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Biomedical subjects

H F Li

Publications and source records attributed to H F Li.

66 records · Page 4Linked to original sources
PubMed1995

[A study on the risk factors of Legionella infection in children].

In order to understand the risk factors of legionella infection in children a case-control study with two kinds of controls was conducted. The stepwise regression analysis included age, sex, season and immunosuppressive therapy in regression equation. The non-conditional logistic regression analysis showed that age, passive smoking and touching soil were associated with legionella infection. The statistics analysis also showed that there were dose-response relationship between age, passive smoking and immunosuppressive therapy and the frequency of legionella infection in children. It was suggested that age, season, immunosuppressive therapy, passive smoking and touching soil were risk factors for legionella infection.

Case-Control Studies↗
PubMed1995

Primary health care: the basis for malaria control in Hubei, China.

By 1992 malaria morbidity in Hubei, China had decreased steadily to its lowest level since 1970. Much of this achievement was through an integration of the primary health services with malaria control activities. However, in some areas malaria has been unstable due to weaknesses in the three tier health network. This has particularly been at the township and village level. The future of village doctors and appropriate measures of malaria control at the village levels are threatened by the change to a market economy. As part of the provincial health program, primary care services need to be improved in service provision, service organization and service quality.

China↗
PubMed1994

[A benign neuroendocrine tumor of the lung: study on the origin of the so-called sclerosing hemangioma of the lung].

31 cases of the so-called sclerosing hemangiomas of the lung were studied by light microscope, immunohistochemical and electron microscopy. This tumor is benign and has 3 histologic patterns: papillary, hemangioma-like and solid type. Characteristic morphology being uniform round tumor cells, lying within the stroma in different patterns and regarded as the major component of sclerosing hemangioma, expressing neuroendocrine markers which include chromagranin A, neuron-specific enolase, ACTH, growth hormone, calcitonin and gastrin. Only a few tumor cells were positive for epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA), all the tumor cells were negative for keratin (Polyclonal, Z622) stain. However, in contrast to the round tumor cells, the cells lining papillary projections or cystic spaces, which presented as normal or hyperplastic alveolar cells, stained positive for keratin, EMA and CEA but negative for neuroendocrine markers. Both the surface cells and tumor cells were negative for Factor VIII-related antigen and alpha 1-AT. Therefore, pulmonary sclerosing hemangioma was regarded to be a benign tumor originating from the neuroendocrine cells of the lung and we suggest that it be renamed as benign neuroendocrine tumor of the lung (LBNET). This viewpoint has not been previously reported in the literature.

Adenoma↗
PubMed1988

Maximum length sequence applied to the measurement of brainstem auditory evoked responses.

An evoked response may be assumed to consist of synchronous electrical activities of groups of neurons in response to a stimulus. Unfortunately, this response is usually weak and often masked by the background EEG activity generated spontaneously by the brain. In order to extract the embedded evoked response we have employed the theory of maximum length sequence, assuming only a temporal linearity of the system from which measurements are taken. The technique has been applied successfully with the aid of a microcomputer. The system also supports the same measurement by a conventional averaging technique. The results of the two are compared, indicating the advantages of the maximum length technique: improved signal-to-noise ratio, repeatability and speed.

Animals↗
PubMed1984

A microcomputer-based binaural measurement system.

A microcomputer is used to control a dual-channel, sine-wave generator as the excitation to both the left and right ears in experimental subjects, and for on-line measurement of the neuronal spike counts. The effects of varying the walking pattern and phase angle between the two channels can be investigated. After normalisation of spike counts, the result can be displayed as a 3-D plot on a CRT or an x-y plotter. The system is useful for general steady state and transient binaural measurement.

Biomedical Engineering↗
PubMedDate not supplied

Velocity-encoded, phase-difference cine MRI measurements of coronary artery flow: dependence of flow accuracy on the number of cine frames.

Phase-contrast magnetic resonance imaging (PC-MRI) can be used to produce multiframe cine flow images of the coronary arteries. Accurate coronary flow measurement requires the elimination of respiratory motion artifacts using k-space segmentation to acquire the data in a single breath-hold. However, the duration of the breath-hold is proportional to the number of cine frames. In the present study, the number of cine frames was varied and the accuracies of the coronary flow measurements were assessed using perivascular US. For the range of flows studied (2 ml/min to 147 ml/min), the correlation coefficients for PC-MRI and US increased (.70-.98) and the limits of agreement improved (+/-45 ml.min-1 to +/-10 ml.min-1) as the number of cine frames increased from one to six. The results suggest that the accuracy of breath-hold cine PC-MRI measurements of coronary artery flow improves as the number of cine frames increases.

Animals↗
PubMedDate not supplied

Microcomputer-based spike train analysis.

A system has been developed to analyse statistically the information contained within neuronal spike trains in the central nervous system. The system consists of a microprocessor development system, together with the peripheral components and transducers. Suitable software packages have been developed to analyse statistical parameters including the mean, variance, entropy, conditional entropy, serial correlation coefficients, Markov dependency and Markov order. By linking up the required routines, the system is capable of responding in real-time and plotting the desired results from the spike train obtained. Such system has been used to study the neuronal spike trains recorded from central vestibular neurons which could be affected by positional changes, anaesthetics and various drugs for the relief of motion sickness.

Animals↗
PubMedDate not supplied

A method for fully automated quantitative analysis of arterial flow using flow-sensitized MR images.

While the recent developments in the velocity-sensitive MR imaging offer great potential for non-invasive assessment of blood flow in major blood vessels, the clinical applications of this technique have been hampered by tedious, human-assisted data processing techniques. In this paper, we describe a robust system for automated extraction of quantitative as well as qualitative flow information from velocity-sensitive, phase contrast MR images. The algorithm accomplishes reliable segmentation of blood vessels using multiresolution analysis based on wavelet transform, and employs a multivariate scoring criterion to minimize the impact of imaging artifacts such as partial volume averaging and flow turbulence, which normally cause incomplete or inaccurate detection of vascular boundaries.

Algorithms↗