Biomedical subjects

S Gao

Publications and source records attributed to S Gao.

At least 91 records · Page 5Linked to original sources

PubMed2000

Microchimerism and rejection: a meta-analysis.

AIMS: To study the relationship between graft rejection and microchimerism with and without donor bone marrow infusion in recipients of kidney, liver, heart and lung transplants. Selection of manuscripts. Thirty-seven manuscripts presenting clinical data on microchimerism and rejection, published between 1991 and 1997, were identified. Of these, 16 were excluded due to duplication or insufficient data. Inclusion criteria were data on microchimerism, bone marrow infusion and rejection episodes. STATISTICAL TESTS: A mixed effect logistic model was used to test for homogeneity of transplant centers. The centers were found to be homogeneous for rejection rates controlling for microchimerism and bone marrow infusion. Using rejection episodes at 3, 6, and 12 months post-transplant as the outcome, we evaluated logistic regression models to derive odds ratios for rejection with microchimerism and with bone marrow infusion for each organ. RESULTS: Microchimerism was generally associated with a higher incidence of acute rejection for heart, lung, and kidney transplants and a lower incidence for liver transplants, especially at 12 months and above. Bone marrow infusion decreased the risk of acute rejection for heart transplants and increased the risk for lung and, to a lesser extent, for liver transplants. No consistent effect was seen in kidney transplants. At 12 months and longer, microchimerism was associated with a decreased incidence of chronic rejection in recipients of lung transplants, but there were insufficient data to determine this outcome for other organs. CONCLUSIONS: (i) Microchimerism was detected in the majority of patients. (ii) The effect of microchimerism and bone marrow infusion on rejection episodes varied with the organ and, for a given organ, it was time-dependent. (iii) These findings demonstrate the need for more extensive studies on microchimerism and donor-specific hyporesponsiveness.

Graft Rejection↗

PubMed2000

Pro- and macroglycogenolysis in contracting rat skeletal muscle.

Glycogen is present in skeletal muscle in smaller acid-insoluble proglycogen particles and larger acid-soluble macroglycogen particles. The present study was designed to investigate the relative contribution of pro- and macroglycogen to glycogenolysis during muscle contractions. Rats were subjected to a glycogen-depleting exercise bout and refed with either a carbohydrate-rich or fat-rich diet, resulting in widely different muscle glycogen contents. The following day, isolated hindlimbs were perfused and electrically stimulated to contract for 10 min. Pre- and postcontraction muscle samples of soleus, white and red gastrocnemius were analysed for pro- and macroglycogen. Contractions caused significant reductions in both pro- and macroglycogen in all glycogen groups and muscle types. In glycogen-supercompensated gastrocnemius muscles, the relative utilization of macroglycogen was significantly higher than the relative utilization of proglycogen. In muscles with normal to low initial glycogen contents, proglycogen was much more abundant than macroglycogen and therefore contributed more to glycogenolysis in absolute numbers. In conclusion, both proglycogen and macroglycogen are suitable substrates during skeletal muscle contractions, although macroglycogen, when amply available, seems to be more easily broken down. This may provide an explanation for the dependence of the glycogenolytic rate on the total muscle glycogen content.

Animals↗

PubMed2000

Epidemiology of dementia in Nigeria: results from the Indianapolis-Ibadan study.

We determined the prevalence of dementia in a cohort of 2494 elderly Nigerians residents in Idikan Community, Ibadan, Nigeria. We utilized the Community Screening Instrument for Dementia to select subjects for clinical assessment in the second stage. The findings were compared with those of 2212 African Americans living in Indianapolis, studied simultaneously using similar methodology. The overall age-adjusted prevalence rates of dementia and Alzheimer's disease in Ibadan were 2.29% and 1.41%, respectively. These rates were much lower than the respective values of 8.24% and 6.24% obtained for African Americans. In Ibadan, Alzheimer's disease accounted for 64.3% of the cases, with old age and female gender being the significant risk factors, whilst 'living with others' appeared to be protective (P < 0.05). Amongst African Americans, on the other hand, old age, rural living below the age of 19 years, low educational attainment and family history of dementia were the risk factors. There was a lack of association between Alzheimer's disease and possession of the apolipoprotein E epsilon4 allele in the Nigerian sample, unlike the finding in African Americans, where significant association was shown. In addition, the frequencies of the vascular risk factors investigated were lower in Nigerians. Our results showed lower prevalence of dementia and Alzheimer's disease in Nigerians, compared with African Americans. There was no association between Alzheimer's disease and apolipoprotein E (epsilon4 allele) in the former. The differences in the frequencies of vascular risk factors between Nigerian subjects and African Americans would suggest involvement of environmental factors in disease process.

Age Factors↗

PubMed2000

Hepatocyte encapsulation for enhanced cellular functions.

An efficient bioartificial liver-assisted device can sustain the lives of patients with acute liver failure. Among different configurations of the bioreactor design, hepatocyte encapsulation has important features that satisfy most requirements of the device. We have encapsulated rat hepatocytes in a two-layer polymeric membrane by complex coacervation using a simple setup and demonstrated enhanced cellular functions up to three times higher than those of the monolayer control. These microcapsules of the functioning hepatocytes have a 2- to 3-microm outer layer of synthetic polymer with 25% 2-hydroxyethyl methacrylate, 25% methacrylic acid, and 50% methyl methacrylate and an inner layer of positively charged modified collagen as a suitable substrate for the enhanced cellular functions. Permeable only to small molecules up to albumin, the microcapsules should allow unimpeded exchange of nutrients, oxygen, growth factors, and metabolites but prevent attack by immunoglobulins of the immune system, and no "skin effect" of the collagen has been observed. Mechanical properties of the microcapsules measured with a nano-indentation method suggest that the microcapsules should be suitable for use in a bioartificial liver-assisted device.

Animals↗

PubMed2000

Distinctive functions of Syk N-terminal and C-terminal SH2 domains in the signaling cascade elicited by oxidative stress in B cells.

Syk plays a crucial role in the transduction of oxidative stress signaling. In this paper, we investigated the roles of Src homology 2 (SH2) domains of Syk in oxidative stress signaling, using Syk-negative DT40 cells expressing the N- or C-terminal SH2 domain mutant [mSH2(N) or mSH2(C)] of Syk. Tyrosine phosphorylation of Syk in cells expressing mSH2(N) Syk after H(2)O(2) treatment was higher than that in cells expressing wild-type Syk or mSH2(C) Syk. The tyrosine phosphorylation of wild-type Syk and mSH2(C) Syk, but not that of mSH2(N), was sensitive to PP2, a specific inhibitor of Src-family protein-tyrosine kinase. In oxidative stress, the C-terminal SH2 domain of Syk was demonstrated to be required for induction of tyrosine phosphorylation of cellular proteins, phospholipase C (PLC)-gamma2 phosphorylation, inositol 1,4, 5-triphosphate (IP(3)) generation, Ca(2)(+) release from intracellular stores, and c-Jun N-terminal kinase activation. In contrast, in mSH2(N) Syk-expressing cells, tyrosine phosphorylation of intracellular proteins including PLC-gamma2 was markedly induced in oxidative stress. The enhanced phosphorylation of mSH2(N) Syk and PLC-gamma2, however, did not link to Ca(2)(+) mobilization from intracellular pools and IP(3) generation. Thus, the N- and C-terminal SH2 domains of Syk possess distinctive functions in oxidative stress signaling.

Animals↗

PubMed2000

catena-Poly

Explore the source record for details and available documents.

Journal Article↗

PubMed2000

The association between vascular risk factor-mediating medications and cognition and dementia diagnosis in a community-based sample of African-Americans.

OBJECTIVE: To determine the association between medications that ameliorate vascular risk factors and the prevalence of cognitive impairment and dementia in an older African-American population. DESIGN: A community-based survey to identify subjects with and without evidence of cognitive impairment and subsequent diagnostic evaluation of a stratified sample of these subjects using formal diagnostic criteria for dementia and Alzheimer's disease (AD). SETTING: Urban neighborhoods in Indianapolis, Indiana. SUBJECTS: A random sample of 2,212 African-American adults aged 65 years and older residing in 29 contiguous census tracts. MEASUREMENTS: Subjects' scores on the Community Screening Instrument for Dementia (CSID), formal diagnostic and clinical assessments for dementia, current medication use and history of medical illnesses, both self-report and, where possible, from an informant. Four outcome measures were defined by the following criteria: (1) cognitive impairment as defined by the subject's performance on the CSID cognitive scale; (2) cognitive/ functional impairment as defined by the total CSID score that included a relative's assessment of the subject's functional abilities; (3) dementia as defined by explicit diagnostic criteria; and (4) possible or probable Alzheimer's Disease as defined by explicit criteria. RESULTS: The vascular risk factor mediating medications, when analyzed together, were associated with a significantly decreased risk of diagnosis of cognitive impairment after controlling for age, education, and stroke (OR 0.73, P = .01) and also a significantly decreased risk of cognitive/functional impairment (OR 0.66, P = .02). Antihypertensive agents, excluding centrally acting sympatholytic drugs were associated with a significantly reduced risk of diagnosis of cognitive impairment (OR 0.56, P < .01) and cognitive/functional impairment (OR 0.64, P = .01). Centrally acting sympatholytic agents were associated with an increased risk of diagnosis of cognitive impairment (OR 2.24, P < .01). There was a trend toward protection from a diagnosis of AD and dementia for the vascular risk factor mediating medications and for the antihypertensive medication, but this did not reach significant levels. CONCLUSIONS: These data suggest that the use of medications to ameliorate vascular risk factors, particularly antihypertensive medication, may also be useful in reducing the risk of cognitive impairment in older subjects. However, they also suggest that physicians should be cautious in prescribing antihypertensive drugs with centrally acting sympatholytic properties to older subjects.

Aged↗

PubMed2000

The association of demographic factors and physical illness with personality change in a community sample of elderly African Americans.

In a community-based dementia study of African Americans age 65 and older living in Indianapolis, key informants were asked to assess the types of personality change in all subjects. Information was also collected on demographic factors, cognitive functioning, physical well-being, and medical illness. Twenty-nine percent of subjects without dementia had reported personality change. Reports of personality change were significantly associated with being male, having poor daily functioning scores, suffering from physical disability, and having a history of cancer.

Activities of Daily Living↗

PubMed2000

[Chromosome localization of the dentinogenesis imperfecta type II locus].

OBJECTIVE: To scrutinize the linkage between dentinogenesis imperfecta type II and chromosome 4q21 in a Tianjin-Tanggu family. METHODS: Blood samples were collected from 13 members of the family. DNA was analyzed with 4 short tandem repeat polymorphisms markers UGATA62A11, DSP(P), SPP1 and D4S1563 Y using fluorescence-based PCR. The linkage between four markers on chromosome 4q21 and dentinogenesis imperfecta type II was tested by Lod score analysis. RESULTS: GATA62A11 and DSP(P) suggested linkage and yielded a Lod score of 1.63 at theta =0, and 1.68 at theta =0 by means of the MLINK software, respectively. Genotype and haplotype were acquired. CONCLUSION: The disease gene of the dentinogenesis imperfecta type II family is located on chromosome 4q. The result will be helpful for the further identification of the dentinogenesis imperfecta type II gene.

Chromosome Mapping↗

PubMed2000

[The realization methods of 3D ultrasonic blood flow mapping].

3D ultrasonic blood flow mapping has undergone significant technological refinements in image acquisition, signal processing and display techniques since its introduction in 1982. This paper describes the realization methods of 3D ultrasonic blood flow mapping systems. The performances of different systems are evaluated from the views of 3D localization, design of wall filters, velocity estimation and 3D visualization.

Blood Flow Velocity↗

PubMed2000

[The software method for cross-talk correction in ultrasound Doppler blood flow measurement].

The cross-talk in ultrasound Doppler measurement will lead to wrong decision in clinical diagnosis. In order to reduce cross-talk, the software method for cross-talk correction was presented in this paper. The cross-talk error was obtained by signal correlation technique first, the correction for blood flow signal was then realized. Simulation results prove that the software method can be used to correct cross-talk error well. It is a promising method.

Blood Flow Velocity↗

PubMed2000

Assessment of trigeminal somatosensory evoked potentials in burning mouth syndrome.

OBJECTIVE: The measurement of pain threshold (PT) and the assessment of trigeminal somatosensory evoked potentials (TSEPs) were performed. These experiments indicated the pathological conditions of nerve afferent and efferent pathways in patients with burning mouth syndrome (BMS). This study also explored the probable pathophysiological mechanisms in BMS. MATERIALS AND METHODS: The dorsum linguae of 38 samples in 19 subjects (22 BMS with pain, 10 BMS with numbness, and 6 controls) were stimulated by electroneuromyography. PT was measured as the lowest stimulation intensity the subjects could detect. N3, P4 latency, and spike potential latency of TSEP were recorded by stimulating the lingual nerve. RESULTS: Pain thresholds were significantly lower, N3, P4 latencies were significantly shorter, and the spike potential appeared earlier in the BMS with pain group (P < 0.01). The opposite tendency of these values presented in the BMS with numbness group (P > 0.05). CONCLUSIONS: The results indicated that the nerve sensitivity was elevated in the BMS with pain group, and that these patients were easily affected by etiological factors. In the BMS with numbness group, partial or complete nerve blockage may have been indicated. This study suggested that selfreports of BMS pain appeared to be of value, and that there were pathological conditions in nerve transmission. It supported the theory that peripheral or central nervous system involvement might play an important role in BMS. It was possible to show the pathogenesis of BMS. All of these objectively explain the clinical understanding of BMS, and may be of assistance in the treatment of BMS.

Afferent Pathways↗

PubMed2000

Eosinophilic ulcer of the oral mucosa: a clinicopathological analysis.

OBJECTIVE: To explore the clinical characteristics, histologic features, method of treatment, and possible etiology of eosinophilic ulcer of the oral mucosa. METHOD: Eight cases of eosinophilic ulcer of the oral mucosa were analyzed. RESULTS: In all cases, the ulcer site was the tongue. Ulcers were unifocal, had a benign course, and three of patients had a history of EUOM recurrence. Pathological features showed an extensive inflammatory cell infiltration, with predominantly eosinophilic cells throughout the submucosa. All ulcers were treated with either conservative excision or incisional biopsy. CONCLUSIONS: Eosinophilic ulcer is a rare, self-limiting benign disease that often appears in older adults or children. Its etiology remains obscure and may be associated with traumatic factors. This study provides useful information on clinical and pathological features, diagnosis, treatment, and prognosis, as well as the possible etiology of this disease.

Adolescent↗

PubMed2000

[Mature time demarcation of human immature myocardium].

OBJECTIVE: To study the mature time demarcation of human immature myocardium. METHODS: The morpho-ultrastructure, calcium metabolism, energy metabolism and oxygen free radicals metabolism of myocardium of children with ventricular septal defect without pulmonary hypertension or any clinical symptoms were studied at different ages. RESULTS: The immature myocardium possessed its own structure and functional characteristics. Before viripotent period, the age-related myocardial changes developed progressively to mature and almost approached to mature levels at 6-9 years old. The indices of immature myocardium developing to mature levels were inconsistent. CONCLUSION: The structure and function of human immature myocardium approaches to mature levels at 6-9 years old.

Adolescent↗

PubMed2000

[Studies on chemical constituents from the flower of Albizzia julibrissin Durazz].

OBJECTIVE: To study the chemical constituents in the flower of Albizzia julibrissin. METHOD: Chromatographic and spectroscopic analyses were used to isolate and elucidate the chemical constituents in the plant. RESULT: Two compounds were isolated from the petroleum ether and ethyl acetate fractions of the flower and identified as tetracosanoic acid and quercitrin. CONCLUSION: These two compounds were obtained from the plant for the first time.

Albizzia↗

PubMed2000

[Cloning and expression of Shiga-like toxin type II variant B gene of E. coli].

A structure sequence and a DNA fragment including the signal peptide sequence and structure sequence of Shiga-like toxin II variant B subunit gene were amplified from E. coli strain O138 by PCR. After digested with restriction endonuclease EcoRI and BamHI, the two genes were orientally inserted into the polycloning site of expression vector pYA3334 (asd+) respectively. Recombinant plasmids pB0 and pB1 were constructed and amplified in E. coli X6212 (asd-). pB0 and pB1 were then introduced into avirulent Salmonella typhimurium vaccine strain X4550 (asd-) by serial transformation through intermediate strain X3730 (asd-) to construct recombinant SLT-IIvB strain. Results of nucleotide sequencing of the cloned fragments in pB0 and pB1 revealed that they were in correct ORF of SLT-IIvB. The results of SDS-PAGE and Western-blot showed that 7.6 kD protein of SLT-IIvB antigen was expressed at pretty high level in recombinant strain X4550(pB0). The results of mice immunization indicated X4550(pB0) could initiate the host to produce specific antibodies to SLT-IIvB and LPS-O antigen of X4550. So the recombinant strain X4550 (pB0) is worth considering as a candidate vaccine strain against porcine edema disease and Salmonella typhimurium infections.

Animals↗

PubMed1999

Self-assembly of DNA-streptavidin nanostructures and their use as reagents in immuno-PCR.

The self-assembly of bis-biotinylated double-stranded DNA and the tetravalent biotin-binding protein streptavidin (STV) have been studied by non-denaturing gel electrophoresis and atomic force microscopy (AFM). The rapid self-assembly reproducibly generated populations of individual oligomeric complexes. Most strikingly, the oligomers predominantly contained bivalent STV molecules bridging two adjacent DNA fragments to form linear nanostructures. Trivalent STV branch points occurred with a lower frequency and the presence of tetravalent STV was scarce. However, valency distribution, size and the exchange dynamics of the supramolecular aggregates were highly sensitive to stoichiometric variations in the relative molar coupling ratio of bis-biotinylated DNA and STV. The largest aggregates were obtained from equimolar amounts while excess STV led to the formation of smaller oligomers appearing as fingerprint-like band patterns in electrophoresis. Excess DNA, however, induces a complete breakdown of the oligomers, likely a consequence of the instability of STV conjugates containing more than two biotinylated DNA fragments. It was demonstrated that the oligomers can further be functionalized, for instance by the coupling of biotinylated immunoglobulins. Both pure and also antibody-modified DNA-STV oligomers were used as reagents in immuno-PCR (IPCR), a highly sensitive detection method for proteins and other antigens. Employment of the supramolecular reagents led to an approximately 100-fold enhanced sensitivity compared to the conventional IPCR procedure.

Base Sequence↗

PubMed1999

Building fluorescent sensors by template polymerization: the preparation of a fluorescent sensor for D-fructose.

[formula: see text] The application of molecular imprinting in making fluorescent sensors has been hampered by the lack of suitable fluorescent tags, which would respond to the binding event with significant fluorescence intensity changes. We have designed and synthesized a fluorescent monomer which allows for the preparation of fluorescent sensors of cis diols using molecular imprinting methods. This monomer was used for the preparation of sensitive fluorescent sensors for D-fructose.

Fluorescent Dyes↗