Homogeneous Catalyzed Direct Conversion of Furfural to Gamma-Valerolactone

Herein, we report the direct conversion of biomass-derived furfural to γ-valerolactone (GVL) in a one-pot system, using the combination of Ru-MACHO-BH and a Brønsted acid (H3 PO4 ). A GVL yield of 84 % is achieved under mild reaction conditions using 1 mol% of Ru-MACHO-BH and 3.8 M H3 PO4 (aq) at 100 °C for 7 hours.

Versatile CO2 Hydrogenation-Dehydrogenation Catalysis with a Ru-PNP/Ionic Liquid System

High catalytic activities of Ru-PNP [Ru = ruthenium; PNP = bis alkyl- or aryl ethylphosphinoamine complexes in ionic liquids (ILs) were obtained for the reversible hydrogenation of CO₂ and dehydrogenation of formic acid (FA) under exceedingly mild conditions and without sacrificial additives. The novel catalytic system relies on the synergic combination of Ru-PNP and IL and proceeds with CO₂ hydrogenation already at 25 °C under a continuous flow of 1 bar of CO₂/H₂ (1:5), leading to 14 mol % FA with respect to the IL. A pressure of 40 bar of CO₂/H₂ (1:1) provides 126 mol % of FA/IL corresponding to a space-time yield (STY) of FA of 0.15 mol L^-1 h^-1. The conversion of CO₂ contained in imitated biogas was also achieved at 25 °C. Furthermore, the Ru-PNP/IL system catalyzes FA dehydrogenation with average turnover frequencies up to 11,000 h^-1 under heat-integrated conditions for proton-exchange membrane fuel cell applications (<100 °C). Thus, 4 mL of a 0.005 M Ru-PNP/IL system converted 14.5 L FA over 4 months with a turnover number exceeding 18,000,000 and a STY of CO₂ and H₂ of 35.7 mol L^-1 h^-1. Finally, 13 hydrogenation/dehydrogenation cycles were achieved with no sign of deactivation. These results demonstrate the potential of the Ru-PNP/IL system to serve as a FA/CO₂ battery, a H₂ releaser, and a hydrogenative CO₂ converter.

Use of diamond sensors for a high-flux, high-rate X-ray pass-through diagnostic

X-ray free-electron lasers (XFELs) deliver pulses of coherent X-rays on the femtosecond time scale, with potentially high repetition rates. While XFELs provide high peak intensities, both the intensity and the centroid of the beam fluctuate strongly on a pulse-to-pulse basis, motivating high-rate beam diagnostics that operate over a large dynamic range. The fast drift velocity, low X-ray absorption and high radiation tolerance properties of chemical vapour deposition diamonds make these crystals a promising candidate material for developing a fast (multi-GHz) pass-through diagnostic for the next generation of XFELs. A new approach to the design of a diamond sensor signal path is presented, along with associated characterization studies performed in the XPP endstation of the LINAC Coherent Light Source (LCLS) at SLAC. Qualitative charge collection profiles (collected charge versus time) are presented and compared with those from a commercially available detector. Quantitative results on the charge collection efficiency and signal collection times are presented over a range of approximately four orders of magnitude in the generated electron-hole plasma density.

Development and validation of a UHPLC-ESI-QTOF mass spectrometry method to analyze opines, plant biomarkers of crown gall or hairy root diseases

Opines are low-molecular-weight metabolites specifically biosynthesized by agrobacteria-transformed plant cells when plants are struck by crown gall and hairy root diseases, which cause uncontrolled tissue overgrowth. Transferred DNA is sustainably incorporated into the genomes of the transformed plant cells, so that opines constitute a persistent biomarker of plant infection by pathogenic agrobacteria and can be targeted for crown gall/hairy root disease diagnosis. We developed a general, rapid, specific and sensitive analytical method for overall opine detection using ultra-high-performance liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-ESI-MS-QTOF), with easy preparation of samples. Based on MS, MS/MS and chromatography data, the detection selectivity of a wide range of standard opines was validated in pure solution and in different plant extracts. The method was successfully used to detect different structural types of opines, including opines for which standard compounds are unavailable, in tumors or hairy roots induced by pathogenic strains. As the method can detect a wide range of opines in a single run, it represents a powerful tool for plant gall analysis and crown gall/hairy root disease diagnosis. Using an appropriate dilution of plant extract and a matrix-based calibration curve, the quantification ability of the method was validated for three opines belonging to different families (nopaline, octopine, mannopine), which were accurately quantified in plant tissue extracts.

Impact of Paraburkholderia phytofirmans PsJN on Grapevine Phenolic Metabolism

Phenolic compounds are implied in plant-microorganisms interaction and may be induced in response to plant growth-promoting rhizobacteria (PGPRs). Among PGPR, the beneficial bacterium Paraburkholderia phytofirmans PsJN was previously described to stimulate the growth of plants and to induce a better adaptation to both abiotic and biotic stresses. This study aimed to investigate the impact of PsJN on grapevine secondary metabolism. For this purpose, gene expression (qRT-PCR) and profiling of plant secondary metabolites (UHPLC-UV/DAD-MS QTOF) from both grapevine root and leaves were compared between non-bacterized and PsJN-bacterized grapevine plantlets. Our results showed that PsJN induced locally (roots) and systemically (leaves) an overexpression of PAL and STS and specifically in leaves the overexpression of all the genes implied in phenylpropanoid and flavonoid pathways. Moreover, the metabolomic approach revealed that relative amounts of 32 and 17 compounds in roots and leaves, respectively, were significantly modified by PsJN. Once identified to be accumulated in response to PsJN by the metabolomic approach, antifungal properties of purified molecules were validated in vitro for their antifungal effect on Botrytis cinerea spore germination. Taking together, our findings on the impact of PsJN on phenolic metabolism allowed us to identify a supplementary biocontrol mechanism developed by this PGPR to induce plant resistance against pathogens.

Differential Contribution of Plant-Beneficial Functions from Pseudomonas kilonensis F113 to Root System Architecture Alterations in Arabidopsis thaliana and Zea mays

Fluorescent pseudomonads are playing key roles in plant-bacteria symbiotic interactions due to the multiple plant-beneficial functions (PBFs) they are harboring. The relative contributions of PBFs to plant-stimulatory effects of the well-known plant growth-promoting rhizobacteria Pseudomonas kilonensis F113 (formerly P. fluorescens F113) were investigated using a genetic approach. To this end, several deletion mutants were constructed, simple mutants ΔphlD (impaired in the biosynthesis of 2,4-diacetylphloroglucinol [DAPG]), ΔacdS (deficient in 1-aminocyclopropane-1-carboxylate deaminase activity), Δgcd (glucose dehydrogenase deficient, impaired in phosphate solubilization), and ΔnirS (nitrite reductase deficient), and a quadruple mutant (deficient in the four PBFs mentioned above). Every PBF activity was quantified in the wild-type strain and the five deletion mutants. This approach revealed few functional interactions between PBFs in vitro. In particular, biosynthesis of glucose dehydrogenase severely reduced the production of DAPG. Contrariwise, the DAPG production impacted positively, but to a lesser extent, phosphate solubilization. Inoculation of the F113 wild-type strain on Arabidopsis thaliana Col-0 and maize seedlings modified the root architecture of both plants. Mutant strain inoculations revealed that the relative contribution of each PBF differed according to the measured plant traits and that F113 plant-stimulatory effects did not correspond to the sum of each PBF relative contribution. Indeed, two PBF genes (ΔacdS and ΔnirS) had a significant impact on root-system architecture from both model plants, in in vitro and in vivo conditions. The current work underscored that few F113 PBFs seem to interact between each other in the free-living bacterial cells, whereas they control in concert Arabidopsis thaliana and maize growth and development.

Activation of aldehydes by exocyclic iridium(i)-η4:π2-diene complexes derived from 1,3-oxazolidin-2-ones

The Ir(i) complexes [Tp^Me2Ir(η⁴-1,4-diene)] 2b and 2c react thermally with a variety of aromatic aldehydes, 3a-e, to generate the metallabicyclic compounds 4e-k and the Fischer-type carbenes 5a-b in moderate yields. These reactions are proposed to take place with the initial formation of η¹-aldehyde adducts as key intermediates. The formation of the metallabicyclic compounds 4e-k involves a formal decarboxylation process at the exo-2-oxazolidinone diene and an ortho metallation of the aromatic ring. The generation of the Fischer-type carbenes 5a-b is the result of a series of metal-based rearranged intermediates with no decarboxylation observed. Treatment of the η⁴-diene complex 2b with a variety of Lewis bases induces a change in the binding mode of the diene ligand from η⁴:π² to η²:σ² to form the Ir(iii) derivatives 6b-d of composition Tp^Me2Ir-(η⁴:π²-1,4-diene)(L) (L = CO, MeCN, and C₅H₅N). A study of reactions of complex 2b with either mono- or poly-deuterated aldehydes was performed to understand the mechanisms of such processes. The results of these studies were used to determine plausible formation mechanisms of the metallabicyclic compounds 4e-4k and Fischer-type carbenes 5a-b compound series. These mechanisms were corroborated by density functional theory (DFT) calculations of the free energy profiles.

Preparation and characterization of a tungsten(V) corrole dichloride complex

The first example of a tungsten(V) corrole complex, ( Mes 2(p- OMePh ) corrole ) WCl 2, has been prepared through a metathesis reaction of a lithium corrole ( Mes 2(p- OMePh ) corrole ) Li 3 ⋅ 6 THF and WCl 6. The product constitutes the first example of a tungsten(V) corrole complex synthesized under mild conditions and only the second example of a tungsten corrole complex.

Treatment of hypertension in type 2 diabetes

Hypertension is one of the most common medical conditions in the United States, affecting 50 million American adults and accounting for one of four physician office visits. It is often undetected and undertreated, creating significant public health consequences. In diabetes, hypertension is an even greater problem, as diabetes has become the most common single cause of end-stage renal disease (ESRD) in the world, and diabetes is increasing in prevalence. The most important factor in slowing the decline of renal function in diabetes is aggressive treatment of hypertension. Recent guidelines have emphasized that the target blood pressure levels for patients with diabetes should be lower than in other hypertensive groups. The best specific approach for the treatment of hypertension in diabetic patients is the subject of much debate. It may be in the end that the specific drug choice has less overall importance than the actual attainment of adequate blood pressure control. In addition, more credence must be placed on the value of treating systolic hypertension than has traditionally been given. Coexisting diabetes and hypertension are a common clinical scenario that can set off a vicious cycle of increasing renal damage, rising blood pressure, and increased cardiovascular morbidity and mortality. Treatment often requires multiple drugs to effectively preserve renal function and prevent complications.

Use of curanderismo in a public health care system

BACKGROUND

Curanderismo ("the healing") is a centuries-old synthesis of Mexican Indian culture and beliefs.

OBJECTIVE

To evaluate the rate of use of curanderismo among Hispanic subjects seeking medical care at the Denver Health Medical Center, Denver, Colo.

METHODS

We conducted a survey of 405 Hispanic subjects attending outpatient primary and urgent care clinics at Denver Health Medical Center, the public hospital system for Denver. The main outcome measure was independent predictors of use of curanderos.

RESULTS

Of the 405 subjects, 118 (29.1%) (95% confidence interval, 20.9-37.3) had been to a curandero at some time in their lives. Of all the subjects, 91.3% knew what a curandero was. Univariate analyses demonstrated an association between those who had been to a curandero and level of income, level of education, and whether the subject was bilingual. The results of fitting a stepwise logistic regression model revealed an independent association with subjects who had been to a curandero and level of household income (>$20 000 vs <$10 000), with an odds ratio of 2.19 (95% confidence interval, 1.20-4.01) (P =.01), and level of education (post--high school vs elementary school), with an odds ratio of 3.16 (95% confidence interval, 1.45-6.86) (P =.004).

CONCLUSIONS

Many Hispanic patients who receive their health care at a public hospital system use the services of curanderos. This potentially has important implications for their health care.

Mechanisms by which T7 lysozyme specifically regulates T7 RNA polymerase during different phases of transcription

Bacteriophage T7 lysozyme binds to T7 RNA polymerase (RNAP) and regulates its transcription by differentially repressing initiation from different T7 promoters. This selective repression is due in part to a lysozyme-induced increase in the KNTP of the initiation complex (IC) and to intrinsically different NTP concentration requirements for efficient initiation from different T7 promoters. While lysozyme represses initiation, once the enzyme has left the promoter and formed an elongation complex (EC) it is generally resistant to the effects of lysozyme. The mechanism by which the inhibitory effects of lysozyme are largely restricted to the initiation phase of transcription is not well understood. We find that T7 lysozyme destabilizes initial transcription complexes (ITCs) and increases the rate of release of transcripts from these complexes but does not destabilize ECs. However, if the RNA:RNAP interaction proposed to be important for EC stability is disrupted by proteolysis of the RNA-binding domain or use of templates which interfere with establishment of this RNA:RNAP interaction, the EC becomes sensitive to lysozyme. Comparison of the X-ray structures of T7RNAP and of a T7RNAP:T7 lysozyme complex reveals that lysozyme causes the C terminus of the polymerase to flip out of the active site. Experiments in which carboxypeptidase A is used to probe the lysozyme-induced exposure of the C terminus reveal a large decrease in carboxypeptidase sensitivity following transcription initiation, suggesting that interactions with the 3'-end of the RNA help stabilize the active site in a functional (carboxypeptidase protected) conformation. Thus, the resistance of the EC to lysozyme appears to be due to the consecutive establishment of two sets of RNA:RNAP interactions. The first is made with the 3'-end of the RNA and helps stabilize a functional conformation of the active site, thereby suppressing the effects of lysozyme on KNTP. The second is made with a more upstream element of the RNA and keeps the EC from being destabilized by lysozyme binding.

Efficient synthesis of nucleic acids heavily modified with non-canonical ribose 2'-groups using a mutantT7 RNA polymerase (RNAP)

A T7 RNAP mutant (Y639F) which eliminates discrimination of the chemical character of the NTP ribose 2'-group, facilitates incorporation of non-canonicalsubstrates into nucleic acids. However, transcripts containing a high percentage of non-canonical NMPs are poorly extended due to effects of the 2'-substituents on the transcript:template hybrid conformation. We tested the addition of compounds that stabilize A-type helix geometry to the reaction. High concentrations of polyamines, together with other changes in reaction conditions, greatly increased the synthesis of transcripts heavily substituted with non-canonical ribose 2'-groups. Template structures that facilitate promoter opening increased the efficiency of reactions where non-canonical substrates were incorporated during transcription of +1 to +6.

Initiating a chaplaincy program for a hospital police department

The authors discuss the creation of a police chaplain program at their hospital--why it was needed, the preparations that were necessary, the recruitment process, and the important role the police chaplain plays.

Mechanism of ribose 2'-group discrimination by an RNA polymerase

The mechanism by which T7 RNA polymerase (RNAP) discriminates between rNTP and dNTP substrates has been characterized. During transcript elongation T7 RNAP uses rNTPs 70-80-fold more efficiently than dNTPs. Discrimination of the hydrogen-bonding character of the ribose 2'-substituent contributes a largely Km-mediated factor of approximately 20 to this preference for rNTPs. Discrimination of 2'-substituent H-bonding character appears to be made through a hydrogen bond to the hydroxyl group of tyrosine 639. This hydrogen bond makes little net contribution to either rNTP ground or transition state binding energy apparently because it is balanced by the energy of desolvation of the tyrosine hydroxyl. This mechanism may reflect a strategy to facilitate translocation by minimizing contributions from polymerase-NMP moiety interactions to NTP binding energy so as to minimize the affinity of the NTP binding site for the 3'-NMP of the product nucleic acid.

The beta-tubulin monomer release factor (p14) has homology with a region of the DnaJ protein

p14 is a molecular chaperone involved in beta-tubulin folding which catalyzes the release of beta-tubulin monomers from intermediate complexes. Here we demonstrate that active p14 protein which we have purified from an overproducing Escherichia coli strain can also release beta-tubulin monomers from tubulin dimers in the presence of an additional cofactor (Z). Analysis of p14 secondary structure suggests that this protein may belong to a family of conserved proteins which share structural similarities with the J-domain of DnaJ. We have constructed deletions and site-directed mutations in the p14 gene. A single D to E mutation in the region shown in DnaJ to be an essential loop for its function affected the monomer-release activity of p14. These results support the hypothesis that this p14 loop interacts with beta-tubulin in a similar fashion as DnaJ interacts with DnaK and suggest a possible role of p14 in the folding process.

Protein kinases involved in the phosphorylation of human tau protein in transfected COS-1 cells

Human tau phosphorylation has been studied in transfected COS-1 cells. Treatment with okadaic acid alters the electrophoretic mobility of human tau protein transiently expressed in transfected cells, due to an increase in the level of phosphorylation. Treatment with okadaic acid also results in an increased phosphorylation of Alzheimer's disease-type phosphoepitopes. Tau phosphorylation within COS-1 cells is partially inhibited by in vivo treatment with DRB, a protein kinase inhibitor. Double treatment of transfected cells with okadaic acid and DRB reveals that phosphorylation of tau protein at the AT8 epitope is achieved by a DRB-resistant protein kinase which is different from that responsible for tau phosphorylation at the SMI-31 epitope, which appears to be sensitive to DRB.

Tyrosine phosphorylation of focal adhesion kinase (p125FAK): regulation by cAMP and thrombin in mesangial cells

Stress fibers, composed of actin filaments, converge upon and associate with a number of proteins, including focal adhesion kinase (p125FAK), and integrin receptors to form areas of close contact between cells and the extracellular matrix referred to as focal adhesions. Treatment of mesangial cells with cAMP-elevating agents causes a loss of focal adhesions, fragmentation of stress fibers, and decreased tyrosine phosphorylation of p125FAK. Thrombin reverses these effects of cAMP, and this model can be used to address some of the cellular mechanisms involved in regulating the loss and formation of focal adhesions. This study reports the effects of cAMP and thrombin on mesangial cell shape, distribution of actin, formation of stress fibers, and tyrosine phosphorylation of p125FAK. cAMP-treated cells display a condensed cell body with slender processes that traverse the area formerly covered by the cell. Addition of thrombin to these cells restores actin filaments (stress fibers) and increases tyrosine phosphorylation of p125FAK, and the cells resume a flattened morphology, even in the continued presence of cAMP-elevating agents. Peptides that mimic the tethered ligand portion of the thrombin receptor have the same effects on cell morphology and stress fiber formation as thrombin. In selected experiments, agents that disrupt either stress fibers (cytochalasin D) or microtubules (nocodazole; Sigma Chemical, St. Louis, MO) were used to examine the role of these cytoskeletal elements in thrombin-induced restoration of focal adhesions. Cytochalasin D blocked the ability of thrombin to restore focal adhesions and phosphorylate p125FAK. The effects of nocodazole, an agent that destabilizes microtubules (but which has no known receptor), are very similar to those of thrombin. The findings discussed in this study indicate that thrombin can modulate the formation of focal adhesions. The organization of stress fibers and microtubules is apparently intimately related to the phosphorylation of p125FAK and can be modulated by soluble receptor agonists such as thrombin or via altered polymerization of microtubules.

Prevention of oral injuries

The importance of protection during various types of sports activities cannot be overemphasized. The use of mouth guards has been instrumental in preventing dental injuries. Dentists, however, must be knowledgeable in the pitfalls of these various types of protective devices.

A mutant T7 RNA polymerase as a DNA polymerase

We have identified a T7 RNA polymerase (RNAP) mutant that efficiently utilizes deoxyribonucleoside triphosphates. In vitro this mutant will synthesize RNA, DNA or 'transcripts' of mixed dNMP/rNMP composition depending on the mix of NTPs present in the synthesis reaction. The mutation is conservative, changes Tyr639 within the active site to phenylalanine and does not affect promoter specificity or overall activity. Non-conservative mutations of this tyrosine also reduce discrimination between deoxyribo- and ribonucleoside triphosphates, but these mutations also cause large activity reductions. Of 26 mutations of other residues in and around the active site examined none showed marked effects on rNTP/dNTP discrimination. Mutations of the corresponding tyrosine in DNA polymerase (DNAP) I increase miscoding, though effects on dNTP/rNTP discrimination for the DNAP I mutations have not been reported. This conserved tyrosine may therefore play a similar role in many polymerases by sensing incorrect geometry in the structure of the substrate/template/product due to inappropriate substrate structure or mismatches. T7 RNAP can use RNA templates as well as DNA templates and is capable of both primer extension and de novo initiation. The Y639F mutant retains the ability to use RNA or DNA templates. Thus this mutant can display de novo initiated or primed DNA-directed DNA polymerase, reverse transcriptase, RNA-directed RNA polymerase or DNA-directed RNA polymerase activities depending simply on the templates and substrates presented to it in the synthesis reaction.

[The role of radical surgery in the treatment of epidermoid carcinoma of the anal canal]

In order to define the role of radical surgery in the actual treatment of epidermoid carcinoma of the anal canal (ECAC), we retrospectively reviewed the charts of patients with primary ECAC, treated with radical surgery in the Hospital de Oncología, National Medical Center IMSS. We analyzed the recurrence pattern, its treatment and the contemporary literature was reviewed. From 1975 to 1990, we treated 16 patients; 13 females, 3 males, mean age was 64 years. The presurgical stage was T2, 6; T3 7; T4, 3. An abdominoperineal resection was performed in 12 patients; a posterior pelvic exenteration in 3; a total pelvic exenteration in 1. Ten patients developed surgical complications, 4 of them were major, 2 required surgical reintervention. There was no operative mortality. We obtained local tumor control in 5/16 patients (32%); the local recurrence by stage were T2, 3/6 (50%); T3, 5/7 (71%); T4, 3/3 (100%) p = 0.04. Ten of them were located at the pelvis brim and 1 was located to the central pelvis (vagina, perineum), 9 were treated with radiation therapy (RT) a mean dose of 45 Gy, only the patient with central local recurrence obtained local tumor control. Regional recurrences were as follows: T2 patients, 1/6 (16%); T3, 2/7 (28%); T4, 2/3 (66%). The 2 patients with metachronous inguinal lymph node metastases were treated with a radical groin dissection, with tumor control. In conclusion, the radical surgical treatment is associated with a low loco-regional tumor control; the pelvic tumor relapses were located at the pelvis brim and with no response to RT. With the results herein obtained and the results with other treatment modalities such as RT and its associations with chemotherapy (C) in regard to local tumor control, the actual role of the radical surgical treatment in the salvage of central pelvic relapses to primary treatment with RT or C-RT.

Binding of heat-shock protein 70 (hsp70) to tubulin

Binding of heat-shock protein (hsp70) to polymerized tubulin has been investigated by in vitro experiments. The tubulin region involved in binding to hsp70 corresponds to the carboxy-terminal residues 431-444, also involved in the association with other microtubule-associated proteins (MAPs). Additionally, the putative tubulin binding motif in the hsp70 protein contains a sequence related to the motif described for MAP1B protein.

Role of the carboxy terminal region of beta tubulin on microtubule dynamics through its interaction with the GTP phosphate binding region

The dynamic instability of microtubules depends on the GTP binding to tubulin, the rate of hydrolysis of GTP bound to tubulin molecules, at the microtubule caps, and on the affinity and exchange rate of tubulin for GTP versus GDP. It has been demonstrated that the binding of microtubule-associated proteins (MAPs) such as Tau or MAP2 notably enhances microtubule stability in vivo. These MAPs bind to the tubulin carboxy terminal domain. Consequently, an attractive hypothesis to explain the modulation of microtubule dynamics by MAPs is that the carboxy terminal domain of tubulin interacts with a region close to the GTP binding site, preventing the binding of GTP or exchange of GDP for GTP. By carrying out a combined analysis of crosslinking and limited proteolysis, an intramolecular interaction between the carboxy terminus and the tubulin region containing the GTP binding site in beta tubulin has been observed. It is proposed that this interaction modifies the binding of GTP to the tubulin beta-subunit and, therefore, affects tubulin assembly dynamics. This suggests a molecular explanation for the effect of MAPs in facilitating tubulin polymerization through the regulation of the interaction of GTP.

Sports dentistry: coming of age in the '90s

As the country becomes more health conscious, many of our patients are becoming involved in sporting activities, from organized teams to the occasional weekend warrior. As a result, the incidence of oral trauma is increasing. Dentistry today must respond to these patient's specialized needs, providing them with the quality of care they deserve. This paper discusses the prevention, diagnosis and treatment of sports-related dental trauma for the general dentist. Injury management, smokeless tobacco, mouth guard comparisons, custom mouth guard fabrication, marketing techniques and liability are presented.

Stimulation of the thrombin receptor of human glomerular mesangial cells by Ser-Phe-Leu-Leu-Arg-Asn-Pro-Asn-Asp-Lys-Tyr-Glu-Pro-Phe peptide

We have studied the effects of thrombin (alpha-thrombin) and Ser-Phe-Leu-Leu-Arg-Asn-Pro-Asn-Asp-Lys-Tyr-Glu-Pro-Phe (SFLL), a peptide agonist of the platelet thrombin receptor in cultured human mesangial cells, and find that SFLL can reproduce the biochemical and morphological effects of thrombin. Treatment of mesangial cells with cAMP-elevating agents causes fragmentation of stress fibers, loss of the vitronectin receptor from sites of focal adhesion, and produces a change in shape from a flat to a more arborized configuration. These effects are prevented by both thrombin and SFLL. Thrombin and SFLL also initiate biochemical signaling events in mesangial cells by stimulating the metabolism of phospholipids. Both thrombin and SFLL stimulate release of inositol phosphates from [3H]inositol-labeled cells, elevation of cytosolic calcium, the formation of [3H]myristic acid-labeled diacylglycerol, an increase in the mass of diacylglycerol, 32P incorporation into phospholipids, and release of unesterified [3H]arachidonic acid from cells prelabeled with [3H]arachidonic acid. When present together, the effects of SFLL and thrombin on diacylglycerol formation, arachidonic acid production, and inositol phosphate production were not additive. This suggested that SFLL and thrombin were acting on the same receptor. This was further supported by our observations that cells pretreated with SFLL and subsequently exposed to thrombin (or vice versa) did not show elevated cytosolic calcium. We also show that phospholipase D is activated by demonstrating production of radiolabeled phosphatidylethanol when cells are treated with SFLL in the presence of ethanol. These findings indicate that SFLL can be used to study the receptor-mediated effects of thrombin in mesangial cells, thereby avoiding thrombin's proteolytic actions.

Calmodulin binds to a tubulin binding site of the microtubule-associated protein tau

Previous studies have demonstrated that the microtubule-associated proteins MAP-2 and tau interact selectively with common binding domains on tubulin defined by the low-homology segments alpha (430-441) and beta (422-434). It has been also indicated that the synthetic peptide VRSKIGSTENLKHQPGGG corresponding to the first tau repetitive sequence represents a tubulin binding domain on tau. The present studies show that the calcium-binding protein calmodulin interacts with a tubulin binding site on tau defined by the second repetitive sequence VTSKCGSLGNIHHKPGGG. It was shown that both tubulin and calmodulin bind to tau peptide-Sepharose affinity column. Binding of calmodulin occurs in the presence of 1 mM Ca 2+ and it can be eluted from the column with 4 mM EGTA. These findings provide new insights into the regulation of microtubule assembly, since Ca2+/calmodulin inhibition of tubulin polymerization into microtubules could be mediated by the direct binding of calmodulin to tau, thus preventing the interaction of this latter protein with tubulin.

The tubulin-binding sequence of brain microtubule-associated proteins, tau and MAP-2, is also involved in actin binding

The interaction of actin with a synthetic peptide which corresponds to one of the repeated tubulin-binding sites present in tau and MAP-2 (microtubule-associated protein 2) proteins has been analysed. The analysis, which uses affinity chromatography of G-actin on a column containing the synthetic peptide, and the co-sedimentation and co-localization of F-actin and the peptide (as determined by immunoelectron microscopy), indicates that the part of the amino acid sequence of tau involved in the binding of tubulin is also involved in actin binding.

A subset of antibodies from the sera of patients with systemic lupus erythematosus react with vimentin and DNA

Sera from patients with systemic lupus erythematosus were tested for the simultaneous presence of antibodies to intermediate filaments (vimentin) and to DNA, using radioimmunoassay and immunofluorescence techniques. Our results indicate that 3 of 17 sera tested contain an IgM population which recognizes an antigenic determinant common to vimentin and DNA by a solid phase immunoassay.

Removal of the carboxy terminus of beta-tubulin subunit produces lateral annealing of microtubules with different orientations

1. Tubulin, lacking the carboxy terminus region of its beta subunit assembles into composite microtubule structures showing opposite polarity. 2. Since in these polymers, microtubules are laterally bound, this type of interaction could lead to the generation of microtubules with different polarities, as those found in some cellular types.

Linear growth of children with nephrotic syndrome: effect of alkylating agents

Growth velocity measurements were assessed in 12 children with steroid responsive but frequent relapsing or dependent nephrotic syndrome prior to and following treatment with either cyclophosphamide or chlorambucil and alternate day prednisone. Patients averaged 6 +/- 3 years (mean +/- SD) of age at the time of treatment. All of the patients underwent renal biopsy prior to treatment; 5 of the 12 showed mesangial proliferation; and in 10 of the 12, IgM deposits were seen within the mesangium of the glomerulus. Growth rates before treatment with the alkylating agent were 4.3 +/- 1.3 cm/y increasing to 8.7 +/- 2.5 cm/y (P less than .001) after therapy despite the relapses that occurred in 5 of the patients in the year following treatment. Short-term side effects of the treatment were minimal. The significant increase in growth associated with diminished use of steroids makes the use of alkylating agents reasonable for children with nephrosis who show signs of decreased growth velocity.

[Uropathogenic Serratia marcescens of hospital origin: analysis of the adhesion mechanism of 2 strains]

We isolated 2 Serratia marcescens strains, fim (0) and fim (-), from patients with urinary tract infection. Adhesion properties were studied by hemagglutination, response of uroepithelial cells and electron microscopy techniques. S marcescens fim (+) showed high adherence to uroepithelial cells, hemagglutination capacity and peculiar electron microscopy characteristics. All of these are absent in the fim (-) variety. The fim (+) strain was resistant to nitrofurantoin, nalidixic acid, tetracyclin, ampicillin, gentamycin, cefradine, cephotaxime and cotrimoxazole, whereas the fim (-) strain was sensitive to all. An absence of extrachromosomal DNA was demonstrated in S marcescens fim (+) suggesting that its characteristics are not coded in plasmids.

Iodination of proteins on nitrocellulose blotting paper

A procedure is described for radioiodination to a high specific activity of proteins immobilized on nitrocellulose membranes. After radioiodination, the proteins can be removed from the nitrocellulose to perform such structural analyses as proteolytic mapping. This method allows the detection of small amounts of protein recognized by immunoblotting and may be used to compare the structure of immunologically related proteins.