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Biomedical subjects

H Wen

Publications and source records attributed to H Wen.

At least 91 records · Page 5Linked to original sources
PubMed1996

[Mutations of p53 gene exons 5 to 8 in human ovarian cancer and its clinical significance].

OBJECTIVES: To detect p53 mutations in human ovarian cancer and to look for correlations between p53 mutation and clinicopathologic features. METHODS: Mutations in exons 5-8 of p53 gene in 41 patients with primary ovarian cancer were screened by polymerase chain reaction-single strand conformation polymorphism analysis with non-isotopic silver staining method. RESULTS: Mutations of p53 were found in 17 cases (41.5%); p53 mutation was not correlated with the age, the FIGO stage and the histologic type of the patients. However, it was associated with grade and lymph node metastasis in a univariate analysis. CONCLUSION: Mutations of p53 occur commonly in human ovarian cancer. p53 mutation is an early event in ovarian carcinogenesis and may serve as a genetic marker for early diagnosis and prognosis.

Adolescent↗
PubMed1995

An in vivo automated shimming method taking into account shim current constraints.

Many in vivo imaging techniques require magnetic field homogeneity in the volume of interest. Shim coils of the second and third order spherical harmonics have been used successfully to compensate for complicated field variations caused by the human anatomy itself. The available currents of these coils are invariably limited. In this note we demonstrate that these limits significantly affect the optimal shim condition. We propose an automated in vivo shimming method for arbitrary volumes of interest using 3-dimensional (3D) field maps. This method is a modification of previous works using least-squares criteria. The main difference is that a constrained optimization is performed in vivo under the current limits of the shim coils, which improved the field homogeneity significantly over simple truncations of the least-squares solutions. This shimming method was used with head scans of five normal volunteers on a 4.0 tesla scanner. A fast double-echo sequence was used to obtain field maps, and a new field uniformity measure was derived for this method. The field mapping sequence was tested against a standard single-echo Dixon sequence used by previous investigators, and the stability of the shimming method was tested by repeated studies on the same subject.

Algorithms↗
PubMed1995

Binaural noise suppresses linear click-evoked otoacoustic emissions more than ipsilateral or contralateral noise.

We studied the efferent suppression of click-evoked otoacoustic emissions with 65 dB SPL of white noise presented to left, right, or sometimes both, ears for 408 ms. Each burst of noise preceded a series of four unipolar 80 microseconds 65 dB peak Sound Pressure clicks, presented to the left ear only. The first click of the four-click group followed the end of the noise by either 1, 2, 5, 10, 20, 50, 100 or 200 ms; each subsequent click was offset by 20 additional ms via an ILO88 system with special programming modifications. Conditions were alternated so that a 'without noise' condition preceded a 'with noise' condition for three repetitions of 600 clicks per trial. Seven subjects with normal hearing participated in the study, and three of the seven participated in a test-retest reliability study. Results showed the greatest suppression followed binaural stimulation ending within one to five ms of the first click in the pulse train. Somewhat less suppression was seen following ipsilateral stimulation. The least amount of suppression was seen following contralateral stimulation, suggesting that previous research using contralateral stimulation may underestimate efferent effects. We saw no effects when the end of the noise was 100 ms or more away from the beginning of the click train.

Acoustic Stimulation↗
PubMed1995

Immunoblot evaluation of IgG and IgG-subclass antibody responses for immunodiagnosis of human alveolar echinococcosis.

Antigen binding of total-IgG and IgG-subclass antibodies from patients with alveolar or cystic echinococcosis (AE and CE) was assessed by immunoblotting. Antigen extracts were prepared from Echinococcus multilocularis protoscoleces (EmP) or from homogenized E. multilocularis metacestode tissue (EmCH). Antigens of approximately 44, 35, 21, 17.5 and 16.5 were recognized by total-IgG and IgG1- and IgG4-subclass antibodies in some of 50 human AE sera from China, Japan or France. The 44- and 35-kDa polypeptides, present in both EmP and EmCH extracts, were recognized by total-IgG antibodies in sera from 82% and 66% of the AE patients, respectively. However, over 30% cross-reactivity occurred between these two antigens and sera from CE and Taenia solium cysticercosis patients. The immunoblot specificities of the 27-, 21- and 17.5-kDa antigens in EmP for E. multilocularis infection were 73%, 88% and 93%, respectively. Recognition of the 17.5-kDa antigen in the EmP immunoblot was much higher for the Japanese AE cases (11/13; 85%) than for the French (9/19; 47%) or Chinese (9/18; 50%) AE cases. None of the CE cases from Uruguay or Libya, where human AE has not been reported, was seropositive for the 17.5-kDa antigen. Antibodies from three (7.3%) of the 41 Chinese CE cases recognized the 17.5-kDa antigen. Within the 13 Japanese AE sera, the combined detection by IgG1, IgG4 and total-IgG antibodies of the 27-, 21- and 17.5-kDa antigens in either EmP or EmCH immunoblots was greater than that by each class/subclass alone, increasing the overall sensitivity for AE patients. A combined ELISA/immunoblot approach, including IgG-subclass detection using E. multilocularis protocolex or cyst extracts, could be useful for the differential diagnosis of human alveolar echinococcosis. An algorithm for such an approach is given.

Algorithms↗
PubMed1995

Musculoskeletal MR imaging at 4 T and at 1.5 T: comparison of relaxation times and image contrast.

PURPOSE: To evaluate the relaxation time-based contrast between the main tissues of the musculoskeletal system as measured in the human knee with magnetic resonance imaging at 4 T and 1.5 T. MATERIALS AND METHODS: Five volunteers underwent 4-T and 1.5-T imaging. Inversion-recovery series were used to measure T1 values, and T2 values were measured with a spin-echo sequence. RESULTS: T1 values increased in all tissues with 4-T imaging. Values increased in muscle from 1 to 1.8 seconds, in fat from 0.3 to 0.4 seconds, and in cartilage from 0.8 to 1.5 seconds. T2 values were 10%-20% shorter in all tissues at 4 T. CONCLUSION: Advantages of 4-T imaging compared with 1.5-T imaging include a higher signal-to-noise ratio and an improved signal difference-to-noise ratio. However, any improvement in signal-to-noise ratio at high field strengths can partially be reduced by the increase in the T1 value. The slightly shorter T2 values at 4 T do not affect image contrast.

Cartilage, Articular↗
PubMed1995

[Clinical study on treatment of male infertility with shengjing pill].

202 cases of male infertility were treated with Shengjing Pill. After treatment, quantity and quality of sperm were significantly improved (P < 0.001), levels of follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone (T) were enhanced to normal in 96 patients (P < 0.001), levels of anti-sperm-antibody was reduced to normal in 45 cases (P < 0.001), of 148 follow-ups. Their 116 spouses became pregnant and have borne 108 well-developed babies.

Adult↗
PubMed1995

[Diagnosis and treatment of postmenopausal uterine bleeding by hysteroscopy].

OBJECTIVES: To evaluate the value of hysteroscopy in diagnosis and treatment of patients with postmenopausal uterine bleeding. METHODS: One hundred and thirty-five patients with postmenopausal bleeding hospitalized in our department from July 1990 to July 1994 were examined by hysteroscopy. The results of 124 cases were compared with pathological findings obtained during uterine curettage. Thirty-nine patients were operated simultaneously under hysteroscopy. RESULTS: Under hysteroscopy, atrophic endometrium, endometrial polyps, cervical polyps, endometrial carcinoma, endometrial hyperplasia, submucous myoma were diagnosed in 62 cases (45.9%), 25 cases (18.5%), 13 cases (9.6%), 13 cases (9.6%), 11 cases (8.2%) and 5 cases (3.7%) respectively. The remaining 6 (4.5%) had IUD insertion. These findings were confirmed pathologically in 115 out of 124 cases (92.7%). There were 9 cases misdiagnosed by hysteroscopy. 6 cases had false negative results during previous curettage. Twenty-two cases of endometrial polyps, 13 cases of cervical polyps and 4 cases of pediculated submucous myoma were removed hysteroscopically without any complication. CONCLUSIONS: Hysteroscopy is an effective method for identifying the causes of postmenopausal uterine bleeding, which is superior to curettage of uterus. For some selected patients hysteroscopic operations can be performed at the same time.

Aged↗
PubMed1994

The design and test of a new volume coil for high field imaging.

A major problem in the development of high field (> 100 MHz) large volume (> 6000 cm3) MR coils is the interaction of the coil with the subject as well as the radiation loss to the environment. To reduce subject perturbation of the coil resonance modes, a volume coil that uses an array of freely rotating resonant elements radially mounted between two concentric cylinders was designed for operation at 170 MHz. Substantial electromagnetic energy is stored in the resonant elements outside the sample region without compromising the efficiency of the overall coil. This stored energy reduces the effect of the subject on the circuit and maintains a high Q, facilitating the tuning and matching of the coil. The unloaded Q of the coil is 680; when loaded with a head, it was 129. The ratio of 5.3 of the unloaded to loaded Q supports the notion that the efficiency of the coil was maintained in comparison with previous designs. The power requirement and signal-to-noise performance are significantly improved. The coil is tuned by a mechanism that imparts the same degree of rotation on all of the elements simultaneously, varying their degree of mutual coupling and preserving the overall coil symmetry. A thin radiofrequency shield is an integral part of the coil to reduce the radiation effect, which is a significant loss mechanism at high fields. MR images were collected at 4T using this coil design with high sensitivity and B1 homogeneity.

Equipment Design↗
PubMed1994

Comparison of EPI gradient-echo contrast changes in cat brain caused by respiratory challenges with direct simultaneous evaluation of cerebral oxygenation via a cranial window.

A gradient-echo echo planar imaging (EPI) sequence has been used to generate images of cat brain during respiratory challenges. Direct spectrophotometric measurements have been made simultaneously in order to correlate the changes in oxygen saturation as measured by spectrophotometry with the image intensity changes seen in the gradient-echo images. When blood volume remains approximately constant, as derived from the spectrophotometry data, good correlation is seen between calculated plots made of changes in the transverse relaxation rate, delta R2*, and the oxygen saturation as measured by spectrophotometry for much of the time course of the respiratory challenges of anoxia, apnea and hypercapnia. In some cases, the correlation is poorer during the recovery periods of the apnea and anoxia challenges. Those lower correlations can often be accounted for by changes in blood volume, which also affects the NMR relaxation rate. These results contribute to the understanding of the image intensity changes seen during functional brain imaging studies in humans.

Animals↗
PubMed1994

Initial observation on albendazole in combination with cimetidine for the treatment of human cystic echinococcosis.

Concentrations of albendazole were measured, by high-pressure liquid chromatography, in 19 patients being treated for cystic echinococcosis. All of the patients were given three 4-week courses of albendazole (20 mg/kg/day), separated by 10-day-long drug-free intervals. Seven patients also received three courses of cimetidine (10 mg/kg/day). Concentrations of albendazole sulphoxide (ABZSX) were significantly higher in samples of bile and hydatid cyst fluid from the patients receiving albendazole and cimetidine than in those from patients receiving albendazole alone (P < 0.05). The therapeutic benefit of the combined drug treatment, which was well-tolerated, was more than that with albendazole alone.

Albendazole↗
PubMed1994

The First Jerger Lecture. Contralateral suppression of otoacoustic emissions: an index of the function of the medial olivocochlear system.

We can now distinguish, in part, between nerve deafness and hair cell deafness through the use of otoacoustic emissions. We can also assess the efferent system by carefully quantifying the effects of contralateral stimulation on these same otoacoustic emissions. The suppression of transient evoked emissions by continuous contralateral white noise is an ostensibly small effect of 2 or 3 dB when studied over a 20-msec window. However, when subjected to microstructural analysis, the effect can exceed 6 to 8 dB in the zones from 10 to 20 msec after the stimulus has subsided. Temporal and spectral analyses reveal robust effects of contralateral lateral stimulation, although in any given normal subject it may be difficult to separate middle ear effects from efferent effects. Evidence is strong that the efferent effect is mediated in part by cholinergic-primarily nicotinic-receptors in the outer hair cell. However, a unique type of patient, who shows nearly normal pure-tone audiograms and absent ABRs, shows virtually no contralateral suppression of transient evoked emissions. Some other patients, with symptoms of Charcot-Marie-Tooth disease, may paradoxically show extremely poor audiograms, but perfectly normal evoked emissions along with absent contralateral suppression. The ABR, along with middle ear muscle reflexes and masking level differences, are all absent in these patients; we therefore think they have a disorder that desynchronizes most of their primary auditory nerve fibers and thereby disconnects them from any efferent activity or masking cancellation. The existence of such an auditory disorder, characterized by severe dysfunction in speech comprehension-especially when listening in noise-suggests that what appears to be a "central auditory imperception" might stem instead from a systemic peripheral primary neuropathy.

Adolescent↗
PubMed1994

Immunoglobulin G subclass responses in human cystic and alveolar echinococcosis.

Immunoglobulin G (IgG) subclass-specific antibody responses were investigated in both human cystic echinococcosis (CE) and alveolar echinococcosis (AE) by enzyme-linked immunosorbent assay (ELISA) and Western blotting. Sera were tested from 81 CE and 50 AE surgically confirmed cases using partially purified hydatid cyst fluid antigen B (EgB), and crude hydatid cyst fluid (EgCF) from Echinococcus granulosus and a protoscolex extract (EmP) prepared from E. multilocularis metacestodes. Eighty-nine percent of CE patients and 94% of AE patients were seropositive for total IgG antibodies. The dominant IgG antibody isotype in both CE and AE was IgG4, for which 73% of CE and 84% of AE cases were seropositive in the ELISA. Anti-Echinococcus IgG1 antibodies were detected in 58% of CE and 84% of AE patients. Sensitivity for IgG2 and IgG3 was significantly lower for both CE and AE patients. The IgG4 antibodies in CE patients predominantly recognized the E. granulosus antigen B subunits, i.e., at 20, 16 and 12 kD, while IgG1 antibodies primarily bound to the 38-kD subunit of antigen 5 from E. granulosus hydatid fluid. The possible functional significance of an IgG4 response and the potential use of combined assessment of total IgG, IgG1, and IgG4 antibodies in serologic diagnosis and follow-up for human echinococcosis are discussed.

Animals↗
PubMed1993

Functional mapping of the human visual cortex at 4 and 1.5 tesla using deoxygenation contrast EPI.

The effects of photic stimulation on the visual cortex of human brain were studied by means of gradient-echo echo-planar imaging (EPI). Whole-body 4 and 1.5 T MRI systems, equipped with a small z axis head gradient coil, were used. Variations of image intensity of up to 28% at 4 T, and up to 7% at 1.5 T, were observed in primary visual cortex, corresponding to an increase of blood oxygenation in regions of increased neural activity. The larger effects at 4 T are due to the increased importance of the susceptibility difference between deoxygenated and oxygenated blood at high fields.

Adult↗
PubMed1993

Contralateral suppression of non-linear click-evoked otoacoustic emissions.

Click-evoked otoacoustic emissions from nominal 80 dB pSP (peak sound pressure) 80-microseconds pulses presented at 50 pulses per second were collected from the right ears of eleven normal hearing subjects using an ILO88 Otodynamic Analyzer in the non-linear mode. Clicks, pure tones, and narrow bands of noise were then presented to their left ears through insert earphones. The 80-microseconds contralateral clicks ranged in intensity from 80 dB pSP in 5 dB steps down to 60 dB pSP but data on only 10 of the subjects were collected successfully. The pure tones and narrow bands of noise centered at 250, 500, 1000, 2000, and 4000 Hz were also presented through insert phones at 20, 40, 60 and 80 dB HL (Hearing Level) to all 11 subjects. The mean overall 'echo amplitude' without contralateral stimuli was 11 dB SPL and underwent more than 3 dB of overall suppression in response to the noises which were the most effective of the contralateral suppressors. When we analyzed the echo suppression to noise in 2-ms segments, we found consistent contralateral suppression of 3-4 dB concentrated in the time zones after 8 ms. Time shifts of more than 200 microseconds between the control and experimental traces were also observed in the same zones. The clicks were the next most effective suppressors, but showed their amplitude and time effects in somewhat earlier time zones. The tones were the least effective suppressors suggesting that efferent effects we measured in the human system are not strongly tonotopic. Because 'non-linear' mode high intensity clicks were deliberately selected as stimuli to evoke the TEOAE's, the emissions and their suppression can represent neither the 'true' TEOAE nor all of the efferent system's suppression abilities.

Acoustic Stimulation↗
PubMed1992

Coproantigen detection for immunodiagnosis of echinococcosis and taeniasis in dogs and humans.

Three ELISA assays, based on hyperimmune rabbit serum raised against adult cestode somatic antigen, were applied in this study for the detection of Taenia- and Echinococcus-specific antigens in host faeces. The first assay, using an antiserum against Taenia pisiformis antigen extract, was used in a time-course of T. pisiformis experimental infection in dogs. The assay was shown to be considerably more sensitive than microscopical detection of eggs in faeces. Antigen was present in faeces before patency and antigen levels were independent of T. pisiformis egg output. The second assay, involving a test for human taeniasis based on antibodies against T. solium, was applied in two field studies carried out in China and Guatemala. The test was highly specific, no false positive reactions occurred with human faecal samples and the test was capable of diagnosing individuals who would not have been detected by coproscopy or treatment to recover the tapeworm. A third assay was designed for E. granulosus and demonstrated 87.5% sensitivity and 96.5% specificity with samples from naturally and experimentally infected dogs with Echinococcus or Taenia infections. In both the human Taenia and canine Echinococcus studies antigen could be detected in faecal samples from infected hosts stored in 5% formalin for 6 months. Further refinements to these tests for field application are discussed.

Animals↗