Biomedical subjects
Publications and source records attributed to H Yan.
During a 28-year period, 110 patients with small cell lung cancer were treated at our hospital. Fifty-nine patients received surgery, and 58 patients (including 7 cases after exploratory thoracotomy) received chemotherapy and/or radiotherapy. The 5-year survival rate of the surgically treated group was 17%, while none in the non-surgical group survived for more than 5 years.
Studies of 82 skin specimens from 81 cases of lichen sclerosus et atrophicus (LSA) are reported. Typical LSA pathological changes showed atrophy of the epidermis, hydropic degeneration at the basal layer, and homogenization of the collagen fibers in the superficial dermis with inflammatory cell infiltration underneath. Ultrastructural changes showed intercellular spaces enlarged, particularly near basal cells. Some mitochondria were swollen and rough endoplasmic reticula were enlarged. Some basement membranes were thinner, collagen fibers of varying diameters were arranged in irregular shapes and the fine structures had become unclear and had sometimes even disappeared.
The paper presents experimental asbestosis treated with hydroxy piperquin phosphate (HPQP) in dogs. Results showed that the total cell number of bronchoalveolar lavage fluid, the viability of alveolar macrophages and the enzyme activities of lactate dehydrogenase, acid phosphatase and beta-glucuronidase of alveolar macrophages in treated dogs were higher than those in exposed dogs, asbestos fibers contents in the lungs and the mean scores of lung lesions in the treated dogs were markedly less than those in the exposed dogs. These findings support that HPQP may play a role in protecting alveolar macrophages from damage and inhibiting the progression of lung fibrosis, and that the clinical application of HPQP is somehow evidenced by this study.
In magnetic resonance imaging using two-dimensional Fourier transform techniques, motion causes ghosting in the phase-encoded direction and loss of image resolution. Although numerous techniques have been proposed to suppress these motion artifacts, they are a continuing problem. In this paper a new technique is presented to reduce the artifact from motion along the slice selection axis. It is shown that such motion causes an amplitude modulation of the data, and an iterative algorithm is developed to reduce this modulation by post-processing the data using signal processing techniques. The algorithm is tested on simulated data, and shown to perform well, even with significant levels of noise added to the data.
Ciclopirox olamine, a new synthetic substituted pyridone derivative, is an antimycotic agent with activity against a broad spectrum of pathogenic and nonpathogenic fungi. The clinical efficacy and safety of 8% ciclopirox olamine nail liquor were evaluated in 100 cases with finger (or great toe) onychomycosis. After 16 weeks and 24 weeks of treatment for finger and great toe onychomycosis, respectively, the overall therapeutic results were excellent in 36 cases, good in 17, fair in 24, and poor in 23. The period of treatment was extended in 31 cases; among them, 10 cases showed further improvement. As for in vitro inhibitory activity, the MIC of ciclopirox olamine against T. rubrum and C. albicans was 1 to 4 mg/L and 1 to 16 mg/L, respectively. This study indicates that 8% ciclopirox olamine nail liquor, with its satisfactory efficacy and lack of side effects, is a good remedy for onychomycosis.
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In magnetic resonance imaging, low frequency components can be allowed to saturate the analog to digital converter to reduce the quantization noise. These components can be estimated using least squares error estimation based low frequency restoration methods or the iterative Gerchberg-Papoulis algorithm. In this paper, we show the relationship between the closed form estimation methods and the iterative algorithm, propose a method for improving the speed of iteration, and discuss the advantages and disadvantages of two types of methods.
Optimal control methods have been recently introduced to improve the design of selective radio frequency pulses and several optimized selective pulses that can produce excellent slice profiles have been reported. These pulses usually require high peak rf amplitudes to implement and thus can not be widely utilized because of the limitations of the specific absorption rate and the rf power amplifier of a clinical system. We have a Siemens 1.5 T MRI clinical system. Several pulse files which consist of the bandwidth matched 90 degrees and 180 degrees selective pulses are provided. Some of these can produce excellent slice profiles. However, they can only be used in the pulse sequences with the pulse length of 5.12 msec. The purpose of this paper is to improve the slice profiles produced by the pulse file in the pulse sequences with the shorter 2.56 msec pulse length. A pulse file optimized by the conjugate gradient method is proposed to substitute the 2.56 msec Siemens pulse file. Our experimental results confirm that the slice profiles and images are improved by the optimized pulse file with a lower peak voltage. The proposed pulse file can also be applied in other clinical MRI systems.
We have purified cassava (Manihot esculenta) linamarase to apparent homogeneity using a simplified extraction procedure using low pH phosphate buffer. Three isozymes of cassava linamarase were identified in leaves based on differences in isoelectric point. The enzyme is capable of hydrolyzing a number of beta-glycosides in addition to linamarin. The enzyme is unusually stable and has a temperature optimum of 55 degrees C. Immunogold labeling studies indicate that linamarase is localized in the cell walls of cassava leaf tissue. Since linamarin must cross the cell wall following synthesis in the leaf for transport to the root, it is likely that linamarin must cross the cell wall in a nonhydrolyzable form, possibly as the diglucoside, linustatin. In addition, we have quantified the levels of linamarin and linamarase activity in leaves of cassava varieties which differ in the linamarin content of their roots. We observed no substantial differences in the steady state linamarin content or linamarase activity of leaves from high or low (root) cyanogenic varieties. These results indicate that the steady state levels of linamarin and linamarase in leaves of high and low cyanogenic varieties are not correlated with the varietal differences in the steady state levels of linamarin in roots.
Radioreceptor assays (RRAs) provide useful information about the bioactivity of peptide hormones. We have developed a RRA for human GH using membranes prepared from human liver. The assay has 1% cross-reactivity with human PRL, 0.11% cross-reactivity with human chorionic somatomammotropin, and negligible cross-reactivity with bovine and rat GH. The assay has distinct advantages over the IM-9 lymphocyte RRA in having reduced nonspecific interference from serum proteins and providing a uniform source of receptors which can be stored for long periods at -70 C. The coefficient of variation of the assay is 13%. In studies of 55 sera from short children with normal or elevated serum GH concentrations the mean ratio of RRA GH to immunoradiometric assayed GH was 1.28. This assay provided important information about the total GH activity in pregnancy. There was a progressive rise in RRA GH during pregnancy, reaching 64.7 +/- 2.5 (+/- SE) micrograms/L at term. This level is 2-3 times higher than suggested by earlier estimates made with monoclonal antibody RIAs for pituitary GH. At term the contributions to total GH activity of serum are less than 3% from the pituitary, 12% from human chorionic somatomammotropin reacting with the GH receptor, and 85% from placental GH. Despite this great increase in receptor-reactive GH, somatomedin activity by bioassay is reduced, and IGF-I, determined by RIA after acid-gel filtration, is minimally elevated.
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The paper reports 174 cases of brain operations in temporo-fronto-occipital region by using the regime of combined acupuncture and medication. The patients comprised of 122 males and 52 females. The acupoints consisted of ear needling and body needling. Adjuvant drugs used were half-dosage Innovar and 0.1% lidocaine for scalp infiltration. According to the documented two-grade scaling criteria, 97.1% patients belonged to grade I. No obvious discrepancy existed between ear needling group and body needling one. Three controlled groups are presented for comparison: 1) 0.1% lidocaine alone; 2) acupuncture plus normal saline; 3) acupuncture plus 0.1% lidocaine. The resultant P value was less than 0.005, with remarkable statistical significance. It is revealed that 0.1% lidocaine per se cannot achieve satisfactory analgesia, whereas the efficacy of acupuncture can be greatly enhanced by the combination of 0.1% lidocaine and acupuncture. This method is proved as an effectual means to offset the incomplete analgesia of acupuncture, especially for those requiring intraoperative demonstration of surgical effects, to avoid impairment to functional areas of cerebral cortex, which are undoubtedly superior to general anesthesia.
The quality of Magnetic Resonance imaging systems has improved to the point that the motion is the most important limitation in many examinations. Gross movements of the patient cause a ghost artifact in the image which can interfere with the diagnosis. In this paper a new method is presented to suppress the translational motion artifact caused by gross movements. The method uses postprocessing on a standard two-dimensional Fourier transform image. It is shown that translational motion causes an additional phase factor in the detected signal and that this phase error can be removed using an iterative algorithm of generalised projections. The method has been tested using computer simulations and successfully removed most of the artifact, even in the presence of noise.
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BALB/c mice were infected per os with the infective larvae (L1) of Trichinella spiralis, and challenged by injecting 0.2ml soluble L1 antigen 3 days before cell fusion. SP2/0 myeloma and immune spleen cells were fused at the ratio of 1:5 in the presence 30%PEG (MW 4,000). The fusion rate and antibody positive rate were 92.1% and 16.6% respectively using ELISA. Among these the chromosomes of 4 strains were 2n greater than 100 and that of the SP2/0 myeloma cells 2n less than or equal to 70. The titer of McAb in the ascites was found to be 1/640 or 1/1,280. Eight strains were of IgG1, 1 IgG2a and 3 IgM in an agar system. Three strains of McAbs, which could recognize specifically the L1 antigen fractions by immuno-blotting technique, were used as probes to localize the target antigens in sections of T. spiralis L1. Staining was performed using an indirect technique consisting of goat anti-mouse IgG-conjugated horseradish peroxidase on de-paraffin sections, and substrate DAB. The results revealed that the antigens reacted most strongly with the specific McAbs were located in the cuticle and stichosome, followed by the lining of gut. Among the 3 strains of McAbs used, 2E5F11A5 reacted most strongly with the antigen, followed by 2E5E9E4. 2E5E9G5 was the weakest.