The mouse Naip gene cluster on Chromosome 13 encodes several distinct functional transcripts.
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Amino Acid Sequence↗
Biomedical subjects
S Huang
Publications and source records attributed to S Huang.
Comparison of the core size distribution in iron dextran complexes using Mössbauer spectroscopy and X-ray diffraction.
Mössbauer spectra of a series of iron dextran complexes in the intermediate temperature range where both sextet and doublet coexist may be used to obtain a qualitative description of the distribution of core sizes in these samples. Eight samples from five suppliers have been examined at 100 and 77 K. These differ markedly in the relative doublet contribution to the total spectral area and also in the hyperfine fields characterizing the sextets. The results indicate three distinct types of distribution. One sample from each type has also been examined at 4 K, where the doublet component has vanished and the hyperfine field distribution has become narrow and symmetric. These data are compared with estimates of average core diameters from X-ray line broadening.
Iron-Dextran Complex↗
Involvement of intermediary metabolites in the pathway of extracellular Ca2+-induced mitogen-activated protein kinase activation in human fibroblasts.
Human fibroblasts in culture will grow in serum-free medium containing serum replacement factors, but without protein growth factors, as long as the Ca2+ level is 1.0-2.0 mM. When the Ca2+ is reduced to 0.1 mM, the cells stop cycling, but they can be reinduced to cycle by raising the Ca2+ level to 1.0 mM Ca2+ or to higher concentrations that result in activation of mitogen-activated protein kinase (MAPK). We now report that exposure of human fibroblasts to extracellular Ca2+ increased the level of inositol (1,4,5)-trisphosphate in the cytoplasm and caused a transient rise in the concentration of intracellular free Ca2+. Ca2+-induced MAPK activation was partly abolished by treatment of the cells with pertussis toxin. It was also decreased by treatment of cells with thapsigargin, which depletes intracellular Ca2+ stores; with phorbol 12-myristyl 13-acetate (PMA), which down-regulates protein kinase C (PKC); with the calmodulin antagonists N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide HCl (W-7), and calmidazolium (24571); as well as with lanthanum, a Ca2+ channel inhibitor. Ca2+ stimulation did not result in phosphorylation of the c-raf-1 protein. Our results suggest that extracellular Ca2+ stimulates MAPK activation through a pathway(s) involving a pertussis toxin-sensitive G protein, phospholipase C, intracellular free Ca2+, calmodulin, and PKC.
Animals↗
The structural and mechanical complexity of cell-growth control.
Tight control of cell proliferation is required to ensure normal tissue patterning and prevent cancer formation. The analysis of cultured cells has led to an explosion in our understanding of the molecules that trigger growth and mediate cell-cycle progression. However, the mechanism by which the local growth differentials that drive morphogenesis are established and maintained still remains unknown. Here we review recent work that reveals the importance of cell binding to the extracellular matrix, and associated changes in cell shape and cytoskeletal tension, to the spatial control of cell-cycle progression. These findings change the paradigm of cell-growth control, by placing our understanding of molecular signalling cascades in the context of the structural and mechanical complexity of living tissues.
Animals↗
Mitochondria unfold precursor proteins by unraveling them from their N-termini.
Protein unfolding is a key step in the life cycle of many proteins, including certain proteins that are degraded by ATP-dependent proteases or translocated across membranes. The detailed mechanisms of these unfolding processes are not understood. Precursor proteins are unfolded and imported into mitochondria by a macromolecular machine that spans two membranes and contains at least nine different proteins. Here we examine import of a model precursor protein derived from the ribonuclease barnase and show that mitochondria unfold this protein by unraveling it from its N-terminus. Because barnase in free-solution unfolds by a different pathway, our results demonstrate that mitochondria catalyze unfolding in the way that enzymes catalyze reactions, namely by changing reaction pathways. The effectiveness of this mechanism depends on the structure of the N-terminal part of the precursor protein.
Animals↗
Protective immunization against melanoma by gp100 DNA-HVJ-liposome vaccine.
DNA-based vaccine immunization effectively induces both humoral and cell-mediated immunity to antigens and can confer protection against numerous infectious diseases as well as some cancers. Human and mouse melanomas consistently express the tumor-associated antigen interacted with the melanogenesis pathway. Gp100 is immunogenic and has been shown to induce both antibody and cytotoxic T cell (CTL) responses in humans. To explore the potential use of DNA immunization to induce melanoma-specific immune responses, we assessed HVJ-AVE liposome incorporated with plasmid DNA encoding human gp100. The gp100 DNA vaccine was used in a mouse melanoma model to assess immunity against the B16 melanoma of C57BL/6 mice. Intramuscular injection of the DNA-HVJ-AVE liposomes induced both anti-gp100 antibody and CTL responses. Gp100 DNA-HVJ-AVE liposome immunization significantly delayed tumor development in mice challenged with B16 melanoma cells. Mice immunized with gp100 DNA-HVJ-AVE liposomes survived longer compared with control mice immunized with HVJ-AVE liposome alone. These results indicate that immunization with human gp100 DNA by HVJ-AVE liposomes can induce protective immunity against melanoma in this pre-clinical mouse model. This strategy may provide an effective approach for vaccine therapy with tumor-associated antigens against human melanoma.
Animals↗
Interleukin-1 stimulates Jun N-terminal/stress-activated protein kinase by an arachidonate-dependent mechanism in mesangial cells.
BACKGROUND: We have studied interleukin-1 (IL-1)-stimulated signals and gene expression in mesangial cells (MCs) to identify molecular mechanisms of MC activation, a process characteristic of glomerular inflammation. The JNK1 pathway has been implicated in cell fate decisions, and IL-1 stimulates the Jun N-terminal/stress-activated protein kinases (JNK1/SAPK). However, early postreceptor mechanisms by which IL-1 activates these enzymes remain unclear. Free arachidonic acid (AA) activates several protein kinases, and because IL-1 rapidly stimulates phospholipase A2 (PLA2) activity release AA, IL-1-induced activation of JNK1/SAPK may be mediated by AA release. METHODS: MCs were grown from collagenase-treated glomeruli, and JNK/SAPK activity in MC lysates was determined using an immunocomplex kinase assay. RESULT: Treatment of MCs with IL-1 alpha induced a time-dependent increase in JNK1/SAPK kinase activity, assessed by phosphorylation of the activating transcription factor-2 (ATF-2). Using similar incubation conditions, IL-1 also increased [3H]AA release from MCs. Pretreatment of MCs with aristolochic acid, a PLA2 inhibitor, concordantly reduced IL-1-regulated [3H]AA release and JNK1/SAPK activity, suggesting that cytosolic AA in part mediates IL-1-induced JNK1/SAPK activation. Addition of AA stimulated JNK1/SAPK activity in a time- and concentration-dependent manner. This effect was AA specific, as only AA and its precursor linoleic acid stimulated JNK1/SAPK activity. Other fatty acids failed to activate JNK1/SAPK. Pretreatment of MCs with specific inhibitors of AA oxidation by cyclooxygenase, lipoxygenase, and cytochrome P-450 epoxygenase had no effect on either IL-1- or AA-induced JNK1/SAPK activation. Furthermore, stimulation of MCs with the exogenous cyclooxygenase-, lipoxygenase-, phosphodiesterase-, and epoxygenase-derived arachidonate metabolites, in contrast to AA itself, did not activate JNK1/SAPK. CONCLUSION: We conclude that IL-1-stimulated AA release, in part, mediates stimulation of JNK1/SAPK activity and that AA activates JNK1/SAPK by a mechanism that does not require enzymatic oxygenation. JNK1 signaling pathway components may provide molecular switches that mediate structural rearrangements and biochemical processes characteristic of MC activation and could provide a novel target(s) for therapeutic intervention.
15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
Pharmacokinetics of didanosine in antepartum and postpartum human immunodeficiency virus--infected pregnant women and their neonates: an AIDS clinical trials group study.
Didanosine (ddI) pharmacokinetics in antepartum and postpartum human immunodeficiency virus (HIV)-infected women and their neonates were studied. HIV-infected pregnant women received an intravenous (iv) ddI infusion (1.6 mg/kg/h) or an oral dose (200 mg bid or 125 mg bid) at 31 weeks antepartum and 6 weeks postpartum. Blood samples were obtained regularly up to 6 or 8 h after drug administration. The same oral dose of ddI (bid) was administered until labor began. Then, ddI was infused iv until delivery. An oral pharmacokinetic study (60 mg/m2) was conducted in infants at day 1 and at week 6 after birth. Plasma concentrations of ddI were measured by radioimmunoassay. After iv ddI administration, only the maternal plasma clearance was found to be significantly increased antepartum (1028+/-231 mL/min) versus postpartum (707+/-213 mL/min). No pharmacokinetic parameters after oral administration were significantly affected by pregnancy. The pharmacokinetics of ddI in the neonates were highly variable. We conclude that the oral ddI dose need not be adjusted during pregnancy.
Anti-HIV Agents↗
Cooperation between transcription factor AP-1 and NF-kappaB in the induction of interleukin-8 in human pancreatic adenocarcinoma cells by hypoxia.
The expression of interleukin-8 (IL-8) has been shown to play an important role in the growth and metastasis of human pancreatic cancer. In the present study, we investigated the regulation of IL-8 gene expression by hypoxic environments. Exposure of the human pancreatic cancer cells COLO357 and FG to hypoxia in culture resulted in a time-dependent increase in steady-state levels of IL-8 mRNA and IL-8 protein secretion. The induction of IL-8 expression was correlated with transcriptional activation of the IL-8 gene. Deletion and point mutation analyses of the IL-8 promoter revealed that both AP-1 and NF-kappaB binding sites were necessary for IL-8 induction by hypoxia. Consistently, hypoxia induced both AP-1 and NF-kappaB activity. These data suggest that hypoxic environments upregulate the IL-8 gene via cooperation of NF-kappaB and AP-1 and contribute to the progression and metastasis of human pancreatic cancer.
Adenocarcinoma↗
Regulation of tumor growth and metastasis by interleukin-10: the melanoma experience.
Because interleukin-10 (IL-10) has potent immunosuppressive and anti-inflammatory properties and is produced by some cancers, including melanoma, we hypothesized that its production by tumor cells may contribute to the escape from immune surveillance. To test this hypothesis, we transfected human A375P melanoma cells that do not express IL-10 with the murine IL-10 gene and subsequently analyzed for changes in tumor growth and metastasis in nude mice. Surprisingly, IL-10 gene transfer resulted in a loss of metastasis and significant inhibition of tumor growth. In addition, the growth of other murine or human melanoma cells was also inhibited when they were admixed with IL-10-transfected cells before injection into nude mice. We provide evidence that IL-10 exerts its antitumor and antimetastatic activity by inhibiting angiogenesis in vivo. The in vivo decrease in neovascularization found in IL-10-secreting tumors is most likely due to the ability of IL-10 to downregulate the synthesis of vascular endothelial growth factor (VEGF), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), IL-6, and matrix metalloproteinase-9 (MMP-9) in tumor-associated macrophages. Other studies have shown that IL-10 inhibits tumor metastasis through a natural killer (NK) cell-dependent mechanism. The inhibitory effects of IL-10 on tumor growth and metastasis were also demonstrated in other tumor models, including breast cancers. Furthermore, administration of rIL-10 into mice resulted in inhibition of tumor metastasis. Because IL-10 has little toxicity when given systemically to human volunteers, its efficacy as an antimetastatic agent should be further explored, both as an independent and in combination with other inhibitors of neovascularization.
Angiogenesis Inducing Agents↗
Preservation of function and histologic appearance in the injured glottis with topical mitomycin-C.
OBJECTIVE: To evaluate the functional and histological effects of a single application of topical mitomycin-C after laser injury in the posterior canine glottis. STUDY DESIGN: A prospective, randomized study of 16 canines. METHODS: A supersaturated (1%) solution of topical mitomycin-C was applied to a unilateral, laser-induced injury near the cricoarytenoid joint in eight dogs. The mitomycin-soaked pledget was placed immediately after induction of the injury and was left in contact with exposed cartilage for 3 minutes. The opposite side was not injured to provide an internal control. In eight additional dogs, the same laser injury was allowed to heal untreated. After 6 weeks, the animals were sacrificed and their larynges harvested. Arytenoid adduction sutures were placed bilaterally, and the force required to bring the vocal folds to midline was measured for each side using tensiometry. Gross and microscopic histological analysis was performed. Statistical analysis was accomplished using a two-tailed Student t test of unpaired samples, and the Wilcoxon Signed Rank Test where appropriate. RESULTS: The mitomycin-C treated larynges demonstrated improved cricoarytenoid joint mobility (P = .007), decreased granulation tissue development (P = .03), and complete prevention of secondary "vocal granuloma" formation (P = .0004) when compared with eight dogs with identical laser injuries allowed to heal untreated. No complications were noted. CONCLUSIONS: This study demonstrates functional preservation and improved histological appearance of the injured glottis after a single treatment with topical mitomycin-C. Potential applications of these findings include prophylactic use of topical mitomycin-C on glottic insults that commonly progress from granulation tissue formation to scarring and decreased vocal fold function.
Administration, Topical↗
Histologic and physiologic effects of electrocautery, CO2 laser, and radiofrequency injury in the porcine soft palate.
OBJECTIVES: This study was undertaken to compare the effects of electrosurgery, CO2 laser, and radiofrequency on the histological structure and physiological properties of the soft palate. These surgical techniques are used for stiffening and reducing the soft palate in the treatment of snoring and mild sleep apnea. STUDY DESIGN: Fifteen pigs were divided into five groups. METHODS: group 1 underwent electrosurgery incision of the lateral soft palate and excision of the uvula. Group 2 underwent the same procedure with the CO2 laser. Group 3 underwent CO2 laser ablation of the midline soft palate mucosa. Group 4 underwent radiofrequency volumetric reduction. Group 5 served as control. After 5 weeks the animals were sacrificed. Soft palate mucosa and muscle were subjected to tensiometric and histological analysis. Statistical analysis of tensiometric measurements was done with an ANOVA using a Bonferroni-Dunn correction. RESULTS: Tensiometric measurements of the mucosa were increased over normal controls when the surgical technique resulted in mucosal disruption. When the surgical technique resulted in primarily muscle disruption (radiofrequency) tensiometric measurements of the muscle were increased over controls. Histological analysis demonstrated normal remucosalization in all specimens, with fibrosis increased at the site of the primary injury. CONCLUSIONS: The type of injury produced resulted in identifiable patterns of physiological and histological change. Understanding of the effects of available surgical techniques is important in guiding our choice of surgical approach and allows us to better counsel our patients on their surgical options.
Animals↗
Racial and gender variation in use of diagnostic colonic procedures in the Michigan Medicare population.
BACKGROUND: There is accumulating evidence that screening programs can alter the natural history of colorectal cancer, a significant cause of mortality and morbidity in the US. Understanding how the technology to diagnose colonic diseases is utilized in the population provides insight into both the access and processes of care. METHOD: Using Medicare Part B billing files from the state of Michigan from 1986 to 1989 we identified all procedures used to diagnose colorectal disease. We utilized the Medicare Beneficiary File and the Area Resource File to identify beneficiary-specific and community-sociodemographic characteristics. The beneficiary and sociodemographic characteristics were, then, used in multiple regression analyses to identify their association with procedure utilization. RESULTS: Sigmoidoscopic use declined dramatically with the increasing age cohorts of Medicare beneficiaries. Urban areas and communities with higher education levels had more sigmoidoscopic use. Among procedures used to examine the entire colon, isolated barium enema was used more frequently in African Americans, the elderly, and females. The combination of barium enema and sigmoidoscopy was used more frequently among females and the newest technology, colonoscopy, was used most frequently among White males. CONCLUSION: The existence of race, gender, and socioeconomic disparities in the use of colorectal technologies in a group of patients with near-universal insurance coverage demonstrates the necessity of understanding the reason(s) for these observed differences to improve access to appropriate technologies to all segments in our society.
Black or African American↗
Ultrasound biomicroscopic features of anterior proliferative vitreoretinopathy.
PURPOSE: To evaluate the utility of ultrasound biomicroscopy (UBM) in the diagnosis of anterior proliferative vitreoretinopathy (APVR). METHODS: Ultrasound biomicroscopy (frequency, 50 MHz; depth of penetration, 5 mm; resolution, 40 microm) was used to examine 53 eyes of 52 subjects with rhegmatogenous or traumatic retinal detachment (RD). The results were compared with findings during vitrectomy. RESULTS: In 43 eyes (42 patients), RD was detected using UBM, attaining 81% consistency with observations during operation. Among 36 eyes with surgically proved APVR, 33 (92%) had APVR detected by UBM. The UBM images showed shallow RD, circumferential contraction, or anterior displacement around the ora serrata. The anterior displacement could be classified into C-shaped anterior displacement, ciliary body adhesion, and pupil adhesion. Ultrasound biomicroscopy showed that a retinal step was formed on the surface of the ora serrata and the ciliary body. Failure to detect APVR by UBM may be due to severe choroidal detachment or a narrow palpebral fissure that hampers exposure of the ora serrata and the part of the eyeball posterior to it. CONCLUSION: Ultrasound biomicroscopy is a useful tool for the evaluation of APVR, which is difficult by ordinary methods. Ultrasound biomicroscopic images of APVR have typical features that may be used to help guide surgery and estimate prognosis.
Adolescent↗
Mutation analysis of the MEN1 tumour suppressor gene in malignant melanoma.
During the initiation and progression of malignant melanoma a series of genetic events accumulate, including alterations of chromosome 11q. Recently, an important tumour suppressor gene, the multiple endocrine neoplasia type 1 (MEN1) gene, has been mapped on 11q13 and has been cloned. To assess whether the MEN1 region is involved in tumour initiation and progression, we analysed 23 primary cutaneous melanomas and 17 metastases for loss of heterozygosity (LOH) using two informative polymorphic markers closely linked to the MEN1 gene (PYGM and D11S449). To search for mutations within the gene, single-strand conformation polymorphism (SSCP) analysis was performed using 13 primer sets with designed intronic sequences to amplify the MEN1 coding sequence exons 2 to 10. None of the cases showed LOH at the MEN1 gene locus. By SSCP analysis, no aberrant bands were identified on exons 3 to 10. Analysis of exon 2 revealed the presence of aberrant bands in two of the analysed melanomas. Sequencing analysis revealed a genetic polymorphism at S145S (AGC-->ACT) in both sections. None of the cases analysed showed MEN1 gene mutations. This study represents the first genetic analysis of the MEN1 gene in sporadic melanomas. Our data demonstrate no evidence of deletion or mutation of the MEN1 gene in primary or metastatic melanoma. Therefore, MEN1 gene alterations appear not to be associated with tumorigenesis of malignant melanoma. The MEN1 gene appears to be a highly specific tumour suppressor gene only involving tumours within the spectrum of MEN1 disease.
Alleles↗
The Mycobacterium tuberculosis small heat shock protein Hsp16.3 exposes hydrophobic surfaces at mild conditions: conformational flexibility and molecular chaperone activity.
Hsp16.3, the alpha-crystallin-related small heat shock protein of Mycobacterium tuberculosis that is maximally expressed during the stationary phase and is a major membrane protein, has been reported to form specific trimer-of-trimers structure and to act as an effective molecular chaperone (Chang Z et al., 1996, J. Biol Chem 271:7218-7223). However, little is known about its action mechanism. In this study, Hsp16.3 conformational intermediates with dramatically increased chaperone activities were detected after treatment with very low concentrations of guanidine hydrochloride (0.05 M), urea (0.3 M), or mild heating (30 degrees C). The intermediates showed a significant increase in their capacity to bind the hydrophobic probe 1-anilino-8-naphthalene sulfonate (ANS), indicating an increased exposure of hydrophobic surfaces. Interestingly, the greatest chaperone activities of Hsp16.3 were observed in the presence of 0.3 M guanidine HCl or when heated to 35 degrees C. CD spectroscopy studies revealed no significant changes in protein secondary and tertiary structures at these mild treatments. Our in vitro studies also indicate that long-time-heated Hsp16.3, heated even to temperatures as high as 85 degrees C, has almost the same, if not a slightly greater, chaperone activities as the native protein when cooled to room temperature and its secondary structures also almost recovered. Together, these results suggest that Hsp16.3 modulates its chaperone activity by exposing hydrophobic surfaces and that the protein structure is highly stable and flexible, thus highly adapted for its function.
Anilino Naphthalenesulfonates↗
How stable is stable? Function versus community composition.
The microbial community dynamics of a functionally stable, well-mixed, methanogenic reactor fed with glucose were analyzed over a 605-day period. The reactor maintained constant pH and chemical oxygen demand removal during this period. Thirty-six rrn clones from each of seven sampling events were analyzed by amplified ribosomal DNA restriction analysis (ARDRA) for the Bacteria and Archaea domains and by sequence analysis of dominant members of the community. Operational taxonomic units (OTUs), distinguished as unique ARDRA patterns, showed reproducible distribution for three sample replicates. The highest diversity was observed in the Bacteria domain. The 16S ribosomal DNA Bacteria clone library contained 75 OTUs, with the dominant OTU accounting for 13% of the total clones, but just 21 Archaea OTUs were found, and the most prominent OTU represented 50% of the clones from the respective library. Succession in methanogenic populations was observed, and two periods were distinguished: in the first, Methanobacterium formicicum was dominant, and in the second, Methanosarcina mazei and a Methanobacterium bryantii-related organism were dominant. Higher variability in Bacteria populations was detected, and the temporal OTU distribution suggested a chaotic pattern. Although dominant OTUs were constantly replaced from one sampling point to the next, phylogenetic analysis indicated that inferred physiologic changes in the community were not as dramatic as were genetic changes. Seven of eight dominant OTUs during the first period clustered with the spirochete group, although a cyclic pattern of substitution occurred among members within this order. A more flexible community structure characterized the second period, since a sequential replacement of a Eubacterium-related organism by an unrelated deep-branched organism and finally by a Propionibacterium-like species was observed. Metabolic differences among the dominant fermenters detected suggest that changes in carbon and electron flow occurred during the stable performance and indicate that an extremely dynamic community can maintain a stable ecosystem function.
Bacteria↗
A single amino acid in the adenovirus type 37 fiber confers binding to human conjunctival cells.
A 46-kDa receptor, coxsackievirus-adenovirus (Ad) receptor (CAR), mediates cell attachment of a number of different Ad serotypes; however, not all Ad serotypes utilize this receptor for infection. Moreover, the precise amino acid sequences in the Ad fiber protein that mediate cell attachment have yet to be identified. We investigated the interaction of subgroup D Ads with human ocular cells. Ad serotype 37 (Ad37), a virus associated with epidemic keratoconjunctivitis, but not a closely related virus serotype, Ad19p, exhibited preferential binding to and infection of human conjunctival cells. A single amino acid substitution in the Ad19p fiber distal domain (knob), Glu240 to Lys, conferred binding to conjunctival cells, while the reverse substitution in the Ad37 fiber abrogated cell binding. These findings provide new information on the fiber sequences that regulate Ad host cell tropism.
Adenoviridae↗