Search PubMed⌕ Search

Biomedical subjects

H Wen

Publications and source records attributed to H Wen.

At least 55 records · Page 3Linked to original sources
PubMed1999

Volumetric Hall effect tomography--a feasibility study.

Hall effect imaging is an ultrasound-based method of mapping spatial variations in the dielectric constants of an acoustically-uniform sample. This paper presents three-dimensional Hall effect images of phantoms obtained by scanning a single transducer across a two-dimensional grid, effectively simulating two-dimensional phased-array signal reception. The experiments demonstrate the feasibility of volumetric Hall effect tomography and show the advantage of volumetric scans over planar scans. The images reflect several limitations of the current scanning method and point to directions for further hardware development. The inherent limitations of Hall effect imaging are also discussed in light of these results.

Algorithms↗
PubMed1999

Urinary excretion of aquaporin-2 in rat is mediated by a vasopressin-dependent apical pathway.

Clinical studies have shown that aquaporin-2 (AQP2), the vasopressin-regulated water channel, is excreted in the urine, and that the excretion increases in response to vasopressin. However, the cellular mechanisms involved in AQP2 excretion are unknown, and it is unknown whether the excretion correlates with AQP2 levels in kidney or levels in the apical plasma membrane. The present study was undertaken to clarify these issues. Immunoblotting of rat urine samples revealed significant excretion of AQP2, whereas AQP3, being a basolateral aquaporin in the same cells, was undetectable. Thus, there was a nonproportional excretion of AQP2 and AQP3 (compared with kidney levels), indicating that AQP2 is excreted predominantly via a selective apical pathway and not by whole cell shedding. Urinary AQP2 was associated with small vesicles, membrane fragments, and multivesicular bodies as determined by immunoelectron microscopy and negative staining techniques. In rats with normal water supply, daily urinary excretion of AQP2 was 3.9+/-0.9% (n = 6) of total kidney expression. Treatment with desmopressin acetate subcutaneously caused a fourfold increase in urinary excretion of AQP2 during 8 h. Forty-eight hours of thirsting, known to increase endogenous vasopressin secretion, resulted in a three-fold increase in kidney AQP2 levels but urinary excretion increased ninefold to 15+/-3% (n = 6) of AQP2 in kidney of thirsted rats. Moreover, rats that were thirsted for 48 h and subsequently allowed free access to water for 24 h produced a decrease in urinary AQP2 excretion to 38+/-15% (n = 6) of that during thirsting. In Brattleboro rats or lithium-treated normal rats completely lacking vasopressin action, and hence having extremely low levels of AQP2 in the apical plasma membrane, AQP2 was undetectable in urine. Thus, conditions with known altered vasopressin levels and altered levels of AQP2 in the apical plasma membrane were associated with corresponding major changes in AQP2 urine excretion. In contrast, in such conditions, kidney AQP2 levels and urinary AQP2 excretion did not show a proportional relationship.

Animals↗
PubMed1999

[Renal protective effect of valsartan in diabetic rats].

OBJECTIVE: To investigate the mechanism of valsartan in protecting the renal lesion of diabetic rats. METHODS: The following groups of rats were studied: normal control rats, streptozotocin diabetic rats and diabetic rats treated with valsartan (8 mg x kg(-1) x d(-1)). Mean arterial pressure, plasma glucose, serum insulin, serum creatinine, urinary albumin, ACE activity and Ang II concentration of kidney as well as profile of kidney hypertrophy were observed after 2, 4, 8 weeks of treatment, while TGF beta(1) mRNA expression of kidney cortex was assessed by Northern blot analysis, TGF beta(1), fibronectin and collagen IV expression were measured by immunohistochemistry. RESULTS: Serum creatinine level (P < 0.05), urinary albumin excretion and kidney hypertrophy index (P < 0.01) of valsartan treated group were significantly lower than those of diabetic untreated group. There was a significant increase in mRNA expression of TGF beta(1) and protein expression of of TGF beta(1) fibronectin and collagen IV in diabetic rats (P < 0.01). The expression of TGF beta(1) mRNA and protein (P < 0.01) as well as the protein expression of fibronectin and collagen IV (P < 0.05) in the valsartan group were much lower than that in the diabetic group. CONCLUSION: The results suggested that valsartan has some renal protective effect on diabetes in rats, partly through down-regulating TGF beta(1) expression and reducing deposition of glomerular ECM.

Animals↗
PubMed1999

[Intermittent-pulse treatment of onychomycosis with orally administered itraconazole].

Fifty-four patients received an intermittent regimen of itraconazole (26 of them were finger onychomycosis and 28 toe onychomycosis) and were followed-up for nine months. The result showed that the clinical cure rate of fingernails was 88.5% and the mycologic cure rate was 96.4%, while the clinical cure rate of toes was 82.1% and the mycologic cure rate was 96.4%. Few adverse events were observed by 7.4%, just like nausea, gastric discomfort etc. It suggests that the pulse administration system is highly effective and has a few side-effects.

Adolescent↗
PubMed1999

[Study on regulators of the cell cycle in cutaneous squamous cell carcinoma].

In order to investigate the relationship between the regulators of cell cycle and cutaneous squamous cell carcinoma(SCC), we used an immunohistochemical staining technique to examine the expression of cyclin D1, p16 and Rb in the paraffin embedded skin cancer tissues of 30 patients with SCC. The positive percentage of cyclin D1, CDK4, p16 and Rb was 66.7%, 53.3%, 33.3%, and 36.7%, respectively. The overexpression of cyclin D1 and CDK4 could be observed frequently in low grade of differentiated cells, especially in marginal cells of the cancer nest. The results indicate that the aberrant expression of positive and negative regulators of the cell cycle may be involved in the carcinogenesis and evolution of SCC.

Carcinoma, Squamous Cell↗
PubMed1999

[Evaluation of diagnostic value of 18 kDa antigen in alveolar echinococcosis].

AIM: To evaluate the 18 kDa antigen in diagnosis of human alveolar echinococcosis. METHODS: A total of 214 sera from patients with alveolar echinococcosis (AE, 33), cystic echinococcosis (CE, 69), cysticercosis (30) and healthy controls (82) were examined by Western blotting to detect the antibodies against 18 kDa antigen using both antigens from protoscoleces of E. granulosus (Eg) and E. multilocularis (Em). All the sera were tested simultaneously by ELISA to detect the antibodies against hydatid cystic fluid antigens of sheep as a comparison. RESULTS: The positive rate by ELISA was 93.9% in AE, 85.5% in CE, 50% in cysticercosis and 6.1% in healthy controls, respectively, suggesting a critical cross-reaction and a certain degree of nonspecific reaction. The serum positive rates by Western blotting with the 18 kDa antigen of Eg and Em were 90.9% and 90.9% in AE, 10.1% and 13% in CE, 13.3% and 16.7% in cysticercosis, respectively. No positive was found in the sera from healthy controls. CONCLUSION: The 18 kDa antigen may be used in the differential diagnosis of AE from CE.

Antigens, Helminth↗
PubMed1999

[Effect of liposomal albendazole on the ultrastructure of Echinococcus granulosus cysts in mice].

AIM: To observe the histopathological changes of Echinococcus granulosus cysts in mice treated with liposomal albendazole and co-administration with cimetidine by light microscopy and electron microscopy. METHODS: An oral dose of liposomal ABZ with different formulations was given at 200 mg/kg.d. Cimetidine was administered daily at an oral dose of 100 mg/kg.d. Sixty-seven mice were orally given different drugs six days per week for a total of twelve weeks. RESULTS: The histopathological changes indicated that there were significant differences (P < 0.01) between treated groups and control group. The degeneration and necrosis of E. granulosus cysts were marked in liposomal albendazole combined with cimetidin group. CONCLUSION: Liposomal albendazole was more effective against E. granulosus cyst than albendazole. Cimetidine had an apparent synergistic effect when given in combination with liposomal albendazle.

Albendazole↗
PubMed1998

Hall effect imaging.

This paper presents a new imaging method based on the classical Hall effect (HE), which describes the origin of a detectable voltage from a conductive object moving in a magnetic field. HE images are formed using ultrasound imaging techniques in a magnetic field. These images reflect the electrical properties of the sample. To demonstrate the feasibility of this method, images of plastic and biological samples are collected. The contrast mechanism and signal-to-noise issues are discussed. Since electrical parameters vary widely among tissue types and pathological states, HE imaging may be a useful tool for biological research and medical diagnosis.

Adipose Tissue↗
PubMed1998

High-sensitivity fiber-optic ultrasound sensors for medical imaging applications.

This paper presents several designs of high-sensitivity, compact fiber-optic ultrasound sensors that may be used for medical imaging applications. These sensors translate ultrasonic pulses into strains in single-mode optical fibers, which are measured with fiber-based laser interferometers at high precision. The sensors are simpler and less expensive to make than piezoelectric sensors, and are not susceptible to electromagnetic interference. It is possible to make focal sensors with these designs, and several schemes are discussed. Because of the minimum blending radius of optical fibers, the designs are suitable for single element sensors rather than for arrays.

Equipment Design↗
PubMed1998

Shielding of piezoelectric ultrasonic probes in Hall effect imaging.

This paper addresses significant sources of electromagnetic noise in Hall effect imaging. Hall effect imaging employs large electrical pulses for signal generation and high sensitivity ultrasonic probes for signal reception. Coherent noise arises through various coupling mechanisms between the excitation pulse and the probe. In this paper, the coupling mechanisms are experimentally isolated and theoretically analyzed. Several methods of shielding the probe from electromagnetic interference are devised and tested. These methods are able to reduce the noise to levels below the random thermal noise, thereby improving the signal-to-noise ratio in HEI by two orders of magnitude.

Algorithms↗
PubMed1998

Ultrasonic imaging of the electroacoustic effect in macromolecular gels.

The electroacoustic effect occurs in electrolytes and colloidal suspensions. It describes the phenomenon in which a voltage applied to the sample produces an acoustic signal or vice versa. The basic mechanism is that charged particles in the sample have various mobilities due to different masses and viscosities. Under an external voltage they respond differently to the electrical force. This results in an overall acoustic vibration. The electroacoustic effect has been the basis for many measurement tools of solutions and other materials. In this note a method to image macromolecular gel samples using the electroacoustic effect at ultrasound frequencies is presented. Radiofrequency electrical excitation produces ultrasonic signal due to spatial changes in the electroacoustic some amplitude of the sample, which is used to construct an image similar to ultrasonography. This method is demonstrated in agar gel and egg-white protein phantoms. The image contrast mechanism is also discussed.

Gels↗
PubMed1998

The potential for Hall effect breast imaging.

Hall effect imaging is a noninvasive imaging method that combines ultrasound with a strong magnetic field to investigate the electrical properties of tissue. Although technical development is at an early stage, its value for detecting or characterizing pathologies in the breast and other organs is promising. In vitro studies in the past showed that tissue electrical properties are closely related to its physiology and morphology. Hall effect imaging may become a new tool to study these electrical properties in the body and potentially provide unique diagnostic information.

Journal Article↗
PubMed1998

Human cystic echinococcosis in a Uruguayan community: a sonographic, serologic, and epidemiologic study.

A prevalence and transmission study of human cystic echinococcosis (CE), due to infection with the dog tapeworm Echinococcus granulosus, was undertaken in the village of La Paloma in central Uruguay. The human population was registered and screened for CE by abdominal ultrasound scan as well as a number of serologic tests. Dogs were screened for E. granulosus infection by arecoline purgation as well as specific coproantigen testing. The total prevalence of human CE (new cases and those with a previous history) was 5.6% (64 of 1,149); 3.6% (40) of the cases were new ultrasound detected asymptomatic cases (mean age = 45 years). Age prevalence increased from 1.1% in the 4-6-year-old group to > 11% in the > 60-year-old group; the 20-29-year-old group had a significantly higher CE rate of 7.4%, compared with younger and older age groups, and there was no difference between sexes. A CE rate of 3.9% (20 of 514) was also recorded by ultrasound for new cases in the population residing outside the village. Most of the hydatid cysts were located in the liver presenting as either univesicular cysts or a solid mass, and of those 71% and 63%, respectively, with such cyst presentations were seropositive against E. granulosus cyst fluid antigens. Two of eight individuals who were filter paper blood spot seropositive, but ultrasound scan negative, were subsequently diagnosed respectively with pulmonary hydatidosis after radiography, and hepatic hydatidosis after computed tomography scan. Of 36 households with a CE patient, 32 were single cases while four households each harbored two CE cases. This did not represent a clustered distribution within families (23 of 117). Almost 20% of the dogs from La Paloma were found infected with E. granulosus after purge examination, with a mean worm number of 67 (range = 1-1,020). An additional eight dogs that were purge negative were Echinococcus coproantigen positive. The study showed that human CE is highly endemic in Uruguay, with one of the highest local prevalence rates in the world. Transmission appears to occur readily within well-developed towns, as well as on rural sheep ranches. Mass screening by ultrasound scanning with confirmatory serologic testing is an effective approach to case detection at the community level.

Adolescent↗
PubMed1998

[Effect of ginger-processing on the contents of guanosine in Pinelliae rhizoma (banxia)].

OBJECTIVE: To compare the guanosine contents in various products of Pinellia Rhizoma processed by different amounts of ginger and alum. METHOD: Using the technology of HPLC. RESULT: The guanosine contents in the two products of Pinellia Rhizoma processed in line with the pharmacopoeial method and orthogonal method respectively are very close to each other and change every little as compared with raw Pinellia Rhizoma. But the contents in the products of Pinelliae Rhizoma processed in other ways (digged in alum solution or in ginger Juice decocted with ginger juice, etc.) are much less than those of raw Pinellia Rhizoma. CONCLUSION: There are no obvious differences in guanosine contents between Pinellia Rhizoma processed by orthogonal technology and Pinellia Rhizoma processed by pharmacopoeial method. Processing technology has considerable influence on the water soluble components of Pinellia Phizoma.

Chromatography, High Pressure Liquid↗
PubMed1997

Public health importance of cystic echinococcosis in China.

Cystic echinococcosis has been recorded in 21 out of China's 31 provinces, autonomous regions and municipalities (approximately 87% of territory). It constitutes one of the major public health problems, especially in several northwestern provinces and autonomous regions. This paper reviews the general situation, diagnosis, treatment, education and control programmes and international cooperation. Special attention is given to the Xinjiang, an endemic area about one sixth of the country's area with a human population of approximately 16 million.

China↗