Biomedical subjects

L Huang

Publications and source records attributed to L Huang.

At least 271 records · Page 15Linked to original sources

PubMed1999

Induction and regulation of Th1-inducing cytokines by bacterial DNA, lipopolysaccharide, and heat-inactivated bacteria.

Th1 immune responses, characterized by production of gamma interferon (IFN-gamma), are associated with protective immunity to viruses and intracellular bacteria. Heat-killed Brucella abortus promotes secretion of Th1-inducing cytokines such as interleukin-12 (IL-12) and IFN-gamma and has been used as a carrier to induce Th1 responses to vaccines. To explore which bacterial constituents could mediate this response and how it is regulated, murine spleen cells were cultured with B. abortus derived DNA, lipopolysaccharide (LPS), or whole killed organisms. Each constituent induced similar, substantial amounts of IL-10. However, only B. abortus and B. abortus DNA induced high levels of IFN-gamma and IL-12. B. abortus and B. abortus DNA-stimulated IL-12 production was maximal by 6 to 18 h, while IL-10 production steadily accumulated over this time period. These kinetics suggested that IL-10 may eventually downmodulate the Th1-like cytokine response to B. abortus and B. abortus DNA, which was confirmed by using neutralizing antibody. In the absence of IL-10, B. abortus LPS induced strong IFN-gamma responses, but IL-12 p70 levels were still undetectable from BALB/c spleen cells. LPS induced IL-12 if the spleen cells were primed with IFN-gamma and IL-10 was neutralized, indicating that LPS can stimulate IL-12 production under the most favorable conditions. Responses to Escherichia coli LPS and DNA mirrored the responses to B. abortus components, suggesting that immune effects observed with these constituents may be generalizable to many microbial species. In vivo experiments demonstrated the same hierarchy of responses for IL-12 production. These findings support the likelihood that microbial components, if used as carriers or adjuvants, can differ substantially in their ability to effect a Th1 response.

Animals↗

PubMed1999

Assembly of the cleavage and polyadenylation apparatus requires about 10 seconds in vivo and is faster for strong than for weak poly(A) sites.

We have devised a cis-antisense rescue assay of cleavage and polyadenylation to determine how long it takes the simian virus 40 (SV40) early poly(A) signal to commit itself to processing in vivo. An inverted copy of the poly(A) signal placed immediately downstream of the authentic one inhibited processing by means of sense-antisense duplex formation in the RNA. The antisense inhibition was gradually relieved when the inverted signal was moved increasing distances downstream, presumably because cleavage and polyadenylation occur before the polymerase reaches the antisense sequence. Antisense inhibition was unaffected when the inverted signal was moved upstream. Based on the known rate of transcription, we estimate that the cleavage-polyadenylation process takes between 10 and 20 s for the SV40 early poly(A) site to complete in vivo. Relief from inhibition occurred earlier for shorter antisense sequences than for longer ones. This indicates that a brief period of assembly is sufficient for the poly(A) signal to shield itself from a short (50- to 70-nucleotide) antisense sequence but that more assembly time is required for the signal to become immune to the longer ones (approximately 200 nucleotides). The simplest explanation for this target size effect is that the assembly process progressively sequesters more and more of the RNA surrounding the poly(A) signal up to a maximum of about 200 nucleotides, which we infer to be the domain of the mature apparatus. We compared strong and weak poly(A) sites. The SV40 late poly(A) site, one of the strongest, assembles several times faster than the weaker SV40 early or synthetic poly(A) site.

3' Untranslated Regions↗

PubMed1999

Effect of immune response on gene transfer to the lung via systemic administration of cationic lipidic vectors.

Cationic lipid-mediated intravenous gene delivery shows promise in treating pulmonary diseases including lung tumor metastases, pulmonary hypertension, and acute respiratory distress syndrome. Nevertheless, clinical applications of cationic lipidic vectors via intravenous administration are limited by their transient gene expression. In addition, repeated dosing is not effective at frequent intervals. In an effort to elucidate the mechanism of gene inactivation, we report in this study that cationic lipid-protamine-DNA (LPD) complexes, but not each component alone, can induce a high level of cytokine production, including interferon-gamma and tumor necrosis factor-alpha. Furthermore, we demonstrate that LPD administration triggers apoptosis in the lung, a phenomenon that may be mediated in part by the two cytokines. Treatment of mice with antibodies against the two cytokines prolongs the duration of gene expression and also improves lung transfection on a second administration of LPD. Although the mechanism underlying LPD-induced cytokine production is unclear, methylation of the DNA significantly decreased the level of both interferon-gamma and tumor necrosis factor-alpha, suggesting that unmethylated CpG sequences in plasmid DNA play an important role. These data suggest that decreasing the CpG-mediated immune response while not affecting gene expression may be a useful therapeutic strategy to improve cationic lipid-mediated intravenous gene delivery to the lung.

Animals↗

PubMed1999

Selective A2A adenosine receptor activation reduces ischemia-reperfusion injury in rat kidney.

A2A adenosine receptors (A2A-ARs) are known modulators of renal hemodynamics and potent inhibitors of inflammation. We sought to determine whether selective activation of A2A-ARs protects kidneys from ischemia-reperfusion injury. The ester derivative of DWH-146 (DWH-146e), a selective A2A agonist, was found to be more potent and selective for A2A-ARs than the prototype compound CGS-21680. Osmotic minipumps were implanted subcutaneously to infuse into rats either vehicle or DWH-146e (0.004 microg. kg(-1). min(-1)), during and after ischemia-reperfusion injury. Following 24 and 48 h of reperfusion, the rise in serum creatinine and blood urea nitrogen for vehicle-treated rats was substantially elevated compared with DWH-146e-treated rats. Histological examination revealed widespread tubular epithelial necrosis and vascular congestion in the outer medulla of vehicle-treated compared with DWH-146e-treated animals. ZM-241385, a selective A(2A) antagonist, blocked the protective effect of DWH-146e. Delaying administration of DWH-146e until the initiation of reperfusion also decreased serum creatinine. We conclude that 1) selective A2A-AR activation by DWH-146e reduces ischemia-reperfusion injury in rat kidneys, 2) the effect of DWH-146e is A2A receptor mediated, and 3) the protective effects are mediated by preventing injury during the reperfusion period.

Animals↗

PubMed1999

Neuromechanical interaction in human snoring and upper airway obstruction.

The fact that snoring and obstructive apnea only occur during sleep means that effective neuromuscular functioning of the upper airway during sleep is vital for the maintenance of unimpeded breathing. Recent clinical studies in humans have obtained evidence demonstrating that upper airway neural receptors sense the negative pressure generated by inspiration and "trigger," with a certain delay, reflex muscle activation to sustain the airway that might otherwise collapse. These findings have enabled us to propose a model in which the mechanics is coupled to the neuromuscular physiology through the generation of reflex wall stiffening proportional to the retarded fluid pressure. Preliminary results on this model exhibit three kinds of behavior typical of unimpeded breathing, snoring, and obstructive sleep apnea, respectively. We suggest that the increased latency of the reflex muscle activation in sleep, together with the reduced strength of the reflex, have important clinical consequences.

Airway Obstruction↗

PubMed1999

Disruption of dynamic cell surface architecture of NIH3T3 fibroblasts by the N-terminal domains of moesin and ezrin: in vivo imaging with GFP fusion proteins.

Lamellipodia, filopodia, microspikes and retraction fibers are characteristic features of a dynamic and continuously changing cell surface architecture and moesin, ezrin and radixin are thought to function in these microextensions as reversible links between plasma membrane proteins and actin microfilaments. Full-length and truncated domains of the three proteins were fused to green fluorescent protein (GFP), expressed in NIH3T3 cells, and distribution and behaviour of cells were analysed by using digitally enhanced differential interference contrast (DIC) and fluorescence video microscopy. The amino-terminal (N-)domains of all three proteins localize to the plasma membrane and fluorescence recordings parallel the dynamic changes in cell surface morphology observed by DIC microscopy of cultured cells. Expression of this domain, however, significantly affects cell surface architecture by the formation of abnormally long and fragile filopodia that poorly attach and retract abnormally. Even more striking are abundant irregular, branched and motionless membraneous structures that accumulate during retraction of lamellipodia. These are devoid of actin, endogenous moesin, ezrin and radixin, but contain the GFP-labeled domain. While a large proportion of endogenous proteins can be extracted with non-ionic detergents as in untransfected control cells, >90% of N-moesin and >60% of N-ezrin and N-radixin remain insoluble. The minimal size of the domain of moesin required for membrane localization and change in behavior includes residues 1-320. Deletions of amino acid residues from either end result in diffuse intracellular distribution, but also in normal cell behavior. Expression of GFP-fusions of full-length moesin or its carboxy-terminal domain has no effect on cell behavior during the observation period of 6-8 hours. The data suggest that, in the absence of the carboxy-terminal domain, N-moesin, -ezrin and -radixin interact tightly with the plasma membrane and interfere with normal functions of endogeneous proteins mainly during retraction.

3T3 Cells↗

PubMed1999

Performance of an algorithm to detect Pneumocystis carinii pneumonia in symptomatic HIV-infected persons. Pulmonary Complications of HIV Infection Study Group.

STUDY OBJECTIVES: To determine whether an algorithm consisting of a chest radiograph and the diffusing capacity of the lung for carbon monoxide (D(LCO)) is effective in detecting Pneumocystis carinii pneumonia (PCP) in symptomatic HIV-infected persons; and to establish a benchmark for future comparisons of alternative algorithms. DESIGN: Prospective, 64-month study. SETTING: Multicenter, ambulatory care. PATIENTS: 306 HIV-infected subjects enrolled in the Pulmonary Complications of HIV Infection Study who developed 467 episodes of new or worsening respiratory symptoms. MEASUREMENTS: Chest radiography followed by D(LCO) measurement, if the radiograph was normal or unchanged. RESULTS: An algorithm combining a chest radiograph followed by a D(LCO) measurement, if the radiograph was normal or unchanged, was effective and detected abnormalities that led to a diagnosis of PCP in 78 of 80 evaluable episodes (97.5%). The radiograph (specific parenchymal abnormality, number of lung zones involved) and the D(LCO) (degree of decrease, degree of decrease from baseline) also provided additional information on the probability of PCP. CONCLUSIONS: In symptomatic HIV-infected patients suspected of having PCP, the diagnostic evaluation should begin with a chest radiograph, followed by a D(LCO) measurement, if the radiograph is normal or unchanged. If both of these tests are normal, it may be reasonable to conclude the evaluation rather than to proceed on to additional testing. This algorithm can serve as a benchmark for future comparisons.

AIDS-Related Opportunistic Infections↗

PubMed1999

Evolution of transcriptional control from prokaryotic beginnings to eukaryotic complexities.

Mechanisms for regulating gene transcription became increasingly complex as organisms evolved. In prokaryotes the relatively simple mechanism of repression is based on a few proteins that bind to specific DNA sequences in a ligand-dependent fashion. In eukaryotes large complexes that include ligand binding proteins regulate transcription. Lower eukaryotes developed an additional level of control based on protein complexes that include modifying enzymes. The DNA/histone complex, in combination with gene-specific transcriptional factors, is the basis of gene regulation in eukaryotes. Higher eukaryotes took regulation a level further by methylating CpGs in promoter sequences of DNA, thereby allowing binding of histone deacetylases and inhibiting transcription. Finally, long-lasting "superrepression" provides another mechanism for coordinate transcriptional regulation of large blocks of genes.

Animals↗

PubMed1999

Production of a family of kinase-inhibiting lactones from fungal fermentations.

During the course of our screening for natural products from fungi, extracts of several cultures were found to make a family of related resorcylic acid lactone compounds, which are potent inhibitors of MEK kinase. Comparative and empirical studies of fermentation conditions improved the titers of the compounds of interest. Striking changes in the ratios and amounts of the major and minor compounds in some cases were achieved by manipulations of media composition.

Culture Media↗

PubMed1999

Resorcylic acid lactones: naturally occurring potent and selective inhibitors of MEK.

A resorcylic acid lactone, L-783,277, isolated from a Phoma sp. (ATCC 74403) which came from the fruitbody of Helvella acetabulum, is a potent and specific inhibitor of MEK (Map kinase kinase). L-783,277 inhibits MEK with an IC50 value of 4 nM. It weakly inhibits Lck and is inactive against Raf, PKA and PKC. L-783,277 is an irreversible inhibitor of MEK and is competitive with respect to ATP. L-783,290, the trans-isomer of L-783,277, was isolated from the same culture and evaluated together with several semi-synthetic resorcylic acid lactone analogs. A preliminary structure-activity relationship is presented. Several independent cell-based assays have been carried out to study the biological activities of these resorcylic acid lactone compounds and a brief result summary from these studies is presented.

Adenosine Triphosphate↗

PubMed1999

Development of a comprehensive assessment toolbox for stroke.

Comprehensive databases for the assessment of individuals with stroke are essential for clinical management and evaluation of outcomes for quality management and research. The purpose of this article is to describe a comprehensive data system or "toolbox" developed by clinicians and researchers at the Center on Aging at the University of Kansas Medical Center. The choice of assessments for the toolbox resulted from the Agency for Health Care Policy and Research Post-Stroke Rehabilitation Guidelines, results of the Kansas City Stroke Study, and the authors' work to develop a new stroke measure-the Stroke Impact Scale.

Aged↗

PubMed1999

beta-lapachone induces cell cycle arrest and apoptosis in human colon cancer cells.

BACKGROUND: Human colon cancers have a high frequency of p53 mutations, and cancer cells expressing mutant p53 tend to be resistant to current chemo- and radiation therapy. It is thus important to find therapeutic agents that can inhibit colon cancer cells with altered p53 status. beta-Lapachone, a novel topoisomerase inhibitor, has been shown to induce cell death in human promyelocytic leukemia and prostate cancer cells through a p53-independent pathway. Here we examined the effects of beta-lapachone on human colon cancer cells. MATERIALS AND METHODS: Several human colon cancer cell lines, SW480, SW620, and DLD1, with mutant or defective p53, were used. The antiproliferative effects of beta-lapachone were assessed by colony formation assays, cell cycle analysis, and apoptosis analysis, including annexin V staining and DNA laddering analysis. The effects on cell cycle and apoptosis regulatory proteins were examined by immunoblotting. RESULTS: All three cell lines, SW480, SW620, and DLD1, were sensitive to beta-lapachone, with an IC(50) of 2 to 3 microM in colony formation assays, a finding similar to that previously reported for prostate cancer cells. However, these cells were arrested in different stages of S phase. At 24 hr post-treatment, beta-lapachone induced S-, late S/G2-, and early S-phase arrest in SW480, SW620, and DLD1 cells, respectively. The cell cycle alterations induced by beta-lapachone were congruous with changes in cell cycle regulatory proteins such as cyclin A, cyclin B1, cdc2, and cyclin D1. Moreover, beta-lapachone induced apoptosis, as demonstrated by annexin V staining, flow cytometric analysis of DNA content, and DNA laddering analysis. Furthermore, down-regulation of mutant p53 and induction of p27 in SW480 cells, and induction of pro-apoptotic protein Bax in DLD1 cells may be pertinent to the anti-proliferative and apoptotic effects of beta-lapachone on these cells. CONCLUSIONS: beta-Lapachone induced cell cycle arrest and apoptosis in human colon cancer cells through a p53-independent pathway. For human colon cancers, which often contain p53 mutations, beta-lapachone may prove to be a promising anticancer agent that can target cancer cells, especially those with mutant p53.

Antibiotics, Antineoplastic↗

PubMed1999

[The immunohistochemical studies on estradiol and progesterone receptors in human decidua after terminating early pregnancy by mifepristone].

OBJECTIVE: To investigate the effects of mifepristone on decidua at the cellular level of estrogen receptor (ER) and progesterone receptor (PR) and the mechanism of prolonged uterine bleeding after terminating early pregnancy by mifepristone. METHODS: Thirty decidua specimens were obtained from pregnant women with amenorrhea of 6-7 week duration, 20 women were treated with mifepristone and 10 given mifepristone plus misoprostol respectively. Immunocytochemical reactions of PR nad ER in decidua were compared among three groups using computer image analysis technology. RESULTS: In the control group, the nuclei of the decidual cells were stained positively for ER and PR. Their integral values of receptor level were 5,860,790 +/- 311,691 for ER and 4,905,970 +/- 157,319 for PR. Mifepristone treatment reduced ER and PR staining. The integral values were 3,547,180 +/- 191,858 for ER and 3,700,750 +/- 188,322 for PR in this group, and it was more apparent in the group treated with mifepristone plus misoprostol: 2,021,721 +/- 145,281 for ER and 2,528,580 +/- 240,535 for PR. CONCLUSIONS: The ER and PR level in human decidua decreased after mifepristone or/and misoprostol treatment. This may be related to prolonged uterine bleeding after terminating early pregnancy by mifepristone.

Abortifacient Agents, Nonsteroidal↗

PubMed1999

Investigation on Qiong yao shen shu (Qiongyao's Magical Book).

Written in about the period of late Yuan to early Ming dynasties, Qiongyao's Magical Book is attributed to a Taoist who was also conversant with acupunture art. By investigation, it is found that there are, at least, three books carrying the same title of Qiongyao's Magical Book, including a 3 volume Qiongyao's Magical Book now lost; a 3 - volume Qiongyao's Magical Book of Discovery (also called The Acupuncture Classic of Qiongyao the Immortal printed in the Ming dynasty, which is entirely different from the previous one and is an apocrypha; and a 4 - volume Qiongyao's Magical Book printed in the Qing dynasty also called Qiongyao's Great Collections of Magical Books wiich is a mixture of authentic and apocryphal texts in which 2 medical books irrelevant to the original are attached to the end of volume 3, with supplements by later writers intermingled in other volumes.

Acupuncture Therapy↗

PubMed1999

Liposomes: conquering the nuclear barrier.

The field of non-viral vector gene therapy has become increasingly successful due to the production of improved liposomes, polymers and other formulations. These novel vectors have increased the amount of DNA delivered to cells both in vitro and in vivo, and in turn, have increased gene expression. However, DNA transport to the nucleus still remains one of the largest problems in obtaining efficient, high levels of gene expression. This review addresses the reasons why the nucleus is a major barrier to transfected DNA and introduces the cytoplasmic expression system as a possible alternative to nuclear expression.

Biological Transport↗

PubMed1999

Blocking effect of puerarin on calcium channel in isolated guinea pig ventricular myocytes.

OBJECTIVE: To identify whether Puerarin (Puer) has blocking effects on L-type calcium channel. METHODS: We used whole-cell recording of patch-clamp techniques to analyse calcium channel current in ventricular myocytes isolated from Langendorff guinea pig hearts by collagenase. RESULTS: In control group, peak calcium channel current was decreased by 10.6% and 29.8% at 5, 10 min of recording time, respectively. For the same period, 0.1 mmol/L Puer reduced calcium current by 23.9% and 72.4%. 0.1 and 1 mmol/L Puer inhibited the amplitude of peak Calcium channel current by 40.6% and 63.2% after perfusing for 10 min. Compared with control group in which "rundown" phenomenon was observed, Puer also demonstrated its blocking effect on L-type channel. While washout of Puer with perfusing solution, calcium channel current went down further instead of recovery. Current-voltage (I-V) curves showed that the levels of calcium channel current were obviously decreased by Puer (both 0.1 mmo/L and 1 mmo/L) form -40 mV to +10 mV. CONCLUSION: Puer has blocking effect on L-type calcium channel in a concentration dependent manner.

Animals↗

PubMed1999

[Detection of aberrant chromosomes in acute lymphoblastic leukemia by fluorescence in situ hybridization].

OBJECTIVE: To investigate the value of fluorescence in situ hybridization (FISH) in detecting aberrant chromosomes in acute lymphoblastic leukemias. METHODS: Conventional banding techniques and FISH were used to detect trisomy 17, 18 and 21 in 38 patients with acute lymphoblastic leukemia. Lymphoid DNA probes specific for chromosomes no. 17, 18 and 21 were used for FISH. RESULTS: Out of the 38 patients, 18 had + 17, 22 + 18 and 23 + 21. The number of trisomy cells ranged from 7% to 80%. Ten normal bone marrow samples were hybridized with the chromosomes 17, 18 and 21 probes. CONCLUSION: FISH is more sensitive than conventional cytogenetic analysis and allows systematic study on large cohort of patients without the need of metaphase preparations.

Adolescent↗

PubMed1999

[Clinical and experimental study of jianruling in treating hyperplasia of mammary gland].

OBJECTIVE: To observe the therapeutic effect of Jianruling (JRL) on hyperplasia of mammary gland (HMG) and to explore its mechanism in regulating sex hormones. METHODS: Clinical changes of HMG were observed and serum sex hormones measured before and after JRL treatment. In experimental study, the effect of JRL was estimated by using electron microscope, pathologic and radioimmunoassay. RESULTS: JRL could not only cure HMG, but also regulate the sex hormone secretion both in HMG patients and in rats. Clinical study showed that the clinical cure rate was 72.5%, and the total effective rate was 90.8%, it demonstrated a significant difference in comparing with the control group, P < 0.01. The estradiol and prolactin levels of patients lowered significantly after JRL treatment, P < 0.05, while progestogen and testosterone increased significantly, P < 0.05, but no significantly change of follicle-stimulating hormone and luteinizing hormone was found. JRL showed marked effect in treating and preventing experimental HMG in rats, it could modulate the secretive function of sex hormone, and improve the construction of mammary gland. CONCLUSION: JRL has significant effect in treating HMG, it can adjust the endogenous sex hormone level, delay the development of chronic cystic hyperplasia of mammary gland.

Adolescent↗