Biomedical subjects

J Hao

Publications and source records attributed to J Hao.

At least 37 records · Page 2Linked to original sources

PubMed2001

Continuous cardiac output monitoring system.

A continuous cardiac output monitoring system has been developed in the laboratory to allow the real-time measurement of the cardiac output. This form of continuous cardiac output measurement allows the doctor to view the beat-to-beat cardiac output and can be employed to measure artery constrictions as well. The sensor comprises a laser Doppler velocimeter and an impedance measurement unit. The laser Doppler velocimeter is capable of measuring bi-directional blood flow within the vessel while the impedance measurement unit determines the cross-sectional area of the vessel. In laboratory tests, it was demonstrated on a heart-lung machine that the product of the two parameters measured is proportional to the actual flow volume of up to 6 lmin(-1) with a mean percentage error of 12.4% and a mean square error of 0.09 (using the lmin(-1) scale) were obtained. This is significantly more accurate than the measurement made using the thermodilution cathether.

Cardiac Output↗

PubMed2001

Investigation into the mechanism of the loss of laminin 5 (alpha3beta3gamma2) expression in prostate cancer.

Laminin 5 is a pivotal hemidesmosomal protein involved in cell stability, migration, and anchoring filament formation. Protein and gene expression of the alpha3, beta3, and gamma2 chains of laminin 5 were investigated in normal and invasive prostate carcinoma using immunohistochemistry, Northern analysis, and in situ hybridization. Laser capture microdissection of normal and carcinomatous glands, in conjunction with RNA amplification and reverse Northern analysis, were used to confirm the gene expression data. Protein and mRNA expression of all three laminin 5 chains were detected in the basal cells of normal glands. In contrast, invasive prostate carcinoma showed a loss of beta3 and gamma2 protein expression with variable expression of alpha3 chains. Despite the loss of protein expression, there was retention of beta3 and gamma2 mRNA expression as detected by in situ hybridization, Northern and reverse Northern analysis. Our findings imply that an altered mechanism of translation of beta3 or gamma2 mRNAs into functional proteins contributes to failure of anchoring filaments and hemidesmosomal formation. The resultant hemidesmosome instability or loss would suggest a less stable epithelial-stromal junction, increased invasion and migration of malignant cells, and disruption of normal integrin signaling pathways.

Carcinoma↗

PubMed2001

Preparation and mechanical properties of nanocomposites of poly(D,L-lactide) with Ca-deficient hydroxyapatite nanocrystals.

Nanocomposites of high molecular poly(D,L-lactide) (PLA) with Ca-deficient hydroxyapatite nanocrystals (d-HAP) were successfully prepared through solvent-cast technique. Such composites are of great importance to make bone-like substitutes as d-HAP nanocrystals have similar composition, morphology and crystal structure as natural apatite crystals. Of all the PLA solvents studied, N,N-dimethylformamide is the best one to disperse d-HAP nanocrystals. The resultant sol is a blue, stable dispersion that could preserve several days with only slight precipitation. The bright-field TEM micrograph shows that d-HAP nanocrystals form homogeneous dispersion in the PLA matrix at a microscopic level. The tensile modulus for PLA/d-HAP nanocomposites increases with d-HAP loading. Theoretical prediction of the modulus has been made by assuming the nanocomposites as short fiber filled systems. The calculated values based on Halpin-Tsai equations show excellent agreement with the experimental results. The yield stress for the nanocomposites has not been undermined by the presence of the nanocrystals. This preservation of strength for PLA/d-HAP nanocomposites may be due to the homogeneous dispersion of d-HAP nanocrystals in the PLA matrix as well as the good interfacial adhesion.

Biomechanical Phenomena↗

PubMed2001

Assessment of vehicular pollution in China.

As the motor vehicle population in China continues to increase at an annual rate of approximately 15%, air pollution related to vehicular emissions has become the focus of attention, especially in large cities. There is an urgent need to identify the severity of this pollution in China. Based on an investigation into vehicle service characteristics, this study used a series of driving cycle tests of in-use Chinese motor vehicles for their emission factors in laboratories, which indicated that CO and HC emission factors are 5-10 times higher, and NOx 2-5 times higher, than levels in developed countries. The MOBILE5 model was adapted to the Chinese situation and used to calculate the emission of pollutants from motor vehicles. Results show that vehicle emission is concentrated in major cities, such as Beijing, Guangzhou, Shanghai, and Tianjin. Motor vehicle emissions contribute a significant proportion of pollutants in those cities, with contribution rates of CO and NOx greater than 80% and 40%, respectively, in Beijing and Guangzhou. Urban air quality is far worse than the national ambient air quality standard. In conclusion, although China has a relatively small number of motor vehicles, most of them are concentrated within metropolitan areas, and their emissions are closely related to urban air pollution problems in large cities.

Air Pollutants↗

PubMed2001

Source contributions to ambient concentrations of CO and NOX in the urban area of Beijing.

An emission inventory based on GIS technology was developed in this study, and used to estimate the spatial distribution of the stationary and mobile sources in the urban area of Beijing. The stationary sources were divided into various types of finer classes depending on different usage, stack height and emission factors. The mobile sources were treated as both line sources and area sources. It was shown that total anthropogenic CO and NOX emissions had reached 1.4 million and 233 thousand tons, respectively, and vehicle sources emissions of CO and NOX accounted for 76.8% and 40.2%, respectively, of the total emissions in 1995. ISCST3, a Gaussian dispersion air quality model, was modified at low wind speed condition, and then used to facilitate the study of source contributions to ambient concentrations of CO and NOX in Beijing. The simulation results showed that emissions from the vehicle sources had contributed 76.5% and 68.4% of the total CO and NOX concentrations in urban atmosphere of Beijing in 1995, and were even higher in the city core (86.3% of the CO and 72.0% of the NOX). Therefore, strategies for CO and NOX pollution control will of necessity need to focus on the vehicle sources.

Air Movements↗

PubMed2001

[Analysis on effect of inspection and maintenance (I/M) program for vehicle emission reduction].

An Inspection and maintenance(I/M) programme aims to ensure that motor vehicle emission control systems are functioning properly throughout the two stage idle test. Based on three factors including data from inspection, standard for inspection and failure rate, the effectiveness of the current I/M program was studied through the cumulative distributions. The disadvantages of the cutpoints, institution settings, management, and supervision was also analyzed. The fundamental law of emission limits was proposed.

Carbon Monoxide↗

PubMed2001

[Biological removal of VOCs emissions].

The designed test conditions were following: vacancy velocity was from 0.7 cm/s to 3.5 cm/s, retention time was from 30 s to 80 s. Column activated carbon was selected as the filler of the reactor and toluene was taken as representative of VOCs. The biodegradation of toluene using biofilter reactor and the influence of concentration, flow and humidity on the toluene removal were investigated and the removal model was set up. The experimental results showed that the biofilter reactor had higher toluene removing ability. The observation of biotic community demonstrated that the microbes consisted of fungi, bacillus and spore bacillus. Of them spore bacillus was dominant.

Biodegradation, Environmental↗

PubMed2001

[A new briquetting method for biomass coal and its influencing factors].

Regarding to the limitation and low economical efficiency of conventional biomass coal briquetter determined by its briquetting method, a new briquetting mechanism using the linkage function of biomass fiber was established. The effect of different coal, briquetting pressure, biomass shape and content, water content on new brequtting mechanism was studied preliminarily. The results showed that the new mechanism was suitable for varied kinds coal and biomass. The briquette mechanical performance was improved as biomass content increased with a reasonable low limitation of about 15%. Pure biomass also could be briquetted. The briquetting pressure which could consolidate the linkage of biomass fiber was no more than 120 MPa. There would be a negative effect at too high pressure. Increasing biomass content and decreasing pressure at certain degree could offset the negative effect of water content significantly, with a permissive limitation over 10% for Datong coal.

Biomass↗

PubMed2001

[Motor vehicle source contributions to air pollutants in Beijing].

Beijing's motor vehicle emission inventory based on GIS technology was developed, and used to estimate the contribution rate of different types of vehicles and different areas of vehicles to the total vehicular emissions in the urban area of Beijing. ISCST3, a gaussian dispersion air quality model, was modified at low wind speed condition, and then used to facilitate the study of the spatial and temporal distribution of CO and NOx concentrations in Beijing. It was shown that vehicle source emissions of CO and NOx accounted for 76.8% and 40.2%, respectively, of the total emissions in 1995. The simulation results also showed that emissions from the vehicle sources had contributed 76.5% and 68.4% of the total CO and NOx concentrations in urban atmosphere of Beijing in 1995, and were even higher at down-town and near the arteries. Therefore, strategies for CO and NOx pollution control will of necessity need to focus on the vehicle sources.

Air Pollutants↗

PubMed2001

Gynecological procedures under gasless laparoscopy.

OBJECTIVE: To evaluate gasless laparoscopy in treating gynecological conditions. METHODS: With Kirschner wire lifting, transversely or longitudinally introduced into abdominal wall subcutaneously, we exposed the operative field and pelvic organs with routine operative instruments under epidural anesthesia. When a dense pelvic adhesion was confronted, we used the temporarily low-pressured pneumolaparoscopy to dissect it. RESULTS: All procedures were carried out without organ injury, hematoma, or other complications. The operative field can be clearly seen with this method. The mean time for appendagectomy was one hour and for laparoscopic assisted vaginal hysterectomy 80 minutes. CONCLUSION: Gasless laparoscopy avoids the complications which occur in the routine laparoscopy such as subcutaneous or mediastinal pneumatoma, hypercarbonemia, air embolism, cardiopulmonary dysfunction. Our lifting method is simple, convenient, time and money saving, as well as more flexible for treating gynecological conditions.

Adult↗

PubMed2001

[The effect of rhIL-11 on hematopoiesis of rhesus monkeys irradiated with 60Co gamma-rays].

OBJECTIVE: To study the therapeutic effect of recombinant human interleukin-11 (rhIL-11) on acute radiation sickness in monkeys. METHODS: rhIL-11 (30, 60, 120 micrograms.kg-1.d-1, s.c., on days 0-13 after TBI) or vehicle was administered to rhesus monkeys irradiated with 3.0 Gy 60Co gamma-rays. RESULTS: The nadirs of platelet count were significantly improved after treatment with rhIL-11. The duration of platelet and leukocyte numbers below 50% of their baseline values was shortened. Erythrocyte recovery was also accelerated. Semi-solid bone marrow cell culture demonstrated that rhIL-11 could stimulate monkey's bone marrow cell to form more CFU-MK, CFU-Mix, CFU-E and BFU-E in vitro, especially at the dose of 60 micrograms.kg-1.d-1. Histopathological observation revealed that bone marrow of the untreated controls showed large area of bleeding whereas that of the rhIL-11 treated monkeys was in active proliferation. CONCLUSION: rhIL-11 can accelerate hematopoietic recovery of monkeys received 3.0 Gy total body gamma-rays irradiation.

Animals↗

PubMed2001

[Diagnosis and treatment of primary trigeminal neurilemmoma].

OBJECTIVE: A series of 51 patients with trigeminal neurillemmoma were analyzed with respect to the clinical manifestations, radiologic features, operative approaches and factors influencing tumor total resection. METHODS: Three different approaches were used to remove the tumors according to the site of tumor growth. Tumors in middle fossa were removed via extended middle fossa approach or extended transpterion approach. Dumbbel tumors on petrosal bone were resected by presigmoid approach. Retrosigmoid approach was used to excise tumors in posterior fossa. RESULTS: Tumors removed completely in 80.0% of patients, 75.0% of the patients had a normal cranial nerve function after operation. Tumors recurred in two patients 2 years after operation. CONCLUSION: The new operative approach increases the complete tumor resection rate.

Adolescent↗

PubMed2001

[Research on transparent apinoid enemator].

Transparent apinoid enemator is made of polymethacrylate material. It is composed of external shell, big cover, small cover, liquor drain tube and suspension belt. Lateral surface of the shell has 100-1500 ml volume mark. Liquor drain tube is made of PVC, its inner diameter is 6 mm. The cover can reduce contamination and maintain liquor temperature. The transparent enemator made by us can overcome the shortcomings of non-transparent enamel enemator which has been used for many years.

Animals↗

PubMed2001

McCune-Albright syndrome: radiological and MR findings.

McCune-Albright syndrome (MAS) is a non-inherited disorder due to the GNAS1 gene mutation. The syndrome is characterized with the triad of polyostotic fibrous dysplasia, pigmented skin lesions, endocrinopathy, and precocious puberty. We report the case of a 14-year-old boy, presenting with sclerotic type of polyostotic fibrous dysplasia. Radiological methods including plain X-ray film, MR and whole body bone scintigraphy suggested the diagnosis of MAS. MRI provided more directly perceived images and it was more sensitive in demonstrating the lesion: its shape, contents, especially the size of the affected region. Histopathological study and the identification of mutant gene finally confirmed the diagnostic result.

Adolescent↗

PubMed2000

Chiral Palladium(II)-catalyzed asymmetric glyoxylate-Ene reaction: alternative approach to the enantioselective synthesis of alpha-hydroxy esters

An effective chiral palladium catalyst [Pd(CH(3)CN)(2)(S)-Tol-BINAP](SbF(6))(2) (2b) is developed for asymmetric glyoxylate-ene reactions. This palladium dicationic catalyst provides a simple but efficient approach to the asymmetric synthesis of alpha-hydroxy esters in excellent yields with high enantioselectivities at relatively higher reaction temperature (60 degrees C).

Journal Article↗

PubMed2000

Intracerebroventricular infusion of nerve growth factor induces pain-like response in rats.

New strategies have recently been developed where infusion of neurotrophic factors into the brain can rescue different neuronal populations. However, negative side effects have been observed in clinical trials infusing nerve growth factor (NGF) into the lateral ventricle in man, namely pain. Little is known about pain behavior in animals after intracerebroventricular (i.c.v.) neurotrophic injections. Thus, we have examined the effects of i.c.v. infusion of NGF for 2 weeks on the behavioral response of rats to mechanical, cold and heat stimulation. Seven micrograms/day of NGF elicited a significant decrease in vocalization threshold to mechanical stimulation and a significantly increased response to cold and heat stimuli as compared with control. The concentration of NGF in cerebrospinal fluid (CSF) was significantly increased as compared with non-allodynic rats. The enhanced responses to mechanical and heat, but not to cold, stimulation were significantly reduced by CP-99994, a selective antagonist to tachykinin NK-1 receptors. When NGF was infused into the brain parenchyma (striatum, cortex and septum) no allodynic nor hyperalgesic responses could be detected. These results indicate that in rats i.c.v. but not intraparenchymal infusion of NGF induce mechanical and cold allodynia as well as heat hyperalgesia, which is mediated, at least in part, by activation of NK-1 receptors.

Animals↗

PubMed2000

Electric-field-induced soft-mode hardening in SrTiO3 films

We have studied electric-field-induced Raman scattering in SrTiO3 thin films using an indium-tin-oxide/SrTiO3/SrRuO3 structure grown by pulsed laser deposition. The soft mode polarized along the field becomes Raman active. Experimental data for electric-field-induced hardening of the soft modes and the tuning of the static dielectric constant are in agreement described by the Lyddane-Sachs-Teller formalism. The markedly different behavior of the soft modes in thin films from that in the bulk is explained by the existence of local polar regions.

Journal Article↗

PubMed2000

Soft-mode hardening in SrTiO3 thin films

Understanding the behaviour of the dielectric constant in ferroelectric thin films remains a challenging problem. These ferroelectric materials have high static dielectric constants, and so are important for their applications in high-storage-density capacitor structures such as dynamic random access memory (DRAM). But the dielectric constant tends to be significantly reduced in thin films, thereby limiting the potential benefit of ferroelectrics for memory devices. Extensive studies have shown that this phenomenon could be caused by a 'dead layer' of very low dielectric constant between the ferroeletric film and the electrode. And, although very few direct measurements are in fact available, it has been recognized that the lattice dynamical properties in the thin films should also play a key role in the reduction of the dielectric constant. Here we report far-infrared ellipsometry and low-frequency dielectric measurements in SrTiO3 thin films, which demonstrate that the Lyddane-Sachs-Teller relation between the optical-phonon eigenfrequencies and the dielectric constant is fully maintained, as is the case in the bulk material. This indicates that the dramatic reduction of the dielectric constant is a consequence of a profound change of the lattice dynamical properties, in particular of the reduced softening of its lowest optical-phonon mode. Our results therefore provide a better understanding of the fundamental limitations of the dielectric constant values in ferroelectric thin films.

Journal Article↗