MyD88: an adapter that recruits IRAK to the IL-1 receptor complex

IL-1 is a proinflammatory cytokine that signals through a receptor complex of two different transmembrane chains to generate multiple cellular responses, including activation of the transcription factor NF-kappaB. Here we show that MyD88, a previously described protein of unknown function, is recruited to the IL-1 receptor complex following IL-1 stimulation. MyD88 binds to both IRAK (IL-1 receptor-associated kinase) and the heterocomplex (the signaling complex) of the two receptor chains and thereby mediates the association of IRAK with the receptor. Ectopic expression of MyD88 or its death domain-containing N-terminus activates NF-kappaB. The C-terminus of MyD88 interacts with the IL-1 receptor and blocks NF-kappaB activation induced by IL-1, but not by TNF. Thus, MyD88 plays the same role in IL-1 signaling as TRADD and Tube do in TNF and Toll pathways, respectively: it couples a serine/threonine protein kinase to the receptor complex.

Recruitment of IRAK to the interleukin 1 receptor complex requires interleukin 1 receptor accessory protein

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.

Renal amylin binding in normotensive and hypertensive rats: effects of angiotensin converting enzyme inhibition with perindopril

OBJECTIVES

To investigate the effect of angiotensin converting enzyme inhibition with perindopril on the binding density of [125I]-rat amylin in the renal cortex in normotensive Sprague-Dawley rats, renally ablated hypertensive rats and spontaneously hypertensive rats.

DESIGN

Sprague-Dawley rats, renally ablated hypertensive rats and spontaneously hypertensive rats were administered either the angiotensin converting enzyme inhibitor perindopril or no treatment.

METHODS

The density of [125I]-rat amylin binding was measured in the renal cortex using autoradiography in vitro. The systolic blood pressure was measured by indirect tail-cuff plethysmography. The plasma renin activity was measured by radioimmunoassay.

RESULTS

The density of [125I]-amylin binding was reduced by approximately 50% in Sprague-Dawley and subtotally nephrectomized Sprague-Dawley rats after treatment with perindopril. These changes were associated with a reduction in systolic blood pressure and an increase in plasma renin activity. In contrast, amylin binding in the perindopril-treated spontaneously hypertensive rats was not reduced, despite the prevention of a rise in systolic blood pressure and an increase in plasma renin activity.

CONCLUSIONS

These findings provide further evidence for the hypothesis that there is an association among renal amylin binding, the renin-angiotensin system and blood pressure for rats of the Sprague-Dawley strain. In contrast, the lack of an effect of angiotensin converting enzyme inhibition on renal amylin binding for rats of the spontaneously hypertensive rat strain is consistent with previous findings that the changes in amylin binding in rats of this strain are not linked directly to the prevailing systemic blood pressure but may be associated with a developmental abnormality in the kidney of these rats.

IkappaB kinase-beta: NF-kappaB activation and complex formation with IkappaB kinase-alpha and NIK

Activation of the transcription factor nuclear factor kappa B (NF-kappaB) by inflammatory cytokines requires the successive action of NF-kappaB-inducing kinase (NIK) and IkappaB kinase-alpha (IKK-alpha). A widely expressed protein kinase was identified that is 52 percent identical to IKK-alpha. IkappaB kinase-beta (IKK-beta) activated NF-kappaB when overexpressed and phosphorylated serine residues 32 and 36 of IkappaB-alpha and serines 19 and 23 of IkappaB-beta. The activity of IKK-beta was stimulated by tumor necrosis factor and interleukin-1 treatment. IKK-alpha and IKK-beta formed heterodimers that interacted with NIK. Overexpression of a catalytically inactive form of IKK-beta blocked cytokine-induced NF-kappaB activation. Thus, an active IkappaB kinase complex may require three distinct protein kinases.

Observation of switching phenomena in a nonether polyphenylquinoxaline planar waveguide with two-wavelength nonlinear prism coupling

We present research on nonether polyphenylquinoxaline film waveguides, and a scheme for an all-optical switching operation of waveguides is suggested. We use the m-line spectroscopy technique to characterize the guiding modes in the waveguide, and the switching phenomenon is observed with two-wavelength nonlinear prism coupling. The measured response time of the switching signal is less than 10(-9) s.

[Improvements of laryngectomy cricopharyngeal anastomosis laryngeal reconstruction (report of 27 cases)]

To alleviate the deglutition and increase decannulation rate in Arslan's operation, 27 patients who had undergone laryngectomy cricopharyngeal anastomosis reconstruction from 1989 to 1995 in our hospital were reported. There were T1bN0 8 cases, T2N0 17 cases, T3N0 2 cases according to UICC staging in 1987. All lesions located in vocale cords bilaterally. On the side of the mild lesion, over half of the vocale cord was invaded. The main points of surgical procedure were that the epiglottic and cricoid cartilage were restored. Hyoid bone and arytenoid cartilages were resected and cricoid cartilage anastomosis with the base of the tongue and submental muscles. Phonation was restored in all postoperative patients. Deglutition was alleviated significantly. Decannulation rate was 92.6% (25/27). The follow-up period of 14 cases was over 3 years. Of the 14 cases, 1 died. The 3 years survival rate was 92.86% (13/14). The follow-up period of 6 cases was over 5 years. Of the 6 cases, 1 was lost, the 5 years survival rate was 83.33% (5/6). The operation has great effects on alleviating deglutition and increasing decannulation rate.

Technical considerations for optimal orthopedic imaging

Over the past 25 years bone scintigraphy has played an essential role in most Nuclear Medicine departments, accounting for 25% to 60% of the patient volumes. No longer is every bone scan ordered as part of a metastatic workup. Today radionuclide bone imaging (RNBI) is included in most orthopedic diagnostic pathways. It is necessary to optimize the bone scan procedure to be sensitive, to carefully localize abnormal uptake for diagnosis, to correlate the bone scans, plain radiographs, computed tomographic (CT) scans, and magnetic resonance (MR) scans that accompany the patient, and to be precise in reporting a final impression. This can be done through meticulous attention to the image acquisition so that it encompasses not only equipment specifications and acquisition parameters, but also patient history, preparation, imaging protocols, positioning, and image correlation. The importance of these considerations, the rationale to explain them, and suggested guidelines for their implementation will be discussed in this article.

Role of angiotensin II and bradykinin in experimental diabetic nephropathy. Functional and structural studies

We explored the relative roles of the suppression of angiotensin II and the prevention of bradykinin degradation in mediating the renoprotective effects of ACE inhibitors in experimental diabetic nephropathy. Over a 24-week period, we studied male Sprague-Dawley diabetic and control rats and Sprague-Dawley diabetic rats treated with the ACE inhibitor ramipril, the angiotensin II-AT1 receptor antagonist valsartan, the bradykinin-B2 receptor antagonist HOE 140 (icatibant), and a combination of ramipril and icatibant. Serial measurements of urinary albumin excretion, blood pressure, and glycated hemoglobin were performed monthly. After 6 months, the animals were killed for the measurement of kidney weight and the assessment of glomerular ultrastructure. Over 24 weeks, urinary albumin excretion showed a continuous rise in the untreated diabetic rats. Both ramipril and valsartan, which were equihypotensive, prevented the increase in urinary albumin excretion over the whole study period. Icatibant therapy did not attenuate the antialbuminuric effect of the ACE inhibitor, nor did it have any effect as the sole therapy. Diabetes was associated with increased glomerular basement membrane thickness, glomerular volume, and total mesangial volume. Both ACE inhibition and angiotensin II receptor antagonism attenuated the glomerular ultrastructural changes to a similar degree. Icatibant did not attenuate the effects of ramipril on glomerular morphology. ACE inhibitors and angiotensin II-AT1 receptor blockers appear to confer similar benefits in experimental diabetic nephropathy, and bradykinin-B2 receptor blockers do not influence this effect. These findings suggest that the blockade of angiotensin II is the major pathway responsible for renoprotection afforded by ACE inhibition in experimental diabetic nephropathy.

A triple-head SPECT system with parallel-hole collimators of different acceptance angles

We proposed to use three different parallel-hole collimators for a triple-head SPECT system. One of the collimators had a small collimator acceptance angle to provide ultra-high spatial resolution and the other two had larger collimator acceptance angles to achieve high counts. A new 2D reconstruction algorithm that combined the data acquired from different collimators was derived to take advantages of both high resolution and high sensitivity. The algorithm was evaluated using a computer-simulated matrix of spherical sources. For noise-free data, the accuracy (mainly determined by spatial resolution) obtained from combination of the collimator acceptance angles of 1.35, 4.05 and 6.75 degrees (or 1.35, 5.40 and 9.45 degrees) was slightly inferior to that obtained from three same LEHR collimators (with a 2.70 degrees collimator acceptance angle). This is because the modulation transfer function (MTF) resulting from three different collimators decreases more quickly at low frequencies but becomes comparable at high frequencies as compared with the MTF of the 2.70 degrees collimator. With noisy data, however, the image quality obtained with three different collimators was better than that resulting from any combinations of three same collimators. The improvement was only achieved by using the derived algorithm, while the conventional FBP algorithm did not improve image quality even with the same collimator configuration.

[Biocompatibility evaluation of Ti50Ni50-xCux shape memory alloys (I)--corrosion resistance]

By means of electrochemical methods, the corrosion resistance of Ti50Ni50 and Ti50Ni50-xCux (x = 1,2, 4,6,8) was investigated. It is discovered that repassivation potential of Ti50Ni50-xCux (x = 2,4,6,8) alloys is about 200 mV higher than that of Ti50Ni50 alloy. This means that the added Cu raises the repassivation of TiNi shape memory alloys and improves corrosion resistance. Pitting potentials of Ti50Ni50 and Ti50Ni50-xCux (x = 1,2,4,6,8) alloys increase with the rising solution pH value, but the repassivation potentials keep constant. The added Cu has no obvious influence on pitting potential (Epit) of TiNi alloys, meanwhile, the corrosion potential and corrosion rate of Ti50Ni50-xCux (x = 1,2,4,6,8) alloys are irrelevant to its Cu content and the values are almost the same as that of TiNi alloys.

Effects of photon attenuation on increased counts in fanbeam collimation

This study examined the effects of photon attenuation on the increased sensitivity (gain of counts) produced by a fanbeam collimator with imaging geometry similar to clinical practice.

METHODS

The number of counts was measured in experiments and by computer simulations for two cylindrical phantoms of different sizes using a fanbeam and a parallel-hole (parallel-beam) collimator with the same spatial resolution. The phantoms were located either in air (simulating the brain) or in a cubic water tank (simulating a source in the body). The ratio of the counts from the fanbeam collimator versus the parallel-beam collimator was obtained as a function of the distance between the phantom and detector.

RESULTS

Even with attenuation inside the phantom, the count ratio for the phantom located in air remains almost the same as that theoretically predicted without attenuation. But the count ratio obtained in the cubic water tank was decreased compared to the predicted values. The amount of decrease (reduced sensitivity) depended on the distance from the detector, the size of the source and the depth of the source.

CONCLUSION

For brain studies, attenuation caused little change in the gain of counts provided by a fanbeam collimator. When imaging a structure located deep within the body, however, the gain of counts (sensitivity) may be appreciably reduced due to a longer path of photons within the body which results in more photon attenuation in fanbeam geometry.

Increased density of renal amylin binding sites in experimental hypertension

High-affinity binding sites for the pancreatic beta-cell hormone amylin have been reported in the kidney, and it has been postulated that these sites may be involved in the genesis of hypertension. In the present study, we have used in vivo injection of 125I-amylin and in vitro autoradiographic techniques to assess renal amylin binding in both a genetic and a surgically induced model of hypertension. In the spontaneously hypertensive rat (SHR) at 6 weeks of age, before the rise in systolic blood pressure, there was a 36% increase in density of amylin binding compared with their normotensive counterpart, the Wistar-Kyoto rat (WKY). In SHR, there was a further increase in the density of amylin binding (to 53% greater) as the systolic blood pressure rose between 6 and 12 weeks of age. Histological examination of kidneys from SHR at 12 weeks of age revealed staining for a brush border glycoprotein, normally restricted to the proximal tubules, extending from the urinary pole into half of the epithelial lining of the glomerular capsule. In contrast to WKY, these cells also bound 125I-amylin with high density in SHR. In a rat model of renal ablation and hypertension, systolic blood pressure correlated with the density of 125I-amylin binding in the renal cortex (r=.54, P=.003, n=28). The changes in amylin binding reported here suggest a possible role for this peptide and/or activation of its receptor in the genesis as well as the maintenance of hypertension.

Biphasic binding kinetics between FepA and its ligands

The Escherichia coli FepA protein is an energy- and TonB-dependent, ligand-binding porin that functions as a receptor for the siderophore ferric enterobactin and colicins B and D. We characterized the kinetic and thermodynamic parameters associated with the initial, energy-independent steps in ligand binding to FepA. In vivo experiments produced Kd values of 24, 185, and 560 nM for ferric enterobactin, colicin B, and colicin D, respectively. The siderophore and colicin B bound to FepA with a 1:1 stoichiometry, but colicin D bound to a maximum level that was 3-fold lower. Preincubation with ferric enterobactin prevented colicin B binding, and preincubation with colicin B prevented ferric enterobactin binding. Colicin B release from FepA was unexpectedly slow in vivo, about 10-fold slower than ferric enterobactin release. This slow dissociation of the colicin B.FepA complex facilitated the affinity purification of FepA and FepA mutants with colicin B-Sepharose. Analysis of a fluorescent FepA derivative showed that ferric enterobactin and colicin B adsorbed with biphasic kinetics, suggesting that both ligands bind in at least two distinct steps, an initial rapid stage and a subsequent slower step, that presumably establishes a transport-competent complex.

[Chemotherapy repeated injection via pelvic retroperitoneal cannulation]

OBJECTIVE

To investigate the feasibility of chemotherapy for lymphatic metastases of gynecologic cancer by repeated injection via pelvic retroperitoneal cannulation.

METHODS

5-fluorouracil (5-FU), thiotepa, methofrexate were repeatedly injected into the pelvic retroperitoneal space of 25 dogs and 24 patients respectively via cannulation. Microscope and high-performance liquid chromatography were used to observe the drug concentration of 5-FU and pathologic changes of the involved tissues.

RESULTS

Animal experiment showed no toxicity to vessels, ureter and the normal tissues involved; nodal 5-FU concentration of repeated injection side was 7 to 9 times of that on the peripheral connective tissue (P < 0.05). Clinical study revealed: (1) the external iliac, hypogastric, obturator, deep inguinal and most of the common iliac lymph nodes were submerged in the 5-FU solution; (2) pelvic and periaortic nodal 5-FU concentrations of repeated injection side were 20 to 73 and 27 to 110 times of that on single injection side respectively; nodal 5-FU concentration was 11 to 20 times of that on the peripheral connective tissue; (3) metastatic cancer cells of nodal in the study group showed obvious degeneration and necrosis while no changes in the control; (4) no severe complications or adverse effects were observed.

CONCLUSION

Repeated injection via pelvic retroperitoneal cannulation was feasible and probably more effective for the treatment of lymphatic metastases of gynecologic cancer.

Identification and characterization of an IkappaB kinase

Activation of the transcription factor NF-kappaB by tumor necrosis factor (TNF) and interleukin-1 (IL-1) requires the NF-kappaB-inducing kinase (NIK). In a yeast two-hybrid screen for NIK-interacting proteins, we have identified a protein kinase previously known as CHUK. Overexpression of CHUK activates a NF-kappaB-dependent reporter gene. A catalytically inactive mutant of CHUK is a dominant-negative inhibitor of TNF-, IL-1-, TRAF-, and NIK-induced NF-kappaB activation. CHUK associates with the NF-kappaB inhibitory protein, IkappaB-alpha, in mammalian cells. CHUK specifically phosphorylates IkappaB-alpha on both serine 32 and serine 36, modifications that are required for targeted degradation of IkappaB-alpha via the ubiquitin-proteasome pathway. This phosphorylation of IkappaB-alpha is greatly enhanced by NIK costimulation. Thus, CHUK is a NIK-activated IkappaB-alpha kinase that links TNF- and IL-1-induced kinase cascades to NF-kappaB activation.

Benign HEXA mutations, C739T(R247W) and C745T(R249W), cause beta-hexosaminidase A pseudodeficiency by reducing the alpha-subunit protein levels

Two benign mutations, C739T(R247W) and C745T(R249W), in the alpha-subunit of beta-hexosaminidase A (Hex A) have been found in all but one of the currently identified Hex A-pseudodeficient subjects. To confirm the relationship of the benign mutations and Hex A pseudodeficiency and to determine how the benign mutations reduce Hex A activity, we transiently expressed each of the benign mutations, and other mutations associated with infantile, juvenile, and adult onset forms of GM2 gangliosidosis, as Hex S (alphaalpha) and Hex A (alphabeta) in COS-7 cells. The benign mutations decreased the expressed Hex A and Hex S activity toward the synthetic substrate 4-methylumbelliferyl-6-sulfo-beta-N-acetylglucosaminide (4-MUGS) by 60-80%, indicating that they are the primary cause of Hex A pseudodeficiency. Western blot analysis showed that the benign mutations decreased the enzymatic activity by reducing the alpha-subunit protein level. No change in heat sensitivity, catalytic activity, or the substrate specificity to the synthetic substrates, 4-methylumbelliferyl-beta-N-acetylglucosaminide or 4-methylumbelliferyl-6-sulfo-beta-N-acetylglucosaminide, was detected. The effects of the benign mutations on Hex A were further analyzed in fibroblasts, and during transient expression, using pulse-chase metabolic labeling. These studies showed that the benign mutations reduced the alpha-subunit protein by affecting its stability in vivo, not by affecting the processing of the alpha-subunit, i.e. phosphorylation, targeting, or secretion. Our studies also demonstrated that these benign mutations could be readily differentiated from disease-causing mutations using a transient expression system.

Ligand-specific opening of a gated-porin channel in the outer membrane of living bacteria

Ligand-gated membrane channels selectively facilitate the entry of iron into prokaryotic cells. The essential role of iron in metabolism makes its acquisition a determinant of bacterial pathogenesis and a target for therapeutic strategies. In Gram-negative bacteria, TonB-dependent outer membrane proteins form energized, gated pores that bind iron chelates (siderophores) and internalize them. The time-resolved operation of the Escherichia coli ferric enterobactin receptor FepA was observed in vivo with electron spin resonance spectroscopy by monitoring the mobility of covalently bound nitroxide spin labels. A ligand-binding surface loop of FepA, which normally closes its transmembrane channel, exhibited energy-dependent structural changes during iron and toxin (colicin) transport. These changes were not merely associated with ligand binding, but occurred during ligand uptake through the outer membrane bilayer. The results demonstrate by a physical method that gated-porin channels open and close during membrane transport in vivo.

[Determination of oridonin in Rabdosia rubescens by TLC-scanning method]

We have determingd the content of oridonin in Rabdosia rubescens Hemsl by TLC-scenning method. This method is proved to be simple, fast, precise and sensitive, and the result is stable, repetition property is good. Its rate of recovery is as high as 98.03 percent.

[The change of calcitonin gene-related peptide positive fibers in inflammatory pulps]

Deep cavities were prepared on rats' molars, and fresh carious dentin was enclosed in to establish animal pulpitis model. Immunohistochemical method was used to observe the distribution of calcitonin gene-related peptide (CGRP) positive nerve fibers in rats' normal dental pulps and inflammatory pulps at 4d, 8d, 14d respectively. CGRP positive fibers were found throughout the normal pulps, a large number of fibers penetrated into dentinal tubules. In 4d group, CGRP positive fibers became denser and the number of fibers penetrating into dentinal tubules also increased. In 8d group, a necrotic zone could be found in the coronal pulps, lots of fibers accumulated around the necrotic zone. In the radical pulps, CGRP positive fibers formed multiple arborizations. 14d postinflammation, all the pulps were necrotic, and the periapexs were richly innervated by CGRP positive fibers. The results suggesting that CGRP may play a role in the inflammation and repair of dental pulp.

Double mutagenesis of a positive charge cluster in the ligand-binding site of the ferric enterobactin receptor, FepA

Siderophores and colicins enter bacterial cells through TonB-dependent outer membrane proteins. Using site-directed substitution mutagenesis, we studied ligand recognition by a prototypic Escherichia coli siderophore receptor, FepA, that binds the iron chelate ferric enterobactin and colicins B and D. These genetic experiments identified a common binding site for two of the three ligands, containing multiple positive charges, within cell surface residues of FepA. Elimination of single residues in this region did not impair the adsorption or transport of ferric enterobactin, but double mutagenesis in the charge cluster identified amino acids (Arg-286 and Arg-316) that participate in siderophore binding and function in FepA-mediated killing by colicins B and D. Ferric enterobactin binding, furthermore, prevented covalent modification of FepA within this domain by either a fluorescent probe or an arginine-specific reagent, corroborating the involvement of this site in ligand recognition. These results identify, for the first time, residues in a TonB-dependent outer membrane protein that participate in ligand binding. They also explain the competition between ferric enterobactin and the colicins on the bacterial cell surface: all three ligands interact with the same arginine residues within FepA during their penetration through the outer membrane.

Compensation for displacement of the focal point in cone beam single photon emission computed tomography reconstruction

This study examined the effects of focal point displacement on image quality in cone beam single photon emission computed tomography (SPECT). A new image reconstruction algorithm that accounts for the focal point shift was derived and three shift geometries were investigated. The geometries included a lateral shift with a fixed focal length but off-center focusing, a linear axial shift with a variable focal length that depends linearly on the distance between a bin of the detector and the center of the detector, and a random axial shift with a randomly varying focal length. Computer simulation was conducted to evaluate the shift effects with a phantom that was composed of 118 small spherical sources. The results demonstrated that the lateral shift of the focal point was more critical to image quality than was the axial shift. With a 0.64 cm (1 pixel) lateral shift, noticeable artifacts was observed, while an axial shift resulted in minimal changes in image quality until it reached 8 cm (12.5 pixels). The derived reconstruction algorithm eliminated most of the artifacts caused by a fixed lateral shift or a linear axial shift of the focal point, but failed to do so for a random axial shift since the linear distribution assumed in image reconstruction did not match the random shift occurred in acquisition of the data.

[Sample pretreatment method for assay of chlorogenic acid in Chinese medicinal preparations]

This paper introduces a sample pretreatment method for assaying chlorogenic acid-D101-column separation-precipitation method. The method features thorough removal of impurities, complete separation of chlorogenic acid and simple operational procedures. The experimental result of four samples from three preparations shows that this method is good in reliability and applicability.

Differential effects mediated by GABAA receptors in thalamic nuclei in lh/lh model of absence seizures

Absence seizures represent synchronized burst-firing of thalamocortical neurons, which are driven by tonic GABAergic output of nucleus reticularis thalami (NRT). Activation of GABAA receptors on NRT neurons reduces NRT output and retards thalamocortical burst-firing. Although this mechanism in NRT may underlie antiabsence effects of benzodiazepines, it does not explain observations that barbiturates can worsen absence-seizures. In this study we tested the hypothesis that clonazepam and phenobarbital produce differential effects on GABAA receptors in the lh/lh genetic model of absence seizures after microinjection into NRT compared to VLa, a prototypic relay nucleus containing thalamocortical neurons. In NRT, phenobarbital (16-1600 nmol/cannula), clonazepam (160-2200 pmol/cannula) and muscimol (8.8-263 pmol/cannula) significantly suppressed absence seizure frequency. In VLa, phenobarbital (1.6 nmol) and muscimol (0.88 pmol) increased seizure frequency, whereas higher doses (160 nmol and 88 pmol, respectively) significantly suppressed seizure frequency. In contrast, clonazepam produced no effect on seizure frequency even at a dose of 2.2 nmol; this same dose significantly suppressed absence seizures after microinjection into NRT. These findings suggest that activation of GABAA receptors in NRT may suppress absence seizures, and that phenobarbital may worsen absence seizures through actions on GABAA receptors in thalamocortical cells (VLa). Region-specific GABAA receptor isoforms may underlie the contrasting effects of clonazepam after microinjection into NRT and VLa.