Synthesis of Fluoropolymers in Supercritical Carbon Dioxide

Fluoropolymers are used in many technologically demanding applications because of their balance of high-performance properties. A significant impediment to the synthesis of variants of commercially available amorphous fluoropolymers is their general insolubility in most solvents except chlorofluorocarbons (CFCs). The environmental concerns about CFCs can be circumvented by preparing these technologically important materials in supercritical fluids. The homogeneous solution polymerization of highly fluorinated acrylic monomers can be achieved in supercritical carbon dioxide by using free radical methods. In addition, detailed decomposition rates and efficiency factors were measured for azobisisobutyronitrile in supercritical carbon dioxide and were compared to those obtained with conventional liquid solvents.

Chain walking: A new strategy to control polymer topology

Ethylene pressure has been used to control the competition between isomerization (chain walking) and monomer insertion processes for ethylene coordination polymerization catalyzed by a palladium-alpha-diimine catalyst. The topology of the polyethylene varies from linear with moderate branching to "hyperbranched" structures. Although the overall branching number and the distribution of short-chain branching change very slightly, the architecture or topology of the polyethylene changes from linear polyethylene with moderate branches at high ethylene pressures to a hyperbranched polyethylene at low pressures.

Depletion of hematogenous macrophages promotes partial hindlimb recovery and neuroanatomical repair after experimental spinal cord injury

Traumatic injury to the spinal cord initiates a series of destructive cellular processes which accentuate tissue damage at and beyond the original site of trauma. The cellular inflammatory response has been implicated as one mechanism of secondary degeneration. Of the various leukocytes present in the spinal cord after injury, macrophages predominate. Through the release of chemicals and enzymes involved in host defense, macrophages can damage neurons and glia. However, macrophages are also essential for the reconstruction of injured tissues. This apparent dichotomy in macrophage function is further complicated by the overlapping influences of resident microglial-derived macrophages and those phagocytes that are derived from peripheral sources. To clarify the role macrophages play in posttraumatic secondary degeneration, we selectively depleted peripheral macrophages in spinal-injured rats during a time when inflammation has been shown to be maximal. Standardized behavioral and neuropathological analyses (open-field locomotor function, morphometric analysis of the injured spinal cord) were used to evaluate the efficacy of this treatment. Beginning 24 h after injury and then again at days 3 and 6 postinjury, spinal cord-injured rats received intravenous injections of liposome-encapsulated clodronate to deplete peripheral macrophages. Within the spinal cords of rats treated in this fashion, macrophage infiltration was significantly reduced at the site of impact. These animals showed marked improvement in hindlimb usage during overground locomotion. Behavioral recovery was paralleled by a significant preservation of myelinated axons, decreased cavitation in the rostrocaudal axis of the spinal cord, and enhanced sprouting and/or regeneration of axons at the site of injury. These data implicate hematogenous (blood-derived) macrophages as effectors of acute secondary injury. Furthermore, given the selective nature of the depletion regimen and its proven efficacy when administered after injury, cell-specific immunomodulation may prove useful as an adjunct therapy after spinal cord injury.

The neuropathological and behavioral consequences of intraspinal microglial/macrophage activation

Activated microglia and macrophages (CNS macrophages) have been implicated in the secondary or "bystander" pathology (e.g. axon injury, demyelination) that accompanies traumatic or autoimmune injury to the brain and spinal cord. These cells also can provide neurotrophic support and promote axonal regeneration. Studying the divergent functional potential of CNS macrophages in trauma models is especially difficult due to the various degradative mechanisms that are initiated prior to or concomitant with microglial/macrophage activation (e.g. hemorrhage, edema, excitotoxicity, lipid peroxidation). To study the potential impact of activated CNS macrophages on the spinal cord parenchyma, we have characterized an in vivo model of non-traumatic spinal cord neuroinflammation. Specifically, focal activation of CNS macrophages was achieved using stereotaxic microinjections of zymosan. Although microinjection does not cause direct mechanical trauma, localized activation of macrophages with zymosan acts as an "inflammatory scalpel" causing tissue injury at and nearby the injection site. The present data reveal that activation of CNS macrophages in vivo can result in permanent axonal injury and demyelination. Moreover, the pathology can be graded and localized to specific white matter tracts to produce quantifiable behavioral deficits. Further development of this model will help to clarify the biological potential of microglia and macrophages and the molecular signals that control their function within the spinal cord.

Induction of cyclooxygenase-2 by the activated MEKK1 --> SEK1/MKK4 --> p38 mitogen-activated protein kinase pathway

The mitogen-activated protein kinase (MAPK) cascade is believed to function as an important regulator of prostaglandin biosynthesis. Previously we reported that interleukin-1beta induces activation of JNK/SAPK and p38 MAPK with concomitant up-regulation of cyclooxygenase (Cox)-2 expression and prostaglandin E2 (PGE2) synthesis. Our experiments demonstrate that overexpression of DeltaMEKK1 (a constitutively active truncation mutant of MEKK1 containing the C-terminal 324 amino acids) increases Cox-2 expression and PGE2 production which is completely blocked by SC68376, a pharmacologic inhibitor of p38 MAPK. DeltaMEKK1 overexpression results in activation of both c-Jun N-terminal kinases/extracellular signal-regulated kinases (JNK/SAPK) and p38 MAPK. Furthermore, activation of MEKK1 increases SEK1/MKK4 but not MKK3 or MKK6 activity. These findings suggest that MEKK1 --> SEK1/MKK4 may function as an upstream kinase capable of activating both p38 MAPK and JNK/SAPK with subsequent induction of Cox-2 expression and PGE2 production. We also found that overexpression of the constitutively active form of SEK1 (SEK1-ED) increases both p38 MAPK and JNK/SAPK phosphorylation, and increases PGE2 production and Cox-2 expression. By comparison, overexpression of the dominant negative form of SEK1 (SEK1-AL) decreases the phosphorylation of both p38 MAPK and JNK/SAPK and reduces Cox-2 expression. Together, this data suggests a potential role for the MEKK1 --> SEK1/MKK4 --> p38 MAPK -->--> Cox-2 cascade linking members of the MAPK pathway with prostaglandin biosynthesis.

Interleukin-1beta-induced cyclooxygenase-2 expression requires activation of both c-Jun NH2-terminal kinase and p38 MAPK signal pathways in rat renal mesangial cells

The inflammatory cytokine interleukin-1beta (IL-1beta) induces cyclooxygenase-2 (Cox-2) expression with a concomitant release of prostaglandins from glomerular mesangial cells. We reported previously that IL-1beta rapidly activates the c-Jun NH2-terminal/stress-activated protein kinases (JNK/SAPK) and p38 mitogen-activated protein kinase (MAPK) and also induces Cox-2 expression and prostaglandin E2 (PGE2) production. The current study demonstrates that overexpression of the dominant negative form of JNK1 or p54 JNK2/SAPKbeta reduces Cox-2 expression and PGE2 production stimulated by IL-1beta. Similarly, overexpression of the kinase-dead form of p38 MAPK also inhibits IL-1beta-induced Cox-2 expression and PGE2 production. These results suggest that activation of both JNK/SAPK and p38 MAPK is required for Cox-2 expression after IL-1beta activation. Furthermore, our experiments confirm that IL-1beta activates MAP kinase kinase-4 (MKK4)/SEK1, MKK3, and MKK6 in renal mesangial cells. Overexpression of the dominant negative form of MKK4/SEK1 decreases IL-1beta- induced Cox-2 expression with inhibition of both JNK/SAPK and p38 MAPK phosphorylation. Overexpression of the kinase-dead form of MKK3 or MKK6 demonstrated that either of these two mutant kinases inhibited IL-1beta-induced p38 MAPK phosphorylation and Cox-2 expression but not JNK/SAPK phosphorylation and activation. This study suggests that the activation of both JNK/SAPK and p38 MAPK signaling cascades is required for IL-1beta-induced Cox-2 expression and PGE2 synthesis.

Brain-derived neurotrophic factor stimulates hindlimb stepping and sprouting of cholinergic fibers after spinal cord injury

Neurotrophic factors have been proposed as a therapeutic treatment for traumatic brain and spinal cord injury. The present study determined whether exogenous administration of one such factor, brain-derived neurotrophic factor (BDNF), could effect behavioral recovery and/or histopathological changes after spinal cord injury. Adult rats received a mild or moderate contusion injury or complete transection of the mid-thoracic spinal cord. Immediately thereafter, they were infused intrathecally with vehicle or BDNF for 28 days. Behavioral recovery was evaluated for 6 weeks after injury, at which time the rats were sacrificed and the spinal cord tissue was examined histologically. The infusion of BDNF resulted in acute stimulation of hindlimb activity. These effects included activation of alternating airstepping in injured rats when the hindlimbs were unloaded as well as slight improvements in the rate of recovery in open field locomotion score. BDNF infusion was also associated with enhanced growth of cholinergic fibers at the injury epicenter, but did not affect white matter sparing or density of serotonergic axons at or below the injury site. Based on immunohistochemical detection of BDNF protein distribution, these described effects are likely to be mediated by the activation of cells and axons within the central injury region and the along the peripheral rim of the spinal cord. Together, these findings demonstrate that the exogenous infusion of BDNF after spinal trauma can influence postinjury outcome through mechanisms that include acute stimulation of hindlimb activity and neuritogenesis at the injury site.

Traumatic spinal cord injury produced by controlled contusion in mouse

Previous work from this laboratory has described a rat spinal cord injury (SCI) model in which the mid-thoracic spinal cord is subjected to a single rapid and calibrated displacement at the site of a dorsal laminectomy. Injury is initiated at the tip of a vertical shaft driven by an electromagnetic shaker. Transducers arranged in series with the shaft record the patterns of displacement and force during the impact sequence. In the present study, this device and the relevant surgical procedures were adapted to produce a spinal contusion injury model in laboratory mice. The signal generator for the injury device has also been converted to a computer-controlled interface to permit extension of the model to other laboratories. Mice were subjected to SCI across a range of severities by varying the amplitude of displacement and the magnitude of measured preload force on the dural surface. A moderate injury produced by displacement of 0.5 mm over 25 msec resulted in initial paralysis and recovery of locomotion with chronic deficits in hindlimb function. The magnitude of the peak force, impulse, power, and energy generated at impact were correlated with behavioral outcome at 1 day postinjury, while peak displacement and impulse were the best predictors of behavioral outcome at 28 days postinjury. The shape of the force recording proved to be a highly sensitive measure of subtle variations in the spinal compartment that were otherwise difficult to detect in this small species. The results demonstrate that the electromagnetic spinal cord injury device (ESCID) can be used to produce a well-controlled contusion injury in mice. The unique features of controlled displacement and monitoring of the biomechanical parameters at the time of impact provide advantages of this model for reducing outcome variability. Use of this model in mice with naturally occurring and genetically engineered mutations will facilitate understanding of the molecular mechanisms of pathophysiology following traumatic spinal cord injury.

Decrease and structural modifications of phosphatidylethanolamine plasmalogen in the brain with Alzheimer disease

Several lipid modifications, some of which were attributed to oxidative stress, have been reported in the brains of patients with Alzheimer disease (AD). To evaluate this possibility, all phospholipids and their ether subclasses from the frontal cortex, hippocampus, and the white matter of AD brain were analyzed by high performance liquid chromatography and gas chromatography. The total phospholipid in the frontal cortex and hippocampus decreased on a DNA basis by about 20% and this change was essentially explained by a selective decrease in phosphatidylethanolamine and phosphatidylcholine. The lower content of phosphatidylethanolamine was due to a specific decrease in the plasmalogen subclass. Phosphatidylethanolamine plasmalogen was also the only lipid exhibiting major structural modifications: a significant decrease in polyunsaturated fatty acids and oleic acid as well as a shift of the aldehyde pattern from 18:1 to 18:0. The only modification observed in the other phospholipids was a decrease in oleic acid in diacyl-phosphatidylethanolamine and diacyl-phosphatidylcholine. None of these changes were observed in the white matter. Both the vinyl ether bond of phosphatidylethanolamine plasmalogen and polyunsaturated fatty acids are major targets in oxidative stress; thus, these specific lipid modifications strongly support the involvement of free radicals in the pathogenesis of AD.

p38 mitogen-activated protein kinase down-regulates nitric oxide and up-regulates prostaglandin E2 biosynthesis stimulated by interleukin-1beta

The inflammatory cytokine interleukin 1beta (IL-1beta) induces both cyclooxygenase-2 (Cox-2) and the inducible nitric-oxide synthase (iNOS) with increases in the release of prostaglandins (PGs) and nitric oxide (NO) from glomerular mesangial cells. However, the intracellular signaling mechanisms by which IL-1beta induces iNOS and Cox-2 expression is obscure. Our current studies demonstrate that IL-1beta produces a rapid increase in p38 mitogen-activated protein kinase (MAPK) phosphorylation and activation. Serum starvation and SC68376, a drug which selectively inhibits p38 MAPK in mesangial cells, were used to investigate whether p38 MAPK contributes to the signaling mechanism of IL-1beta induction of NO and PG synthesis. Serum starvation and SC68376 selectively inhibited IL-1beta-induced activation of p38 MAPK. Both SC68376 and serum starvation enhanced NO biosynthesis by increasing iNOS mRNA expression, protein expression, and nitrite production. In contrast, both SC68376 and serum starvation suppressed PG release by inhibiting Cox-2 mRNA, protein expression, and PGE2 synthesis. These data demonstrate that IL-1beta phosphorylates and activates p38 MAPK in mesangial cells. The activation of p38 MAPK may provide a crucial signaling mechanism, which mediates the up-regulation of PG synthesis and the down-regulation of NO biosynthesis induced by IL-1beta.

Delayed administration of darbepoetin or erythropoietin protects against ischemic acute renal injury and failure

Administration of human recombinant erythropoietin (EPO) at time of acute ischemic renal injury (IRI) inhibits apoptosis, enhances tubular epithelial regeneration, and promotes renal functional recovery. The present study aimed to determine whether darbepoetin-alfa (DPO) exhibits comparable renoprotection to that afforded by EPO, whether pro or antiapoptotic Bcl-2 proteins are involved, and whether delayed administration of EPO or DPO 6 h following IRI ameliorates renal dysfunction. The model of IRI involved bilateral renal artery occlusion for 45 min in rats (N = 4 per group), followed by reperfusion for 1-7 days. Controls were sham-operated. Rats were treated at time of ischemia or sham operation (T0), or post-treated (6 h after the onset of reperfusion, T6) with EPO (5000 IU/kg), DPO (25 mug/kg), or appropriate vehicle by intraperitoneal injection. Renal function, structure, and immunohistochemistry for Bcl-2, Bcl-XL, and Bax were analyzed. DPO or EPO at T0 significantly abrogated renal dysfunction in IRI animals (serum creatinine for IRI 0.17 +/- 0.05 mmol/l vs DPO-IRI 0.08 +/- 0.03 mmol/l vs EPO-IRI 0.04 +/- 0.01 mmol/l, P = 0.01). Delayed administration of DPO or EPO (T6) also significantly abrogated subsequent renal dysfunction (serum creatinine for IRI 0.17 +/- 0.05 mmol/l vs DPO-IRI 0.06 +/- 0.01 mmol/l vs EPO-IRI 0.03 +/- 0.03 mmol/l, P = 0.01). There was also significantly decreased tissue injury (apoptosis, P < 0.05), decreased proapoptotic Bax, and increased regenerative capacity, especially in the outer stripe of the outer medulla, with DPO or EPO at T0 or T6. These results reaffirm the potential clinical application of DPO and EPO as novel renoprotective agents for patients at risk of ischemic acute renal failure or after having sustained an ischemic renal insult.

The protective role of plasmalogens in iron-induced lipid peroxidation

The role of plasmalogens in iron-induced lipid peroxidation was investigated in two liposomal systems. The first consisted of total brain phospholipids with and without plasmalogens, and the second of phosphatidylethanolamine/phosphatidylcholine liposomes with either diacyl- or alkenylacyl-phosphatidylethanolamine. By measuring thiobarbituric acid reactive substances, oxygen consumption, fatty acids and aldehydes, we show that plasmalogens effectively protect polyunsaturated fatty acids from oxidative damage, and that the vinyl ether function of plasmalogens is consumed simultaneously. Furthermore, the lack of lag phase, the increased antioxidant efficiency with time, and the experiments with lipid- and water-soluble azo compounds, indicate that plasmalogens probably interfere with the propagation rather than the initiation of lipid peroxidation, and that the antioxidative effect cannot be related to iron chelation.

Nitric oxide amplifies interleukin 1-induced cyclooxygenase-2 expression in rat mesangial cells

Interleukin 1 and nitric oxide (NO) from infiltrating macrophages and activated mesangial cells may act in concert to sustain and promote glomerular damage. To evaluate if such synergy occurs, we evaluated the effect if IL-1 beta and NO on the formation of prostaglandin (PG)E2 and cyclooxygenase (COX) expression. The NO donors, sodium nitroprusside and S-nitroso-N-acetylpenicillamine, alone did not increase basal PGE2 formation. However, these compounds amplified IL-1 beta-induced PGE2 production. Similarly, sodium nitroprusside and S-nitroso-N-acetylpenicillamine by themselves did not induce mRNA and protein for COX-2, the inducible isoform of COX; however, they both potentiated IL-1 beta-induced mRNA and protein expression of COX-2. The stimulatory effect of NO is likely to be mediated by cGMP since (a) an inhibitor of the soluble guanylate cyclase, methylene blue, reversed the stimulatory effect of NO donors on COX-2 mRNA expression; (b) the membrane-permeable cGMP analogue, 8-Br-cGMP, mimicked the stimulatory effect of NO donors on COX-2-mRNA expression; and (c) atrial natriuretic peptide, which increases cellular cGMP by activating the membrane-bound guanylate cyclase, also amplified IL-1 beta-induced COX-2 mRNA expression. These data indicate a novel interaction between NO and COX pathways.

Human ZIP1 is a major zinc uptake transporter for the accumulation of zinc in prostate cells

The prostate gland of humans and other animals accumulates a level of zinc that is 3-10 times greater than that found in other tissues. Associated with this ability to accumulate zinc is a rapid zinc uptake process in human prostate cells, which we previously identified as the hZIP1 zinc transporter. We now provide additional evidence that hZIP1 is an important operational transporter that allows for the transport and accumulation of zinc. The studies reveal that hZIP1 (SLC39A1) but not hZIP2 (SLC39A2) is expressed in the zinc-accumulating human prostate cell lines, LNCaP and PC-3. Transfected PC-3 cells that overexpress hZIP1 exhibit increased uptake and accumulation of zinc. The V(max) for zinc uptake was increased with no change in K(m). Along with the increased intracellular accumulation of zinc, the overexpression of hZIP1 also results in the inhibition of growth of PC-3 cells. Down-regulation of hZIP1 by treatment of PC-3 cells with hZIP1 antisense oligonucleotide resulted in a decreased zinc uptake. Uptake of zinc from zinc chelated with citrate was as rapid as from free zinc ions; however, the cells did not take up zinc chelated with EDTA. The cellular uptake of zinc is not dependent upon an available pool of free Zn(2+) ions. Instead, the mechanism of transport appears to involve the transport of zinc from low molecular weight ligands that exist in circulation as relatively loosely bound complexes with zinc.

Growth factor-like phospholipids generated after corneal injury

The present study provides evidence that growth factor-like glycerophosphate mediators of the lysophosphatidic acid (LPA) family are present in the aqueous humor and the lacrimal gland fluid of the rabbit eye. By use of a combination of HPLC, two-dimensional TLC, mass spectrometry, and the Xenopus oocyte bioassay, the LPA-like phospholipids LPA, cyclic PA, alkenyl-glycerophosphate (GP), lysophosphatidylserine, and phosphatidic acid were detected as physiological constituents of the fluids bathing the cornea. Corneal injury resulted in an increased production of some of these mediators. Alkenyl-GP, a novel member of the LPA family, has been identified in postinjury aqueous humor, establishing that it is generated endogenously. LPA and its homologues were found to be mitogenic in freshly dissociated keratocytes from uninjured corneas. There appears to be a link between the occurrence of LPA responsiveness in keratocytes activated by injury and the increase in LPA-like activity in aqueous humor. These data suggest that LPA and its homologues are involved in maintaining the integrity of the normal cornea and in promoting cellular regeneration of the injured cornea.

Antimuscarinics for treatment of storage lower urinary tract symptoms in men: a systematic review

Despite potential benefits, primary care clinicians may avoid using antimuscarinics in men with overactive bladder (OAB) symptoms because of safety concerns. To review the efficacy and safety of antimuscarinics, alone or in combination with an α-blocker, for the treatment of men with OAB symptoms, we conducted a systematic review of articles published before 22 July 2010, using PubMed. Data from 12-week, randomised, double-blind, placebo-controlled trials of tolterodine extended release (ER), oxybutynin and solifenacin show that combined antimuscarinic+α-blocker treatment is generally more effective than monotherapy or placebo in men with OAB symptoms. The efficacy and safety of tolterodine ER+α-blocker treatment was not affected by prostate size or prostate-specific antigen (PSA) level. In men meeting entry criteria for OAB and benign prostatic obstruction trials, tolterodine ER alone was effective selectively in men with prostate size or PSA level below study medians. Incidence of acute urinary retention (AUR) in men receiving antimuscarinics with or without an α-blocker was ≤3% in all of these trials; changes in postvoid residual volume and maximum flow rate did not appear clinically meaningful. Post hoc analyses from double-blind, placebo-controlled trials and prospective studies of fesoterodine, oxybutynin, propiverine, solifenacin and tolterodine also suggest that antimuscarinics are generally safe and efficacious in men. A retrospective database study found that risk of AUR in men was the highest in the first month of treatment and decreased considerably thereafter. Antimuscarinics, alone or with an α-blocker, appear to be efficacious and safe in many men with predominant OAB symptoms or persistent OAB symptoms despite α-blocker or 5-α-reductase inhibitor treatment. However, antimuscarinics are not approved for the treatment of benign prostatic hyperplasia. Monitoring men for AUR is recommended, especially those at increased risk, and particularly within 30 days after starting antimuscarinic treatment.

Determination of Fura-2 dissociation constants following adjustment of the apparent Ca-EGTA association constant for temperature and ionic strength

The accurate calibration of Fura-2 fluorescence in living cells is dependent upon the apparent dissociation constant (Kd) of Fura-2 for Ca2+. If Ca-EGTA calibration buffers are used to construct an in vitro calibration curve, then the calculated value of the apparent Ca-EGTA association constant (K'CaEGTA) will have an important influence on the Kd of Fura-2 and thus the calculated free [Ca2+] in cells. In order to simulate experimental conditions, the individual proton and Ca2+ association constants for EGTA in these experiments were adjusted for both ionic strength and temperature using a semi-empirical form of the Debye-Huckel limiting law and the Van't Hoff isochore, respectively, as described by Harrison and Bers. The modified individual binding constants were then employed in the calculation of K'CaEGTA using the SPECS computer program of Fabatio. At pH = 7.05, ionic strength = 0.15 M, temp = 20 degrees C, K'CaEGTA = 3.232 x 10(6) M-1; at pH = 6.84, temp = 36 degrees C, K'CaEGTA = 1.652 x 10(6) M-1. These values differed substantially from those obtained with unadjusted individual association constants. Calibration buffers of varying [Ca2+] were prepared using the corrected values of K'CaEGTA, and Fura-2 fluorescence ratios were measured during superfusion of these buffers in the experimental chamber at both 20 degrees C and 37 degrees C. The Kd of Fura-2 for Ca2+ was determined to be 236 nM at 20 degrees C and 285 nM at 37 degrees C, utilizing the value of K'CaEGTA adjusted by the method of Harrison and Bers.(ABSTRACT TRUNCATED AT 250 WORDS)

Pegylated brain-derived neurotrophic factor shows improved distribution into the spinal cord and stimulates locomotor activity and morphological changes after injury

The neurotrophin brain-derived neurotrophic factor (BDNF) shows promise for the treatment of central nervous system (CNS) trauma and disease. Effective delivery methods are required, however, for BDNF to be useful as a therapeutic agent. To this end, we examined the penetration of intrathecally infused N-terminal pegylated BDNF (peg-BDNF) compared to similar infusion of native BDNF after spinal cord injury (SCI). Pegylation dramatically improved delivery of BDNF to the spinal cord and induced the expression of Fos in spinal cord neurons. To test whether enhanced delivery would improve the modest effects on behavioral recovery and axonal outgrowth observed with native BDNF infusion, we assessed the efficacy of 2-week 25 microg/day peg-BDNF treatment, beginning 12-24 h (early) or 15 days (delayed) after midthoracic spinal contusion. Similar to native BDNF, early treatment with peg-BDNF accelerated the recovery of stepping in the open-field and acutely stimulated locomotor central pattern generator activity, as seen by the activation of hindlimb airstepping during either period of administration. The infusion of peg-BDNF, regardless of the timing of delivery, was related to enhanced sprouting of putative cholinergic fibers, like that observed after high dose native BDNF treatment. Despite improved delivery, however, neither axonal responses nor the extent of locomotor recovery were enhanced compared to native BDNF treatment. This suggests that alternative strategies, such as neurotrophin treatment in conjunction with cell transplantation techniques, or treatment nearer the cell bodies of target neurons might be employed in an attempt to effect significant repair after SCI.

A glucose-sensing polymer

We have prepared a robust polymer that can be used to measure glucose concentrations in complex biological media. At alkaline pH, the metal-complexing polymer binds glucose and instantly releases protons in proportion to the glucose concentration over a clinically relevant range (0 to 25 mM). The inexpensive polymer is sufficiently selective to provide an easily measurable response to glucose in porcine plasma. The polymer's ability to function at nonphysiological pH (at which the buffer capacity of biological samples is small) makes it possible to design simple and inexpensive sensing devices based on measurement of changes in proton concentration.

Effects of flexible-dose fesoterodine on overactive bladder symptoms and treatment satisfaction: an open-label study

AIMS

To evaluate the efficacy and tolerability of flexible-dose fesoterodine in subjects with overactive bladder (OAB) who were dissatisfied with previous tolterodine treatment.

METHODS

This was a 12-week, open-label, flexible-dose study of adults with OAB (> or = 8 micturitions and > or = 3 urgency episodes per 24 h) who had been treated with tolterodine (immediate- or extended-release) for OAB within 2 years of screening and reported dissatisfaction with tolterodine treatment. Subjects received fesoterodine 4 mg once daily for 4 weeks; thereafter, daily dosage was maintained at 4 mg or increased to 8 mg based on the subject's and physician's subjective assessment of efficacy and tolerability. Subjects completed 5-day diaries, the Patient Perception of Bladder Condition (PPBC) and the Overactive Bladder Questionnaire (OAB-q) at baseline and week 12 and rated treatment satisfaction at week 12 using the Treatment Satisfaction Question (TSQ). Safety and tolerability were assessed.

RESULTS

Among 516 subjects treated, approximately 50% opted for dose escalation to 8 mg at week 4. Significant improvements from baseline to week 12 were observed in micturitions, urgency urinary incontinence episodes, micturition-related urgency episodes and severe micturition-related urgency episodes per 24 h (all p < 0.0001). Approximately 80% of subjects who responded to the TSQ at week 12 reported satisfaction with treatment; 38% reported being very satisfied. Using the PPBC, 83% of subjects reported improvement at week 12 with 59% reporting improvement > or = 2 points. Significant improvements from baseline (p < 0.0001) exceeding the minimally important difference (10 points) were observed in OAB-q Symptom Bother and Health-Related Quality of Life (HRQL) scales and all four HRQL domains. Dry mouth (23%) and constipation (5%) were the most common adverse events; no safety issues were identified.

CONCLUSION

Flexible-dose fesoterodine significantly improved OAB symptoms, HRQL, and rates of treatment satisfaction and was well tolerated in subjects with OAB who were dissatisfied with prior tolterodine therapy.

Bacillus subtilis arsenate reductase is structurally and functionally similar to low molecular weight protein tyrosine phosphatases

Arsenate is an abundant oxyanion that, because of its ability to mimic the phosphate group, is toxic to cells. Arsenate reductase (EC; encoded by the arsC gene in bacteria) participates to achieve arsenate resistance in both prokaryotes and yeast by reducing arsenate to arsenite; the arsenite is then exported by a specific transporter. The crystal structure of Bacillus subtilis arsenate reductase in the reduced form with a bound sulfate ion in its active site is solved at 1.6-A resolution. Significant structural similarity is seen between arsenate reductase and bovine low molecular weight protein tyrosine phosphatase, despite very low sequence identity. The similarity is especially high between their active sites. It is further confirmed that this structural homology is relevant functionally by showing the phosphatase activity of the arsenate reductase in vitro. Thus, we can understand the arsenate reduction in the light of low molecular weight protein tyrosine phosphatase mechanism and also explain the catalytic roles of essential residues such as Cys-10, Cys-82, Cys-89, Arg-16, and Asp-105. A "triple cysteine redox relay" is proposed for the arsenate reduction mechanism.

T-cell activation and receptor downmodulation precede deletion induced by mucosally administered antigen

The fate of antigen-specific T cells was characterized in myelin basic protein (MBP) T-cell receptor (TCR) transgenic (Tg) mice after oral administration of MBP. Peripheral Th cells are immediately activated in vivo, as indicated by upregulation of CD69 and increased cytokine responses (Th1 and Th2). Concurrently, surface TCR expression diminishes and internal TCR levels increase. When challenged for experimental autoimmune encephalomyelitis during TCR downmodulation, Tg mice are protected from disease. To characterize Th cells at later times after antigen feeding, it was necessary to prevent thymic release of naive Tg cells. Therefore, adult Tg mice were thymectomized before treatment. TCR expression returns in thymectomized Tg mice 3 days after MBP feeding and then ultimately declines in conjunction with MBP-specific proliferation and cytokine responses (Th1-type and Th2-type). The decline correlates with an increase in apoptosis. Collectively, these results demonstrate that a high dose of fed antigen induces early T-cell activation and TCR downmodulation, followed by an intermediate stage of anergy and subsequent deletion.

Mechanisms through which gangliosides inhibit PDGF-stimulated mitogenesis in intact Swiss 3T3 cells: receptor tyrosine phosphorylation, intracellular calcium, and receptor binding

Several potential mechanisms through which gangliosides could modulate PDGF-stimulated events in Swiss 3T3 cells were studied using intact cells. Of the gangliosides studied, at low micromolar concentrations GM2 was the only one that inhibited PDGF-stimulated DNA synthesis, but GT1b was the most potent between 25 and 100 microM; GM1 was generally the least effective, and GD1a and GM3 had intermediate effects. All gangliosides tested inhibited the PDGF-stimulated increases in free intracellular calcium concentrations ([Ca2+]i) with the rank order of potency being GM1 > or = GT1b > GM2 > GM3. PDGF stimulated phosphorylation on tyrosine of a protein with apparent M(r) = 170 kDa which was immunoprecipitated by an anti-PDGF receptor (beta) antibody, indicating that it is a PDGF receptor. Preincubating the cells with specific gangliosides inhibited tyrosine phosphorylation of this protein in a dose-responsive fashion with the following rank order of potency GD1a = GT1b > GM1 > GM2 > GM3. Autoradiography showed that this was due to a decrease in the proportion of cells synthesizing DNA, and a time study showed that ganglioside did not delay entry of the cells into S phase. These effects were not due to gangliosides interfering with PDGF binding to its receptor because results of competitive binding studies showed that none of the gangliosides studied had an effect on either receptor number or affinity, and did not bind to PDGF in solution. These results show that gangliosides affect several specific components of the complex responses to PDGF in intact cells. The relative effectiveness of individual gangliosides, however, varied among the different cellular and molecular responses. This is interpreted to mean that specific gangliosides modulate to different degrees several molecular mechanisms which converge on the common biological response of mitogenesis, and suggests that gangliosides as a family of molecules may function as coordinators of different molecular events involved in complex cellular processes.

Both p38alpha(MAPK) and JNK/SAPK pathways are important for induction of nitric-oxide synthase by interleukin-1beta in rat glomerular mesangial cells

Interleukin 1beta (IL-1beta) induces expression of the inducible nitric-oxide synthase (iNOS) with concomitant release of nitric oxide (NO) from glomerular mesangial cells. These events are preceded by activation of the c-Jun NH(2)-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38(MAPK). Our current study demonstrates that overexpression of the dominant negative form of JNK1 or p54 SAPKbeta/JNK2 significantly reduces the iNOS protein expression and NO production induced by IL-1beta. Similarly, overexpression of the kinase-dead mutant form of p38alpha(MAPK) also inhibits IL-1beta-induced iNOS expression and NO production. In previous studies we demonstrated that IL-1beta can activate MKK4/SEK1, MKK3, and MKK6 in renal mesangial cells; therefore, we examined the role of these MAPK kinases in the modulation of iNOS induced by IL-1beta. Overexpression of the dominant negative form of MKK4/SEK1 decreases IL-1beta-induced iNOS expression and NO production with inhibition of both SAPK/JNK and p38(MAPK) phosphorylation. Overexpression of the kinase-dead mutant form of MKK3 or MKK6 demonstrated that either of these two mutant kinase inhibited IL-1beta-induced p38(MAPK) (but not JNK/SAPK) phosphorylation and iNOS expression. Interestingly overexpression of wild type MKK3/6 was associated with phosphorylation of p38(MAPK); however, in the absence of IL-1beta, iNOS expression was not enhanced. This study suggests that the activation of both SAPK/JNK and p38alpha(MAPK) signaling cascades are necessary for the IL-1beta-induced expression of iNOS and production of NO in renal mesangial cells.