Effects of HCO3- on cell composition of rabbit ciliary epithelium: a new model for aqueous humor secretion

PURPOSE: To determine whether the Na+-K+-2Cl- symport or the parallel Na+/H+ and Cl-/HCO3- antiports provide the dominant pathway for NaCl uptake into the ciliary epithelium. Both pathways are known to support NaCl entry from the stroma into the pigmented ciliary epithelial (PE) cells, after which Na+ and Cl- diffuse across the gap junctions into the nonpigmented ciliary epithelial (NPE) cells and are released into the aqueous humor. METHODS: Rabbit iris ciliary bodies were preincubated in HCO3-/CO2-containing or HCO3-/CO2-free solutions before quick freezing, cryosectioning, dehydration, and electron probe x-ray microanalysis. RESULTS: The NPE and the PE cells contained more K and Cl when incubated with bicarbonate. Inhibition of carbonic anhydrase with 0.5 mM acetazolamide had little effect in HCO3--free medium but prevented the increase in Cl in both cell types in HCO3-/CO2 solution. Inhibition of the Na+-K+-2Cl- symport with 10 to 500 microM bumetanide caused Cl loss from both cell types in HCO3--free solution, but bumetanide produced a paradoxical increase in Cl and Na in HCO3-/CO2 solution. Together, acetazolamide and bumetanide resulted in significant Cl loss in HCO3--free solution and prevented the gains of Cl and Na in HCO3-/CO2 solution. CONCLUSIONS: The present results indicate that the dominant entry pathway of NaCl from the stroma into the ciliary epithelial syncytium is through an acetazolamide-inhibitable Cl-/HCO3 and a parallel Na+/H+ antiport. The dominant release pathways into the aqueous humor appear to be a Na+-K+-2Cl-symport, which can be outwardly directed under physiological conditions, together with the Na+/K+-exchange pumps and Cl- channels.     

Properties controlling the diffusion and release of water-soluble solutes from poly(ethylene oxide) hydrogels: 3. Device geometry

The diffusive release from hydrogels can be determined by both composition and geometry. This paper presents a theoretical and experimental comparison of the release characteristics of proxyphylline in water-swollen slabs, spheres, and cylinders of a urethane cross-linked poly(ethylene oxide). Contrary to general conventional wisdom it was found that practically cylinders and spheres, which have considerable potential advantages for oral delivery, can provide good 'anomalous' rates for which the 'exponent of release' into water from the dry xerogels is c. 0.8 compared with 1.0 for zero order. An exponent of 0.94 was found for release into water from 'larger' xerogel flat slabs thus confirming that these configurations can provide essentially constant delivery formulations from which the active agent cannot be 'dumped'. For up to 40% total drug release, the theoretical release profiles were essentially of identical form for all three geometries in the swollen state and, as expected in theory and practice, showed an exponent for release of close to 0.5. However, the experimental release of proxyphylline was found to be more sustained from swollen spheres of these polymers than theory would predict. The half life times for release were further extended by approximately two and a half times for the initially dry devices compared with the initially swollen ones.     

Isolated noncompaction of the ventricular myocardium

PURPOSE: This retrospective study was undertaken to review the clinical signs and management of patients with perforating eye injuries associated with regional anaesthesia for ophthalmic surgery. METHODS: Fifteen consecutive patients presenting with inadvertent perforation of the globe were evaluated. Eleven required vitreoretinal surgery. The indications were retinal detachment (six eyes), vitreous haemorrhage (four) and an epiretinal membrane (one eye). RESULTS: Those eyes with retinal detachments generally had a poor functional outcome in spite of the retinae being attached in five of the six eyes. The operative findings of those eyes with vitreous haemorrhage but attached retina demonstrated varying retinal tear configurations. CONCLUSIONS: Eyes with perforating injuries following intraorbital anaesthesia are at risk of developing a retinal detachment. In those eyes presenting with dense vitreous but attached retina, consideration of vitrectomy and laser photocoagulation is advised.     

Directed forgetting of trauma cues in adult survivors of childhood sexual abuse with and without posttraumatic stress disorder

The authors used a directed-forgetting task to investigate whether psychiatrically impaired adult survivors of childhood sexual abuse exhibit an avoidant encoding style and impaired memory for trauma cues. The authors tested women with abuse histories, either with or without posttraumatic stress disorder (PTSD), and women with neither abuse histories nor PTSD. The women saw intermixed trauma words (e.g., molested), positive words (e.g., confident), and categorized neutral words (e.g., mailbox) on a computer screen and were instructed either to remember or to forget each word. Relative to the other groups, the PTSD group did not exhibit recall deficits for trauma-related to-be-remembered words, nor did they recall fewer trauma-related to-be-forgotten words than other words. Instead, they exhibited recall deficits for positive and neutral words they were supposed to remember. These data are inconsistent with the hypothesis that impaired survivors exhibit avoidant encoding and impaired memory for traumatic information.     

伦敦的住宅区

这片引人注目的公寓住宅区坐落于伦敦东部的银镇,看起来和那些低成本的建筑似乎并不相同,然而它也是严格限制费用的产物。年轻的建筑师提出的竞标口号事实上就是“经济型住宅的新理念“。室内空间因大开度的开窗使视线范围扩大到室外城市景观，从而区别于其他建筑。墙面是白色清漆．所构想的整体布局既普遍又实用，给居住者留下了自己设计居住环境的余地。     

Peri-infarct angiographic behavior of "non-culprit" coronary infarct lesions]

Because systemic factors, such as lipoproteins, autoantigens, infectious agents, may facilitate plaque rupture, thrombus formation and coronary occlusion, the question may arise of whether thrombosis be only a local plaque event or the consequence of an acute activity of the entire coronary tree. Taking changes at the narrowest point of non culprit lesions as reflecting progression or regression of the disease when > 0.27 mm, early (within a few days) and late (within 1 month) coronarographic findings in 23 patients with first infarction were compared with those of patients with stable angina, in whom coronary angiography was performed for diagnostic purposes and was repeated 1 month later, before angioplasty. Sixteen infarction patients had progression, 4 had regression, 1 had both, and 2 had steadiness; corresponding values in stable angina group were 2 (p < 0.001), 1 (NS), 0 (NS) and 20 (p < 0.001). In the infarction group, 17 out of the 45 non culprit lesions progressed and 5 regressed; corresponding figures in stable angina group were 2 (p < 0.001) and 1 (p < 0.05). Three of the infarction patients developed interim angina at rest that was associated with progression of a culprit lesion in each of them. These results support the hypothesis that in a number of cases infarction may not reflect an arbitrary plaque event but rather a systemic coronary disease activity with maximal expression at the level of the offending plaque.     

Changes in the phase structure of the polyethylenes after long-time storage at room temperatures

Summary The long-time crystallization of a set of polyethylenes, that have a variety of different molecular structures, has been studied under storage conditions well removed from those where partial melting or relatively rapid crystallization takes place. For high molecular weight linear polyethylenes, branched polyethylenes and ethylene copolymers a density increase of about 5% is observed. However, analysis of the Raman internal modes indicates that the core crystallinity remains constant. It is found that the density change reflects an increase in the partially ordered interfacial region at the expense of the disordered liquid-like region.     

APC-mediated proteolysis of Ase1 and the morphogenesis of the mitotic spindle

The molecular mechanisms that link cell-cycle controls to the mitotic apparatus are poorly understood. A component of the Saccharomyces cerevisiae spindle, Ase1, was observed to undergo cell cycle-specific degradation mediated by the cyclosome, or anaphase promoting complex (APC). Ase1 was degraded when cells exited from mitosis and entered G1. Inappropriate expression of stable Ase1 during G1 produced a spindle defect that is sensed by the spindle assembly checkpoint. In addition, loss of ASE1 function destabilized telophase spindles, and expression of a nondegradable Ase1 mutant delayed spindle disassembly. APC-mediated proteolysis therefore appears to regulate both spindle assembly and disassembly.