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Biomedical subjects

L Huo

Publications and source records attributed to L Huo.

32 records · Page 2Linked to original sources
PubMed1998

[Can acupuncture prevent cystitis in women?].

67 adult women with a history of recurrent lower urinary tract infection (UTI) were randomized for acupuncture treatment, sham acupuncture, or no treatment. The incidence rate of UTI over the following six months was noted. In the acupuncture group a total of 85% was free of cystitis during the six-month observational period, as compared to 58% in the sham group (p < 0.05), and 36% in the control group (p < 0.01). Compared to the acupuncture group, twice as many incidents of cytitis occurred in the sham group, and three times as many in the control group (p < 0.05). Acupuncture seems a worthwhile alternative in the prevention of frequently recurring cystitis in women.

Acupuncture Therapy↗
PubMed1997

Induction of STAT protein signaling through the CD40 receptor in B lymphocytes: distinct STAT activation following surface Ig and CD40 receptor engagement.

Cross-linking CD40 mediates B lymphocyte growth and differentiation and regulates cell death pathways by an unknown mechanism. Previous reports have suggested that protein tyrosine kinase activity is critical for CD40-mediated biologic responses. We show here that CD40 engagement on murine B cells results in the rapid tyrosine phosphorylation of the STAT6 transcription factor and the transactivation of a reporter gene containing an IFN-regulatory factor-1 STAT-binding site. In earlier studies, surface Ig engagement was found to produce rapid activation of STAT6 accompanied by later induction of STAT1, which is not observed after CD40 ligation. Thus, these results define mitogenic receptor-specific induction of STAT proteins in B cells and identify a novel and direct signal transduction pathway from the cell surface to the nucleus activated in B cells stimulated through CD40 that regulates a gene previously shown to be involved in oncogenesis and programmed cell death.

Animals↗
PubMed1997

Signal transducer and activator of transcription-3 (STAT3) is constitutively activated in normal, self-renewing B-1 cells but only inducibly expressed in conventional B lymphocytes.

Cytokine and growth factor receptor engagement leads to the rapid phosphorylation and activation of latent, cytosolic signal transducers and activators of transcription (STAT) proteins, which then translocate to the nucleus where they regulate transcriptional events from specific promoter sequences. STAT3 expression in particular has been associated with Abl, Src, and HTLV-1 transformation of normal cells. B-1 lymphocytes are self-renewing, CD5+ B cells that display a propensity for malignant transformation and are the normal counterpart to human chronic lymphocytic leukemias. Further, B-1 cells are characterized by aberrant intracellular signaling, including hyperresponsiveness to phorbol ester PKC agonists. Here we demonstrate that B-1 lymphocytes constitutively express nuclear activated STAT3, which is not expressed by unmanipulated conventional (B-2) lymphocytes. In contrast, STAT3 activation is induced in B-2 cells after antigen receptor engagement in a delayed fashion (after 3 h). Induction of STAT3 is inhibited by both the serine/threonine protein kinase inhibitor H-7 and the immunosuppressive drug rapamycin and requires de novo protein synthesis, demonstrating novel coupling between sIg and STAT proteins that differs from the classical paradigm for STAT induction by cytokine receptors. The inability of prolonged stimulation of conventional B-2 cells with anti-Ig, a treatment sufficient to induce CD5 expression, to result in sustained STAT3 activation suggests that STAT3 is a specific nuclear marker for B-1 cells. Thus, STAT3 may play a role in B cell antigen-specific signaling responses, and its constitutive activation is associated with a normal cell population exhibiting intrinsic proliferative behavior.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1996

Isolation and characterization of murine fra-1: induction mediated by CD40 and surface Ig is protein kinase C dependent.

The murine fra-1 gene, encoding Fos-related Ag 1, was isolated from a splenic cDNA library and sequenced. Murine fra-1 was highly homologous to rat and human fra-1. Oligonucleotide primers based on the murine sequence were used to construct a quantitative reverse transcription-PCR assay for gene expression. B lymphocyte stimulation via both CD40 and surface Ig (sIg) receptors substantially induced fra-1 expression, and for both receptors, induction was protein kinase C (PKC) dependent. This contrasts with induction of c-fos by both CD40 and sIg, which is PKC independent and indicates that CD40 is capable of signaling through PKC or a closely related kinase. Induction of fra-1 following engagement of CD40 did not require protein synthesis, suggesting that the PKC-dependent linkage between CD40 and fra-1 is direct. CD40-mediated fra-1 induction did require tyrosine kinase activity. These results demonstrate that CD40, like sIg, may employ PKC in producing select outcomes, that individual B cell receptors may signal downstream events via both PKC-dependent and PKC-independent pathways, and that multiple signal transduction pathways may be used to activate the expression of closely related genes.

Animals↗
PubMed1996

Delayed tyrosine phosphorylation and nuclear expression of STAT1 following antigen receptor stimulation of B lymphocytes.

The regulation of the STAT1 alpha transcription factor was assessed during B cell activation induced by cross-linking the surface IgM Ag receptor. Surface Ig ligation or pharmacologic stimulation with PMA and ionomycin resulted in the delayed (2-3 h after stimulation) nuclear appearance of tyrosine-phosphorylated STAT1 alpha, in contrast to the rapid induction that follows cytokine treatment. Nuclear expression of phosphorylated STAT1 alpha was abrogated by co-incubation of anti-Ig-treated B cells with the protein synthesis inhibitor cycloheximide (CHX), with the protein kinase inhibitor H-7, or with the immunosuppressive drug rapamycin. Tyrosine-phosphorylated STAT1 alpha was found to be recruited to the STAT binding site of the IFN regulatory factor-1 (IRF-1) gene promoter only after 2 to 3 h, and this association was also inhibitable by CHX and rapamycin. The arrival of STAT1 alpha coincided with attenuation of anti-Ig-induced STAT-binding activity specific for the IRF-1 promoter site, and both rapamycin and CHX treatment counteracted the loss of this activity. Furthermore, basal transcription of the endogenous IRF-1 gene was decreased as a result of anti-Ig treatment, and this effect of anti-Ig was blocked by co-incubation with rapamycin. Thus, STAT1 alpha plays a dynamic role in the composition of IRF-1 promoter-specific DNA binding complexes stimulated by B cell Ag receptor ligation, and nuclear expression of phosphorylated STAT1 alpha is regulated in a unique fashion by Ag receptor engagement. In addition, surface Ig cross-linking imparts negative regulatory control of IRF-1 gene expression, possibly through activation of STAT1 alpha.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1996

[Effects of thermal injury on heart sialic acid content in rats].

The myocardial sialic acid content, ATPase activities, and Ca2+ level were investigated in rats with full thickness burn of 30% TBSA. The results showed that the burned rats had a decreased level of myocardial sialic acid which was only 58.8% of controls at 3 h postburn. Myocardial Na+, K(+)-ATPase, Ca2+, Mg(2+)-ATPase and Ca(2+)-ATPase activities were inhibited in burned rats. As compared to controls, the burned rats showed a higher level of Ca2+ in heart tissue. This study indicated that there were abnormal energy metabolism, dysfunction of ion pump, and paradox Ca2+ overload in burned rats, which may be associated with the decrease in sialic acid content in myocardium.

Animals↗
PubMed1995

Receptor-specific induction of individual AP-1 components in B lymphocytes.

The inducible nuclear transcription factor complex, AP-1, typically consists of heterodimers between Jun and Fos proteins. Although components are drawn from families of related molecules, little is known about the physiologic regulation of jun- and fos-related gene products. In particular, it is not known whether expression of individual family members is stimulus-specific or whether the same signaling pathways are responsible for induction of all subunits. To clarify these issues, AP-1 components were examined following activation of primary B lymphocytes through two separate receptors, the surface Ig Ag receptor, and the CD40 receptor for T cell influences. Both forms of stimulation led to expression of JunB and JunD mRNA and protein; however, induction of JunB mediated by anti-Ig Ab was protein kinase C (PKC)-dependent, whereas induction mediated by CD40 ligand was resistant to PKC depletion. The two forms of stimulation diverged even further with respect to Fos expression. Although both stimuli induced c-Fos, expression of FosB was stimulus specific at both the mRNA and protein levels, in that this component was induced by anti-Ig but not by CD40 ligand. Stimulated expression of c-Fos and FosB was in all cases PKC-independent. These results provide evidence for receptor-specific differences in the expression of AP-1 components, primarily with respect to FosB. They also indicate that separate intracellular pathways may be used for induction of jun and fos gene products and that the same transcription factor (junB) may be triggered by two surface receptors through separate pathways that differ in PKC dependence.

Animals↗
PubMed1994

Activation of AP-1 in primary B lymphocytes by surface immunoglobulin requires de novo Jun-B synthesis.

We demonstrate herein that resting primary B lymphocytes do not contain detectable levels of AP-1 (TRE)-binding activity. Upon cross-linking of surface immunoglobulin (sIg) receptors, TRE-binding activity is induced within 2 hr and its appearance requires de novo protein synthesis. Antisera to Jun-B inhibits the vast majority of TRE-binding activity, indicating that Jun-B is a primary component of B cell TRE-binding complexes. In keeping with this, Jun-B protein is not detectable in cytosol or nuclear extracts from resting B lymphocytes, as determined by immunoblotting with Jun-B antisera. However, the nuclear expression of Jun-B is induced within 2 hr following sIg cross-linking and is completely blocked by cycloheximide. 35S-labeling studies suggest that the increase in Jun-B expression results from de novo protein synthesis. Moreover, Jun-B migrates in SDS-polyacrylamide gels as two distinct electrophoretic proteins that correspond to a 41-kDa species and a phosphorylated 47-kDa form. These results suggest that the induction of AP-1-binding activity in primary B lymphocytes following sIg cross-linking does not result from post-translational phosphorylation of a preexisting cellular pool of Jun-B protein, but rather is coupled to the stimulation of de novo Jun-B synthesis. Thus Jun-B synthesis represents an integral event in the production of receptor-mediated AP-1 in B cells. The significance of these results with respect to the role of Jun-B in controlling gene expression during the activation of primary B cells is discussed.

Animals↗
PubMed1992

Repression of the araBAD promoter from araO1.

DNA looping between the araO2 and araI sites holds the uninduced or basal level of expression of the araBAD genes from the pBAD promoter at a low level. Despite the presence of another and closer site potentially capable of mediating looping to araI, no repression from this site, called araO1, is observed. Here we show, using both in vivo and in vitro experiments, that the araO1 site is not normally occupied by AraC protein under repressing conditions, but that if AraC protein is overproduced and the araO2 site is absent, araO1 is then occupied and repression of pBAD can be observed.

AraC Transcription Factor↗
PubMed1988

Alternative DNA loops regulate the arabinose operon in Escherichia coli.

The araCBAD regulatory region of Escherichia coli contains two divergently oriented promoters and three sites to which AraC, the regulatory protein of the operon, can bind. This paper presents the results of in vivo dimethyl sulfate "footprinting" experiments to monitor occupancy of the three AraC sites and measurements of activity of the two promoters. These measurements were made both in the absence of the inducer arabinose and at various times after arabinose addition to growing cells containing the wild-type ara regulatory region or the regulatory region containing various deletions and point mutations. The data lead to the conclusion that two different DNA loops can form in the ara regulatory region. These loops are generated by AraC protein molecules binding to two different DNA sites and binding to each other. One of these loops predominates in the absence of arabinose and plays a major role in repressing activity of one of the promoters. Upon the addition of arabinose the amount of the first loop type, the repression loop, decreases and the amount of a second loop increases. Formation of this second loop precludes the counterproductive formation of the repression loop.

AraC Transcription Factor↗
PubMed1986

The DNA loop model for ara repression: AraC protein occupies the proposed loop sites in vivo and repression-negative mutations lie in these same sites.

Two sets of experiments have been performed to test the DNA loop model of repression of the araBAD operon of Escherichia coli. First, dimethyl sulfate methylation protection measurements on normally growing cells show that the AraC regulatory protein occupies the araI site in the presence and absence of the inducer arabinose. Similarly, the araO2 site is shown to be occupied by AraC protein in the presence and absence of arabinose; however, its occupancy by AraC is greatly reduced when araI and adjacent sequences are deleted. Thus, AraC protein binds to araO2 cooperatively with some other component of the ara system located at least 60 base pairs away. Second, the mutational analysis presented here shows that the DNA components required for repression of araBAD are araI, araO2, and perhaps the araBAD operon RNA polymerase binding site.

AraC Transcription Factor↗