The mechanism of methanol to hydrocarbon catalysis.

The process of converting methanol to hydrocarbons on the aluminosilicate zeolite HZSM-5 was originally developed as a route from natural gas to synthetic gasoline. Using other microporous catalysts that are selective for light olefins, methanol-to-olefin (MTO) catalysis may soon become central to the conversion of natural gas to polyolefins. The mechanism of methanol conversion proved to be an intellectually challenging problem; 25 years of fundamental study produced at least 20 distinct mechanisms, but most did not account for either the primary products or a kinetic induction period.

Treatment of migrainous vertigo.

Migraine and balance disorders are becoming increasingly recognized as comorbid conditions. Diagnostic criteria have recently been developed to facilitate the identification of patients for whom balance complaints are likely to be symptoms of migraine. The significant impact that associated balance complaints add to migraine requires evaluation for specific treatment of balance disorder symptoms in migraineurs.

Tips for managing chronic pain. Implementing the latest guidelines.

Recently revised guidelines from the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) call for an increased awareness of the impact of chronic pain and recommend that physicians assess and treat pain complaints seriously. Although significant and persistent chronic pain is a common reason for primary care visits, the incidence of psychologic distress and personality disorder in patients with chronic pain often makes this population a difficult one for physicians and staff to treat. This discussion offers practical tips for managing patients with chronic pain and reducing staff burnout.

Motor sequence learning and reading ability: is poor reading associated with sequencing deficits?

Although it is widely assumed that children with learning disabilities have "sequencing problems," these have not been well specified. A non-verbal serial reaction time (SRT) paradigm was used to evaluate motor sequence learning in 422 children between ages 7 and 11 in relation to reading, cognitive ability level, and attention problems. The children demonstrated the response profile typically associated with motor sequence learning, but the component of the profile indicative of implicit sequence learning was not reliably associated with any of the predictors.

Durable clinical benefit following Sr90 Beta irradiation therapy for in-stent restenosis in high-volume community practice.

Although randomized clinical trials have demonstrated efficacy of coronary irradiation versus placebo for the treatment of in-stent restenosis (ISR), durable long-term benefit in community practice is less well defined. From January 1, 2001, through June 30, 2002, consecutive percutaneous coronary intervention (n = 3,869) were analyzed at our center with a total of 330 patients undergoing coronary irradiation for ISR (53, Ir192; 12, P32; 265 Novoste Sr90). Novoste Sr90 was successfully performed in 265 of 270 (98%) of patients attempted by 10 operators.

The negotiation state of mind: specifics in negotiating managed care contracts.

Physicians are now finding that the contracts they signed so uncritically in the early years of managed care have left them a legacy of bad contracts, poor fee schedules, and dysfunctional relationships with payors. The negotiating process offers physicians an alternative strategy for effectively achieving their goals in their relationships with the payors. This article explores three specific scenarios--relationships with an economically failing health plan, disputes over coding and bundling of services, and fee discussions between payors and physicians--and illustrates strategies that practices can use to bring about outcomes that are favorable to physicians.

Adenosine stimulates anion secretion across cultured and native adult human vas deferens epithelia.

Experiments were conducted to determine the responsiveness of human vas deferens epithelial cell monolayers to adenosine and related agonists. Human abdominal vas deferens epithelial cells have been isolated from adult tissues and grown to confluence on permeable supports. All cells exhibit intense ZO-1 and cytokeratin immunoreactivity.

Disability and chronic posttraumatic headache.

Objective: To test the hypothesis that chronic posttraumatic headache is associated with greater severity and psychological distress than headache of nontraumatic origin.

Methods: Two hundred eighty-nine consecutive patients with chronic headache attending a university headache clinic were evaluated. Questionnaires about headache symptoms, quality of life (Medical Outcome Survey SF-36 Health Survey), and psychological distress were completed.

Migrainous vertigo: development of a pathogenetic model and structured diagnostic interview.

Purpose Of Review: Vestibular symptoms occur frequently in patients with migraine. This review refines recently proposed diagnostic criteria for migraine-related vestibular symptoms, and develops a pathophysiological model for the interface between migraine and the vestibular system.

Recent Findings: The epidemiological link between migraine and vestibular symptoms and signs suggests shared pathogenetic mechanisms.

MAP kinase and beta-catenin signaling in HGF induced RPE migration.

Purpose: Hepatocyte growth factor (HGF) has been implicated in retinal pigment epithelial (RPE) cell proliferation and migration that occurs in proliferative retinal diseases such as proliferative vitreoretinopathy (PVR). The aim of this study is to investigate HGF induced signaling pathways that lead to RPE cell migration.

Methods: Localization of beta-catenin was determined by immunofluorescence.

HGF regulation of RPE proliferation in an IL-1beta/retinal hole-induced rabbit model of PVR.

Purpose: To understand molecular events that lead to retinal pigment epithelial (RPE) cell proliferation and migration during the early phases of proliferative vitreoretinopathy (PVR) in a rabbit model.

Methods: Retinal holes were created and interleukin-1beta(IL-1beta) was injected intravitreally. Eyes were examined by indirect ophthalmoscopy and eyecup pieces containing retinal holes were analyzed at different times after the surgery up to 4 weeks.

Norwalk virus-like particle hemagglutination by binding to h histo-blood group antigens.

Noroviruses are a major cause of epidemic acute nonbacterial gastroenteritis worldwide. Here we report our discovery that recombinant Norwalk virus virus-like particles (rNV VLPs) agglutinate red blood cells (RBCs). Since histo-blood group antigens are expressed on gut mucosa as well as RBCs, we used rNV VLP hemagglutination (HA) as a model system for studying NV attachment to cells in order to help identify a potential NV receptor(s).

Scene segmentation and attention in primate cortical areas V1 and V2.

The responses of many neurons in primary visual cortex are modulated by stimuli outside the classical receptive field in ways that may contribute to integrative processes like scene segmentation. To explore this issue, single-unit neuronal responses were recorded in monkey cortical areas V1 and V2 to visual stimuli containing either a figure or a background pattern over the receptive field. Figures were defined either by orientation contrast or by illusory contours.

Chloride secretion by semicircular canal duct epithelium is stimulated via beta 2-adrenergic receptors.

The ductal epithelium of the semicircular canal forms much of the boundary between the K+-rich luminal fluid and the Na+-rich abluminal fluid. We sought to determine whether the net ion flux producing the apical-to-basal short-circuit current (I(sc)) in primary cultures was due to anion secretion and/or cation absorption and under control of receptor agonists. Net fluxes of 22Na, 86Rb, and 36Cl demonstrated a basal-to-apical Cl- secretion that was stimulated by isoproterenol.

Pharmacological characterization of human NPFF(1) and NPFF(2) receptors expressed in CHO cells by using NPY Y(1) receptor antagonists.

Neuropeptide FF (NPFF) belongs to an opioid-modulatory system including two precursors (pro-NPFF(A) and pro-NPFF(B)) and two G-protein coupled receptors (NPFF(1) and NPFF(2)). The pharmacological and functional profiles of human NPFF(1) and NPFF(2) receptors expressed in Chinese hamster ovary (CHO) cells were compared by determining the affinity of several peptides derived from both NPFF precursors and by measuring their abilities to inhibit forskolin-induced cAMP accumulation. Each NPFF receptor recognizes peptides from both precursors with nanomolar affinities, however, with a slight preference of pro-NPFF(A) peptides for NPFF(2) receptors and of pro-NPFF(B) peptides for NPFF(1) receptors.

Sex hormones and chronic headache in women.

Women experience changes in headache pattern in relation to changes in their reproductive cycles. Menarche, menses, pregnancy, menopause and the use of exogenous oestrogen-containing medications frequently alter baseline headache patterns. Changing patterns of headache in women may be linked to alterations in levels of sex hormones.

Targeted ablation of connexin26 in the inner ear epithelial gap junction network causes hearing impairment and cell death.

Mutations in the gene encoding the gap junction protein connexin26 (Cx26) are responsible for the autosomal recessive isolated deafness, DFNB1, which accounts for half of the cases of prelingual profound hereditary deafness in Caucasian populations. To date, in vivo approaches to decipher the role of Cx26 in the inner ear have been hampered by the embryonic lethality of the Cx26 knockout mice. To overcome this difficulty, we performed targeted ablation of Cx26 specifically in one of the two cellular networks that it underlies in the inner ear, namely, the epithelial network.

Nongenomic effects of corticosteroids on ion transport by stria vascularis.

Stria vascularis electrogenically secretes potassium into endolymph and this secretion is known to be under acute control of several hormone receptors including purinergic, adrenergic and muscarinic receptors. Recently, chronic application of glucocorticosteroid hormones in autoimmune mice was reported to restore both hearing and normal strial morphology. The purpose of this study was to investigate the acute nongenomic effects of glucocorticoids and mineralocorticoid on the short circuit current (I(sc,probe)) across isolated stria vascularis of gerbils using the voltage-sensitive vibrating probe.

An oft-studied reaction that may never have been: direct catalytic conversion of methanol or dimethyl ether to hydrocarbons on the solid acids HZSM-5 or HSAPO-34.

Using highly purified reagents and careful tests, we show that methanol and dimethyl ether are apparently unreactive on the two most important methanol-to-hydrocarbon catalysts, HZSM-5 and HSAPO-34. Thus, none of the "direct" mechanisms involving two to four carbon atoms in intermediates such as oxonium ylides, carbenes, carbocations, and free radicals are applicable. Only the "indirect" route (hydrocarbon pool) is an established mechanism for this chemistry.

Pregnancy and chronic headache.

Headache patterns in women change in relation to fluctuations in oestrogen levels. Increasing oestrogen levels in early pregnancy offer a protective effect against headache, particularly for women with migraine. However, some women continue to experience troublesome headache throughout pregnancy.

Immunolocalization of P2Y4 and P2Y2 purinergic receptors in strial marginal cells and vestibular dark cells.

K+ secretion by strial marginal cell and vestibular dark cell epithelia is regulated by UTP and ATP at both the apical and basolateral membranes, suggesting control by P2Y2 and/or P2Y4 purinergic receptors. Immunolocalization was used to determine the identity and distribution of these putative receptors. Membrane proteins from gerbil brain, gerbil vestibular labyrinth and gerbil stria vascularis were isolated and analyzed by Western blot.