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Biomedical subjects

X Cai

Publications and source records attributed to X Cai.

At least 181 records · Page 10Linked to original sources
PubMed1995

[A real-time analysis of 133 normal lens images by a computer].

According to the theory that the light scattering of the lens is correlated with the lens density, we designed a computerized system for the real-time analysis of the lens image. By measurement of the gray scale value of the lens optical section, the lens density is measured objectively and numerically. With the help of the system, 133 normal lens images were investigated. From the analysis of various age groups, we found that the grey scale values of the anterior cortex, posterior cortex and nucleus increase with the increase of age (P < 0.01), the grey scale values of the anterior and posterior cortex are significantly higher than the value of the nucleus (P < 0.05), but there is no significant difference between the values of the anterior and posterior cortex (P > 0.05), and there is also no significant difference in the comparisons of the grey scale values of the respective corresponding lens areas between the male and female.

Adolescent↗
PubMed1995

[The role of intestinal permeability in the pathogenesis of ankylosing spondylitis].

By use of low molecular weight polyethlene glycol (PEG400) as tracer, a revised Chedwick method with capillary gas chromatography was used to examine the intestinal permeability in 49 subjects including patients with ankylosing spondylitis (AS) and rheumatoid arthritis (RA) and healthy controls. Recovery percentage, maximal recovery percentage [Rmax(%)] and Rmax(w) were used to find the effect of bowel permeability in the pathogenesis and disease flare up of AS, as well as the role of HLA-B27 for the bowel permeability. The results showed that in AS group, the recovery of first component (242D) was higher and the Rmax(%) was lower than those in the controls. No statistical difference was found with other indexes. The results indicated that bowel permeability is not elevated in AS. The passage of enteral bacteria antigen into the host may not result from the process of nonspecific penetration. We postulate that there may somehow be a process of "active transportation" in the pathogenesis of AS. More studies of the process are necessary to clarify its importance in the early stage of AS.

Adult↗
PubMed1995

[A study on behavioural characteristics of staying on the mountain and its relationship with malaria infection in Li and Miao minorities in Hainan Province].

A study of sociology combined with epidemiology was conducted in Li Minority's two villages and Miao Minority's two villages nearby the foot of mountain in a historically malaria hyperendemic area, Nanqiao Township of Wanning County in August, 1993. The results showed that malaria infection was closely correlated to the behaviour of staying overnight on the mountain of Li and Miao Minorities during farming seasons. Most of Li people stayed overnight on the mountain for planting areca were adults, accounting for 21.6% of the whole population, the duration of stay was about half a year; Miao people stayed overnight on the mountain planting and harvesting upland rice, always with their family member, so the percentage of people who had stayed on the mountain was as high as 82.1%, the duration of stay was about one and half a month. Blood smear examination showed that the malaria parasite rates in both Li and Miao villages were 11.1% and 24.1%, respectively, the positive rate of P. falciparum was 1.0% and 9.1%, respectively, the positive rate of IFA (titer >or= 1 : 40) was 31.2% and 46.5%, respectively. It is indicated that both the rate of parasitaemia and the P. falciparum infection were much higher in Miao Minority than those in Li Minority (P < 0.001). A cohort analysis showed that the malaria parasite rate of population who having not stayed, having ever stayed and being stayed on the mountain was 6.5%, 27.4% and 42.1%, respectively, of them the rate of P. falciparum infection was 0.5%, 8.8% and 18.4%, respectively. The results suggest that malaria acquired from mountainous forest referring to "up-mountain infection" is a major source of malaria infection and a significant risk factor in determining the prevalence of malaria (especially falciparum malaria) in Hainan Province. This behavioural risk factor has become the main obstacle for malaria control in Hainan Province. Therefore, controlling "up-mountain infection" and adopting appropriate anti-malaria measures to protect the risk population who have to work and stay on the mountain should be strengthened in the malaria control program.

China↗
PubMed1995

[The study of correlation between hemorrheology and fluorescein angiography in open-angle glaucoma].

PURPOSE: To observe the correlation between hemorrheology and arm-retinal filling time of fluorescein angiogaphy in patients with primary open-angle glaucoma. METHODS: The whole blood apparent viscosity in high (125 S-1), moderate (23 S-1) and low (1.2435 S-1) shear rates, plasma viscosity and hematocrit were measured in 50 cases (50 eyes) with primary open-angle glaucoma whose intraocular pressures were controlled. They also underwent fluorescein angiography. The duration from arm to retina arteria filling was named arm-retinal arteria filling time. RESULTS: There were positive correlation between the whole blood apparent viscosity in high and moderate shear rates, hematocrit and arm-retinal arteria filling time (P < 0.05-0.005). The higher blood viscosity, the longer arm-retinal arteria filling time. CONCLUSION: The blood viscosity in patients with primary open-angle glaucoma can affect the arm-retinal arteria filling time of fluorescein angiography. So, the increasing blood viscosity in patients with primary open-angle glaucoma can reduce the blood supply to the optic disc.

Adolescent↗
PubMed1994

Localization of the gene (OGDH) coding for the E1k component of the alpha-ketoglutarate dehydrogenase complex to chromosome 7p13-p11.2.

alpha-Ketoglutarate dehydrogenase (E1k), also designated oxoglutarate dehydrogenase (OGDH; EC 1.2.4.2), is a component of the enzyme complex that catalyzes the conversion of alpha-ketogluterate to succinyl coenzyme A, a critical step in the Krebs tricarboxylic acid cycle. Deficiencies in the activity of this enzyme complex have been observed in brain and peripheral cells of patients with Alzheimer's disease. This finding led us to localize the genes for the polypeptides that compose the alpha-ketoglutarate dehydrogenase complex (KDGHC). The E1k locus was mapped to chromosome 7p13-p11.2 using a pair of human/rodent somatic cell hybrid panels. A second related sequence, possibly a pseudogene, was identified and mapped to chromosome 10.

Base Sequence↗
PubMed1994

Preimplantation embryo development enhanced by epidermal growth factor.

PURPOSE: Enhanced embryo maturity and advanced stages of cleavage at the time of embryo transfer are associated with superior pregnancy rates in in vitro fertilization procedures. This study was performed to assess the potential usefulness of epidermal growth factor (EGF) to enhance the development of murine preimplantation embryos cultured in vitro. Two-cell stage mouse embryos were cultured for 72 hr with EGF at concentrations of 0.1 to 100 ng/ml. The percentage of embryos which developed to the expanded and hatching blastocyst stage at 72 hr was determined. RESULTS: The percentage of fully expanded and hatching murine blastocysts at 72 hr was significantly higher following incubation with EGF at concentrations of 2 ng/ml (44 +/- 4.1%; P < 0.02), 20 ng/ml (41 +/- 3.2%; P = 0.04), 50 ng/ml (43 +/- 2.5%; P < 0.04), and 100 ng/ml (46 +/- 3.6%; P = 0.001) compared to controls. This effect of enhanced embryonic development by EGF was neutralized by coincubation with 1.0 micrograms/ml of anti-EGF antibody. CONCLUSION: EGF at concentrations of 2 to 100 ng/ml significantly enhanced the percentage of expanded and hatching murine blastocysts at 72 hr.

Animals↗
PubMed1994

Pseudogene of dihydrolipoyl succinyltransferase (E2k) found by PCR amplification and direct sequencing of rodent-human cell hybrid DNAs.

Previous studies have indicated that the cDNA for the E2k component of the human alpha-ketoglutarate dehydrogenase complex (KGDHC) hybridized not only to a major locus on chromosome 14q24.3 in a region associated with familial Alzheimer's disease and with Joseph-Machado disease, but also to another locus on chromosome 1p31. We now report that PCR of genomic DNA and direct sequencing indicated that the chromosome 1 locus is an intronless pseudogene. PCR of genomic DNA amplified E2k fragments from mouse-human cell hybrids containing human chromosome 1 DNA but not from hybrids containing human chromosome 14 DNA. The resulting amplicons were of comparable sizes to those when the cDNA was used as template. The direct sequencing of these amplicons confirmed the lack of introns and indicated a frame shift, which led to the presence of four termination codons early in the coding region. PCR followed by direct sequencing of the amplicons appears to be a convenient method for identifying intronless pseudogenes.

Acyltransferases↗
PubMed1994

Isolation, characterization, and mapping of gene encoding dihydrolipoyl succinyltransferase (E2k) of human alpha-ketoglutarate dehydrogenase complex.

We have isolated and sequenced cDNAs representing the full-length (2987-bp) gene for dihydrolipoyl succinyltransferase (E2k component) of the human alpha-ketoglutarate dehydrogenase complex (KGDHC) from a human fetal brain cDNA library. The E2k cDNA was mapped to human chromosome 14 using a somatic cell hybrid panel, and more precisely to band 14q24.3 by in situ hybridization. This cDNA also cross-hybridized to an apparent E2k pseudogene on chromosome 1p31. Northern analysis revealed the E2k gene to be ubiquitously expressed in peripheral tissues and brain. Interestingly, chromosome 14q24.3 has recently been reported to contain gene defects for an early-onset form of familial Alzheimer's disease and for Machado-Joseph disease. Future studies will be necessary to determine whether the E2k gene plays a role in either of these two disorders.

Acyltransferases↗
PubMed1994

Expression and purification of recombinant polyomavirus VP2 protein and its interactions with polyomavirus proteins.

Recombinant polyomavirus VP2 protein was expressed in Escherichia coli (RK1448), using the recombinant expression system pFPYV2. Recombinant VP2 was purified to near homogeneity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electroelution, and Extracti-Gel chromatography. Polyclonal serum to this protein which reacted specifically with recombinant VP2 as well as polyomavirus virion VP2 and VP3 on Western blots (immunoblots) was produced. Purified VP2 was used to establish an in vitro protein-protein interaction assay with polyomavirus structural proteins and purified recombinant VP1. Recombinant VP2 interacted with recombinant VP1, virion VP1, and the four virion histones. Recombinant VP1 coimmunoprecipitated with recombinant VP2 or truncated VP2 (delta C12VP2), which lacked the carboxy-terminal 12 amino acids. These experiments confirmed the interaction between VP1 and VP2 and revealed that the carboxyterminal 12 amino acids of VP2 and VP3 were not necessary for formation of this interaction. In vivo VP1-VP2 interaction study accomplished by cotransfection of COS-7 cells with VP2 and truncated VP1 (delta N11VP1) lacking the nuclear localization signal demonstrated that VP2 was capable of translocating delta N11VP1 into the nucleus. These studies suggest that complexes of VP1 and VP2 may be formed in the cytoplasm and cotransported to the nucleus for virion assembly to occur.

Animals↗
PubMed1994

Purification of recombinant budgerigar fledgling disease virus VP1 capsid protein and its ability for in vitro capsid assembly.

A recombinant system for the major capsid VP1 protein of budgerigar fledgling disease virus has been established. The VP1 gene was inserted into a truncated form of the pFlag-1 vector and expressed in Escherichia coli. The budgerigar fledgling disease virus VP1 protein was purified to near homogeneity by immunoaffinity chromatography. Fractions containing highly purified VP1 were pooled and found to constitute 3.3% of the original E. coli-expressed VP1 protein. Electron microscopy revealed that the VP1 protein was isolated as pentameric capsomeres. Electron microscopy also revealed that capsid-like particles were formed in vitro from purified VP1 capsomeres with the addition of Ca2+ ions and the removal of chelating and reducing agents.

Animals↗
PubMed1994

[Assessment of coronary flow reserve in patients with angina pectoris].

Coronary flow reserve was assessed by using a computer-assisted method in 26 normal controls and 45 patients with significant coronary artery stenosis ( > or = 50% luminal narrowing) and 16 patients with syndrome X. After intracoronary administration of papaverine, the diameter, cross sectional area, blood velocity, flow volume and reserve capacity of both left anterior descending (LAD) and right coronary arteries (RCA) were lower in patients with significant coronary stenosis than in controls. Despite similar changes in the diameter and cross sectional area, the velocity, flow volume and reserve capacity of these two vessels were also lower in patients with syndrome X than in controls. We conclude that coronary flow reserve is reduced in patients with coronary artery stenosis or syndrome X due to different levels of coronary artery abnormalities.

Angina Pectoris↗
PubMed1994

[The Cantonese dialect and mandarin speech audiometric software for computerized audiometer--a preliminary report of exploratory research].

The operation of computerized audiometer depends on softwares. Cassette tapes recorded with 4 Cantonese dialect and 6 Mandarin word lists, both monosyllables and spondees edited and recorded by the author in 1986 were utilized as an original sound source. Each Chinese character and its standard voice were re-edited and saved in computer by means of a Mac digitizing recorder and other computer technic to make a new software. The software is saved in seven 3.5" 2MB floppy dicks. Another copy now is saved in the hardware of a Virtual 320 audiometer at ENT department of Guangdong Provincial Traditional Medical Hospital for further quality checkout and clinical trials. It seems that the quality of this software mostly meets the requirements on recorded speech material suggested by ISO/CD 8253-3 1990.

Audiometry, Speech↗
PubMed1993

Characterization of the DNA binding properties of polyomavirus capsid protein.

The DNA binding properties of the polyomavirus structural proteins VP1, VP2, and VP3 were studied by Southwestern analysis. The major viral structural protein VP1 and host-contributed histone proteins of polyomavirus virions were shown to exhibit DNA binding activity, but the minor capsid proteins VP2 and VP3 failed to bind DNA. The N-terminal first five amino acids (Ala-1 to Lys-5) were identified as the VP1 DNA binding domain by genetic and biochemical approaches. Wild-type VP1 expressed in Escherichia coli (RK1448) exhibited DNA binding activity, but the N-terminal truncated VP1 mutants (lacking Ala-1 to Lys-5 and Ala-1 to Cys-11) failed to bind DNA. The synthetic peptide (Ala-1 to Cys-11) was also shown to have an affinity for DNA binding. Site-directed mutagenesis of the VP1 gene showed that the point mutations at Pro-2, Lys-3, and Arg-4 on the VP1 molecule did not affect DNA binding properties but that the point mutation at Lys-5 drastically reduced DNA binding affinity. The N-terminal (Ala-1 to Lys-5) region of VP1 was found to be essential and specific for DNA binding, while the DNA appears to be non-sequence specific. The DNA binding domain and the nuclear localization signal are located in the same N-terminal region.

Amino Acid Sequence↗
PubMed1993

Polymorphous ventricular tachycardia after intracoronary papaverine: a report of 3 cases.

Three cases with polymorphous ventricular tachycardia following a standard dose of intracoronary papaverine during 102 measurements of coronary flow reserve are reported. This study suggests that all patients should be closely monitored while receiving intracoronary papaverine and that extreme caution should be employed when the drug is administered to patients with QT interval prolongation and poor coronary flow reserve.

Adult↗
PubMed1993

Alternatively spliced fibronectin molecules in the wounded cornea: analysis by PCR.

PURPOSE: To determine whether certain fibronectin isoforms participate in corneal epithelial wound healing, the authors used the polymerase chain reaction to detect different splicing patterns of the EIIIA segment of fibronectin mRNA in epithelial scrape-wounded cornea of rats. METHODS: Specific fibronectin cDNA sequences synthesized from rat cornea with total RNA were amplified with various sets of synthetic oligonucleotide primers. RESULTS: The authors detected both the EIIIA+ and EIIIA- fibronectin mRNA isoforms during corneal wound healing. The kinetics of corneal expression of both total fibronectin mRNA and the EIIIA- fibronectin mRNA isoform was polyphasic; an initial decrease was followed by an increase at 45 minutes, a second increase at 2 hours, and a third increase at 4 days after wounding. EIIIA+ fibronectin mRNA, not found in normal cornea, also was detected during healing. CONCLUSIONS: The expression of total fibronectin mRNA and both the EIIIA+ and EIIIA- fibronectin mRNA is upregulated during corneal epithelial wound healing. The expression of EIIIA+ fibronectin mRNA during wound healing, a fibronectin isoform that was highly expressed in embryonic tissue, suggests that this fibronectin isoform is involved functionally in corneal wound healing.

Alternative Splicing↗
PubMed1992

Expression of yeast hexokinase in pancreatic beta cells of transgenic mice reduces blood glucose, enhances insulin secretion, and decreases diabetes.

It has been proposed that endogenous hexokinases of the pancreatic beta cell control the rate of glucose-stimulated insulin secretion and that genetic defects that reduce beta-cell hexokinase activity may lead to diabetes. To test these hypotheses, we have produced transgenic mice that have a 2-fold increase in hexokinase activity specific to the pancreatic beta cell. This increase was sufficient to significantly augment glucose-stimulated insulin secretion of isolated pancreatic islets, increase serum insulin levels in vivo, and lower the blood glucose levels of transgenic mice by 20-50% below control levels. Elevation of hexokinase activity also significantly reduced blood glucose levels of diabetic mice. These results confirm the role of beta-cell hexokinase activity in the regulation of insulin secretion and glucose homeostasis. They also provide strong support for the proposal that reductions in beta-cell hexokinase activity can produce diabetes.

Animals↗