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[Centering the posterior chamber lens in autopsy eyes with and without pseudoexfoliation syndrome].

The pseudoexfoliation syndrome (PEX) is an important risk factor for cataract surgery. In this study we examined a series of 24 autopsy eyes with PEX that had undergone cataract surgery and intraocular lens (IOL) implantation. The eyes were grossed for IOL fixation and centration. The results were compared to a control group of 25 non-PEX autopsy eyes that matched the PEX series in age distribution, implant duration and anatomical parameters (i.e., axial length) (P > 0.18). The mean IOL decentration in all PEX eyes (0.75 +/- 0.38 mm) was significantly higher than in the control group (0.40 +/- 0.29 mm) (P = 0.0008). Analysis of subgroups with symmetrical bag/bag fixated IOLs also showed significant higher decentration in the PEX group (P = 0.04). The main reason for decentration was decentration of the entire capsular bag in the PEX eyes (0.28 +/- 0.19 vs 0.10 +/- 0.16 in controls; P = 0.001). Patients with PEX showed a higher amount of IOL decentration. The results indicate that the insufficient suspension apparatus of the lens and decentration of the entire capsular bag are the main reasons for IOL decentration in patients with PEX.

Aged↗

Health services reform and human resource management in Hong Kong public hospitals.

This article discusses the empirical study of reform in the human resource management function in the Hong Kong Hospital Authority. It describes the prior management of the hospitals based on the civil service administration model before looking at management reform in general. From this research, the creative tensions between the centrifugal and centripetal forces in the pursuit of 'effectiveness', 'efficiency' and 'economy' are explored in terms of decentralization. A survey of line managers, in eleven Hospital Authority hospitals, revealed the progress of decentralization: a majority of respondents felt that, over the previous five years, managers at their level had been given greater responsibility for human resource management issues. In spite of the widespread perception of increased decentralization, however, it was recognized that there are limits to decentralization. It was the routine administration rather than the policy formulation and interpretation which had been decentralized, and hospitals continued to rely on the Hospital Authority Head of Office for guidance on policy interpretation. Several barriers to the effective decentralization of responsibility for human resource management were identified, including a lack of management skill, knowledge and time, the attitudes of some managers and the tight control of budget.

Data Collection↗

Presynaptic modulation of activity and molecular forms of acetylcholinesterase in the rat superior cervical ganglion during early postnatal development.

Preganglionic nerve trunk of the rat superior cervical ganglion was transected shortly after birth in order to evaluate the influence of preganglionic nerves on the development of acetylcholinesterase and choline acetyltransferase in ganglionic neurons. In spite of an early decentralization, specific activity of acetylcholinesterase in the ganglion is increasing during the first 3 wk of life until it is about equal to the activity which remains in the superior cervical ganglion decentralized in an adult animal. Thus, the preganglionic nerves, which per se contribute the presynaptic fraction of total ganglionic AChE activity in normal innervated ganglia, apparently exert no significant regulatory effect on the specific activity of the fraction of acetylcholinesterase affiliated with the developing ganglionic cells. However, the absence of innervation during development is strongly reflected in the pattern of acetylcholinesterase molecular forms. The activity of the 16 S molecular form of AChE remains high in the developing superior cervical ganglion, decentralized at birth, in contrast to the substantial absolute and relative decrease of specific activity of this form during development of a normally innervated ganglion. A high proportion of 16 S AChE probably reflects a shift of decentralized immature ganglion nerve cells toward a cholinergic character. In accordance with this assumption, choline acetyltransferase activity in early decentralized ganglia is significantly higher than that in the ganglia decentralized in adult animals.

Acetylcholinesterase↗

Secondary intraocular lens implantation for pediatric aphakia.

PURPOSE: We sought to report the outcome of secondary intraocular lens (IOL) implantation in children. METHODS: This was a retrospective case review. RESULTS: A total of 77 eyes were identified. An average age at secondary implantation was 7.8 +/- 5.0 years, whereas the average age at primary cataract surgery was 1.5 +/- 2.6 years. Average follow-up was 2.7 +/- 1.9 years. Thirty eyes received a hydrophobic acrylic IOL implantation whereas 47 eyes received a PMMA IOL. The sites of fixation for implanted IOLs were as follows: anterior-chamber (n = 6), sulcus (n = 42), in-the-bag (n = 14), optic-capture (n = 6), piggyback (n = 4), and sutured (n = 5). Complications included clinically significant decentration, 4 (5.2%); visual axis opacification, 4 (5.2%); dislocation of the IOL, 2 (2.6%); and pupillary capture requiring repositioning of IOL, 1 (1.3%). Clinically significant decentration requiring surgical intervention was noted only in eyes with sulcus-fixated foldable IOLs (28.6%; 4/14). None of the 29 eyes with sulcus-fixated PMMA IOL implantation developed decentration. All the decentrations were in an inferior direction and occurred in eyes of male patients (P = 0.03). Eyes with an axial length of >23 mm were 4 times more likely to develop decentration if implanted with a sulcus-fixated foldable IOL when compared with eyes measuring <23 mm (P = 0.03). Postoperative geometric mean visual acuity was significantly better than preoperative visual acuity (P < 0.001). CONCLUSION: Secondary IOL implantation can be safely achieved in pediatric eyes. In-the-bag fixation of foldable IOLs is associated with a low rate of complications. Foldable lenses appear to have a higher rate of decentration than PMMA lenses when placed in the sulcus in eyes of myopic male patients.

Adolescent↗

Surgical repositioning of dislocated capsular tension rings.

PURPOSE: To present techniques and results of surgical repositioning of subluxed and dislocated capsular tension rings (CTRs). DESIGN: Retrospective interventional case series. PARTICIPANTS: Eleven patients with a previously implanted CTR in-the-bag for zonular weakness who presented with CTR-intraocular lens (IOL)-capsular bag decentration who underwent surgical repositioning. METHODS: Data from 11 patients who underwent surgical repositioning were evaluated retrospectively for underlying diagnosis, interval between initial surgery and decentration, surgical technique, clinical results, and complications. MAIN OUTCOME MEASURES: Capsular tension ring-IOL-capsular bag centration, final best-corrected visual acuity (BCVA), and surgical complications. RESULTS: Of the 11 patients with CTR decentration, 3 had it early in the postoperative period, and 8 had it late. Mean (+/- standard deviation) durations from cataract extraction and CTR implantation to surgical repositioning were 6.1+/-7.9 months for those with decentration early and 49.6+/-15.3 months for late decentrations (overall range, 0.7-74.7). Of the 11 patients, 7 had pseudoexfoliation, and 4 of the 7 had associated glaucoma. Nine patients had subluxation of the CTR-IOL-capsular bag complex, which was managed by an anterior segment approach. A pars plana vitrectomy and levitation of the CTR was required in 2 patients due to complete dislocation of the CTR into the posterior vitreous. Surgical techniques for repositioning included single, double, or 3-point scleral suture loop fixation of the CTR through the capsular bag complex (8 eyes); use of the capsular tension segment (CTS) placed within the capsular bag for scleral suture fixation (2); or iris suture fixation of the IOL haptics (1). All patients achieved successful anatomical repositioning of the CTR-IOL-capsular bag complex. Mean preoperative BCVA improved from 20/100 to 20/40 postoperatively. After repositioning surgery, BCVA improved in 7 patients, was maintained in 2, and worsened in 2 (due to advanced glaucoma). CONCLUSION: Postoperative CTR subluxation or dislocation is a risk for patients with severe or progressive zonulopathy. Decentrations may be effectively managed with scleral suture fixation of the CTR through the capsular bag or the use of the CTS.

Aged↗

Postdecentralization plasticity of voltage-gated K+ currents in glandular sympathetic neurons in rats.

This paper presents the kinetic and pharmacological properties of voltage-gated K(+) currents in anatomically identified glandular postganglionic sympathetic neurons isolated from the superior cervical ganglia in rats. The neurons were labelled by injecting the fluorescent tracer Fast Blue into the submandibular gland. The first group of neurons remained intact, i.e. innervated by the preganglionic axons until the day of current recordings (control neurons). The second group of neurons was denervated by severing the superior cervical trunk 4-6 weeks prior to current recordings (decentralized neurons). In every control and decentralized neuron three categories of voltage-dependent K(+) currents were found. (i) The I(Af) K(+) current, steady state, inactivated at hyperpolarized membrane potentials. This current was fast activated and fast time-dependently inactivated, insensitive to TEA and partially depressed by 4-AP. (ii) The I(As) K(+) current, which was steady-state inactivated at less hyperpolarized membrane potentials than I(Af). The current activation and time-dependent inactivation kinetics were slower than those of I(Af). I(As) was blocked by TEA and partially inhibited by 4-AP. (iii) The IK K(+) current did not undergo steady-state inactivation. In decentralized compared to control neurons the maximum I(Af) K(+) current density (at +50 mV) increased from 116.9 +/- 8.2 to 189.0 +/- 11.5 pA/pF, the 10-90% current rise time decreased from 2.3 to 0.7 ms and the recovery from inactivation was faster. Similarly, in decentralized compared to control neurons the maximum I(As) K(+) current density (at +50 mV) increased from 49.9 +/- 3.5 to 74.3 +/- 5.0 pA/pF, the 10-90% current rise time shortened from 29 to 16 ms and the recovery from inactivation of the current was also faster. The maximum density (at +50 mV) of I(K) in decentralized compared to control neurons decreased from 76.6 +/- 3.9 to 60.7 +/- 6.3 pA/pF. We suggest that the upregulation of voltage-gated time-dependently-inactivated K(+) currents and their faster recovery from inactivation serve to restrain the activity of glandular sympathetic neurons after decentralization.

4-Aminopyridine↗

The effect of social influence on cognitive development and school performance.

Three months before school entrance a sample of 29 children and their mothers was tested for degree of decentred child educability and degree of decentred maternal teaching. Mother and child were tested in two different situations, thus preventing interdependency between the measures of mother and child. Four months after school entrance, teacher judgements of school performance were obtained. A strong correspondence between degree of decentred child educability and degree of decentred maternal teaching was demonstrated. Degree of decentred maternal teaching and degree of decentred child educability were found to be good predictors of school performance, accounting for respectively 45 and 33% of the variance in school performance. In contrast a test of school readiness only accounted for 2% of the variance. A test of intelligence given after the teacher judgement accounted for 31% of the variance. The fact that the mother seems to be a better predictor of her child's school performance than the child himself, supports the assumption that parents, particularly mothers, are important mediators between the child and the outer world.

Achievement↗

Neuropeptide Y and reserpine-resistant vasoconstriction evoked by sympathetic nerve stimulation in the dog skeletal muscle.

1. The effects of sympathetic nerve stimulation (evoked by recordings of authentic irregular vasoconstrictor nerve fibre discharge with average frequencies of 0.59, 2.0 and 6.9 Hz) on the perfusion pressure and the overflow of noradrenaline (NA) and neuropeptide Y-like immunoreactivity (NPY-LI) were investigated in the blood-perfused gracilis muscle of the dog in situ. 2. Nerve stimulation in the untreated control group evoked a frequency-dependent increase in perfusion pressure and overflow of NA. A significant overflow of NPY-LI was found at the highest frequency only. 3. In a separate group of animals, the sympathetic supply was unilaterally interrupted by preganglionic decentralization before the administration of reserpine (1 mgkg-1 i.v.) 24 h before the experiment. Reserpine reduced the NA content of the intact and decentralized gracilis and gastrocnemius muscle by 98-99%. Reserpine also induced a marked (80%) reduction of the muscular content of NPY-LI. The depletion of NPY-LI was, in contrast to that of NA, prevented by the decentralization, suggesting that nerve impulse activity was of primary importance for the reserpine-induced depletion of NPY-LI. 4. A slowly developing and long-lasting perfusion pressure increase was evoked by nerve stimulation, at 2.0 and 6.9 Hz after reserpine treatment. These responses were larger in the decentralized, as compared to the intact gracilis muscle and correlated with the nerve stimulation evoked overflow of NPY-LI (r = 0.79, P less than 0.001). Stimulation at 0.59 Hz caused vasoconstriction in the decentralized but not in the intact gracilis. 5. Administration of alpha,beta,-methylene adenosine triphosphate did not evoke an increase in perfusion pressure in the gracilis muscle of reserpine-treated animals. 6. In conclusion, a large perfusion pressure increase to sympathetic nerve stimulation occurs in the reserpine-pretreated skeletal muscle vasculature of the dog in vivo, providing that preganglionic decentralization has been performed. It is suggested that the released NPY-LI may mediate this vasoconstrictor response.

Adenosine Triphosphate↗

Centration analysis of ablation over the coaxial corneal light reflex for hyperopic LASIK.

PURPOSE: To analyze postoperative topographic centration when the coaxially sighted corneal light reflex was used for laser centration in hyperopic LASIK. METHODS: Centration photographs of 21 eyes (12 patients) that underwent hyperopic LASIK with centration over the coaxially sighted corneal light reflex were reviewed to determine the distance from the entrance pupil center to the coaxially sighted corneal light reflex. Postoperative ablation centration was determined topographically at day 1 and 3 months by four different methods. The difference between the actual decentration and the decentration that would have occurred had the ablation been centered over the entrance pupil center was calculated. RESULTS: The mean deviation of the coaxially sighted corneal light reflex from the entrance pupil center preoperatively was 0.34 +/- 0.24 mm nasal or 4.5 +/- 3.0 degrees. At 1 day, the average decentration was 0.10 mm or 1.3 degrees temporal. The mean decentration that would have occurred if the ablation had been centered over the entrance pupil center was 0.44 mm or 5.5 degrees temporal. At 3 months, the average decentration was 0.07 mm or 0.25 degrees temporal. The mean decentration that would have occurred if the ablation had been centered over the entrance pupil center was 0.45 mm or 5.6 degrees temporal. Mean uncorrected visual acuity (logMAR) improved 3 lines from 0.54 +/- 0.14 (20/70) to 0.22 +/- 0.17 (20/32). No eye lost >2 lines of best spectacle-corrected visual acuity (BSCVA); 2 (10%) eyes lost 1 line of BSCVA at 3-month follow-up. CONCLUSIONS: Excellent centration in hyperopic ablation is possible even in eyes with positive angle kappa when the ablation is centered over the corneal light reflex.

Cornea↗

[Topographical evaluation of centration of excimer laser photorefractive keratectomy].

OBJECTIVE: To evaluate the situation of centrality of excimer laser photorefractive keratectomy (PRK). METHODS: Eyesys Corneal Analysis System was used for the computer-assisted analysis of corneal differential topographical maps gained preoperatively and 10 days postoperatively in 158 eyes of 98 patients with at least six months of follow-up to determine the direction and the distance of the center of ablation zone relative to the center of the entrance pupil, and a comparison in decentration difference was made between one-zone ablated eyes and multi-zone ablated eyes. RESULTS: Concerning the centration of ablated zone relative to the center of entrance pupil: 100 eyes (63.3%) were centered within 0.50 mm, 55 eyes (34.8%) were decentered more than 0.50 mm with 3 eyes (1.9%) being decentered more than 1 mm, and the mean decentration amount was 0.45 mm. 38 eyes were performed by multi-zone ablation and 120 eyes by one-zone ablation, their mean amount of decentration was 0.55 mm and 0.44 mm respectively, the difference being significant (P < 0.05). 4 eyes with decentration greater than 0.50 mm lost one to two lines of their best corrected visual acuity postoperatively due to the decentered ablation. CONCLUSION: Many factors contribute to decentration of the ablated zone. Great decentration will affect the recovery of the postoperative visual acuity. The Passive Eye Tracking System (PET) will contribute to precise centration and reduction of displacement.

Adolescent↗

Optimum form of posterior chamber intraocular lenses to minimize aberrational astigmatism.

To optically determine the optimum form for a posterior chamber intraocular lens (PC IOL), we calculated the aberrational astigmatism induced by tilt and decentration of the PCIOL using an exact raytracing. First, the position and the radii of curvatures of the IOL were determined to make an emmetropic eye model using a paraxial raytracing. Next, the chief rays originating from the fovea centralis were traced backward through the tilted and/or decentrated PC IOL, the center of the pupil and the cornea, using trigonometric raytracing. Finally, the maximum and minimum aberrational astigmatism were calculated based on the Coddington's Equations for the sagittal and the tangential foci of the ray. All the refractive parameters in Gullstrand's No. 1 schematic eye were adopted. The effect of varying anterior corneal asphericity on the results was also examined. Four forms of polymethylmethacrylate PC IOLs (refractive index: 1.491) were analyzed; a plano-convex IOL with the curved surface facing the cornea, and three bi-convex forms with the ratio of anterior-to-posterior radii of curvatures of 1:4, 1:2 and 1:1, respectively. The 1:4 bi-convex form showed the lowest values for the maximum aberrational astigmatism calculated at every combination of tilt and decentration except 0 degrees tilt and/or 0 mm decentration. The aberrational astigmatism with the 1:4 bi-convex form of PC IOL did not exceed 1.0 D at the maximum tilt and decentration. The variation of anterior corneal asphericity did not influence the results. We conclude that the 1:4 bi-convex form of PC IOL minimizes the postoperative astigmatism induced by tilt and/or decentration of the lens.

Astigmatism↗

Analysis of corneal topography after excimer laser photorefractive keratectomy.

Excimer laser photorefractive keratectomy (PRK) is an effective treatment for myopia. We investigated the magnitude of optical zone decentration and qualitative patterns of corneal topography after this treatment. We performed computer-assisted videokeratography on 44 myopic eyes (29 patients) that had undergone PRK before and 1, 6, and 12 months after the procedure. Associations of clinical outcomes with decentration and topographic patterns were assessed. The normalized scale of the topography 1 month postoperatively showed a mean decentration of 0.33 +/- 0.23 mm (range 0-0.9). Thirty-four eyes had decentration of less than 0.50 mm; 10 had an ablation zone decentered from 0.5 to 0.9 mm. Analysis of geometric mean visual acuities between eyes with less than 0.5 mm decentration and those with 0.5 to 0.9 mm decentration demonstrated minimal differences. No eye was decentered more than 1 mm. Four main ablation patterns were noted on subtraction analysis: homogeneous, semicircular, keyhole, and central island. Over time, the number of eyes with a homogeneous pattern increased. Eyes with a homogeneous ablation pattern had significantly better uncorrected visual acuity than those with other patterns. The mean visual acuity was 20/29.1 in the homogeneous group and 20/38.5 in the pooled irregular group 1 month postoperatively (p < 0.05). There was no significant difference among the four ablation patterns at 6 or 12 months after PRK. Topographic patterns were not significantly associated with best-corrected vision.

Cornea↗

Increased expression of galanin in the rat superior cervical ganglion after pre- and postganglionic nerve lesions.

Using immunohistochemistry the expression of galanin (GAL) and galanin message-associated peptide (GMAP) in the superior cervical ganglion (SCG) was investigated 2, 4, 7, and 14 days after unilateral transection of the cervical sympathetic trunk (decentralization) or after cutting the external and internal carotid nerves (axotomy), as well as 7 days after removal of parotid gland tissue. In control SCGs including the sympathetic trunk and the carotid nerves, very few neurons and fibers were GAL/GMAP-positive. Two and 7 days after decentralization, about 5% of all counted neuron profiles in the ipsilateral SCG were GAL/GMAP immunoreactive. Immunoreactive cell bodies were distributed throughout the SCG, with a greater number in the most caudal portion of the ganglion. Many GAL/GMAP-positive nerve fibers were observed in the whole SCG, with strongly fluorescent bundles of immunoreactive fibers accumulated at the caudal end of the SCG. Several GAL/GMAP-immunoreactive nerve fibers were seen ipsilaterally in the external carotid nerve, whereas only a few positive fibers could be observed in the internal carotid nerve. About 2% of all counted neuron profiles in SCGs ipsilateral to decentralization still contained GAL/GMAP-immunoreactivity 14 days after the operation. The number of GAL/GMAP-positive cell bodies was at least doubled in the contralateral SCGs after decentralization compared to controls. After axotomy, about 50% of all counted neuron profiles were GAL/GMAP-positive in the ipsilateral SCG and distributed throughout the SCG. A strong accumulation of immunoreactive nerve fibers was observed in both the internal and external carotid nerves. The number of GAL/GMAP-positive cell bodies was slightly increased in the contralateral SCGs. After unilateral removal of parotid gland tissue, many GAL/GMAP-positive cell bodies and some fibers were observed in the caudal half of the ipsilateral SCG. The number of immunoreactive nerve fibers was increased also in the external carotid nerve, but not in the internal carotid nerve. In situ hybridization revealed prepro GAL mRNA in about 5% of all SCG neuron profiles in decentralized SCGs, paralleling the increase seen in GAL/GMAP peptide content. There was also a small increase in prepro VIP mRNA-positive cells in the caudal part of the SCG. The present results indicate that both pre- and postganglionic lesions increase the content of GAL/GMAP in the SCG, with a much more pronounced increase after transection of the carotid nerves.

Animals↗

Reinnervation of Müller's smooth muscle by atypical sympathetic pathways following neonatal ganglionectomy in the rat: structural and functional investigations of enhanced neuroplasticity.

Müller's extraocular smooth muscle is reinnervated by sympathetic nerves following denervation by ipsilateral superior cervical ganglionectomy in neonates but not in older animals. Experiments were performed to determine: (1) the source and extent of reinnervation, (2) the role of impulse activity in sympathetic outgrowth and (3) the effects of reinnervation on smooth muscle maturation. Müller's muscles were evaluated structurally (muscle volume, catecholamine histochemistry, retrograde labeling of sympathetic neurons) and functionally (contractile responses to electrical stimulation of postganglionic innervation and adrenoceptor agonist) in control preparations and in muscles following neonatal ipsilateral superior ganglionectomy, ipsilateral decentralization, ipsilateral superior ganglionectomy combined with contralateral decentralization of chemical (guanethidine) sympathectomy. Fluorescent tracer injections of muscles in adult control rats labeled cells in the ipsilateral superior (98%) and middle cervical ganglia. Acute ipsilateral superior ganglionectomy produced complete degeneration of sympathetic innervation of Müller's muscle in neonatal and adult rats. In preparations denervated neonatally and maintained chronically, muscles were reinnervated by neurons in both the contralateral superior and ipsilateral middle cervical ganglia. The total number of neurons reinnervating the muscle was one half that of controls. Sectional density of innervation was 45% of control. Electrical stimulation of postganglionic axons in the contralateral pathway produced muscle contractions with a prolonged time course. Reinnervation alleviated, in part, deficits in muscle volume and contraction which occurred following sustained denervation by chemical sympathectomy. Decentralization decreased ipsilateral muscle volume but did not affect numbers of neurons projecting to or nerve density within the muscle. Stimulation frequencies required to produce a 50% maximum contraction were reduced in these preparations. Decentralization of the contralateral ganglion did not impede sprouting into the denervated muscle, as nerve density and number of labeled cells were comparable to muscles reinnervated by contralateral ganglia with intact preganglionic innervation. However, maximum contraction to electrical stimulation was reduced. Comparisons with ipsilaterally decentralized muscles revealed that increased stimulation frequencies were required for 50% maximum contraction.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic Fibers↗

Postdecentralization plasticity of voltage-gated Na+ currents in rat glandular sympathetic neurons.

The kinetic properties of voltage-gated Na(+) currents in two groups of glandular postganglionic sympathetic neurons were assessed. The first group of neurons remained innervated by preganglionic axons until the day of current recordings, while the second--decentralized 4 weeks prior to recordings. An increase of maximum current amplitude and density was noted in decentralized neurons. Na(+) currents activated and time-dependently inactivated more slowly in decentralized than in control neurons. Furthermore, after decentralization the currents steady-state inactivated at less hyperpolarized potentials as well as reactivated faster from inactivation. We conclude that the Na(+) currents in decentralized postganglionic glandular sympathetic neurons undergo up-regulation.

Amidines↗

Comparison of early performance indicators for screening projects within the European Breast Cancer Network: 1989-2000.

In 1989 the European Breast Cancer Network (EBCN) was established by the first pilot projects for breast cancer screening, co-funded by the Europe Against Cancer programme. We report early performance indicators for these EBCN projects while taking into account their organizational setting. Out of 17 projects in the network, 10 projects from six European countries contributed aggregated data on number of invitations, screening examinations, and breast cancers detected over the period 1989-2000. Results were summarized separately for projects in centralized versus decentralized health care environments. The European Guidelines for quality assurance in mammography screening provided reference values for the performance indicators. The most prominent finding in this study was the higher participation rate in centralized versus decentralized projects (average participation in 1998: 74 versus 33%; P<0.001), whereas the invitation system and screening policy in these projects were similar. Detection rates and characteristics of cancers detected at initial and subsequent screening examinations showed no significant differences between centralized and decentralized projects. Even though early performance indicators for centralized versus decentralized projects were similar, the impact of breast screening on mortality from this disease at the population level will differ since the decentralized projects reach only part of the target population.

Adult↗

Centration and fixation of posterior chamber intraocular lenses in eyes with pseudoexfoliation syndrome. An analysis of explanted autopsy eyes.

Pseudoexfoliation syndrome is an important risk factor in cataract surgery. We examined decentration of posterior chamber intraocular lenses in a series of 24 autopsy eyes with pseudoexfoliation syndrome that had undergone cataract surgery and intraocular lens implantation. The results were compared to a control group of 25 normal autopsy eyes that matched the pseudoexfoliation collection for age distribution, implant duration and further anatomical parameters. The mean lens decentration in all pseudoexfoliation eyes (0.75 +/- 0.38 mm) was significantly higher than in the control group (0.40 +/- 0.29 mm) (p = 0.0008). Analysis of subgroups with symmetrical bag/bag fixated intraocular lenses showed a significantly higher decentration in the pseudoexfoliation group (p = 0.04). The main reason for decentration was a decentration of the entire capsular bag in pseudoexfoliative eyes (p = 0.001), which was related to zonular weakness and damage. The results indicate that in patients with pseudoexfoliation syndrome alternative fixation sites, like sulcus or transscleral fixation, should also be considered.

Aged↗

Preponderance for either alpha- or beta-adrenoceptor mediated sensitization in the rat submaxillary gland.

The sensitivity of the rat submaxillary gland was examined 3-4 weeks after either parasympathetic decentralization or sympathetic decentralization or denervation. The threshold doses for secretion of saliva of parasympathomimetic (methacholine) and sympathomimetic (noradrenaline, adrenaline, phenylephrine and isoprenaline) drugs were estimated and the amount of saliva secreted in response to supraliminal doses of these drugs was measured. Each type of operation caused the development of a supersensitivity that involved all three types of receptors, i.e. muscarinic cholinoceptors, alpha-adrenoceptors and beta-adrenoceptors. Following parasympathetic decentralization the sensitization was predominantly mediated via alpha-adrenoceptors, and also via cholinoceptors. Following sympathetic decentralization or denervation the postjunctional sensitization was predominantly mediated via beta-adrenoceptors; most of the supersensitivity to noradrenaline, adrenaline and phenylephrine found after sympathetic denervation was of the prejunctional type. An increase in receptor density and an intracellular arrangement where the response of cholinoceptors and alpha-adrenoceptors is mediated via one pathway and the response of beta-adrenoceptors via another are suggested as factors that may be of importance for the development of the postjunctional supersensitivity. The present study shows that the traffic of secretory impulses in the sympathetic nerve is of importance for the level of sensitivity of the secretory cells. Since postjunctional supersensitivity following sympathetic denervation did not exceed that following sympathetic decentralization it is suggested that under normal conditions a continuous release of noradrenaline from the nerve endings is of little importance for the level of sensitivity.

Animals↗