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Biomedical subjects

Q Y Ma

Publications and source records attributed to Q Y Ma.

At least 19 recordsLinked to original sources
PubMed2007

Screening and mutagenesis of a novel Bacillus pumilus strain producing alkaline protease for dehairing.

AIMS: To characterize and optimize a novel Bacillus pumilus strain isolated from biological waste which produces protease with excellent dehairing effect. This newly isolated strain could be utilized in the industrial leather dehairing process. METHODS AND RESULTS: Bacterial strains secreting proteases were screened from biological wastes. Positive clones were further characterized by analysing their efficacy in dehairing and effects on collagen integrity. Among 171 colonies tested, a strain BA06, identified as B. pumilus, was picked owing to its efficient dehairing capabilities with minimal impact on collagen. By combined mutagenesis using UV, N-methyl-N'-nitro-N-nitrosdguanidine and Co(60)-gamma-rays, this strain was further improved with regard to its alkaline protease production. The alkaline protease activity of the mutant strain SCU11was greatly improved up to 6000 U ml(-1), in comparison with its parent strain BA06 of 1200 U ml(-1). CONCLUSIONS: By using screening and mutagenesis methods, we have successfully created a B. pumilus strain that can produce high levels of alkaline proteases that are able to efficiently remove hair from skin with minimal damage on the collagen. SIGNIFICANCE AND IMPACT OF THE STUDY: This strain could be used in commercial alkaline protease production for leather dehairing.

Animals↗
PubMed2004

Performance of large-size superconducting coil in 0.21T MRI system.

A high-temperature superconductor (HTS) was used on magnetic resonance imaging (MRI) receiver coils to improve image quality because of its intrinsic low electrical resistivity. Typical HTS coils are surface coils made of HTS thin-film wafers. Their applications are severely limited by the field of view (FOV) of the surface coil configuration, and the improvement in image quality by HTS coil is also reduced as the ratio of sample noise to coil noise increases. Therefore, previous HTS coils are usually used to image small in vitro samples, small animals, or peripheral human anatomies. We used large-size HTS coils (2.5-, 3.5-, and 5.5-in mean diameter) to enhance the FOV and we evaluated their performance through phantom and human MR images. Comparisons were made among HTS surface coils, copper surface coils, and cool copper surface coils in terms of the signal-to-noise ratio (SNR) and sensitivity profile of the images. A theoretical model prediction was also used to compare against the experimental result. We then selected several human body parts, including the wrist, feet, and head, to illustrate the advantage of HTS coil over copper coil when used in human imaging. The results show an SNR gain of 200% for 5.5-in HTS coil versus same size copper coils, while for 2.5- and 3.5-in coils it is 250%. We also address the various factors that affect the performance of large size HTS coils, including the coil-to-sample spacing due to cryogenic probe and the coil-loading effect.

Electric Conductivity↗
PubMed2003

Superconducting RF coils for clinical MR imaging at low field.

RATIONALE AND OBJECTIVES: A number of recent reports in the MRI literature have established that substantial signal-to-noise ratio (SNR) gains can be achieved with small samples or low resonance frequencies, through the use of high-quality factor high-temperature superconducting (HTS) RF receive coils. We show the application of HTS coils to the imaging of human subjects with improved SNR compared with copper coils. MATERIALS AND METHODS: HTS coils were constructed from 7.62-cm YBa2Cur3O7-delta thin films on LaAlO3 substrate and cooled in a liquid nitrogen cryostat. Human and phantom images were acquired on a 0.2-T scanner. The SNR improvements compared with equivalent-sized copper coils are reported. RESULTS: SNR gains of 2.8-fold and 1.4-fold were observed in images of a phantom acquired with an HTS coil versus a room temperature copper coil and a liquid nitrogen-cooled copper coil, respectively. Preliminary results suggest higher image quality can be obtained in vivo with an HTS coil compared with copper coil imaging. Images of human orbit, brain, temporomandibular joint, and wrist are presented. CONCLUSION: The experimental results show that benefits can be expected from application of HTS surface coils in human MR imaging with low-field scanners. These potential benefits justify the continued development of practical HTS coil imaging systems despite the considerable technical difficulties involved in cryostat and coil design.

Brain↗
PubMed2001

Hepatitis C virus infection of human hepatoma cell line 7721 in vitro.

AIM: To establish a cell culture system with long-term replication of hepatitis C virus in vitro. METHODS: Human hepatoma cell line 7721 was tested for its susceptibility to HCV by incubating with a serum from a patient with chronic hepatitis C. Cells and supernatant were harvested at various phases during the culturing periods. The presence of HCV RNA, the expression of HCV antigens in cells and/or supernatant were examined by RTPCR, in situ hybridization and immunohistochemistry respectively. RESULTS: The intracellular HCV RNA was first detected on d2 after infection and then could be intermittently detected in both cells and supernatant over a period of at least three months. The expression of HCV NS3,CP10 antigens could be observed in cells. The fresh cells could be infected by supernatant from cultured infected cells and the transmission of viral genome from HCV-infected 7721 cells to PBMCs was also observed. CONCLUSION: The hepatoma line 7721 is not only susceptible to HCV but also supports its long-term replication in vitro.

Antigens, Viral↗
PubMed2000

[Population genetics of Chinese surnames. I. Surname frequency distribution and genetic diversity in Chinese].

This paper deals with the distributional characteristics of Chinese surnames and the factors affecting their distribution. Analysis of alpha and nu values for three periods in the last 1,000 years clearly reveals the distributional pattern of Chinese surnames. In China, communities with the same surname are widespread, especially in the central areas where there are more relatively isolated Y chromosome of the same source (communities with the same surname) and more surnames than in other areas (especially the South China). If each surname has a certain kind of mono-type Y-DNA, then, according to the distribution of surnames, there exist the most mono-type of Y-DNA in the central provinces where are the originating center of Chinese surnames. For the first time, an equation is constructed predicting the kind of Chinese surnames. It has been estimated that there are about 3,100 surnames present in use for the Han nationality.

Genetic Variation↗
PubMed1999

Performance of a high-temperature superconducting probe for in vivo microscopy at 2.0 T.

The use of a high-temperature superconducting probe for in vivo magnetic resonance microscopy at 2 T is described. To evaluate the performance of the probe, a series of SNR comparisons are carried out. The SNR increased by a factor of 3.7 compared with an equivalent copper coil. Quantitative measures of the SNR gain are in good agreement with theoretical predictions. A number of issues that are unique to the application of HTS coils are examined, including the difficulty in obtaining homogenous excitation without degrading the SNR of the probe. The use of the HTS probe in transmit-receive mode is simple to implement but results in nonuniform excitation. The effect of using the probe in this mode of operation on the T1 and T2 contrast is investigated. Methods for improving homogeneity are explored, such as employing a transmit volume coil. It is found that the cost of using an external transmit coil is an increased probe noise temperature and a reduced SNR by approximately 30%. Other important aspects of the probe are considered, including the effect of temperature on probe stability. Three-dimensional in vivo imaging sets are acquired to assess the stability of the probe for long scans. High-resolution images of the rat brain demonstrate the utility of the probe for microscopy applications.

Animals↗
PubMed1997

Combinations of three immunological assays for detecting anti-Toxoplasma IgG in the sera of patients infected with Toxoplasma gondii.

Enzyme-linked immunosorbent assay (ELISA), Dot-ELISA and Dot-immunogold silver staining (Dot-IGSS) were simultaneously used to detect the specific IgG against Toxoplasma gondii in 65 patients infected with the protozoa. The positive rates were 86.51%, 92.51% and 98.64%, respectively. When ELISA and Dot-ELISA results were put together, the positive rate increased to 95.38%. When Dot-IGSS results were combined with those of ELISA or Dot-ELISA, the positive rate was raised to 100%. The difference in positive rate between ELISA and Dot-IGSS was significant (x2 = 6.93, p < 0.01), but no statistically significant differences were found between ELISA and Dot-ELISA or between Dot-ELISA and Dot-IGSS. Paired comparison of the reacting intensities of the sera in the 3 assays showed the correlations were highly significant (p < 0.001), with r = 0.608 between Dot-IGSS and Dot-ELISA, r = 0.8194 between Dot-IGSS and ELISA and r = 0.517 between Dot-ELISA and ELISA. Hence combination of different serological assays may increase their sensitivity and specificity for detecting the anti-Toxoplasma antibodies.

Animals↗
PubMed1996

Superconducting receiver coils for sodium magnetic resonance imaging.

We present the results from sodium magnetic resonance imaging (MRI) experiments using high-temperature superconducting (HTS) receiver coils. Sodium imaging has been shown to have great potential for the assessment of cell integrity but suffers from a substantially lower signal-to-noise ratio (SNR) than that of a hydrogen imaging. The use of an HTS receiver coil was found to significantly increase the SNR relative to an equivalent copper receiver coil at room temperature. The SNR gains afforded by HTS coils can also be used to decrease the imaging time.

Copper↗
PubMed1995

Longitudinal study of the health of cotton workers.

OBJECTIVES: To follow up a group of newly employed workers in a cotton mill, and to report changes in symptoms over time. METHODS: A group of 110 mill workers at a cotton mill in Shijiazhuang, China, was investigated by questionnaire, skin testing, and spirometric measurements of airway responsiveness through forced expiratory volume in one second (FEV1). The workers were examined before starting work, at 10 weeks, and at one year. RESULTS: Decreases in FEV1 over shifts were small at 10 weeks and one year, and slightly higher among people with skin reactions to cotton dust extracts. Airway responsiveness, defined as the average decrease in FEV1 after 1.25 mg methacholine was increased at 10 weeks. It remained about the same after one year, except in the workers positive for the skin test, in whom it was further increased. Subjective symptoms of chest tightness and cough with phlegm increased progressively at 10 weeks and one year; nasal irritation remained unchanged and dry cough decreased between 10 weeks and one year. CONCLUSION: The results suggest that the airway inflammation caused by cotton dust increases with increasing exposure time and that the changes are more notable in workers with reactivity to cotton dust extract.

Adolescent↗
PubMed1989

Points that merit consideration in the diagnosis of retinoblastoma.

According to the clinical appearances and the characteristics of the onset of 86 Rb cases, some points in the diagnosis merit consideration: 1) Since the average symptomatic age was 21.75 months and the mean diagnostic age was 24.32 months, children under 3 years with leukocoria should be carefully examined, while adult Rb should not be neglected. 2) The primary symptom of Rb is mostly leukocoria, but Rb eyes without any symptoms or leukocoria (26 out of 105 eyes in our groups) might also be encountered. 3) 4 out of the 86 cases were retinocytoma which is supposed to be a type of Rb degeneration or benign Rb. 4) Attention should be paid to abnormalities and second primary tumors in Rb patients. 5) The pedigree investigations, twin method and laboratory studies in Rb such as chromosome analysis, EsD, LDH measurement and RFLP technique are useful in the prenatal diagnosis, early diagnosis and the diagnosis of the carriers.

Eye Neoplasms↗
PubMed1989

The ocular findings in glucose-6-phosphate dehydrogenase deficiency.

57 cases with G6PD deficiency and 62 with normal G6PD activities as controls in Chonghua County, Guangdong Province were examined in the respects of visual acuity, color vision, corneal sensitivity, lens, vitreous and fundus. The results showed that the incidences of congenital lenticular opacities and congenital color blindness in G6PD deficiency group were higher than those in the controls. However, there were no findings such as pale conjunctiva, sallow sclera, pallor papillae and macular edema, which could be seen frequently in patients with favism. The hemoglobin values of all the cases were within normal range, which indicated that the subjects with G6PD deficiency usually didn't manifest hemolysis but only had a hereditary susceptibility, and the ocular findings in favism might result from hemolytic anemia, tissue anoxia and unknown toxic substances from vicia faba.

Cataract↗
PubMed1989

The electroretinogram in Marfan's syndrome.

Marfan's syndrome (MS) is an inherited disease of connective tissue. The most characteristic ocular change is dislocation of lens, but myopia and retinal detachment also can occur. We examined 11 MS patients using electroretinography (ERG). 6 cases showed normal ERG. 5 cases had abnormal ERG. One had retinal detachment. 3 had myopia and 1 case suffered from secondary glaucoma. The defects of visual function were shown by electrophysiological test in those MS patients.

Adolescent↗
PubMed1989

Ocular survey of deaf-mute children.

Through routine ocular examination of 279 Deaf-mute students in Lie De School in Guangzhou in 1988 by visual chart, Yu Zi Ping Pseudoisochromatic plate, portable slit lamp and direct ophthalmoscope, 100 persons (35.8%) were found to have ocular defects in one or both eyes. The incidence of ocular defects was higher than that of the normal populations. Among the ocular abnormalities, fundus defects occupied 28.6%, error of refraction, 17.9%. 17.9% of the eyes had the vision lower than 1.0 and the error of refraction was the main cause. Cases of hereditary syndromes were found: Usher syndrome, 2 cases; Goldenhar syndromes, 2 cases (brother and sister); Waardenburg syndrome, 1 case; von Recklinghausen's syndrome, 1 case. In comparing with the other articles, the ocular defect, visual disturbance, error of refraction, way of examination as well as types and characteristics of some syndromes were briefly discussed. The importance of special examinations for diagnosis, early correction of refractive error, avoidance of consanguineal marriage among deaf-mutes were emphasized.

Adolescent↗
PubMed1989

Lymphocyte chromosome survey in 80 patients with retinoblastoma.

Cytogenetic analysis of eight cases of retinoblastoma patients was carried out to determine the occurrence of chromosome aberrations and to identify consistently associated clinical abnormalities. Among the 80 cases, 55 cases were unilateral, 25 cases were bilateral, seventy patients had a positive family history of Rb in 10 families. Normal chromosomes were found in 70 patients. Ten patients showed abnormal karyotypes: two cases of 13q deletion, one case of mosaicism of 13q deletion, one case of translocation between chromosomes 13 and 15 with the interstitial deletion of 13q, one case of 47, xxy, three cases of pericentric inversion of heteromorphic region of chromosome 9, two cases of pericentric inversion of chromosome Y. The patient who had the translocation between 13 and 5 with 13q deletion was found to have the characteristic midfacial appearance associated with 13q-deletion syndrome.

Adolescent↗
PubMed1989

[Iris nodules, ocular findings and blood grouping in neurofibromatosis].

Through the analyses of 22 cases of neurofibromatosis (NF) patient ranging from 3 months to 63 yrs. old. We found that 4 cases had bilateral hearing loss and 2 of them were excluded from acoustic neuroma. The ocular appearance showed lid neurofibroma in 12 cases, orbital bone abnormalities in 4 cases, iris nodules in 20 cases (90%), congenital glaucoma (4 eyes) in 3 cases which showed abnormal gonioscopy in 3 eyes, lens opacity in 2 cases, mild and moderate myopia in 8 eyes, and high myopia in 7 eyes, occupying 16% of the total. 11 cases belong to 5 pedigrees showing autosomal dominant inheritance. The ABO and MN blood grouping of the NF cases and families in the pedigree showed that NF was more related to ABO than MN blood group. The ocular appearance, especially the shape and number of iris nodules in relation to age and diagnosis is discussed. The significance of 1 case of retinitis pigmentosa, 7 cases of high myopia in relation with NF should be further studied.

Adolescent↗
PubMed1989

[Rubinstein-Taybi syndrome--a report of three cases].

The main features of Rubinstein-Taybi syndrome include special facial appearance, broad thumbs, great toes and mental retardation. This syndrome presents many organogenetic and systemic deformities and various congenital ocular abnormalities, such as epicanthus, antimogoloid palpebral fissures, highly arched eyebrows, long eyelashes, obstruction of nasolacrimal ducts, strabismus and iris coloboma. In this paper we report three children with Rubinstein-Taybi syndrome with the above systemic and ocular clinical findings, and think that the lacrimal abnormality should not be overlooked in this syndrome. We brief discuss the genetics of this syndrome and suggest that the search for minimal chromosomal defects by high resolution technique might be useful for etiologic and genetic research.

Chromosome Aberrations↗