Biomedical subjects

X Jiang

Publications and source records attributed to X Jiang.

At least 433 records · Page 24Linked to original sources

PubMed1993

Evidence for a new, high-molecular weight isoform of protein kinase C in rat hippocampus.

We describe a new form of protein kinase C (PKC) with a molecular weight of 97 kDa, higher than the known forms of vertebrate PKC. This putative new high-molecular weight isoform, which we are calling PKC (HMW), is increased in the membrane fraction either upon application of phorbol esters or with afferent synaptic stimulation of Schaffer collaterals in hippocampal slices. The protein cross-reacts on immunoblot with affinity-purified polyclonal antiserum raised against a peptide derived from the carboxy-terminus of PKC eta; it does not cross-react, however, with antiserum against the amino-terminal region of PKC eta. In the tissues examined, PKC(HMW) is localized primarily in brain, in contrast to PKC eta, which is found predominantly in lung and skin.

Amino Acid Sequence↗

PubMed1993

Molecular cloning of a mouse myosin I expressed in brain.

We have isolated two cDNAs that encode putative myosin I heavy chains by polymerase chain reaction amplification of brain cDNA with degenerate oligodeoxynucleotide primers representing myosin I-specific conserved amino acid sequences. We report the complete deduced amino acid sequence of one of these cDNAs. The sequences is most similar to those of the avian and bovine brush border myosin Is, with five putative calmodulin-binding repeats at the head-tail junction. Northern analysis demonstrates that this myosin heavy chain, unlike the brush border myosins, is expressed in many tissues.

Amino Acid Sequence↗

PubMed1993

Association of fasting insulin with blood pressure in young individuals. The Bogalusa Heart Study.

BACKGROUND: The relationship between fasting plasma insulin and blood pressure was studied in a cross-sectional survey of children and young adults aged 5 to 26 years. METHODS: Fasting plasma insulin, glucose, blood pressure, and anthropometric measurements were obtained on 3518 individuals. RESULTS: When divided into four age groups, the analyses showed that fasting insulin was significantly and positively correlated to both systolic and diastolic blood pressure in individuals at all age groups, except at 13 to 17 years. In multivariate regression analyses, fasting insulin remained independently associated with blood pressure levels after controlling for glucose levels, body mass index (weight/height) and skinfold thickness in children (aged 5 to 12 years) and young adults (aged 18 to 26 years), although not in adolescents (aged 13 to 17 years). Moreover, fasting insulin was more strongly related to systolic than to diastolic blood pressure. The fasting blood glucose level did not contribute independently to multivariate prediction of blood pressure in young adults. When the children and young adults were divided into tertiles according to fasting insulin and body mass index, the independent effect of insulin and body mass index on systolic pressure was also seen in children and young adults. CONCLUSIONS: The association between plasma insulin and blood pressure noted even in healthy children and young adults help target areas for cardiovascular risk prevention.

Adolescent↗

PubMed1993

Iron augments macrophage-mediated killing of Brucella abortus alone and in conjunction with interferon-gamma.

Brucella abortus are Gram negative facultative intracellular bacteria, which survive and replicate in host macrophages. We have recently demonstrated that activation of macrophages with interferon-gamma increases their anti-brucella activities but does not result in elimination of intracellular brucellae. Here we demonstrate that iron-loaded macrophages have an enhanced capacity to kill or prevent replication of intracellular brucellae. Iron added bound to transferrin or as a salt, iron-nitrilotriacetate, can mediate the effect. Macrophages supplemented with iron-loaded transferrin in addition to activation with interferon-gamma can frequently eliminate the intracellular organisms by 48 hr after infection. The effect is apparent following phagocytosis of either nonopsonized or antibody-opsonized brucellae, and with both attenuated and virulent strains of B. abortus. The killing can be blocked by the hydroxyl radical scavengers mannitol and thiourea. This is consistent with the Haber-Weiss reaction, in which iron catalyzes the generation of hydroxyl radicals from hydrogen peroxide.

Animals↗

PubMed1993

Detection of murine cytomegalovirus (MCMV) DNA in skin using the polymerase chain reaction (PCR).

We used the polymerase chain reaction (PCR) and primers for the immediate early gene of murine cytomegalovirus (MCMV) to detect MCMV DNA in skin harvested from mice during acute infection. MCMV DNA was also detected in DNA extracted from spleen and salivary gland of MCMV-infected mice, but not in the skin, salivary gland, or spleen of uninfected, seronegative mice. Detection of MCMV DNA in skin provides direct evidence that skin can serve as a vehicle for transmission of MCMV. This observation is relevant to humans, such as burn patients, who receive skin allografts that may be infected with cytomegalovirus.

Acute Disease↗

PubMed1993

Sequence and genomic organization of Norwalk virus.

A library of overlapping cDNAs obtained from Norwalk virus purified from stools of human volunteers (Jiang et al., 1990, Science 250, 1580-1583) was used to obtain the nucleotide sequence of the viral genome. The sequence has a total of 7642 nucleotides, excluding the 3' poly(A) tail, and has a base composition of 48% G + C. Three open reading frames (ORF) are predicted in the sequence. The longest ORF (ORF1, nucleotides (nt) 146 to 5359) is predicted to encode a polyprotein precursor to nonstructural proteins based on identification of sequences similar to the picornavirus 2C protein, 3C protease, and 3D RNA-dependent RNA polymerase. ORF2 (nt 5346 to 6935) is predicted to encode a polypeptide with a predicted molecular weight of 56,571 (56.6K, close to the expected size of the viral capsid protein), and it contains a short region of sequence similarity to the picornavirus structural protein VP3. A third potential ORF (nt 6938 to 7573) could encode a small polypeptide of 22.5K. The genomic organization found in Norwalk virus shares striking similarities with the genome of two caliciviruses, the feline calicivirus and the rabbit hemorrhagic disease virus. The morphology, size, polarity, and genomic organization of the Norwalk virus indicate it is a member of the Caliciviridae family.

Base Sequence↗

PubMed1993

Electromagnetic wave emitting products and "Kikoh" potentiate human leukocyte functions.

Tourmaline (electric stone, a type of granite stone), common granite stone, ceramic disks, hot spring water and human palmar energy (called "Kikoh" in Japan and China), all which emit electromagnetic radiation in the far infrared region (wavelength 4-14 microns). These materials were thus examined for effects on human leukocyte activity and on lipid peroxidation of unsaturated fatty acids. It was revealed that these materials significantly increased intracellular calcium ion concentration, phagocytosis, and generation of reactive oxygen species in neutrophils, and the blastogenetic response of lymphocytes to mitogens. Chemotactic activity by neutrophils was also enhanced by exposure to tourmaline and the palm of "Kikohshi" i.e., a person who heals professionally by the laying on of hands. Despite the increase in reactive oxygen species generated by neutrophils, lipid peroxidation from unsaturated fatty acid was markedly inhibited by these four materials. The results suggest that materials emitting electromagnetic radiation in the far infrared range, which are widely used in Japan for cosmetic, therapeutic, and preservative purposes, appear capable of potentiating leukocyte functions without promoting oxidative injury.

Adolescent↗

PubMed1993

Measurement of the micro-electroretinogram and component analysis.

The authors propose a new technique for detecting micro-electroretinograms (muERG) which uses light-emitting diode (LED) stimulation and frequency analysis. The advantage of this method is the applicability of linear system analysis to a muERG obtained by partial stimulation of a computer-controlled waveform. The paper discusses two basic techniques for detecting the muERG. One is Fourier analysis of a synchronised ERG obtained by sine-wave stimulus, and the other is correlation analysis using a random stimulus. The results of the two methods are compared, and the usefulness of the proposed method is indicated; the muERG is analysed by means of a model consisting of five components of a second-order transfer function with delay. Functions of the central and peripheral areas of the retina could be analysed in more detail by this technique.

Electroretinography↗

PubMed1993

Visualization of dendritic morphology of cortical projection neurons by retrograde axonal tracing.

Currently there is no reliable retrograde tracing technique for visualization of dendritic morphologies of projection neurons. Here we describe a simple and efficient method that can be used to label neurons in Golgi-like fashion. The approach relies on activity-dependent uptake of tracer. For this purpose we inject the glutamate receptor agonist N-methyl-D,L-aspartic acid (NMDA) at the tracer injection site to massively stimulate neurons and to thereby promote uptake of biocytin or biotinylated dextran amine (BDA) by axon terminals. The results show that co-injections of NMDA/biocytin and NMDA/BDA into the extrastriate lateromedial area (LM) of rat visual cortex labels large numbers of neurons in area 17 in Golgi-like fashion. Similarly injections of the lateral geniculate nucleus (LGN) lead to Golgi-like labeling of corticogeniculate neurons in area 17. The distribution of labeled neurons is highly topographic. In addition the method allows excellent preservation of ultrastructure, indicating that this approach is useful for determining the organization of neuronal circuits within the central nervous system.

Animals↗

PubMed1993

Macrophage control of Brucella abortus: influence of cytokines and iron.

Brucella abortus is a facultative intracellular bacterium that can infect and replicate in mononuclear phagocytes. Recent work has elucidated the role of cytokines in activating macrophages to inhibit the intracellular replication of brucellae, and in recruiting macrophages to the site of infection in vivo. There is also evidence that iron increases the ability of cytokine-activated macrophages to control intracellular brucellae by mechanisms involving reactive oxygen intermediates.

Animals↗

PubMed1993

Association of fasting insulin with longitudinal changes in blood pressure in children and adolescents. The Bogalusa Heart Study.

A cohort of children and adolescents (n = 801) aged 5 to 11 years living in Bogalusa, Louisiana was examined in three consecutive cross-sectional surveys over a 6 year period. The relationship between fasting insulin and glucose at baseline and longitudinal changes in blood pressure were examined. Significantly positive correlations were observed between fasting insulin and glucose at baseline and systolic and diastolic blood pressure at follow-up in white boys and girls (r = 0.19 to 0.38, P < .01), but not in blacks. After adjustment for several covariates, the association still existed in whites. In multiple regression analysis, fasting plasma insulin was observed to be a major contributor of subsequent systolic blood pressure levels independent of age, sex, height, obesity, and glucose levels in white children. These data suggest that insulin can be a determinant of blood pressure levels in children as suggested in adults. The relationship of insulin to blood pressure differs between black and white children and is likely modulated by the multiple mechanisms active in maintenance of blood pressure.

Adolescent↗

PubMed1993

Leflunomide, a novel immunosuppressive agent. The mechanism of inhibition of T cell proliferation.

Leflunomide is a novel immunomodulating drug that has recently been demonstrated to prevent acute rejection and reverse ongoing rejection of kidney and cardiac allografts in rats. In vitro studies here demonstrate that leflunomide suppresses proliferation of human PBL stimulated with (1) allogeneic PBL in a one-way MLR (50% inhibition with 50-25 microM); (2) anti-CD3 mABs plus PMA (50% inhibition with 70 microM leflunomide); and (3) anti-CD28 mABs plus PMA (50% inhibition with 65 microM leflunomide). In contrast, CsA only inhibited T cell proliferation stimulated by anti-CD3 plus PMA. Leflunomide partially inhibited IL-2 production of T cells stimulated with anti-CD3 plus PMA or anti-CD28 plus PMA, whereas CsA completely inhibited IL-2 production by T cells stimulated by the CD3 pathway and only partially inhibited IL-2 production by T cells stimulated by the CD28 pathway. Because comparable levels of IL-2 were produced by CD28-stimulated T cells treated with either CsA or leflunomide, but no inhibition of proliferation was observed in the CsA-treated cultures, we hypothesized that the lowering of IL-2 levels was not the mechanism by which leflunomide inhibited T cell proliferation. This hypothesis was supported by the observations that exogenous IL-2 failed to restore the T cell proliferation in the presence of leflunomide. Loss of T cell responsiveness to IL-2 in the presence of leflunomide was not due loss of expression of IL-2 receptors. Collectively, our data suggest that inhibition of T cell proliferation by leflunomide occurs via inhibition of responsiveness to IL-2.

Antigens, CD↗

PubMed1993

Effects of cytokines on intracellular growth of Brucella abortus.

Interleukin 1 alpha (IL-1 alpha), IL-2, IL-4, IL-6, gamma interferon (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), and granulocyte macrophage colony-stimulating factor (GM-CSF) were tested for their abilities to alter the growth of Brucella abortus in BALB/c J774A.1 murine macrophages. IL-1 alpha, IL-4, IL-6, tumor necrosis factor alpha, and granulocyte macrophage-colony-stimulating factor had no consistent or significant effect on the growth of the avirulent B. abortus strain 19. In contrast, the addition of either IFN-gamma or IL-2 at 100 U/ml to the macrophage cultures resulted in a significant reduction in the number of intracellular bacteria that was not attributable to decreased infection rates. With IL-2, the reduction was most often apparent only during the first 24 h after infection, while inhibition with IFN-gamma was apparent throughout the culture period of 48 h. The addition of either IL-2 or IFN-gamma to macrophage cultures also resulted in reduced intracellular CFU of the virulent B. abortus strain 2308 and the attenuated rough mutant B. abortus strain RB51. Inhibition of intracellular growth was not augmented by combinations of cytokines. Additional studies with IFN-gamma and IL-2 indicated that they could mediate the inhibition of intracellular growth of B. abortus in resident and thioglycolate broth-induced BALB/c peritoneal macrophages and in splenic macrophages. IFN-gamma also inhibited bacterial growth when added after infection of the macrophages, although the magnitude of the antibrucellae effects was less than that when it was added before infection. Furthermore, the maximal inhibitory effect was sustained only when IFN-gamma remained in the cultures after infection of the macrophages.

Animals↗

PubMed1993

Detection of antibody to recombinant Norwalk virus antigen in specimens from outbreaks of gastroenteritis.

Norwalk virus and other small round-structured viruses are commonly associated with outbreaks of gastroenteritis. We used a recently described recombinant-expressed Norwalk virus (rNV) capsid protein in enzyme immunoassays to quantitatively measure immunoglobulin G (IgG) and IgA to Norwalk virus in serum pairs from patients involved in outbreaks of gastroenteritis. The outbreaks previously were classified, on the basis of the results of a blocking antibody assay, as Norwalk virus negative, serologically intermediate, or Norwalk virus positive. The rNV IgG assay was more sensitive than the blocking assay for detecting IgG to Norwalk virus in serum from patients in all outbreak classes. There was 79% concordance between seroconversions detected by the blocking antibody assay and those detected by the rNV IgG assay. The rNV IgA assay detected seroconversions to Norwalk virus primarily in patients involved in outbreaks previously classified as Norwalk virus positive.

Antibodies, Viral↗

PubMed1993

Prevalence of antibodies to Norwalk virus in England: detection by enzyme-linked immunosorbent assay using baculovirus-expressed Norwalk virus capsid antigen.

A total of 3,250 serum specimens collected in England in 1991 and 1992 were tested by an indirect enzyme-linked immunosorbent assay for antibody to Norwalk virus using baculovirus-expressed capsid antigen, and 2,382 (73.3%) were positive. The prevalence of Norwalk virus antibody differed regionally. It was lowest (24.6%) in 6- to 11-month-old infants and increased to 89.7% in persons over 60 years old.

Adolescent↗

PubMed1993

Subclass-specific serum antibody responses to recombinant Norwalk virus capsid antigen (rNV) in adults infected with Norwalk, Snow Mountain, or Hawaii virus.

Subclass-specific antibody responses to the Norwalk virus capsid protein in adults challenged with Norwalk, Snow Mountain, or Hawaii virus were evaluated by solid-phase enzyme immunoassay using recombinant Norwalk virus capsid antigen (rNV). Fourfold or greater serum immunoglobulin G (IgG) antibody responses to rNV were detected in 15 of 20 volunteers challenged with Norwalk virus, and serum IgA and IgM antibody responses to rNV were seen in almost all subjects who had rNV IgG responses. Serum rNV IgG antibody responses also were detected in 6 of 15 volunteers challenged with Snow Mountain virus and 2 of 12 volunteers challenged with the Hawaii virus. However, the magnitude of antibody response and the geometric mean postchallenge rNV IgG antibody titers were lower in subjects challenged with Snow Mountain or Hawaii virus, and serum IgA and IgM responses generally did not occur.

Adult↗

PubMed1993

Comparison of the reactivities of baculovirus-expressed recombinant Norwalk virus capsid antigen with those of the native Norwalk virus antigen in serologic assays and some epidemiologic observations.

Since the discovery of the Norwalk virus (NV) by immune electron microscopy (IEM) in 1972, serologic studies with this virus have relied on particle-positive fecal material from infected volunteers as the source of antigen because it has not been possible to propagate this virus in cell culture. However, the recent cloning of the NV (strain 8FIIa) genome and expression of the capsid protein in a baculovirus system to form "virus-like particles" has provided a consistent source of antigen (designated rNV). The purpose of the present study was to compare the antigenicities of these rNV particles with those of native NV antigen derived from human fecal material by using well-characterized sera obtained from earlier studies. In IEM studies, the rNV antigen reacted with NV-specific antibodies in a manner similar to that observed previously when particle-positive fecal material was used as antigen. In addition, a direct enzyme-linked immunosorbent assay, in which the rNV antigen was used as antigen, proved efficient and specific for the detection of serologic responses to NV compared with the previously established techniques of IEM and blocking antibody immunoassays in which particle-positive fecal material was used as the antigen. The availability of an unlimited source of antigen will enable serologic studies that will greatly increase our understanding of the epidemiology of NV and its role in human enteric illness.

Adult↗

PubMed1993

Long-range mapping of Mis-2, a common provirus integration site identified in murine leukemia virus-induced thymomas and located 160 kilobase pairs downstream of Myb.

The nondefective Moloney murine leukemia virus (MuLV) induces clonal or oligoclonal T-cell tumors in mice or rats. The proviruses of these nondefective MuLVs have been shown to act as insertion mutagens most frequently activating an adjacent cellular gene involved in cell growth control. Mutations by provirus insertions, recognized as common provirus integration sites, have been instrumental in identifying novel cellular genes involved in tumor formation. We have searched for new common provirus integration sites in Moloney MuLV-induced thymomas. Using cellular sequences flanking a provirus cloned from one of these tumors, we found one region, designated Mis-2, which was the target of provirus integration in a low (3%) percentage of these tumors. Mis-2 was mapped on mouse chromosome 10, approximately 160 kbp downstream of myb. The Mis-2 region may contain a novel gene involved in tumor development.

Animals↗