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Biomedical subjects

K Deng

Publications and source records attributed to K Deng.

At least 19 recordsLinked to original sources
PubMed2006

Long-term effects of early-life dietary L-carnitine on lymphoid organs and immune responses in Leghorn-type chickens.

The long-term effects of supplementing Leghorn-type chickens with dietary L-carnitine after hatching for 4 weeks on growth, lymphoid organ weights, humoral and cell-mediated immune responses were assessed in a 12-week study. A commercial starter feed supplemented with 0 (control), 100 (LC) or 1,000 (HC) mg L-carnitine/kg was offered to day-old ISA Brown cockerels for 4 weeks, then all birds were given a commercial pullet grower feed for another 8 weeks. No differences (p > 0.05) in growth rates, feed intake or feed utilisation efficiency existed among the dietary treatments throughout the study. Compared with control birds, HC-fed birds had a lower (p < 0.05) thymus weight relative to bodyweight (BW) at Week 4, but a higher (p < 0.05) relative thymus weight at Week 12. A higher (p < 0.05) serum primary antibody response to sheep red blood cells (SRBC) in HC-fed birds than in the other two groups was also detected at Week 12. Relative spleen or bursa weights and cutaneous responses of toe webs to phytohaemagglutimin (PHA) (an in vivo indicator of cell-mediated immune responses) did not differ (p > 0.05) among dietary treatments at any time. It is concluded that a short-term supply of dietary L-carnitine to a conventional commercial feed after hatching enhanced subsequent humoral immunity in Leghorn-type chickens. Further study is warranted to confirm such a long-term effect.

Animal Feed↗
PubMed2005

Long-term effects of early life L-arginine supplementation on growth performance, lymphoid organs and immune responses in Leghorn-type chickens.

The effects of a short-term dietary arginine supplementation after hatching on subsequent growth and the immune system were assessed in growing male Leghorn-type chickens. An arginine-deficient basal diet (67 g/kg) supplemented with 0 (control), 2.7 (LA) or 5.4 (HA) g L-arginine/kg, was offered ad libitum to 1-d-old male ISA Brown chicks for 4 weeks, then all birds were offered ad libitum a commercial pullet grower feed (8.9 g arginine/kg) for another 8 weeks. Supplemented birds had higher growth rates and feed intake than control birds during the 4-week supplementation period, but these effects did not persist into the subsequent periods. When the supplementation ceased at week 4, no differences in lymphoid organ weights relative to body weight (BW), primary serum antibody levels against sheep red blood cells (SRBC) or cutaneous reactivity of toe webs to phytohaemagglutinin (PHA) were detected. LA-fed birds had lower immunoglobulin (Ig) G levels against bovine serum albumin (BSA) than the control at week 4, but this effect did not persist at weeks 8 and 12. No difference in anti-BSA IgM levels was detected among birds at week 4; at week 12, however, the LA-fed birds had a significantly higher anti-BSA IgM level than the control. An increased anti-SRBC antibody level and a reduced relative bursa weight in HA-fed birds were evident at week 8, without any prior effects. It is concluded that short-term supplementary L-arginine had minimal effects on immunity, but some enhancement of SRBC antibody responses in later stages of growth was observed with previous L-arginine administration.

Aging↗
PubMed2005

Carry-over effects of dietary yeast RNA as a source of nucleotides on lymphoid organs and immune responses in Leghorn-type chickens.

1. The carry-over effects of supplementing Leghorn-type chickens with yeast RNA as a dietary source of nucleotides for 4 weeks on growth, lymphoid organ weights and immune responses were assessed in a 12-week study. 2. A commercial starter feed supplemented with 0 (control), 5 (LR) or 10 (HR) g yeast RNA/kg was offered to 1-d-old male ISA Brown chicks for 4 weeks, and then all birds were given a commercial pullet grower feed for another 8 weeks. Growth performance, antibody responses to sheep red blood cells (SRBC) and cutaneous reactivity of toe webs to phytohaemagglutinin (PHA)-M were measured at 4-week intervals. 3. Growth rates, feed intake and feed efficiency were not affected by dietary yeast RNA during the supplementary period, but birds previously offered the HR diet grew faster than control birds during weeks 4 to 8.4. LR-fed birds had a higher spleen weight relative to body weight (BW) than control birds at week 4, but this effect was not detected at other times. 5. Serum primary antibody levels against SRBC were not affected by dietary yeast RNA at any time. 6. The toe-web PHA response was significantly higher at week 8 in control birds than in birds previously given the LR diet, although no difference among dietary treatments was observed at other times. 7. It is concluded that the addition of yeast RNA as a source of nucleotides to a commercial diet selectively stimulated the development of the spleen in young birds, but this effect did not persist into a later stage of the bird's life.

Animal Feed↗
PubMed2001

Investigation of the interaction among the components of the cytolethal distending toxin of Haemophilus ducreyi.

The cytolethal distending toxin (CDT) of Haemophilus ducreyi is encoded by the cdtABC genes, but the composition of active CDT is not known. Both immunoaffinity and metal affinity chromatographic methods were used to purify H. ducreyi CDT from recombinant Escherichia coli strains bearing wild-type or mutated H. ducreyi cdtABC genes. Both affinity-purified preparations contained CdtA, CdtB, and CdtC proteins. These purification efforts also revealed that the formation of a noncovalent CdtB-CdtC complex and production of a fully active CDT complex required the presence of a functional CdtA protein. When purified recombinant CdtB and CdtC proteins were mixed, only very slight CDT activity was detected. In contrast, when a bacterial cell extract containing CdtA was mixed with purified preparations of both CdtB and CdtC, full CDT activity was reconstituted in vitro. These results indicate that CdtA is essential for normal H. ducreyi CDT activity and that CdtA likely modifies or alters either CdtB or CdtC or both to form the active CDT complex.

Bacterial Toxins↗
PubMed2001

Infection density of Wolbachia and incompatibility level in two planthopper species, Laodelphax striatellus and Sogatella furcifera.

Wolbachia, a bacterial endosymbiote of arthropods, causes cytoplasmic incompatibility (CI) in many insect species. CI traits were studied in two planthopper species, Laodelphax striatellus and Sogatella furcifera, and Wolbachia densities in these planthopper species were calculated by quantitative PCR methods. The CI level of L. striatellus was quite high and even aged males strongly caused CI. In contrast, S. furcifera showed partial CI, and males lost their ability to cause CI with age. Wolbachia infecting these two planthopper species were the same with respect to the nucleotide sequences of Wolbachia genes, 16S rDNA, ftsZ gene, groE genes, and wsp gene. Two methods for quantitative PCR, one using a DNA sequencer and the other a real-time sequence detection system, were established to calculate the amount of Wolbachia in the planthoppers. The density of Wolbachia in S. furcifera males was quite low. The difference in CI levels between the two planthopper species seems to be due to different amounts of Wolbachia infecting males.

Animals↗
PubMed2001

Optical, magnetic, and electronic properties of peripherally fused macrocycles: molybdocene porphyrazines.

Metal-free and copper porphyrazines, [H(2)pz] and [Cu pz], have been fused at the periphery with molybdocene dithiolene, [Cp(2)Mo]. The optical, magnetic, and electronic properties of the resulting neutral and cationic complexes are studied, using first-principles density functional theory implemented by the discrete variational method. Analysis of the charge and spin distribution shows that the porphyrazine core is strongly coupled with the peripheral complex. The calculated optical absorption is found to be in reasonable agreement with experimental spectra, lending support to our theoretical model. Under appropriate circumstances one observes interaction of unpaired spins localized in the vicinity of both metal sites. The calculated spin distribution shows that [Cp(2)Mo][Cu pz] and [Cp(2)Mo][H(2)pz](+) have a magnetic moment of 1 micro(B) while [Cp(2)Mo][Cu pz](+) and [Cp(2)Mo][H(2)pz] have no moment, in good agreement with the results of X-band EPR spectra. The Cu-Mo magnetic interaction is antiferromagnetic, being mediated by pyrrol nitrogens, meso nitrogens, carbons, and sulfurs.

Journal Article↗
PubMed2001

Wolbachia infection shared among planthoppers (Homoptera: Delphacidae) and their endoparasite (Strepsiptera: Elenchidae): a probable case of interspecies transmission.

Wolbachia, a group of parasitic bacteria of arthropods, are believed to be horizontally transmitted among arthropod taxa. We present a new probable example of interspecies horizontal transmission of Wolbachia by way of an endoparasite based on the conformity of Wolbachia gene sequences. Field samples of two rice planthoppers, Laodelphax striatellus and Sogatella furcifera possessed identical Wolbachia. Among three major endoparasites of planthoppers, a strepsipteran, Elenchus japonicus, harboured the identical Wolbachia strain, suggesting strepsipteran transmission of Wolbachia from one planthopper to the other. No Wolbachia was detected in a mermithid nematode Agamermis unka, and dryinid wasps possessed different types of Wolbachia.

Animals↗
PubMed2001

Characterization of Haemophilus ducreyi cdtA, cdtB, and cdtC mutants in in vitro and in vivo systems.

Haemophilus ducreyi expresses a soluble cytolethal distending toxin (CDT) that is encoded by the cdtABC gene cluster and can be detected in culture supernatant fluid by its ability to kill HeLa cells. The cdtA, cdtB, and cdtC genes of H. ducreyi were cloned independently into plasmid vectors, and their encoded proteins expressed singly or in various combinations in an Escherichia coli background. All three gene products had to be expressed in order for E. coli-derived culture supernatant fluids to demonstrate cytotoxicity for HeLa cells. Isogenic H. ducreyi cdtA and cdtB mutants were constructed and used in combination with the wild-type parent strain and a previously described H. ducreyi cdtC mutant (M. K. Stevens, J. L. Latimer, S. R. Lumbley, C. K. Ward, L. D. Cope, T. Lagergard, and E. J. Hansen, Infect. Immun. 67:3900-3908, 1999) to determine the relative contributions of the CdtA, CdtB, and CdtC proteins to CDT activity. Expression of CdtA, CdtB, and CdtC appeared necessary for H. ducreyi-derived culture supernatant fluid to exhibit cytotoxicity for HeLa cells. Whole-cell sonicates and periplasmic extracts from the cdtB and cdtC mutants had no effect on HeLa cells, whereas these same fractions from a cdtA mutant had a very modest cytotoxic effect on these same human cells. CdtA appeared to be primarily associated with the H. ducreyi cell envelope, whereas both CdtB and CdtC were present primarily in the soluble fraction from sonicated cells. Both the cdtA mutant and the cdtB mutant were found to be fully virulent in the temperature-dependent rabbit model for experimental chancroid.

Animals↗
PubMed2001

[The MRI diagnosis of aortic dissection].

OBJECTIVE: To analyze and address the MRI manifestations and diagnostic importance of aortic dissection. METHODS: The MRI manifestations in 31 cases of aortic dissection were analyzed retrospectively. Sixteen cases were proved by operation and pathology. RESULTS: MRI depicted an intimal flap and a double lumen in all 31 patients. The site of intimal tear was located in 7 cases. Also demonstrated were the complications: aortic dilation in 15 cases, aortic branches involvement in 5, thrombus formation in the false lumen in 5, aortic regurgitation in 10, left ventricle hypertrophy in 10, and leak into thorax in 2. CONCLUSION: As a non-invading imaging method, MRI can demonstrate the site, range and complications of aortic dissection; it is very valuable in the diagnosis of aortic dissection.

Adult↗
PubMed2001

[The value of three-dimensional helical CT imaging in the diagnosis of maxillofacial fractures].

OBJECTIVE: To assess the diagnostic value of three-dimensional (3D) helical CT imaging in the cases of maxillofacial fractures. METHODS: 25 trauma patients were examined with thin-slice CT scan and 3D reconstruction. RESULTS: Three-dimensional images reconstructed from helical CT clearly and stereoscopically demonstrated the location, shape and extension of maxillofacial fractures. CONCLUSION: 3D helical CT imaging can provide valuable information in demonstrating space relationships of maxillofacial fractures.

Adolescent↗
PubMed2000

Reconstitution of mitochondrial processing peptidase from the core proteins (subunits I and II) of bovine heart mitochondrial cytochrome bc(1) complex.

Mature core I and core II proteins of the bovine heart mitochondrial cytochrome bc(1) complex were individually overexpressed in Escherichia coli as soluble proteins using the expression vector pET-I and pET-II, respectively. Purified recombinant core I and core II alone show no mitochondrial processing peptidase (MPP) activity. When these two proteins are mixed together, MPP activity is observed. Maximum activity is obtained when the molar ratio of these two core proteins reaches 1. This indicates that only the two core subunits of thebc(1) complex are needed for MPP activity. The properties of reconstituted MPP are similar to those of Triton X-100-activated MPP in the bovine bc(1) complex. When Rieske iron-sulfur protein precursor is used as substrate for reconstituted MPP, the processing activity stops when the amount of product formation (subunit IX) equals the amount of reconstituted MPP used in the system. Addition of Triton X-100 to the product-inhibited reaction mixture restores MPP activity, indicating that Triton X-100 dissociates bound subunit IX from the active site of reconstituted MPP. The aromatic group, rather than the hydroxyl group, at Tyr(57) of core I is essential for reconstitutive activity.

Amino Acid Sequence↗
PubMed2000

Minimal phenotype of mice homozygous for a null mutation in the forkhead/winged helix gene, Mf2.

Mf2 (mesoderm/mesenchyme forkhead 2) encodes a forkhead/winged helix transcription factor expressed in numerous tissues of the mouse embryo, including paraxial mesoderm, somites, branchial arches, vibrissae, developing central nervous system, and developing kidney. We have generated mice homozygous for a null mutation in the Mf2 gene (Mf2(lacZ)) to examine its role during embryonic development. The lacZ allele also allows monitoring of Mf2 gene expression. Homozygous null mutants are viable and fertile and have no major developmental defects. Some mutants show renal abnormalities, including kidney hypoplasia and hydroureter, but the penetrance of this phenotype is only 40% or lower, depending on the genetic background. These data suggest that Mf2 can play a unique role in kidney development, but there is functional redundancy in this organ and other tissues with other forkhead/winged helix genes.

Animals↗
PubMed2000

Murine forkhead/winged helix genes Foxc1 (Mf1) and Foxc2 (Mfh1) are required for the early organogenesis of the kidney and urinary tract.

The murine genes, Foxc1 and Foxc2 (previously, Mf1 and Mfh1), encode forkhead/winged helix transcription factors with virtually identical DNA-binding domains and overlapping expression patterns in various embryonic tissues. Foxc1/Mf1 is disrupted in the mutant, congenital hydrocephalus (Foxc1/Mf1(ch)), which has multiple developmental defects. We show here that, depending on the genetic background, most Foxc1 homozygous mutants are born with abnormalities of the metanephric kidney, including duplex kidneys and double ureters, one of which is a hydroureter. Analysis of embryos reveals that Foxc1 homozygotes have ectopic mesonephric tubules and ectopic anterior ureteric buds. Moreover, expression in the intermediate mesoderm of Glial cell-derived neurotrophic factor (Gdnf), a primary inducer of the ureteric bud, is expanded more anteriorly in Foxc1 homozygous mutants compared with wild type. These findings support the hypothesis of Mackie and Stephens concerning the etiology of duplex kidney and hydroureter in human infants with congenital kidney abnormalities (Mackie, G. G. and Stephens, F. G. (1975) J. Urol. 114, 274-280). Previous studies established that most Foxc1(lacZ )Foxc2(tm1) compound heterozygotes have the same spectrum of cardiovascular defects as single homozygous null mutants, demonstrating interaction between the two genes in the cardiovascular system. Here, we show that most compound heterozygotes have hypoplastic kidneys and a single hydroureter, while all heterozygotes are normal. This provides evidence that the two genes interact in kidney as well as heart development.

Abnormalities, Multiple↗
PubMed1999

Molecular cloning and mapping of a novel ADAM gene (ADAM29) to human chromosome 4.

Members of the ADAM family (type I integral membrane protein with a disintegrin and metalloprotease domain) have been implicated in many important biological processes involving cell-cell and cell-matrix interactions, such as fertilization and myoblast fusion. We report here the cDNA sequence of a novel human ADAM gene (ADAM29) that contains a putative fusion peptide. Northern blot analysis revealed that the mRNA of ADAM29 is highly expressed in the testis. By radiation hybrid panel mapping, the ADAM29 gene was assigned to human chromosome 4q34.2-qter.

ADAM Proteins↗
PubMed1999

Roles for the winged helix transcription factors MF1 and MFH1 in cardiovascular development revealed by nonallelic noncomplementation of null alleles.

The murine Mf1 and Mfh1 genes have overlapping patterns of expression in the embryo and encode forkhead/winged helix transcription factors with virtually identical DNA binding domains. Previous studies have shown that Mfh1 null mutants have severe cardiovascular defects, including interruptions and coarctations of the aortic arch and ventricular septal defects (Iida et al., Development 124, 4627-4638, 1997). Here, we show that Mf1(lacZ) homozygous null mutants also have a similar spectrum of cardiovascular abnormalities. Moreover, most embryos doubly heterozygous for Mfh1(tm1) and Mf1(lacZ) die before birth with interruptions and coarctations of the aortic arch, dysgenesis of the aortic and pulmonary valves, ventricular septal defects, and other cardiac anomalies. This nonallelic noncomplementation and the similar patterns of expression of the two genes in the mesenchyme and endothelial cells of the branchial arches, outflow tract, and heart suggest that Mf1 and Mfh1 play interactive roles in the morphogenesis of the cardiovascular system. Implications for the development of human congenital heart defects are discussed.

Alleles↗
PubMed1999

The forkhead/winged-helix gene, Mf1, is necessary for the normal development of the cornea and formation of the anterior chamber in the mouse eye.

Mf1, which encodes a winged-helix/forkhead transcription factor, is the murine homolog of human FKHL7, mutated in individuals with autosomal dominant inherited dysgenesis of the anterior segment of the eye (Axenfeld-Reiger anomaly). Mouse embryos homozygous for null mutations in Mf1 (Mf1(lacZ) and Mf1(ch)) show severely abnormal development of the anterior segment. The cornea fails to separate from the lens, resulting in the complete absence of an anterior chamber. There is no differentiation of the inner corneal endothelial layer, as judged by electron microscopy and by absence of labeling with monoclonal antibody to zonula occludens protein 1, a normal component of occluding junctions in wild-type endothelial cells. In addition, the mutant corneal stroma is disorganized and the epithelium thicker than normal. The Mf1 gene is normally expressed in the periocular mesenchyme at E11.5 but is downregulated as the corneal endothelium differentiates. In contrast, Mf1(lacZ) expression persists longer in mutant corneal mesenchyme, and abnormal expression is also seen in the mutant corneal epithelium. Based on classical studies with the chick embryonic eye, a model is proposed for the differentiation of the mammalian corneal endothelium from mesenchyme in response to putative signals from the lens. Possible roles for Mf1 in this process are discussed.

Animals↗
PubMed1999

Preparation and Characterization of Nanoscopic Organic Semiconductor of Oxovanadium Phthalocyanine.

Nanoscopic particles of oxovanadium phthalocyanine (VOPc, phase-II) with different particle sizes are prepared by aggregation of VOPc molecules in the presence of surfactants for the first time. A size effect in the region of nanoscale was observed in the UV-visible spectra. The photoconductivity of the nanoscopic VOPc is much higher than that of bulk VOPc. Copyright 1999 Academic Press.

Journal Article↗