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Biomedical subjects

M Q Li

Publications and source records attributed to M Q Li.

At least 19 recordsLinked to original sources
PubMed2006

Congenital lumbosacral limb duplication: a case report.

We report a case of congenital lumbosacral limb duplication at the pelvis, lower limb, and foot of a 4-year-old boy. The patient presented with a supernumerary lower limb joined at the lumbosacral region by a bony connection. A pseudo-navel and a pseudo-penis were found on the supernumerary limb and foot duplication was noted at the end. Radiography and a 3-dimensional computed-tomography reconstruction revealed duplication of an inversely oriented pelvis dorsal to the normal pelvis, semi-vertebrae in T7 to T9, thoracolumbar scoliosis, lumbosacral vertebral dysplasia, and dislocation of the left hip. Magnetic resonance imaging demonstrated a tethered spinal cord and an adipoma in the sacral canal. Motor conduction velocity was reduced in the left peroneal nerve. Surgery to remove the supernumerary limb was successfully performed. The patient recovered well and further surgery is planned for functional reconstruction of the left lower limb.

Abnormalities, Multiple↗
PubMed2004

Nanoscale analysis of biofunctional molecules and components.

In basic medical research, as well as in concrete clinical applications, the nanoscale analysis of biofunctional units is of strongly increasing relevance. Dedicated investigations on molecules, molecular composites or functional units can efficiently be performed ex or in situ by scanning probe methods and, namely, by scanning force microscopy. In the following investigations, the folding behavior of DNA is presented as an example of basic research in medicine. In contrast, the investigation of bioadsorption phenomena in systems on which apheresis therapies are based provides a real contribution to applied medicine.

Absorbable Implants↗
PubMed2001

[Allografting for massive bone defect: bone and soft tissue reconstruction and postoperative rehabilitation].

OBJECTIVE: To evaluate the results of limb function and the methods of bone and soft tissue reconstruction of patients treated with allografting. METHODS: From May 1992 to January 1999, 90 patients suffered from bone malignant tumor were treated with allografting in different methods of internal fixations. The average follow-up was 37.5 months. The limb postoperative function, complications related to different surgical methods were compared according to Enneking evaluation system. RESULTS: Skin necrosis, infection, non-union, fracture of allograft were the main complications which affect patients' limb postoperative functions. Of the 90 fresh-frozen allografting procedures, the final results of operation showed that hip joints and knee joints were better than the shoulder joints. More than 80% of the patients treated with interlocked intramedullary nail and allograft-prosthesis combination led to an over-all result that was excellent and good. Interlocked intermedullary nail was of recommended method of internal fixation. Early exercises of operative limbs could promote function recovery. CONCLUSION: Using of interlocked intramedullary nail and allograft-prosthesis combination are of recommended operation method and can be applied with better results, and early exercises of operative limbs will lead to better functions.

Adolescent↗
PubMed2001

[Resolution of overlapping mass spectra of azobiphenyl dyes by subwindow factor analysis technique].

Subwindow factor analysis(SWFA) has been proven to be an effective data processing technique. In this paper, it is applied to the resolution of overlapping GC-MS peaks. A two-component sample of azobiphenyl dyes (3,3'-dichlorobenzidine, 4,4'-methylene-bis-(2-chloroaniline)) was prepared and a data set from a mixture of azobiphenyl dyes recorded by GC-MS was obtained. Then the overlapping GC-MS data were resolved by SWFA. The results show that both mass spectrum and chromatogram of components can be resolved from multicomponent overlapping data. The resolved spectra were in good consistence with the mass spectra of standard samples. At the same time, overlapping GC-MS data were also resolved by WFA. In Comparing with WFA technique, SWFA is more convenient, and the speed of resolution could be increased.

3,3'-Dichlorobenzidine↗
PubMed1999

The structure of the nucleosome core particle of chromatin in chicken erythrocytes visualized by using atomic force microscopy.

The structure of the nucleosome core particle of chromatin in chicken erythrocytes has been examined by using AFM. The 146 bp of DNA wrapped twice around the core histone octamer are clearly visualized. Both the ends of entry/exit of linker DNA are also demonstrated. The dimension of the nucleosome core particles is approximately 1-4 nm in height and approximately 13-22 nm in width. In addition, superbeads (width of approximately 48-57 nm, height of approximately 2-3 nm) are occasionally revealed, two turns of DNA around the core particles are also detected.

Animals↗
PubMed1997

Visualization of chromatin folding patterns in chicken erythrocytes by atomic force microscopy (AFM).

The organization of the higher order structure of chromatin in chicken erythrocytes has been examined with tapping-mode scanning force microscopy under conditions close to their native environment. Reproducible high-resolution AFM images of chromatin compaction at several levels can be demonstrated. An extended beads-on-astring (width of approximately 15-20 nm, height of approximately 2-3 nm for each individual nucleosome) can be consistently observed. Furthermore, superbeads (width of approximately 40 nm, height of approximately 7 nm) are demonstrated. Visualization of the solenoid conformation at the level of 30 nm chromatin fiber is attained either by using AFM or by using electron microscopy. In addition, tightly coiled chromatin fibers (approximately 50-60 nm and approximately 90-110 nm) can be revealed. Our data suggest that the chromatin in the interphase nucleus of chicken erythrocyte represents a high-order conformation and AFM provides useful high-resolution structural information concerning the folding pattern of interphase chromatin fibers.

Animals↗
PubMed1994

[The surgical treatment of partial atrioventricular canal defect].

This paper reports 11 cases of partial atrioventricular canal defect in our hospital. It also discusses the diagnosis of complication prevention and treatment with patient and the disposal during operation term, emphasizes that once definite diagnosis has been made, operation must be taken as soon as possible. Skillfully grasp surgery anatomy and exact suture techniques is the key to avoid conduction damage.

Adolescent↗
PubMed1993

Interaction between HMG proteins (1 + 2) and the negative regulatory region 1 (NCR1) in the 5'-flanking sequence of the human beta-globin gene.

The pattern of high mobility group proteins 1 and 2 (HMG1,2) interaction with the 5'-flanking sequence of the human beta-globin gene has been analyzed by scanning tunnelling microscopy (STM). A 200 bp negative regulatory region in the 5'-flanking sequence of the human beta-globin gene can be folded by HMG proteins 1 and 2 into a circular structure (diameter 70 +/- 6 A) with a linear tail which seems to be a left-handed double helix structure.

Base Sequence↗
PubMed1992

Atomic force microscopy of single- and double-stranded DNA.

A method has been developed for imaging single-stranded DNA with the atomic force microscope (AFM). phi X174 single-stranded DNA in formaldehyde on mica can be imaged in the AFM under propanol or butanol or in air. Measured lengths of most molecules are on the order of 1 mu, although occasionally more extended molecules with lengths of 1.7 to 1.9 mu are seen. Single-stranded DNA in the AFM generally appears lumpier than double-stranded DNA, even when extended. Images of double-stranded lambda DNA in the AFM show more sharp kinks and bends than are typically observed in the electron microscope. Dense, aggregated fields of double-stranded plasmids can be converted by gentle rinsing with hot water to well spread fields.

Bacteriophage lambda↗
PubMed1992

Parallel stranded DNA under the scanning tunnelling microscope.

Using scanning tunnelling microscopy, we have directly observed parallel stranded DNA helixes of 43 nucleotides in length. The double helix is right-handed and has an average spacing, 17.43 A (+/- 1 S.D.: 2.30 A), and an average apparent depth, 4.79 A (+/- 1 S.D.: 1.04 A) for each groove. The average pitch of the helical turn is 34 A (+/- 1 S.D.: 3.35 A) and consists of no more than ten base pairs. The diameter of the helix is approx. 17-20 A. Our results provide direct evidence for the existence of a parallel structure of DNA in vitro and some details of its fine structure.

Base Sequence↗
PubMed1992

Atomic force microscopy of uncoated plasmid DNA: nanometer resolution with only nanogram amounts of sample.

Reproducible, high-contrast, nanometer-resolution AFM images of uncoated plasmid DNA can be obtained with nanogram quantities of DNA with the help of two advances in sample preparation: (1) Heating a DNA solution at 35 degrees C for 10 to 20 minutes before deposition on mica helps separate and spread the DNA, and (2) Using 5 microliter drops of the heated DNA solution in the concentration range of 2 to 10 nanogram/microliter in contact with a specially prepared mica surface for 5 to 10 minutes gives optimal coverage with only nanograms of DNA.

Aluminum Silicates↗
PubMed1992

[Effects of 3 Chinese medical prescriptions on alkaline reflux gastritis in rats].

The experimental alkaline reflux gastritis in rats was established after 9 weeks of anastomosis between stomach and jejunum. The experiment shows that xiangsha liujunzi decoction, xiaochaihu decoction and dahuang gancao decoction all help to inhibit edema, hyperamia and extravasted blood, as well as depress inflammatory infiltration and hyperplasia. The number of intestinal metaplasia in the group treated with xiangsha liujunzi decoction is decreased. All the three prescriptions are not able to lower the contents of bile acid in the stomach.

Animals↗
PubMed1992

An occupational hygiene survey in a Chinese viscose rayon factory.

The retinopathy (microaneurysm/small dot hemorrhage) is an early and specific biological indicator to quantitatively evaluate the CS2 exposure. The appearance of retinal lesions was observed among Yugoslavian, German and American workers exposed to CS2. However, among Finnish CS2 workers a positive result was not obtained. We suggested a different response to CS2 exposure between two ethnic populations. We had an opportunity to do a cross-sectional medical and occupational hygiene survey in a Chinese rayon staple plant. Cross-sectional medical examinations failed to show any chronic CS2 effects on the Chinese workers.

Adult↗
PubMed1991

Determination of eight elements in six human cancer cell lines and two human normal cell lines by PIXE.

Gastric, hepatic, and pulmonary cancer cell lines, and the third passage of normal gastric and pulmonary cell lines were analyzed by proton induced X-ray emission (PIXE) method. The contents of element Sr, Ca, Fe, Zn, P, K, Cu, and As in the cell lines were determined. The Sr, Ca, Fe, Zn, and As contents in cancer cell lines were significantly lower than those in the normal cell lines (p less than 0.05), whereas there were no significant differences for the P, K, and Cu contents (p greater than 0.1). The results suggest that the need of some essential elements has been diminished in cancer cell proliferation.

Cell Line↗
PubMed1991

Conformation of DNA-DNA polymerase I complex observed by scanning tunneling microscopy.

The conformation of a complex of a 41 mer/31 mer DNA fragment and the Klenow fragment of DNA polymerase I of Escherichia coli was studied by scanning tunnelling microscopy (STM). The results shows that near two turns of double helix of this DNA fragment was outside of enzyme while another part containing more than one turn of helix and 10 nucleotides single strand was combined with enzyme. The dimension and shape of DNA polymerase I (KF) in complex were different from that of free enzyme. The conformation of DNA-DNA polymerase I (KF) complex and the application of STM in studying structure of complex of DNA polymerase with DNA were discussed.

Base Sequence↗
PubMed1991

Parallel stranded DNA under scanning tunnelling microscope: the main characteristics of the double helix.

Using the scanning tunnelling microscopy we have directly observed the parallel stranded DNA of 43 bp in length, containing alternating AT-stretches. The double helix is right-handed and has the same width of each grooves equal to 17.4 A. The average pitch of the helical turn is about 34 A. The parallel double helix possesses no more than 8.6 bases per one turn. The diameter of the parallel stranded DNA molecule is 17-18 A. We conclude that in parallel DNA double helix the angle between N-glycoside bounds in trans-Crick-Watson base pairs is close to 180 degrees.

Base Composition↗
PubMed1984

An epidemiological study on carbon disulfide angiopathy in a Chinese viscose rayon factory.

To assess long-term vascular effects of occupational carbon disulfide (CS2) exposure, we examined 376 exposed and 325 unexposed Chinese workers with a medical and work-history questionnaire, a chest-pain questionnaire, blood pressure and blood cholesterol measurements, routine urinary tests, monochromatic fundus photography and other tests. Data from 354 exposed and 177 age- and sex-matched reference workers were evaluated. Personal exposure monitorings were performed simultaneously with a passive dosimeter using gas chromatography. Monochromatic fundus photography revealed no CS2-retinopathy characterized by microaneurysms and/or small dot hemorrhages, and no effects of CS2 on blood pressure and blood cholesterol were found. These negative results may have been due to the low daily exposure averages, which varied between 0.01 and 12.8, with a mean of 1.5 ppm. The present study suggested that the no-effect level of CS2 exposure on the development of retinopathy was around 2 ppm (8-h time weighted average), and the absence of adverse CS2 effects among the workers studied supported the current standard for occupational CS2 exposure of 10 mg m-3 in China.

Adult↗