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Biomedical subjects

Q Zhang

Publications and source records attributed to Q Zhang.

At least 973 records · Page 54Linked to original sources
PubMedDate not supplied

Pharmacokinetics of recombinant human basic fibroblast growth factor in mice using a radioiodination method combined with SDS-PAGE and a sandwich enzyme-linked immunosorbent assay.

Pharmacokinetics of recombinant human basic fibroblast growth factor (rhbFGF) in mice were studied by using a radioiodination method combined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and a sandwich enzyme-Linked immunosorbent assay (ELISA). RhbFGF concentration in serum were dertermined after iv administration of 2.5, 5 and 10 microg/kg of 125I-rhbFGF or rhbFGF. The AUCs were linearly correlated to doses. Concentrations in tissues, recoveries of 125I-rhbFGF in urine and feces were also analyzed following iv dose of 5 microg/kg. Pharmacokinetic profiles of radiolabelled and unlabelled rhbFGF were consistent in trend but exit certain differences. Mice cleared unlabeled rhbFGF markedly faster than their radiolabeled counterparts.

Animals↗
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Pharmacokinetics of Astragaloside IV in rats by liquid chromatography coupled with tandem mass spectrometry.

Pharmacokinetics of Astragaloside IV (AGS-IV) in rats was studied by high performance liquid chromatography coupled with tandem mass spectrometry. The concentration in plasma was determined after i.v. administration of 1, 2, 4 mg/kg and p.o. administration of 20 mg/kg of AGS-IV. The AUC were linearly correlated to doses. Recoveries of AGS-IV in bile, urine and feces were also analyzed following i.v. dose of 2 mg/kg. Cumulative recovery of AGS-IV in bile reached 30.8% in 24h. Cumulative recovery of AGS-IV in urine and feces was 52.14%, which indicates that about 50% of AGS-IV was metabolized in vivo. The bioavailability of AGS-IV after p.o. administration was found to be 3.66%. These findings provide useful information for the research and development of AGS-IV and other potential agents.

Administration, Oral↗
PubMedDate not supplied

Inquiring into indicators and origin of catastrophic events at stratigraphic boundaries.

Since 1982, numerous indicators of catastrophic events have been observed at the main stratigraphic boundaries in China during the Phanerozoic, i.e. Precambrian-Cambrian, Permian-Triassic, Cretaceous-Tertiary as well as Ordovician-Silurian and Devonian-Carboniferous boundaries. These markers are boundary clay layer, microspherules, high Ir anomaly, mass extinction of organisms and impact of meteorite. We support the hypothesis of the extraterrestrial origin of catastrophic events and suggest that the events at different stratigraphic boundaries might be different in features and processes.

Aluminum Silicates↗
PubMedDate not supplied

Correlation of gene structure and psychophysical measurement in red-green color vision deficiency in Chinese.

PURPOSE: To study the correlation of genotype for X-linked red-green gene array with color vision phenotype in 58 subjects with red-green color vision deficiency. METHODS: The molecular structure of red and green pigment genes on 58 X chromosomes was studied exon-by-exon by using heteroduplex-SSCP analysis and sequencing. The color vision of these subjects was determined by a Neitz anomaloscope. RESULTS: Variations in the red and green pigment genes were detected in 43 subjects and a hybrid gene was found in 27 subjects. About 50% of the fusion sites occurred at intron 2-3. All 3 anomalous trichromats with intron 4 fusion were mild type but another 3 with intron 2-3 fusion were severe type. No subjects with mild type of color vision defects had a fusion site at intron 2-3 or its upstream. Three subjects with complete deletion of the green pigment gene manifested deuteranomaly. CONCLUSIONS: Protans can be differentiated from deutans on the basis of genotype. It is still difficult to establish a clear correlation of different anomalous trichromats with genotype. The fusion site of a hybrid gene affects the phenotype to some degree. Intron 2-3 is the common place for gene crossover.

Blotting, Southern↗
PubMedDate not supplied

Iron deficiency decreases dopamine D1 and D2 receptors in rat brain.

Iron deficiency (ID) in early life is known to alter neurological development and functioning, but data regarding specific effects on dopamine biology are lacking. The objective of this study was to determine the extent of functional alterations in dopamine receptors in two dopaminergic tracts in young, growing, iron-deficient rats. Forty male and 40 female weanling Sprague-Dawley rats were fed either an iron-deficient (ID) diet or control (CN) diet for 6 weeks. ID decreased densities of D(1) and D(2) receptors in the caudate-putamen and decreased D(2) receptor densities in the nucleus accumbens. There were no apparent effects of ID on the affinities for the ligands in either receptor in several brain regions. In situ hybridization studies for both dopamine receptors revealed no significant effect of ID on mRNA expression for either receptor. Iron-deficient rats had a significantly higher ED(50) for raclopride-induced hypolocomotion in male and female rats compared to control rats of each sex. The loss of iron in the striatum due to dietary ID was significantly correlated with the decrease in D(2) receptor density; however, this relationship was not apparent in other brain regions. These experiments thus demonstrate abnormal dopamine receptor density and functioning in several brain regions that are related to brain regional iron loss. Importantly, the impact of ID on dopamine was more pronounced in males than females, demonstrating sex-related different sensitivities to nutrient deprivation.

Animals↗
PubMedDate not supplied

Outgrowing schwannomas arising from tympanic segments of the facial nerve.

PURPOSE: Although there have been numerous reports of clinical cases of facial nerve schwannoma, histopathologic studies of its early stages of development are rare. The purpose of this study was to describe the incidence, origin, and pathology of small, asymptomatic schwannomas of the facial nerve. MATERIALS AND METHODS: Fifteen hundred twenty-six ears from the human temporal bone collection of the Otitis Media Research Center Otopathology Laboratory at the University of Minnesota were studied under light microscopy. RESULTS: Twelve bones with morphologic indications of type A Antoni tissue that mimics facial schwannoma in the tympanic cavity were selected. The 12 ears were from nine individuals with asymptomatic histories. The twelve schwannomas developed from perineurium at dehiscences in the facial canal near the oval window, forming defects in the epineurium by growth of Schwann cells downward and outward toward the stapes. No obvious compressions or lesions within fibers in the facial nerve were observed. CONCLUSION: Because these tumors grow slowly without hearing loss or facial nerve symptoms, they may be mistaken for granulation tissue during surgery for chronic otitis media.

Adult↗
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Independent amplification of two classes of Tourists in some Oryza species.

Transposable elements similar to Tourist elements from maize were isolated from the rice genome. The elements were about 300 bp, exhibited short terminal inverted repeats (TIR), and appeared to show preferential insertion at TAA sites. Some rice Tourist elements seem to have recently transposed. Based on the sequences of cloned elements, two classes of rice Tourist elements have been identified. Members of these two classes apparently amplified independently at different times in the past.

Base Sequence↗
PubMedDate not supplied

Strategies for identification of mutations causing hereditary retinal diseases in dogs: evaluation of opsin as a candidate gene.

Progressive retinal atrophy (PRA), like retinitis pigmentosa (RP) in man, represents a clinical classification grouping together a variety of hereditary diseases of the visual cells which have broadly similar clinical characteristics. At least six distinct autosomal recessive and one X-linked retinal disease locus have been identified. As one of the strategies to look for the gene defect causing the different forms of PRA, we are examining first the most promising candidate genes. These include those coding for photoreceptor-specific structural proteins and enzymes of the phototransduction pathway, especially those reported to cause RP. Preeminent among these candidates is the gene for rod opsin, in which multiple causative mutations have been identified in both dominant and recessive forms of RP. In addition, mutations in this gene are also causally associated with congenital stationary night blindness (CSNB) in man. We have used two strategies to examine the rod opsin gene for association with inherited retinal disease in dogs: (1) linkage to determine cosegregation of the disease locus with an intragenic polymorphic marker in the opsin gene in those breeds where suitable informative pedigrees were available; and (2) scanning the coding sequence of the gene in cases where only a limited number of affected or obligate heterozygous samples were available for a breed. We conclude that mutations in the rod opsin gene are not associated with PRA or CSNB in the 11 different dog breeds tested.

Animals↗
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Photoreceptor dysplasia (pd) in miniature schnauzer dogs: evaluation of candidate genes by molecular genetic analysis.

Photoreceptor dysplasia (pd) is one of a group of at least six distinct autosomal and one X-linked retinal disorders identified in dogs which are collectively known as progressive retinal atrophy (PRA). It is an early onset retinal disease identified in miniature schnauzer dogs, and pedigree analysis and breeding studies have established autosomal recessive inheritance of the disease. Using a gene-based approach, a number of retina-expressed genes, including some members of the phototransduction pathway, have been causally implicated in retinal diseases of humans and other animals. Here we examined seven such potential candidate genes (opsin, RDS/peripherin, ROM1, rod cGMP-gated cation channel alpha-subunit, and three subunits of transducin) for their causal association with the pd locus by testing segregation of intragenic markers with the disease locus, or, in the absence of informative polymorphisms, sequencing of the coding regions of the genes. Based on these results, we have conclusively excluded four photoreceptor-specific genes as candidates for pd by linkage analysis. For three other photoreceptor-specific genes, we did not find any mutation in the coding sequences of the genes and have excluded them provisionally. Formal exclusion would require investigation of the levels of expression of the candidate genes in pd-affected dogs relative to age-matched controls. At present we are building suitable informative pedigrees for the disease locus with a sufficient number of meiosis to be useful for genomewide screening. This should identify markers linked to the disease locus and eventually permit progress toward the identification of the photoreceptor dysplasia gene and the disease-causing mutation.

Animals↗
PubMedDate not supplied

Characterization of three microsatellite loci linked to the canine RP3 interval.

X-linked retinitis pigmentosa (XLRP) is one of the most prevalent forms of a genetically heterogeneous group of inherited retinal disorders of man; more than 70% of XLRP families map to the RP2 or RP3 loci on the human X chromosome. Canine X-linked progressive retinal atrophy (XLPRA), observed in the Siberian husky, is the locus homologue of human RP3, but the gene responsible for XLPRA has not yet been identified. To develop polymorphic markers in the RP3 interval in dogs we have isolated microsatellites from canine BAC clones. Three tightly linked microsatellite loci, CUX20001, CUX30001, and CUX40002, have been investigated in 17 dog breeds or breed varieties. Calculated parameters of variability correspond with the number of repeats at each locus. Pedigree analyses showed tight linkage between the canine t-complex-associated testis-expressed 1-like gene (TCTE1l) and the gene ornithine carbamoyltransferase (OTC). Each microsatellite shows conservation within Canidae, and CUX20001 also amplified in Mustelidae and URSIDAE: These markers represent an important tool in the fine mapping process for the canine region homologous to the RP3 disease interval and are valuable for evaluation of conservation and homology of this region among related species.

Animals↗
PubMedDate not supplied

Circadian immune measures in healthy volunteers: relationship to hypothalamic-pituitary-adrenal axis hormones and sympathetic neurotransmitters.

OBJECTIVE: The purpose of this study is to examine the circadian pattern of specific immunologic measures and to compare observed circadian rhythms of these measures with the well-established circadian rhythms of hypothalamic-pituitary-adrenal axis hormones and sympathetic neurotransmitters. METHODS: Blood samples were collected every 2 hours for a total of 24 hours from nine healthy volunteers. The blood samples were assayed for hormones and immune measures, including adrenocorticotropic hormone (ACTH), cortisol, norepinephrine, and epinephrine. The immune measures included percentage and absolute number of neutrophils, lymphocytes, the lymphocyte subsets CD3+ (T cells), CD4+ (T helper/inducer), CD8+ (T suppressor/cytotoxic), CD56+ (natural killer [NK] cells) and NK cell activity (NKCA). RESULTS: The following immune measures exhibited a significant circadian rhythm: the percentages of neutrophils, CD4+ cells, and CD56+ cells; the absolute numbers of total lymphocytes, CD3+ cells, CD4+ cells, and CD8+ cells; and NKCA. Cross-correlations between the circadian rhythms of selected hormones and immune measures indicated a strong inverse association between the circadian rhythms of cortisol and the different T cell subsets on the one hand, and a strong direct association between the rhythms of cortisol and the percentage of CD56+ and NKCA on the other. Cross-correlations involving the circadian rhythms of norepinephrine and the same immune measures were in general much weaker and statistically nonsignificant. CONCLUSION: In healthy individuals, both enumerative and functional immune measures exhibit circadian rhythms that seem to be associated most closely with the circadian rhythm of cortisol.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Comparative effects of three sites of renin-angiotensin blockade on the regression of left ventricular hypertrophy in spontaneously hypertensive rats.

The effects of blockade of the renin-angiotensin system at three different sites on regression of left ventricular hypertrophy (LVH) were investigated in spontaneously hypertensive rats (SHRs). Angiotensin-converting-enzyme (ACE) inhibitor, angiotensin II type 1 (AT1) receptor antagonist, renin inhibitor, or the combination of hydralazine and hydrochlorothiazide was administered for 7 days to SHRs to obtain the same decrease in blood pressure. Treatment with ACE inhibitor, AT1 receptor antagonist, or renin inhibitor significantly decreased left ventricular mass. On the other hand, hydralazine administration failed to diminish LVH in SHRs. These findings indicate that blockade of the renin-angiotensin system regressed LVH irrespective of the site of the blockade and independent of hemodynamic changes.

Angiotensin II↗
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A frequency domain approach to nonlinear and structure identification for long memory systems: application to lung mechanics.

From the input-output point of view, many nonlinear biological systems display long memory characteristics which can become a critical issue using nonparametric time-domain kernel identification due to inevitable truncation of memory length. To avoid these limitations, we present an alternative approach in the frequency domain with application to lung mechanics. Generally, if the system is excited with a periodic wave form, the response will approach a steady state which dominates the long memory transients. Thus, we hypothesized that the kernels at discrete frequencies will not be significantly affected by memory truncation. To test this, we extended the frequency kernel analysis of Victor and Shapley (Biophys. J. 29:459-484, 1980) to a nonwhite input spectrum and developed a new structure test in the frequency domain to differentiate between Wiener and Hammerstein models. These techniques were applied to measured pressure-flow data of isolated lung lobes. The results showed that (1) the important nonlinearities in the pressure-flow relation are of second order, (2) the frequency kernels of the lobes were similar for flat and ventilatory-like input spectra, and (3) the structure test strongly suggested that the pressure-flow relationship during tidal-like excursions is consistent with a Wiener structure.

Animals↗
PubMedDate not supplied

Factors affecting Volterra kernel estimation: emphasis on lung tissue viscoelasticity.

The goal of this study is to quantitatively investigate how the memory length, order of nonlinearity, type of input, and measurement noise can affect the identification of the Volterra kernels of a nonlinear viscoelastic system, and hence the inference on system structure. We explored these aspects with emphasis on nonlinear lung tissue mechanics around breathing frequencies, where the memory length issue can be critical and a ventilatory input is clinically demanded. We adopted and examined Korenberg's fast orthogonal algorithm since it is a least-squares technique that does not demand white Gaussian noise input and makes no presumptions on the kernel shape and system structure. We then propose a memory autosearch method, which incorporates Akaike's final production error criterion into Korenberg's fast orthogonal algorithm to identify the memory length simultaneously with the kernels. Finally, we designed a special ventilatory flow input and evaluated its potential for the kernel identification of the nonlinear systems requiring oscillatory forcing. We found that the long memory associated with soft tissue viscoelasticity may prohibit correct identification of the higher-order kernels of the lung. However, the key characteristics of the first-order kernel may be revealed through averaging over multiple experiments and estimations.

Algorithms↗
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Optical lumen measurement of coronary artery latex casts.

To facilitate calibration and testing of quantitative coronary angiography (QCA) systems, an optical technique has been developed to measure the vessel dimensions of complex coronary artery phantoms. The technique provides accurate geometric data such as centerline position and cross-sectional area of vessel branches. The sequential steps involved in the measurement include taking pictures of different views, tracing magnified images, point-by-point digitizing and computing the center positions and radii along each vessel branch. The accuracy of the optical technique is assessed using the measurement of a precisely known aluminum phantom. Measurement repeatability is assessed by multiple measurement of the same branches on a barium impregnated latex cast which provides a realistic coronary artery phantom. The measurement is demonstrated to be accurate to within 0.01 mm and repeatable to within 0.05 mm on the wire phantom measurement and 0.08 mm on the realistic phantom measurement.

Aluminum↗
PubMedDate not supplied

Characterization of a small round virus associated with the poult enteritis and mortality syndrome.

A small round virus (SRV) identified and isolated in our laboratory from intestinal samples of poults affected with the poult enteritis and mortality syndrome was further characterized. The SRV was propagated in turkey embryos and purified by differential and isopycnic ultracentrifugation. The size of the SRV was 30-32 nm in diameter. The buoyant density of the SRV in cesium chloride was between 1.34 and 1.36 g/cm3. It was resistant to chloroform treatment, stable at pH 3.0, and resistant to heat treatment. Attempts to propagate the SRV in turkey embryo kidney, turkey kidney, Caco-2, Vero, and BGM-70 cells were unsuccessful. Analysis of the SRV capsid proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed three polypeptides with molecular weights of 34.5, 31, and 28 kD. Genome analysis of the SRV showed that the SRV had a single-strand RNA genome about 7500 nucleotides in length. Reverse transcription-polymerase chain reactions (RT-PCRs) with primers specific to conserved sequences of enteroviruses yielded products with expected sizes. However, sequence analysis of the RT-PCR products showed that there was no similarity between the sequences and that of enteroviruses. RT-PCR with primers specific to the 3' end of a SRV RNA genome yielded products with expected sizes. These products were sequenced and found to contain 669 nucleotides, excluding the polyadenylated tail. Sequence analysis indicated that the SRV shared 38.18% amino acid identity in the C-terminal capsid precursor protein and 41.26% nucleotide identity of the 3' end of turkey astrovirus RNA genome (Genbank accession no. Y15936). We concluded that the SRV is a member of the astrovirus family.

Amino Acid Sequence↗
PubMedDate not supplied

[Cloning, sequence analysis and heterologous expression of a beta-mannanase gene from Bacillus subtilis Z-2].

Mannanase, an extracellular enzyme catalyzes the hydrolysis of hemicelluloses to produce oligosaccharides, has a potential to be applied in food industries. In this study, a mannanase gene from B. subtilis Z-2 was isolated through PCR screening of a genomic DNA library. The nucleotide sequence of the mannanase gene, man, contained an open reading frame of 1.080 bp, which codes for a deduced 26 amino-acid signal peptide and a mature protein with the deduced molecular mass of 38 KDa. The man gene can both be expressed heterologously into the periplasm in plasmid pET22b(+) containing intact signal peptide (pET-NdeI18) and the pelB signal peptide of the pET22b(+)vector (pET-NcoI3). The Escherichia coli BL21 (DE3) containing pET-NcoI3 secreted about twice as much mannanase as that harboring pET-NdeI18. In E. coli DH5alpha, expression of man was under the control of the lac promoter in the pRK415 vector and was much more effective when the Shine-Dalgamo (SD) sequence was changed from GGGGAG to AAGGAG and the start codon was changed from TTG to ATG, respectively. These results suggest that genetic modification of the SD sequence and start codon is practical for high-level expression of mannanase in different bacterial strains.

Bacillus subtilis↗