Differential expression of voltage-activated Na+ currents in two prostatic tumour cell lines: contribution to invasiveness in vitro.

The voltage-gated ionic currents of two rodent prostatic cancer cell lines were investigated using the whole-cell patch clamp technique. The highly metastatic Mat-Ly-Lu cells expressed a transient, inward Na+ current (blocked by 600 nM tetrodotoxin), which was not found in any of the weakly metastatic AT-2 cells. Although both cell lines expressed a sustained, outward K+ current, this occurred at a significantly higher density in the AT-2 than in the Mat-Ly-Lu cells. Incubation of the Mat-Ly-Lu cell line with 600 nM tetrodotoxin significantly reduced the invasive capacity of the cells in vitro. Under identical conditions, tetrodotoxin had no effect on the invasiveness of the AT-2 cells.

Quantitative analysis of cone photoreceptor-horizontal cell connectivity patterns in the retina of a cyprinid fish: electron microscopy of functionally identified and HRP-labelled horizontal cells.

Horizontal cells generating photopic luminosity and biphasic/chromaticity-type S-potentials were identified and intracellularly labelled with horseradish peroxidase in the retina of the roach. The synaptic connectivity patterns of the horizontal cell dendrites within pedicles of different spectral types of cone were then quantitatively studied by electron microscopy. Luminosity-type responses were generated by H1-like horizontal cells contacting similar numbers of red- and green-sensitive cones and very few blue-sensitive cones. Most dendritic contacts were lateral to synaptic ribbons. Central contacts with ribbons were made almost exclusively within red-sensitive cone pedicles. Biphasic/chromaticity-type S-potentials were generated by H2-like horizontal cells. The dendrites of the latter contacted green- and blue-sensitive cones, both at central and lateral sites at synaptic ribbons. An attempt was made to correlate cone ribbon connectivity patterns and spectral characteristics of the horizontal cells according to several hypotheses, some proposed in earlier studies.

The application of in vitro isolation, cryopreservation and patch-clamp microelectrode recording methods to adult rat thymic nurse cells.

Characterisation of the ionic mechanisms possessed by immune cells has begun to reveal a range of transmembrane ion channel properties which may have immunological significance. Since thymic epithelial cells appear to influence selection of the T cell repertoire, understanding their membrane physiology may be of importance. A method is therefore outlined for the targeting of patch-clamp electrophysiological measurements to acutely isolated, fresh and cryopreserved adult rat thymic nurse cells. These cells represent a discrete and predominantly cortical population of epithelium. Cells were separated by enzymatic and mechanical dispersal of thymus, enriched by sedimentation and identified on the basis of their characteristic lympho-epithelial, multi-cellular morphologies. Phase-bright cells retaining this anatomical form survived freezing and the voltage-gated conductances in such cells are described. The merits of this approach include the preparation and storage of mature differentiated phenotypes of immune cells for in vitro studies. Their preservation permits temporal separation of experiments, correlative experimentation on identical samples, optimises cell preparation in terms of cost and labour, and reduces animal and tissue requirements.

Transient block of respiratory chain by cyanide triggers NADPH-diaphorase activity (a marker for nitric oxide synthase) in Dunning rat prostatic epithelium.

Synthesis of nitric oxide (NO) has been shown in the glandular epithelium of human prostate, with highest levels in the peripheral zone. This location is believed to be the main source of prostatic cancer. The ability of stromal cells to produce NO may contribute to the malignant process. Since solid tumours are prone to hypoxia and malignant progression, experiments were undertaken to test the effect of respiratory block on the induction of nitric oxide synthase (NOS) by a Dunning rat prostatic epithelial line. A metastatic phenotype (Mat-LyLu) was treated in vitro with brief exposure to cyanide in order to mimic transient hypoxic stress. NADPH-diaphorase activities in paraformaldehyde-fixed cells was used to follow the expression of NOS. NADPH-diaphorase activity was found to be inducible by a range of factors, including mechanical damage and infection of cultures. Cyanide induced a dose-dependent staining that was statistically greater than in untreated cells. Consistent with diaphorase staining being a marker for the inducible isoform of NOS (iNOS), induction and enhancement of staining, respectively, was observed in response to treatment with lipopolysaccharide or withdrawal of dexamethasone supplement. Results demonstrate that prostatic epithelia can be triggered in culture to express iNOS by transient oxidative stress in the form of respiratory poisoning by NaCN. Paradoxically, nitric oxide production by epithelia within hypoxic zones of solid tumours may contribute to the promotion and/or inhibition of tumorigenesis.

Electrophysiological effects of tachykinin analogues on ganglion cell activity in cyprinid fish retina.

Electrical spike activity of ganglion cells has been recorded extracellularly in the teleost (roach) retina, and effects of a variety of tachykinins studied at a working concentration of 1 microM. Application of substance P mostly caused a slow and prolonged increase in background activity. In contrast, the response to carbachol was very brisk and short-lasting. Substance P and physalaemin predominantly induced an enhancement of 'On' and 'Off' components of light-evoked responses, whilst eledoisin and neurokinin A were mostly inhibitory. All effects were independent of chromatic and spatial aspects of the responses. Interestingly, in the presence of a tachykinin antagonist, 'Spantide' [D-Arg1,D-Pro2, D-Trp7.9, Leu11]SP, the profile of the effect of substance P reversed, inhibitory actions becoming much more common. Taken together, the results suggest that a tachykinin system utilising two subtypes of the receptor may be active in the roach retina and these may be involved in differential control of visual sensitivity.

Cat retinal ganglion cells show transient responses to acetylcholine and sustained responses to L-glutamate.

The neuropharmacological basis for the different receptive field properties of cat retinal ganglion cells was investigated using whole cell voltage-clamp recordings from acutely dissociated adult tissue. Subclasses of physiologically characterised ganglion cells were determined on the basis of (i) their soma diameters and (ii) their projection to central visual nuclei (identified by microinjection of fluorescent dyes into the lateral geniculate and/or superior colliculus). The sensitivities of all categories of ganglion cells, prepared from peripheral retina were found to be similar for gamma-amino butyric acid, glycine, acetylcholine and glutamate. The kinetics of desensitisation differed among receptor subtypes, revealing possible physiologically significant molecular specialisations that could be involved in shaping synaptic transmission.

Long-term discission rate after placing posterior chamber lenses with the convex surface posterior.

The incidence of secondary capsulotomy was studied in a group of 757 posterior chamber intraocular lenses placed with the convex surface posterior within the capsular bag. Minimum follow-up was 12 months and ranged up to 61 months, with a mean of 33 months. In the first year, only 2.9% of cases required discission, but this rose to 15.7% at five years. The need for capsulotomy with angled-haptic lenses was 7.9% at three years; it was 15.0% with uniplanar lenses (P = .04). This difference appeared to be due to better apposition of the optic to the posterior capsule in the angled lenses, creating a more effective barrier to epithelial pearl migration. Capsulotomy carries significant risks and lens designs that minimize the long-term need for capsulotomy should be sought. Convex posterior lenses with angled haptics have a low incidence of posterior capsule opacification.

Long-term results with Choyce-Tennant anterior chamber intraocular lens implants.

A consecutive series of 200 Choyce-Tennant rigid anterior chamber intraocular lens implants is reported. The minimum follow-up was four years. Eighty-six percent of patients had 20/40 or better visual acuity at their most recent office visit. Low-grade but persistent inflammation required prolonged use of mild topical steroid drops in approximately 40% of patients. The most serious lens-related complication was pupillary block which occurred in 15 patients (7.5%). There was a year-by-year increase in the number of patients with elevated intraocular pressure, with 14 (7.0%) requiring glaucoma treatment by the seventh year postoperatively.

Biconvex intraocular lenses and Nd:YAG capsulotomy: experimental comparison of surface damage with different poly(methyl methacrylate) formulations.

Biconvex posterior chamber lenses have optical advantages and decrease the risk of capsular opacification, but they are more likely to be pitted during ND:YAG capsulotomy because of apposition of the lens to the capsule. This study reports the likelihood of surface damage to different formulations of poly(methyl methacrylate) at the energy levels required to open posterior capsules. Molded lenses are more easily damaged than higher molecular weight lathe-cut materials (P less than .01), as expected. However, by keeping energy output low, even injection-molded lenses showed minimal damage, with mean pit size 39 +/- 39 microns at 1 mJ. By using a converging contact lens, low power, and keeping the focus behind the capsule, damage to all materials tested should be clinically insignificant.

Neuronal and glial cell types revealed by NADPH-diaphorase histochemistry in the retina of a teleost fish, the grass goby (Zosterisessor ophiocephalus, Perciformes, Gobiidae).

The grass goby is a mud-burrowing fish with a rich retinal vasculature appropriate to its hypoxic habitat. NADPH-diaphorase histochemistry was performed on retinal sections and wholemounts to reveal cells that contain nitric oxide synthase and so may be presumed to synthesise nitric oxide, a gaseous intercellular messenger with many roles including vasodilation. Structures that were consistently stained by this method included cone ellipsoids, horizontal cells, Müller cells and their processes, large displaced ganglion cells in the inner nuclear layer (identified by their axons), large interstitial ganglion cells in the inner plexiform layer, and capillary endothelial cells. In wholemounts, horizontal cells were seen to form a regular pattern, contacting each other at their dendritic terminals. Some cells in the ganglion cell layer were weakly stained, but stained bipolar and amacrine cells were not seen. The diaphorase-positive large ganglion cells all formed large, sparsely branched dendritic trees, arborizing near the scleral border of the inner plexiform layer. The displaced and interstitial cells seemed to belong to distinct morphological types, the interstitial cells having smaller somata and trees. Analysis of their spatial distributions in one representative retina confirmed this: the displaced cells formed a highly regular mosaic with a mean spacing (nearest-neighbour distance) of 303 microm, whereas the interstitial cells formed a separate mosaic, almost as regular but with a smaller mean spacing of 193 microm, rising to 217 microm in a sample that excluded the area retinae temporalis. Spatial correlogram analysis showed that these two mosaics were spatially independent. Nitric oxide probably has many roles in the retina. The presence of its synthetic enzyme in Müller cells, which communicate with retinal blood vessels, is consistent with a role in the control of retinal blood flow. Its function in large, mosaic-forming retinal ganglion cells is unknown.

Communication intervention for individuals with dual sensory and intellectual impairments.

For individuals with dual sensory and intellectual impairments, the lack of effective communication skills places severe limitations on their learning potential and sense of belonging. Educational intervention for this population has recognized the critical need to develop communication skills, yet the complexity of the individual's needs continues to plague progress. Unique needs and situations of individuals in this category, coupled with extremely limited numbers of trained and experienced professionals, challenge the field to develop creative means of addressing this vital issue. Documented case studies provide the field with examples of potential options to employ when addressing the communicative needs of individuals with dual sensory and intellectual impairments. However, these case studies provide partial communication systems that address partial communicative needs. Providing individuals having severe sensory, intellectual, and other disabilities with a true language that can meet all communication needs, both receptive and expressive, is still beyond our grasp. Future efforts with this focus will need to combine early intervention, creative technology, and principles of normalization in order to be successful.

Multiple nitric oxide synthase systems in adult rat thymus revealed using NADPH diaphorase histochemistry.

Nitric oxide (NO) has become recognized as a multifunctional mediator, with roles in vascular physiology, neurotransmission and non-specific immune defense. The histochemical marker associated with the neural and endothelial form of NO synthase (NOS), reduced nicotinamide adenine dinucleotide diaphorase (NADPHd), has enabled the indirect localization of potential sites of NO production. Innervation of the thymus and its immunological functions made this tissue a candidate for utilization of various NO systems. In the present study on adult rat thymus, multiple cellular sites expressing NADPHd activity, thereby implicated as sites of NOS activity, have been identified using morphological criteria alone: blood vessel endothelium, dendritic cells, deep cortical or medullary stromal cells, intrinsic neuron-like profiles, granulocytes (possibly neutrophils) and fat cells. In addition, the availability to the thymic microenvironment of another form of NOS in macrophages, which is not stained by the diaphorase technique, was supported by the observation of these cells at corticomedullary and cortical locations. These results indicate that a wide variety of possible immunomodulatory roles can be expected for NO in the thymus including the induction of tolerance, major histocompatibility complex (MHC) restriction, lymphocyte trafficking and regulation of thymic endocrine output.

Ten-year follow up comparing anterior and posterior chamber intraocular lens implants.

Results achieved in eyes following a single surgeon's first 200 procedures consisting of intracapsular cataract extraction and implantation of a Choyce-Tennant anterior chamber lens (AC-IOL) (1977 to 1980) are compared with those achieved following the same surgeon's first 200 procedures consisting of extracapsular cataract extraction and implantation of a posterior chamber intraocular lens (PC-IOL) (1980 to 1982). For the AC-IOL eyes, follow up ranged from 11.1 to 14.2 years (mean, 12.0 years); for the PC-IOL eyes, from 9.5 to 10.8 years (mean, 10.0 years). The AC-IOL eyes had many early problems: pupillary block (7%), iritis (15%), and secondary glaucoma (8%). Four percent developed corneal edema, 1.5% vitritis, and 2% localized iris holes under the lens. Ectropion uveae appeared in 8.5%, indicating some ongoing inflammation. One and one-half percent of these lenses were removed or exchanged. Seventy-nine and one-half percent of these eyes had 20/40 or better vision at 10 years; 4% had visual loss along with corneal edema or vitritis, apparently related to the AC-IOLs. The PC-IOL eyes had comparatively few lens-related complications: 1% corneal edema, 1.5% iritis, 1% vitritis, and 2% secondary glaucoma. Some localized trapping of the pupil occurred in 8%. One percent of the PC-IOLs were removed, and 1% decentered, requiring McCannell sutures. Final visual acuity at 10 years was 20/40 or better in 77.5%. None of the PC-IOL eyes had decreased vision related to the lens implant.

Neural immunoregulation: emerging roles for nerves in immune homeostasis and disease.

In this review, James Downing and Jaleel Miyan outline emerging evidence for neural mechanisms that contribute to specific categories of host defence. Involvement of direct innervation in the adaptive control of immunological responses complements an established view of neuroendocrine-immune modulation. The challenge remains to understand the integrative and homeostatic functions of 'hardwiring' of peripheral immune effector sites, its bearing on disorder and potential for therapeutic modification.

Change in effective power of posterior chamber lenses placed with the plano surface anterior.

Posterior chamber lenses were inserted with the plano surface anterior because of theoretical optical improvements in spherical and chromatic aberration, less induced magnification, and a reported decrease in late opacification of the posterior capsule. A decrease in effective lens power occurred, with a shift in observed refraction of approximately + 1.50 diopters (D) from that calculated. This finding is explained by the location of the principal planes of a plano-convex lens. Orienting the plano surface anteriorly causes an observed increase in required anterior chamber depth (ACD) calculation that averages 1.1 mm. Required ACD using the Binkhorst formula was 5.1 mm; the Sanders-Retzlaff-Kraff (SRK) A constant required was 118.7. The need for secondary capsulotomy has been only 5.8% with an average follow-up of 19 months and a range of 12-27 months.

Activators of protein kinase C enhance acetylcholine receptor desensitization in sympathetic ganglion neurons.

Recent studies suggest that phosphorylation may regulate the rate of desensitization of nicotinic acetylcholine (AcCho) receptors (AcChoR) in vertebrate muscle and Torpedo. It is not known if phosphorylation is involved in regulation of the neuronal AcChoR, however. In this study we examine the possibility that protein kinase C might regulate nicotinic AcChoR function in neurons. Several activators of protein kinase C (1-oleoyl-2-acetylglycerol, phorbol 12,13-diacetate, and phorbol 12,13-dibutyrate) were tested for their ability to modulate AcChoR function in embryonic chicken sympathetic ganglion neurons. Neurons were voltage-clamped at the resting potential, and the response to AcCho was tested before and after treatment with activators of protein kinase C. We find that all of these agents enhance the rate of decay of AcCho-induced current without affecting peak current amplitude or cellular input resistance. The drugs were ineffective if applied concurrently with AcCho: significant effects could be detected after 60 sec of pretreatment. A phorbol that does not increase protein kinase C activity (4 beta-phorbol) was ineffective in enhancing the decay of AcCho-induced current. Thus, the effects of these agents on AcChoR function are likely to be mediated by their interaction with C kinase, rather than by direct interaction with the AcChoR channel. Our data suggest that kinase C may regulate agonist-induced desensitization of the neuronal AcChoR channel.

A horizontal cell selectively contacts blue-sensitive cones in cyprinid fish retina: intracellular staining with horseradish peroxidase.

A horizontal cell selectively contacting blue-sensitive cones has been intracellularly stained with horseradish peroxidase in the retina of a cyprinid fish, the roach. The light microscopical morphology of the cell belonged to the H3 category of horizontal cells found in cyprinid fish retinae. In response to spectral stimuli, the cell generated chromaticity-type S-potentials that were hyperpolarizing to blue and depolarizing to yellow-orange. A red-sensitive hyperpolarizing component was absent possibly because of suppression of the negative feedback pathway between luminosity-type (H1) horizontal cells and green-sensitive cones.

The cellular origin of an unusual type of S-potential: an intracellular horseradish peroxidase study in a cyprinid fish retina.

L2-type S-potentials are mainly blue/green-sensitive hyperpolarizing responses with a red-sensitive depolarizing component which is either weak or absent. They were first described in the retina of the roach, a cyprinid fish, by Djamgoz (1978, 1984) and Djamgoz & Ruddock (1978, 1979a). The cellular origin of these responses has been determined and characterized by intracellular recording, horseradish peroxidase staining, and light and electron microscopy. They were found to arise in horizontal cells with H2-like morphologies on average (Stell & Lightfoot, 1975). The dendrites of these cells contacted green- and blue-sensitive cone pedicles within which both lateral and central contacts were made at ribbon synapses. The laterally-positioned dendrites had incompletely formed spinules associated with them. A number of similarities between these units and the biphasic, chromaticity (Cb)-type S-potentials have been outlined and it is suggested that L2 units are essentially Cb-units with a weak depolarizing component. In turn, it is suggested that the depolarizing component is reduced as a consequence of the relatively dark-adapted states of the retinae. It is concluded that the negative feed-back pathway that subserves the generation of depolarizing (Cb-type) S-potentials is weak or absent in dark-adapted retinae and that spinules may be the site of this feed-back interaction.

Epidural morphine delivered by a percutaneous epidural catheter for outpatient treatment of cancer pain.

Twenty-three outpatients with cancer pain refractory to other methods of pain control were treated with epidural morphine (EM) delivered through a chronically placed percutaneous lumbar epidural catheter. Patients and their families were taught to administer EM at home. Mean EM doses ranged from 18 to 31 mg/day. Mean catheter lifespan was 6.3 weeks. There were no catheter-related infections or cases of respiratory depression. After 2500 patient treatment days, we have found this method to be a safe and effective method of cancer pain management in outpatients.