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Biomedical subjects

X Hu

Publications and source records attributed to X Hu.

At least 505 records · Page 28Linked to original sources
PubMed1990

[Study on the variation of relaxation time in diabetic cataractous lenses of rats by using NMRA].

Nuclear magnetic resonance analysis (NMRA) was used to measure the relaxation time T1 and T2 of the protons in the different-stage-diseased lenses of rats with diabetic cataract caused by the streptozotocin, and the results were put in comparison with those obtained from the control group, showing that after one month of medication the values of T1 and T2 in the cataractous lenses are greater than those gained from the control group. The variation, as time goes on, becomes greater and greater. T1 and T2 indicate the speed of the free induction decay (FID) signals, and the variation of the FID signals are in direct proportion to that of the proton content of the samples. This shows that an increase in T1 and T2 indicates an increase in the water content in the diseased lenses, and the changes in ratio of "bound" water to free water. Such changes may be explained that the space for "bound" water is occupied by some other macromolecules, causing the alteration of the macromolecular structure, and consequently the aggregation of protein and the degeneration or dehydration or dehydration of the membrane occur, which may give rise to another scattering centre. So the scattering of the lens increases and its transparency decreases. This result is in agreement with some reports in the medical literature. As T1 and T2 are quite different in the normal and pathological tissues, and the protons are the most extensive nucleus in all biological tissues, NMR is a very important method to determine the proton relaxation time in the biological tissue and to judge if it is normal or not.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Electron spin resonance (ESR) study on hair of rats with diabetic cataract].

The hair taken from 40 rats with diabetic cataract and 20 normal controls was tested by using ESR. It was found that the 'g factor' of the hair of the rats with diabetic cataract is higher than that in normal controls. The intensity of ESR signals of the hair taken from rats with diabetic cataract is three times higher than that of ESR signals of the hair from the normal controls. The results have suggested a good reappearance and a remarkable increase in number of the free radicals and other particles of paramagnetic substances during the course of the development of the rats' diabetic cataract. The study provides new scientific data for the theory of free radicals damaging to the crystal in the process of the formation of diabetic cataract.

Animals↗
PubMed1990

[Ultrastructural localization of Leishmania donovani antigen by immunogold labeling technique].

By using Lowicryl K4M, a kind of low temperature embedding resin, to embed promastigotes of Leishmania donovani at -30 degrees C, the protozoal structure was well preserved when visualized by electron microscope. We have determined the distribution of the promastigote antigen of human and canine isolates of Leishmania donovani from Sichuan using two monoclonal antibodies combined with biotinylated goat antimouse IgG and streptavidin/colloidal gold conjugates. The results showed that the antigen recognized by the protective monoclonal antibody 2H6-E3 was mainly distributed in the outer side of promastigote membrane of Leishmania donovani Sichuan canine isolate. According to the high density of localized gold particles this antigen might be abundant in the promastigote membrane. This result facilitates further research on the component, property and function of this antigen. Monoclonal antibody 1H7-C2-E7 recognized the promastigote antigen of both human and canine isolates of Leishmania donovani from Sichuan, suggesting that these two isolates might share a common antigen, and 1H7-C2-E7 antibody might be used to diagnose the leishmaniasis caused by these two isolates.

Animals↗
PubMed1988

The problem of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a lethal X-linked muscular disorder. The biochemical defect remains unknown, but the gene responsible has been mapped to band Xp21. The gene has now been cloned in two laboratories solely from knowledge of its map location. L. M. Kunkel and his colleagues isolated genomic sequences (PERT 87) from within a large deletion causing DMD, whereas our group isolated genomic sequences (XJ) spanning the junction of an X-autosome translocation causing the disease. Chromosome walking by both groups has led to the isolation of over 400 kilobases of the PERT 87 and XJ region. Subclones of PERT 87 and XJ reveal restriction fragment length polymorphisms that segregate with the DMD gene in 95% of meioses, and fail to hybridize with DNA from about 8% of male patients. Selected subclones of PERT 87 and XJ contain exons that hybridize to muscle-derived complementary DNA (cDNA) clones. The cDNA clones detect a large (16 kilobase) message. Analysis of deletions, mutations and translocations suggests a DMD gene of between two million and three million base pairs. The clones obtained so far are useful for attempts to generate antibody against the gene product and for carrier identification and prenatal diagnosis.

Chromosome Mapping↗
PubMed1988

SLIM: spectral localization by imaging.

Nonspectroscopic magnetic resonance (MR) imaging often shows that a slice is composed of several compartments, each of which can be assumed to have a spatially homogeneous magnetic resonance spectrum, e.g., a limb composed of fat, muscle, bone marrow, and tumor. We show how to use structural information from such a nonspectroscopic image in order to increase the efficiency of subsequent localized spectroscopic measurements. Specifically, knowledge of the boundaries of N compartments makes it possible to reconstruct compartmental spectra from spectroscopic signals from an entire cross section with N or more different degrees of phase encoding. Experimental studies of a two-compartment phantom show that this method (SLIM) can be used to derive regional hydrogen spectra of a single slice from signals with as few as 2 phase-encoding steps, although Fourier transform chemical-shift imaging requires 64 steps to achieve a result of comparable accuracy. SLIM required only 16 phase-encoding steps to obtain accurate regional single slice spectra in a human limb with three compartments. Spectra of similar quality, obtained by Fourier transform chemical-shift imaging, required 256 to 1024 steps.

Humans↗
PubMed1988

The effects of high iodine on the brain development of mice.

C57 mice were divided into two groups: (A): experiment group (H group). Each female mouse was injected with 20 microliter iodized oil; (B): control group (N group). Both groups were mated 8 days after iodized oil injection. Urine iodine contents/24 h of H group was 20 times higher than that in N group 7 days after injection and 18 times higher two months later. Serum T4 values were determined. Brain protein, DNA, body weight, motility and learning ability were measured in the progeny. The results indicate that there was no statistically significant difference between the groups in any of the parameters mentioned above. This strongly suggests that a high iodine dose, given as iodized oil, does not have obvious damaging effects on brain development, at least in mice.

Animals↗
PubMed1987

Correlation of dietary aflatoxin B1 levels with excretion of aflatoxin M1 in human urine.

Corn and peanut oil (total, 253 samples) were collected from 32 households in Fushui county of the Guangxi autonomous region of the People's Republic of China, where high liver cancer incidence has been reported, every day over a period of 1 week and analyzed for aflatoxin B1 (AFB). A total of 252 urine samples were collected simultaneously from the residents in the households which were shown to have consumed AFB and were analyzed for aflatoxin M1 (AFM) by a competitive direct enzyme-linked immunosorbent assay. A good correlation between total dietary AFB intake and total AFM excretion in human urine was observed during a 3-day study. A regression equation of 0.143 plus 0.0135 multiplied by the amount of AFB consumed was observed. Between 1.23 and 2.18% of dietary AFB was found to be present as AFM in human urine. A good correlation was also observed between the AFB concentration in corn and the AFM concentration in human urine. The results suggest that analysis of AFM in urine by enzyme-linked immunosorbent assay could be used as an index for human exposure of AFB in an extensive epidemiological study.

Aflatoxin B1↗
PubMed1987

Comparison of tissue preparation methods for assay of nicotinamide coenzymes.

To prepare tissues for analysis of NAD(+), NADH, NADP(+), and NADPH, common practice is to freeze samples in liquid nitrogen, often followed by freeze-drying, before extraction in HCl or NaOH. With cucumber (Cucumis sativus L.) cotyledons, prefreezing in liquid nitrogen or slower freezing to -20 degrees C yielded substantially lower values for NADH and NADPH than obtained from samples homogenized immediately in acid or base. Freeze-drying after freezing in liquid nitrogen generally caused even lower values of those coenzymes. We suggest that direct extraction is more likely to yield accurate results with cotyledons and other plant parts.

Journal Article↗
PubMed1982

Hepatic damage in experimental and clinical paragonimiasis.

The hepatic damage induced by Paragonimus skrjabini, and the migration route of this species and that of P. westermani, were investigated in a series of animal experiments and in 34 clinical and four autopsy cases of paragonimiasis. The major symptoms and signs of an unique case reported from Sichuan Province included hepatic tenderness, disturbance of hepatic functions, remittent fever, and cough with bloody sputum. Laparotomy revealed marked adhesions surrounding the liver, spleen and duodenum. Diagnosis was made by finding P. skrjabini in a bulla on the abdominal wall about 5 months after the onset of illness. After specific treatment with bithional, body temperature and liver functions returned to normal. Twenty-three of 33 cases independently studied from Fujian Province also showed similar hepatic function disturbance. Autopsy cases showed hepatic chronic eosinophilic abscesses with Charcot-Leyden crystals. Experimentally, P. skrjabini infection caused hepatic damage in all laboratory animals used. The main pathologic changes were initially acute eosinophilic abscesses in the liver, worms being found sometimes in the necrotic cavities of the abscesses; hepatomagaly also occurred. Some cysts containing mature worms were found in the liver of dogs 3-9 months after infection. Numerous eggs were deposited in the cyst walls. The migration route of P. skrjabini was studied in young dogs. Worms appeared in the liver initially on day 3 and reached their highest level on day 14. P. westermani also migrated into liver, but their numbers were less than those of P. skrjabini.

Acute Disease↗
PubMedDate not supplied

Methods for assessing accuracy and reliability in functional MRI.

In this paper, methods for assessing the accuracy and the reliability of functional magnetic resonance imaging techniques are presented. First, a modified receiver operating characteristic analysis is described for evaluating the accuracy of fMRI studies. With this modified approach, the true positives or the activated pixels are estimated based on highly averaged experimental data acquired with the same stimulation/task. Unlike ROC analysis based on simulated activation data, the present approach can be applied to experimentally acquired data without simplifying the activation related changes. To assess the reliability of fMRI studies, the kappa statistic was adopted for evaluating the overall agreement of functional activation maps from repeated experiments in individual subjects. To demonstrate the utility of these techniques, both the ROC analysis and the reliability assessment were applied to quantitatively evaluate the improvement in accuracy and reliability of a retrospective technique for physiological noise reduction in fMRI.

Magnetic Resonance Imaging↗
PubMedDate not supplied

Visualization of MR angiographic data with segmentation and volume-rendering techniques.

Novel image processing and computer graphics techniques were developed to create three-dimensional (3D) models of vasculature from magnetic resonance (MR) angiographic images of the head or neck. Region growing was used to produce a mask that isolated the vascular signal in the MR angiographic data. The masked images were subjected to gradient-shaded volume rendering to create 3D views of the vasculature. The computer-derived model of intracranial vasculature was then merged with a 3D model of brain parenchyma derived from a set of MR images. The combined display of vascular and gyral anatomy may be useful for neurosurgical planning.

Brain↗
PubMedDate not supplied

Simpler locally focused tomography in MR imaging.

The author describes a simple technique for performing locally focused tomography with magnetic resonance imaging. In contrast to a previous technique, which utilized wave functions to represent k-space data, the one described here does not require complicated experimental design and reconstruction procedures and is easy to implement and understand. The technique is verified with an experimental study. Technical details and experimental results are presented.

Humans↗