients with hearing loss (58+/-10% and 68+/-9%, respectively) than with sera or a serum protein fraction from a control group (10+/-5% and 17+/-4%, respectively). In addition, several incubation mixtures were analyzed using high performance liquid chromatography. A new chromatographic peak was only found in the incubations of streptomycin with serum protein from patients with hearing loss. The results suggest that sera from individuals sensitive to aminoglycoside antibiotics may metabolize these drugs to cytotoxins.

Adolescent↗
PubMed1999

Inability of interleukin-12 to modulate T-helper 0 effectors to T-helper 1 effectors: a possible distinct subset of T cells.

Interleukin-12 (IL-12) strongly favours the development of T-helper 1 (Th1)-type cells through its ability to induce interferon-gamma (IFN-gamma) production by natural killer cells and T cells. In the present work we analysed the effects of IL-12 on the synthesis and secretion of IFN-gamma and IL-4 by human T-cell clones. Several previously described human T-cell clones exhibiting Th1, Th2 or Th0 phenotypes were used for these analyses. We demonstrated, by enzyme-linked immunosorbent assay (ELISA) and intracytoplasmic staining, that, in Th0 clones, IL-12 up-regulated the production of both IFN-gamma and IL-4 and was unable to modulate these cells to Th1-type. The up-regulation of cytokine gene expression was transcriptionally regulated and was not due to differences in mRNA stability. In Th1 cells, IL-12 up-regulated only IFN-gamma and not IL-4. However, in Th2 cells, both IFN-gamma and IL-4 were up-regulated by IL-12. This suggests that Th2 cells may be less stable than Th1 cells. We also observed that human Th2 cells expressed the IL-12beta2 receptor, in contrast to murine Th2, which lacks this receptor. The observed differences in the effects of IL-12 on the three T-cell subsets may have important ramifications for IL-12-based therapies.

Blotting, Northern↗
PubMed1999

Regulation of alpha1-antitrypsin gene expression in human intestinal epithelial cell line caco-2 by HNF-1alpha and HNF-4.

There is still relatively limited information about mechanisms of gene expression in enterocytes and mechanisms by which gene expression is regulated during enterocyte differentiation. Using the human intestinal epithelial cell line Caco-2, which spontaneously differentiates from a cryptlike to a villouslike enterocyte, we have previously shown that there is a marked increase in transcription of the well-characterized alpha1-antitrypsin (alpha1-AT) gene during enterocyte differentiation. In this study we examined the possibility of identifying the cis-acting elements and trans-acting DNA-binding proteins responsible for expression of the alpha1-AT gene in Caco-2 cells during differentiation. Footprint analysis and electrophoretic mobility shift assays showed that hepatocyte nuclear factor-1alpha (HNF-1alpha), HNF-1beta, and HNF-4 from nuclear extracts of Caco-2 cells specifically bound to two regions in the proximal promoter of the alpha1-AT gene. Cotransfection studies showed that HNF-1alpha and HNF-4 had a synergistic effect on alpha1-AT gene expression. RNA blot analysis showed that HNF-1alpha and HNF-4 mRNA levels and electrophoretic mobility shift assays showed that HNF-1alpha binding activity increase coordinately with alpha1-AT mRNA levels during differentiation of Caco-2 cells. Finally, overexpression of antisense ribozymes for HNF-1alpha in Caco-2 cells resulted in a selective decrease in endogenous alpha1-AT gene expression. Together, these results provide evidence that HNF-1alpha and HNF-4 play a role in the mechanism by which the alpha1-AT gene is upregulated during enterocyte differentiation in the model Caco-2 cell system.

Base Sequence↗
PubMed1999

A regulatory perspective on pharmacokinetic/pharmacodynamic modelling.

We present an integrated summary from statistical and pharmacological perspectives of pharmacokinetic/pharmacodynamic (PK/PD) modelling and its use in drug development and regulation for guiding appropriate dosing. An overview of the technical aspects of PK/PD modelling describes how structural models are constructed and refined using pharmacokinetic and pharmacodynamic principles and how random effects models are used to account for individual differences in desired (and undesired) responses due to patient characteristics. Lastly, we describe applications of PK/PD modelling for the purposes of drug labelling, for resolving a safety concern, and for improving therapeutic monitoring of anaesthetic depth during surgery.

Biometry↗
PubMed1999

Population pharmacokinetics. A regulatory perspective.

The application of population approaches to drug development is recommended in several US Food and Drug Administration (FDA) guidance documents. Population pharmacokinetic (and pharmacodynamic) techniques enable identification of the sources of inter- and intra-individual variability that impinge upon drug safety and efficacy. This article briefly discusses the 2-stage approach to the estimation of population pharmacokinetic parameters, which requires serial multiple measurements on each participant, and comprehensively reviews the nonlinear mixed-effects modelling approach, which can be applied in situations where extensive sampling is not done on all or any of the participants. Certain preliminary information, such as the compartment model used in describing the pharmacokinetics of the drug, is required for a population pharmacokinetic study. The practical design considerations of the location of sampling times, number of samples/participants and the need to sample an individual more than once should be borne in mind. Simulation may be useful for choosing the study design that will best meet study objectives. The objectives of the population pharmacokinetic study can be secondary to the objectives of the primary clinical study (in which case an add-on population pharmacokinetic protocol may be needed) or primary (when a stand-alone protocol is required). Having protocols for population pharmacokinetic studies is an integral part of 'good pharmacometric practice'. Real-time data assembly and analysis permit an ongoing evaluation of site compliance with the study protocol and provide the opportunity to correct violations of study procedures. Adequate policies and procedures should be in place for study blind maintenance. Real-time data assembly creates the opportunity for detecting and correcting errors in concentration-time data, drug administration history and covariate data. Population pharmacokinetic analyses may be undertaken in 3 interwoven steps: exploratory data analysis, model development and model validation (i.e. predictive performance). Documentation for regulatory purposes should include a complete inventory of key runs in the analyses undertaken (with flow diagrams if possible), accompanied by articulation of objectives, assumptions and hypotheses. Use of diagnostic analyses of goodness of fit as evidence of reliability of results is advised. Finally, the use of stability testing or model validation may be warranted to support label claims. The opinions expressed in this article were revised by incorporating comments from various sources and published by the FDA as 'Guidance for Industry: Population Pharmacokinetics' (see the FDA home page http:/(/)www.fda.gov for further information).

Data Interpretation, Statistical↗
PubMed1999

[Cloning and sequencing of variable region genes of HAb25 McAb against hepatocellular carcinoma].

OBJECTIVE: To clone the variable genes of HAb25 McAb against hepatocellular carcinoma. METHODS: The HAb25 variable region genes were isolated by RT-PCR technique from the HAb25 hybridoma, and its nucleic acid sequences were analyzed by the sanger's dideoxy-mediated chain-termination method. RESULTS: The gene of VH was 360 bp long encoding 120 amino acids and the gene of VL was 330 bp long encoding 110 amino acids. Only one open reading frame could be found in each of the variable genes. A comparison of the sequences of VH and VL domatins derived from the HAb25 antibody with those of the published mouse Ig genes in GenBank by computer revealed that the VH gene was homologous to the VH186.2 germline gene family (84.00%) and VL gene was homologous to the MMIgGKAVAG(82.00%). CONCLUSION: Both of the two genes are rearranged variable region genes, which are VHDJH3 for the VH and VK J K4 for the VL.

Amino Acid Sequence↗
PubMed1999

[The influence of nerve growth factor on inferior alveolar nerves regeneration in the silicone tubes].

OBJECTIVE: To explore the effect of exogenous nerve growth factor(NGF) in the regeneration of adult white rabbits inferior alveolar nerve within the silicone tubes. METHODS: In 24 adults white rabbits. A bilateral 8 mm inferior alveolar nerve gaps were created, and the proximal and distal stumps were inserted into a 12 mm silicone tube. The silicone tube of the right side was filled with exogenous NGF(experimental group) and the contralateral side was filled with saline (control group). Regeneration of the nerves was assessed by histological exam and nerve electrophysiological appreciation. Total number of the regenerating myelinated nerve fibers, the conduction velocities of nerves the thickness of myelin sheaths and the cross section area of myelinated nerve fibers between the experimental and the control groups were compared. RESULTS: The results showed that: 1. The experimental groups demonstrated more myelinated nerve fibers than that of the controls in 12 and 18 weeks. 2. At the same time following surgery, the myelin sheath thickness and the cross section area of myelinated nerves in the experimental groups were significantly greater than that in the controls. 3. In 12 and 18 weeks, the conduction velocities of regenerating nerves in the experimental groups were faster than that of the controls. CONCLUSION: This study suggested that exogenous NGF can enhance regeneration of inferior alveolar nerve with necovery of its sensory function.

Animals↗
PubMed1999

[Differentially expressed cDNA sequences homologous with known genes in human nasopharyngeal carcinoma].

In order to search the tumor suppressor genes correlated with pathogenesis of human nasopharyngeal carcinoma(NPC), we applied the PCR-based subtractive hybridization technique of representational difference analysis (RDA) to the primary culture cells of normal human nasopharyngeal epithelial and HNE1, a poorly differentiated NPC cell line. Following four successive subtractions of HNE1 complementary DNA from normal human nasopharyngeal epithelial cells complementary DNA, difference products were cloned into pGEM-T easy vector and nucleotide sequences determined. Comparison of cDNA sequences against the databases identified 9 known genes. Known genes included TRIP1(TGF beta receptor interacting protein), TAF, ezrin, MHC II, actinin, Histone H1 zero, Cytokeratin 13, Squalene Synthetase and RNA Synthetase-like. Some of them have an effective suppressive ability on the tumor. In this study, we have demonstrated that cDNA RDA is an effective strategy for systematically isolating differences in gene expression between two related but functionally distinct cells. Our results also indicated that the NPC includes interaction of multigenes and this experiment offers a new route for NPC research.

Carcinoma, Squamous Cell↗
PubMed1999

[A comparative study of finger plethysmography and aortic pressure for monitoring the effect of external counterpulsation].

Invasive pressure detecting and monitoring of aortic root was conducted in 20 volunteers so as to study the effect of Enhanced External Counterpulsation (EECP) on aortic pressure and finger plethysmography. The results demonstrated that the changes of aortic diastolic pressure linearly related to the counterpusation's bladder pressure, and the aortic augmentation increased to the top of 168.56 mmHg with a D/S ratio of 2.75(amplitude ratio of diastolic waveform and systolic waveform, D/S ratio) following the bladder pressure of 0.45 Kg/cm2. With the increase of bladder pressure, the dp/dt of aortic augmentation elevated gradually, but a down-regulating trend was seen in systolic waveform. During EECP, the starting time of plethysmographic augmentation had a mean delay of 108.20 +/- 25.70 ms comparing with that of aortic augmentation. The duration between the starting time of aortic systolic waveform and that of finger plethysmogram was arround 96.69 +/- 38.70 ms. When the bladder pressure changed, no significant difference was observed among them. The D/S ratio of finger plethysmographic waveform changed in concord with that of aortic pressure with the promotion of bladder pressure. Therefore, a relationship between aortic D/S ratio (Y) and plethysmographic D/S ratio (x) was constructed by the linear regression analysis: Y = 0.376 + 0.457X. It can be concluded that EECP has significant effects on aortic D/S ratio, aortic peak augmentation and its dp/dt value. Finger plethysmography, to date, still plays important roles in monitoring and controlling EECP work safely and effectively.

Adolescent↗