Biomedical subjects
Publications and source records attributed to J Huang.
This paper reports the identification of Pholidota cantonensis on medicinal materials character, microscopical characteristic, TLC and UV. The results supply a basis for the identification of Herba Dendrobii medicinal materials.
Using the FTIR and 1H NMR methods, the structures, relative ratio and inventory ratio of segmented poly (urea) urethanes which are synthesized with different extenders (1,4-butandiol, ethylene diamine and their mixtures)have been studied successfully and the ratationship between the branch ratio and inventory ratio has been determined.
The EDXRF extrapolate-regression method described in this paper combines regression method with the fundamental formula of fluorescence intensity. The contents of Ni and Pd in white karat gold jewellery were calculated theoretically according to the spectrum of the sample. The content of gold was deternined without standards. The precision was 0.1% and the deviation was 0.3% compared with AA.
PURPOSE: Changes in retinal photopigments represent a fundamental step in the evolution of visual systems, in that addition of new pigment types or alterations in the spectral absorption properties of existing pigments modify visual capacities and thus open new visual worlds. To provide a tool that would allow direct examination of the changes caused by the presence of novel photopigments, this study was designed to determine whether a gene encoding a human cone photopigment introduced into the mouse genome would be expressed in a cone-specific manner and would support phototransduction. METHODS: Mice transgenic for the human long wavelength-sensitive (L) photopigment were generated by microinjection of fertilized mouse eggs. RNA expression in different tissues was monitored by reverse transcription-polymerase chain reaction analysis. Photopigment protein was localized in retinal cross sections and wholemounts by antibody staining. Light transduction of the cone photopigments was assessed by flicker photometric electroretinography (ERG). RESULTS: The human transgene was expressed specifically in the mouse cones in quantities comparable to those of the mouse middle wavelength-sensitive (M) pigment gene. Immunocytochemical analysis showed that the human L pigment was abundantly synthesized in most mouse cones, was translocated to the outer segments, and caused no detectable cone degeneration. Electroretinographic spectral sensitivity analysis showed that the human L pigment was efficient in eliciting an electrical response. The degree of expression of the transgene in the two founders correlated well with the spectral responsivity of the ERG. CONCLUSIONS: The human L photopigment transduces light efficiently in mouse cones, implying that all protein domains necessary for efficient interaction with intracellular transport and signal transduction machineries in mouse cones have been conserved through evolution. The expression of the human L photopigment gene in both classes of cone of the mouse retina indicates that the transgene did not have the regulatory elements necessary for restricting its expression to mouse M cones or that such elements are not recognized in mouse UV-sensitive cones.
Fifty files were evaluated to determine the normal anatomy of the cranial nerves. All the cranial nerves were studied including the labyrinth, in different planes with a 3DFT-CISS imaging technique. The 3DFT-CISS is especially interesting to study cranial nerves because of the excellent contrast with CSF-fluid and the possibility of thin sections. It might be essential for the diagnosis of neuralgia and cranial nerves paralysis.
pJB-B5 was a recombinant plasmid of pRK415 containing the 5.9 kb B5 fragment from exoR'-11. After pJB-B5 was mutagenized by MT614 (mal::Tn5), 10 plasmids TN1-1, TN1-12, TN2-2, TN2-3, TN3-1, TN4-1, TN9-1, TN10-1, TN13-1, and TN14-1 with different Tn5 insertions in the B5 fragment were constructed. By conjugation of TN1-1, etc., into Rhizobium huakuii 107 containing the P-group plasmid pPH1JI which is incompatible with pRK415, and simultaneous selection for Rifr (conferred by strain 107), Gm(r) (conferred by pPH1JI), and Nmr (retention of Tn5), R. huakuii 107 transconjugant yields a strain in which Tn5 has recombined into the R. huakuii 107 genome. Three EPS-deficient (Exo-) mutants 107 (TN2-2), 107 (TN10-1), and 107 (TN13-1) were isolated and their inserted Tn5 was certified as the result of a double homologous recombinant event by Southern hybridization analysis. This result showed the Tn5 region-directed mutagenesis is an efficient way to select Exo- mutant in R. huakuii.
This review discusses the recent advances in imaging and surgical techniques, and their impact on the management of liver metastases. It also considers how the dismal prognosis may be improved with early detection and more precise surgery.
OBJECTIVE: To investigate possible asbestos contamination of paraffin and migration by asbestos fibers during the tissue-embedding process. DESIGN: Three sample categories were included in the study: (1) commercially available paraffin samples; (2) procedural control samples, which were prepared by processing the paraffin through the use of standard solvents and instruments; and (3) samples taken from areas adjacent to embedded tissue and evaluated for migration of asbestos from the tissue into the surrounding paraffin. The analysis of collected material from all samples was performed with analytical transmission electron microscopy. RESULTS: Only one extremely small tremolite fiber was found in any of the commercially available samples of paraffin. No asbestos fibers were found either in the procedural control samples or in the samples taken adjacent to the embedded lung tissue. CONCLUSIONS: First, it was extremely unlikely that any of the commercial paraffin samples would have skewed data due to embedded tissue. Second, the processing and instrumentation was not found to contribute asbestos material to the paraffin during the preparations. Finally, embedded tissue that contained high numbers of fibers, both uncoated fibers and asbestos bodies, did not contribute asbestos to the adjacent paraffin.
In summary, PDAPP mice overexpressing a mutation associated with some cases of familial early-onset AD express several of the major pathological hallmarks associated with AD. Amyloid plaques in PDAPP mice appear quite similar to A beta deposits in AD as shown by a variety of different antibodies and stains, and are of both the diffuse and compacted varieties. Additionally, a subset of these amyloid plaques appear to be neuritic plaques. Neurodegenerative changes, including the loss of synaptic and dendritic proteins, abnormal phosphorylation of cytoskeletal elements, subcellular degenerative changes, and the deposition of lysosomal and acute phase proteins has also been seen in PDAPP mouse brains. Reactive astrocytosis and microgliosis have also been observed in association with the amyloid plaques in the PDAPP mice. No neurofibrillary tangles or paired helical filaments have been found in the mice to date. It remains unknown whether mice are capable of generating these in a manner comparable to AD in less than two years. Extensive behavioral analyses are currently being performed in these mice, and preliminary results indicate that the PDAPP mice are significantly impaired on a variety of different learning and memory tests. In conclusion, the PDAPP mouse model doesn't display all the pathological hallmarks of AD, but it does display most of them in a robust manner that increases with age and gene dosage. Therefore, this transgenic model provides evidence that alterations in APP processing and A beta production can result in AD-like neuropathology, can contribute to a mechanistic understanding of AD (since examination of AD brains yields a static view, and we are unable to view the development of various pathological changes), as well as providing an useful animal model for the testing of various therapeutic interventions directed towards specific aspects of the neurodegenerative process.
Toluene diisocyanate (TDI) causes occupational asthma characterized by inflammation and hyperreactivity of airways to irritants and bronchoconstrictor drugs. We examined the non-immune, direct effect of TDI on airway reactivity in vitro in the absence of an inflammatory response using the guinea-pig isolated, perfused trachea preparation to measure reactivity to methacholine (MCh), and fixed point ion mobility spectrometry to measure moment to moment levels of TDI vapor in air that was delivered to the tracheal mucosa. MCh was added to the mucosal modified Krebs-Henseleit (MKH) perfusing solution to generate control concentration-response curves for contractile responses. The lumen was then emptied and perfused with air or air containing 5, 20 or 70 ppb TDI vapor, after which the trachea was perfused with MKH solution and reactivity to MCh was re-examined. After only 30 min of treatment, TDI vapor concentration-dependently increased reactivity of the trachea to MCh (2.4- and 2.9-fold, respectively, for 20 and 70 ppb TDI; 5 ppb TDI and air alone had no effect). In tracheas treated in vitro with 2 microM capsaicin to deplete tachykinins, TDI caused the same (4-fold) increase in reactivity to MCh that was observed in control tracheas. However, TDI vapor (70 ppb) no longer enhanced reactivity to MCh in tracheas from which the epithelium had been removed. Our results indicate that a direct, non-immune, non-inflammatory action of TDI on respiratory epithelium leads to hyperreactivity of airways in vitro.
The N-myc oncogene plays a key role in the biology of neuroblastoma and the differentiation process. N-myc expression is associated with metastatic disease, as well as the undifferentiated state of normal neuroblasts migrating from the neural crest during embryogenesis. Its down-regulation is a pivotal event in the differentiation of neuroblastoma cells by retinoic acid (RA). Our previous work has shown that RA works synergistically with other agents, such as interferon-gamma (IFN-gamma), to down-regulate N-myc expression and induce differentiation. The present study demonstrates that IFN-gamma, like RA, decreases N-myc transcription. However, functional analysis of N-myc upstream regulatory sequences using 5' deletion mutants of a promoter-CAT construct containing germ line sequences from nucleotide position -887 to +151 showed that IFN-gamma and RA act through different sites on the N-myc promoter. In addition to its transcriptional effect, IFN-gamma was also found to shorten the half-life of N-myc mRNA. Taken together, these findings provide a mechanistic basis for the synergistic action of IFN-gamma and RA in inducing neuroblastoma differentiation and a rationale for the possible development of combination differentiation therapy for clinical use.
Cellular processes are mediated by complex networks of molecular interactions. Dissection of their role most commonly is achieved by using genetic mutations that alter, for example, protein-protein interactions. Small molecules that accomplish the same result would provide a powerful complement to the genetic approach, but it generally is believed that such molecules are rare. There are several natural products, however, that illustrate the feasibility of this approach. Split-pool synthesis now provides a simple mechanical means to prepare vast numbers of complex, even natural product-like, molecules individually attached to cell-sized polymer beads. Here, we describe a genetic system compatible with split-pool synthesis that allows the detection of cell-permeable, small molecule inhibitors of protein-protein interactions in 100- to 200-nl cell culture droplets, prepared by a recently described technique that arrays large numbers of such droplets. These "nanodroplets" contain defined media, cells, and one or more beads containing approximately 100 pmol of a photoreleasable small molecule and a controlled number of cells. The engineered Saccharomyces cerevisiae cells used in this study express two interacting proteins after induction with galactose whose interaction results in cell death in the presence of 5-fluoroorotic acid (inducible reverse two-hybrid assay). Disruption of the interaction by a small molecule allows growth, and the small molecule can be introduced into the system hours before induction of the toxic interaction. We demonstrate that the interaction between the activin receptor R1 and the immunophilin protein FKBP12 can be disrupted by the small molecule FK506 at nanomolar concentrations in nanodroplets. This system should provide a general method for selecting cell-permeable ligands that can be used to study the relevance of protein-protein interactions in living cells or organisms.
Band III is a disorder and conformation-sensitive near-infrared (approximately 760 nm) charge transfer absorption band characteristic of equilibrium and nonequilibrium five coordinate ferrous high-spin hemes. The time evolution of this absorption band subsequent to photodissociation of six coordinate ferrous hemoglobin or myoglobin can provide detailed information regarding conformational relaxation, including the thermally driven fluctuations that result in the transition from inhomogeneous to homogeneous ligand rebinding kinetic. Such time-resolved measurements over a range of temperatures are difficult due to long sample recovery times at cryogenic temperatures. A new restoring technique that allows for the rapid movement of a large optically accessible cryostat is used in combination with nanosecond time-resolved near-infrared absorption spectroscopy to generate band III as a function of time for the photoproducts of the carbon monoxide derivative of adult human hemoglobin (COHbA) and, to a more limited extent, horse myoglobin (COMb). The measurements are made over a wide range of temperatures extending from well below the solvent (75% glycerol:water) glass transition at approximately 180 K to ambient temperatures. Three temperature- and/or viscosity-dependent phenomena are observed. At the highest temperatures, only conformational relaxation is observed for the 75% glycerol sample. At very high viscosity (> or = 400 cp), conformational relaxation slows dramatically, and both kinetic hole burning followed by the filling in of the "hole" (dynamic hole filling) are observed. As the temperature is lowered, conformational relaxation slows and finally ceases. Kinetic hole burning and dynamic hole filling as well as additional broadening of band III are observed down to 140 K. The observation of kinetic hole burning (KHB) is indicative of the sample being inhomogeneous on the time scale of the ligand rebinding giving rise to KHB. The onset of hole filling is a direct manifestation of the thermal homogenization of the initial inhomogeneous distribution of conformational substates responsible for KHB. The observed dynamics are used to explain the inverse temperature effect associated with the non-Arrhenius slow down of geminate rebinding above approximately 180 K. The inverse temperature effect appears to arise not only from the onset of conformational relaxation but also from the increase in the rate on thermal averaging of the initial inhomogeneous distribution of conformational substates.
The proinflammatory cytokine interleukin 1 (IL-1) activates the transcription of many genes encoding acute phase and proinflammatory proteins, a function mediated primarily by the transcription factor NF-kappaB. An early IL-1 signaling event is the recruitment of the Ser/Thr kinase IRAK to the type I IL-1 receptor (IL-1RI). Here we describe the function of a previously identified IL-1 receptor subunit designated IL-1 receptor accessory protein (IL-1RAcP). IL-1 treatment of cells induces the formation of a complex containing both IL-1RI and IL-1RAcP. IRAK is recruited to this complex through its association with IL-1RAcP. Overexpression of an IL-1RAcP mutant lacking its intracellular domain, the IRAK-binding domain, prevented the recruitment of IRAK to the receptor complex and blocked IL-1-induced NF-kappaB activation.
Estrogens and progesterone could be among the environmental signals that govern uterine immune cell synthesis of pro-inflammatory substances. In order to investigate this possibility, we first mapped expression of the inducible nitric oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-alpha) genes in the leukocytes of cycling and pregnant mouse uteri, then tested the ability of estradiol-17 beta (E2) and progesterone to influence gene expression. Immunohistochemistry, in situ hybridization, and other experimental approaches, revealed that the iNOS and TNF-alpha genes are expressed in mouse uterine mast cells, macrophages and natural killer cells (uNK). Gene expression in each cell type was noted to be dependent upon stage of the cycle or stage of gestation, implying potential relationships with levels of female hormones and state of cell differentiation or activation. Further in vivo and in vitro experiments showed that individual hormones have cell type-specific effects on synthesis of iNOS and TNF-alpha that are exerted at the level of transcription. In uterine mast cells, iNOS and TNF-alpha are promoted by E2 whereas preliminary studies in macrophages suggest that transcription and translation of the two genes are unaffected by E2 but are inhibited by progesterone. Uterine NK cell production of iNOS and TNF-alpha is strongly related to cell differentiation, which is initiated and sustained by progesterone. Collectively, the results indicate that regulation of synthesis of pro-inflammatory molecules by hematopoietic cells in cycling and pregnant uterus comprises a new and potentially critical role for female steroid hormones.
Heat shock transcription factor 1 (HSF1) functions as the master regulator of the heat shock response in eukaryotes. We have previously shown that, in addition to its role as a transcription factor, HSF1 stimulates the activity of the DNA-dependent protein kinase (DNA-PK). DNA-PK is composed of two components: a 460-kDa catalytic subunit and a 70- and 86-kDa heterodimeric regulatory component, also known as the Ku protein. We report here that HSF1 binds specifically to each of the two components of DNA-PK. Binding occurs in the absence of DNA. The complex with the Ku protein is stable and forms at a stoichiometry close to unity between the Ku protein heterodimer and the active HSF1 trimer. The binding is blocked by antibodies against HSF1. Our results show that HSF1 also binds directly, but more weakly, to the catalytic subunit of DNA-PK. Both interactions are dependent on a specific region within the HSF1 regulatory domain. This sequence is necessary but not sufficient for HSF1 stimulation of DNA-PK activity. The ability of HSF1 to interact with both components of DNA-PK provides a potential mechanism for the activation of DNA-PK in response to heat and other forms of stress.
BACKGROUND: The upper limit of vulnerability (ULV) hypothesis for defibrillation predicts that maneuvers that alter the ULV will cause a similar alteration in the defibrillation threshold (DFT). The purpose of this study was to test this prediction by evaluating the effects of electrode polarity and waveform duration on the relationship between the DFT and the ULV. METHODS AND RESULTS: Platinum spring electrodes were placed in the right ventricular (RV) apex and the superior vena cava in 12 pigs. Strength-duration curves were constructed for the DFT and ULV for each electrode polarity with monophasic waveforms (6 pigs) of different durations (2 to 14 ms) and biphasic truncated exponential waveforms (6 pigs) having phase 1 equal to 4 ms and phase 2 of different durations (0 to 10 ms). ULV data were gathered by scanning of the T wave. The ventricular pacing threshold (VPT) and ventricular fibrillation threshold (VFT) were also determined with these same waveforms. For the RV electrode as a cathode for monophasic and the first phase of biphasic stimuli, VPTs for the same waveform duration were significantly lower than for the configuration with the RV electrode as an anode. VFTs were not significantly different for the two electrode polarities with either monophasic or biphasic waveforms. The DFT changed in a fashion similar to the ULV with changes in electrode polarity and phase duration for both monophasic and biphasic waveforms. The ULV and DFT for each waveform duration for each polarity were strongly correlated (r=.83 to .99). CONCLUSIONS: The almost identical changes in ULV and DFT with changes in electrode polarity and waveform duration provide new evidence to support the ULV hypothesis of defibrillation.
BACKGROUND: Reduced doses of cytotoxic chemotherapy or standard-dose therapy plus a myeloid colony-stimulating factor decreases hematologic toxicity and its complications in patients with non-Hodgkin's lymphoma associated with infection with the human immunodeficiency virus (HIV). However, the effect of reducing the doses of cytotoxic chemotherapeutic agents on clinical outcome is not known. METHODS: We randomly assigned 198 HIV-seropositive patients with previously untreated, aggressive non-Hodgkin's lymphoma to receive standard-dose therapy with methotrexate, bleomycin, doxorubicin, cyclophosphamide, vincristine, and dexamethasone (m-BACOD) along with granulocyte-macrophage colony-stimulating factor (GM-CSF; n=94) or reduced-dose m-BACOD with GM-CSF administered only as indicated (n=98). RESULTS: A complete response was achieved in 39 of the 94 assessable patients assigned to low-dose therapy (41 percent) and in 42 of the 81 assessable patients assigned to standard-dose therapy (52 percent, P= 0.56). There were no significant differences in overall or disease-free survival; median survival times were 35 weeks for patients receiving low-dose therapy and 31 weeks for those receiving standard-dose therapy (risk ratio for death in the standard-dose group=1.17; 95 percent confidence interval, 0.84 to 1.63; P=0.25). Toxic effects of chemotherapy rated grade 3 or higher occurred in 66 of 94 patients assigned to standard-dose therapy (70 percent) and 50 of 98 patients assigned to low-dose treatment (51 percent, P=0.008). Hematologic toxicity accounted for the difference. CONCLUSIONS: As compared with treatment with standard doses of cytotoxic chemotherapy (m-BACOD), reduced doses caused significantly fewer hematologic toxic effects yet had similar efficacy in patients with HIV-related lymphoma. Dose-modified chemotherapy should be considered for most HIV-infected patients with lymphoma.