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Head-fixation of mice enables high-resolution monitoring of neuronal activity coupled with precise control of environmental stimuli. Virtual reality can be used to emulate the visual experience of movement during head fixation, but a low inertia floating real-world environment (mobile homecage, MHC) has the potential to engage more sensory modalities and provide a richer experimental environment for complex behavioral tasks. However, it is not known whether mice react to this adapted environment in a similar manner to real environments, or whether the MHC can be used to implement validated, maze-based behavioral tasks. Here, we show that hippocampal place cell representations are intact in the MHC and that the system allows relatively long (20 min) whole-cell patch clamp recordings from dorsal CA1 pyramidal neurons, revealing sub-threshold membrane potential dynamics. Furthermore, mice learn the location of a liquid reward within an adapted T-maze guided by 2-dimensional spatial navigation cues and relearn the location when spatial contingencies are reversed. Bilateral infusions of scopolamine show that this learning is hippocampus-dependent and requires intact cholinergic signalling. Therefore, we characterize the MHC system as an experimental tool to study sub-threshold membrane potential dynamics that underpin complex navigation behaviors., (© 2024. The Author(s).)

Background: At-risk alcohol use is associated with increased adverse health consequences, yet is undertreated in healthcare settings. People residing in rural areas need improved access to services; however, few interventions are designed to meet the needs of rural populations. Mobile interventions can provide feasible, low-cost, and scalable means for reaching this population and improving health, and behavioral economic approaches are promising., Methods: We conducted a pilot randomized controlled trial focused on acceptability and feasibility of a mobile behavioral economic intervention for 75 rural-residing adults with at-risk alcohol use. We recruited participants from a large healthcare system and randomized them to one of four virtually-delivered conditions reflecting behavioral economic approaches: episodic future thinking (EFT), volitional choice (VC), both EFT and VC, or enhanced usual care control (EUC). The intervention included a telephone-delivered induction session followed by two weeks of condition-consistent ecological momentary interventions (EMIs; 2x/day) and ecological momentary assessments (EMAs; 1x/day). Participants completed assessments at baseline, post-intervention, and two-month follow-up, and provided intervention feedback., Results: All participants completed the telephone-delivered session and elected to receive EMI messages. Average completion rate of EMAs across conditions was 92.9%. Among participants in active intervention conditions, 89.3% reported the induction session was helpful and 80.0% reported it influenced their future drinking. We also report initial alcohol use outcomes., Discussion: The behavioral economic intervention components and trial procedures evaluated here appear to be feasible and acceptable. Next steps include determination of their efficacy to reduce alcohol use and public health harms., Competing Interests: The authors of this paper have no conflicts of interest to declare., (© 2024 The Author(s).)

Understanding cortical function requires studying multiple scales: molecular, cellular, circuit, and behavioral. We develop a multiscale, biophysically detailed model of mouse primary motor cortex (M1) with over 10,000 neurons and 30 million synapses. Neuron types, densities, spatial distributions, morphologies, biophysics, connectivity, and dendritic synapse locations are constrained by experimental data. The model includes long-range inputs from seven thalamic and cortical regions and noradrenergic inputs. Connectivity depends on cell class and cortical depth at sublaminar resolution. The model accurately predicts in vivo layer- and cell-type-specific responses (firing rates and LFP) associated with behavioral states (quiet wakefulness and movement) and experimental manipulations (noradrenaline receptor blockade and thalamus inactivation). We generate mechanistic hypotheses underlying the observed activity and analyzed low-dimensional population latent dynamics. This quantitative theoretical framework can be used to integrate and interpret M1 experimental data and sheds light on the cell-type-specific multiscale dynamics associated with several experimental conditions and behaviors., Competing Interests: Declaration of interests The authors declare no competing interests., (Crown Copyright © 2023. Published by Elsevier Inc. All rights reserved.)

Background: In vivo patch-clamp recording techniques provide access to the sub- and suprathreshold membrane potential dynamics of individual neurons during behavior. However, maintaining recording stability throughout behavior is a significant challenge, and while methods for head restraint are commonly used to enhance stability, behaviorally related brain movement relative to the skull can severely impact the success rate and duration of whole-cell patch-clamp recordings., New Method: We developed a low-cost, biocompatible, and 3D-printable cranial implant capable of locally stabilizing brain movement, while permitting equivalent access to the brain when compared to a conventional craniotomy., Results: Experiments in head-restrained behaving mice demonstrate that the cranial implant can reliably reduce the amplitude and speed of brain displacements, significantly improving the success rate of recordings across repeated bouts of motor behavior., Comparison With Existing Method(s): Our solution offers an improvement on currently available strategies for brain stabilization. Due to its small size, the implant can be retrofitted to most in vivo electrophysiology recording setups, providing a low cost, easily implementable solution for increasing intracellular recording stability in vivo., Conclusions: By facilitating stable whole-cell patch-clamp recordings in vivo, biocompatible 3D printed implants should accelerate the investigation of single neuron computations underlying behavior., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Touchscreen-based behavioral assays provide a robust method for assessing cognitive behavior in rodents, offering great flexibility and translational potential. The development of touchscreen assays presents a significant programming and mechanical engineering challenge, where commercial solutions can be prohibitively expensive and open-source solutions are underdeveloped, with limited adaptability., New Method: Here, we present Visiomode (www.visiomode.org), an open-source platform for building rodent touchscreen-based behavioral tasks. Visiomode leverages the inherent flexibility of touchscreens to offer a simple yet adaptable software and hardware platform. The platform is built on the Raspberry Pi computer combining a web-based interface and powerful plug-in system with an operant chamber that can be adapted to generate a wide range of behavioral tasks., Results: As a proof of concept, we use Visiomode to build both simple stimulus-response and more complex visual discrimination tasks, showing that mice display rapid sensorimotor learning including switching between different motor responses (i.e., nose poke versus reaching)., Comparison With Existing Methods: Commercial solutions are the 'go to' for rodent touchscreen behaviors, but the associated costs can be prohibitive, limiting their uptake by the wider neuroscience community. While several open-source solutions have been developed, efforts so far have focused on reducing the cost, rather than promoting ease of use and adaptability. Visiomode addresses these unmet needs providing a low-cost, extensible platform for creating touchscreen tasks., Conclusions: Developing an open-source, rapidly scalable and low-cost platform for building touchscreen-based behavioral assays should increase uptake across the science community and accelerate the investigation of cognition, decision-making and sensorimotor behaviors both in health and disease., Competing Interests: Declaration of Competing Interest The authors declare no declarations of competing interest., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Motor cortex generates descending output necessary for executing a wide range of limb movements. Although movement-related activity has been described throughout motor cortex, the spatiotemporal organization of movement-specific signaling in deep layers remains largely unknown. Here we record layer 5B population dynamics in the caudal forelimb area of motor cortex while mice perform a forelimb push/pull task and find that most neurons show movement-invariant responses, with a minority displaying movement specificity. Using cell-type-specific imaging, we identify that invariant responses dominate pyramidal tract (PT) neuron activity, with a small subpopulation representing movement type, whereas a larger proportion of intratelencephalic (IT) neurons display movement-type-specific signaling. The proportion of IT neurons decoding movement-type peaks prior to movement initiation, whereas for PT neurons, this occurs during movement execution. Our data suggest that layer 5B population dynamics largely reflect movement-invariant signaling, with information related to movement-type being routed through relatively small, distributed subpopulations of projection neurons., Competing Interests: Declaration of interest The authors declare no competing interests., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Motivational incentive interventions are highly effective for smoking cessation. Yet, these interventions are not widely available to people who want to quit smoking, in part, due to barriers such as administrative burden, concern about the use of extrinsic reinforcement (i.e., incentives) to improve cessation outcomes, suboptimal intervention engagement, individual burden, and up-front costs., Purpose: Technological advancements can mitigate some of these barriers. For example, mobile abstinence monitoring and digital, automated incentive delivery have the potential to lower the clinic burden associated with monitoring abstinence and administering incentives while also reducing the frequency of clinic visits. However, to fully realize the potential of digital technologies to deliver motivational incentives it is critical to develop strategies to mitigate longstanding concerns that reliance on extrinsic monetary reinforcement may hamper internal motivation for cessation, improve individual engagement with the intervention, and address scalability limitations due to the up-front cost of monetary incentives. Herein, we describe the state of digitally-delivered motivational incentives. We then build on existing principles for creating just-in-time adaptive interventions to highlight new directions in leveraging digital technology to improve the effectiveness and scalability of motivational incentive interventions., Conclusions: Technological advancement in abstinence monitoring coupled with digital delivery of reinforcers has made the use of motivational incentives for smoking cessation increasingly feasible. We propose future directions for a new era of motivational incentive interventions that leverage technology to integrate monetary and non-monetary incentives in a way that addresses the changing needs of individuals as they unfold in real-time., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Coughlin, Bonar, Walton, Fernandez, Duguid and Nahum-Shani.)

Executing learned motor behaviors often requires the transformation of sensory cues into patterns of motor commands that generate appropriately timed actions. The cerebellum and thalamus are two key areas involved in shaping cortical output and movement, but the contribution of a cerebellar-thalamocortical pathway to voluntary movement initiation remains poorly understood. Here, we investigated how an auditory "go cue" transforms thalamocortical activity patterns and how these changes relate to movement initiation. Population responses in dentate/interpositus-recipient regions of motor thalamus reflect a time-locked increase in activity immediately prior to movement initiation that is temporally uncoupled from the go cue, indicative of a fixed-latency feedforward motor timing signal. Blocking cerebellar or motor thalamic output suppresses movement initiation, while stimulation triggers movements in a behavioral context-dependent manner. Our findings show how cerebellar output, via the thalamus, shapes cortical activity patterns necessary for learned context-dependent movement initiation., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Cerebellar climbing-fiber-mediated complex spikes originate from neurons in the inferior olive (IO), are critical for motor coordination, and are central to theories of cerebellar learning. Hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels expressed by IO neurons have been considered as pacemaker currents important for oscillatory and resonant dynamics. Here, we demonstrate that in vitro, network actions of HCN1 channels enable bidirectional glutamatergic synaptic responses, while local actions of HCN1 channels determine the timing and waveform of synaptically driven action potentials. These roles are distinct from, and may complement, proposed pacemaker functions of HCN channels. We find that in behaving animals HCN1 channels reduce variability in the timing of cerebellar complex spikes, which serve as a readout of IO spiking. Our results suggest that spatially distributed actions of HCN1 channels enable the IO to implement network-wide rules for synaptic integration that modulate the timing of cerebellar climbing fiber signals., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

From patch-clamp techniques to recombinant DNA technologies, three-dimensional protein modeling, and optogenetics, diverse and sophisticated methods have been used to study ion channels and how they determine the electrical properties of cells., (© 2017 Cold Spring Harbor Laboratory Press.)

Knowledge of synaptic input is crucial for understanding synaptic integration and ultimately neural function. However, in vivo, the rates at which synaptic inputs arrive are high, so that it is typically impossible to detect single events. We show here that it is nevertheless possible to extract the properties of the events and, in particular, to extract the event rate, the synaptic time constants, and the properties of the event size distribution from in vivo voltage-clamp recordings. Applied to cerebellar interneurons, our method reveals that the synaptic input rate increases from 600 Hz during rest to 1000 Hz during locomotion, while the amplitude and shape of the synaptic events are unaffected by this state change. This method thus complements existing methods to measure neural function in vivo.

Feedforward excitatory and inhibitory circuits regulate cerebellar output, but how these circuits interact to shape the somatodendritic excitability of Purkinje cells during motor behaviour remains unresolved. Here we perform dendritic and somatic patch-clamp recordings in vivo combined with optogenetic silencing of interneurons to investigate how dendritic excitation and inhibition generates bidirectional (that is, increased or decreased) Purkinje cell output during self-paced locomotion. We find that granule cells generate a sustained depolarization of Purkinje cell dendrites during movement, which is counterbalanced by variable levels of feedforward inhibition from local interneurons. Subtle differences in the dendritic excitation-inhibition balance generate robust, bidirectional changes in simple spike (SSp) output. Disrupting this balance by selectively silencing molecular layer interneurons results in unidirectional firing rate changes, increased SSp regularity and disrupted locomotor behaviour. Our findings provide a mechanistic understanding of how feedforward excitatory and inhibitory circuits shape Purkinje cell output during motor behaviour.

Classical feed-forward inhibition involves an excitation-inhibition sequence that enhances the temporal precision of neuronal responses by narrowing the window for synaptic integration. In the input layer of the cerebellum, feed-forward inhibition is thought to preserve the temporal fidelity of granule cell spikes during mossy fiber stimulation. Although this classical feed-forward inhibitory circuit has been demonstrated in vitro, the extent to which inhibition shapes granule cell sensory responses in vivo remains unresolved. Here we combined whole-cell patch-clamp recordings in vivo and dynamic clamp recordings in vitro to directly assess the impact of Golgi cell inhibition on sensory information transmission in the granule cell layer of the cerebellum. We show that the majority of granule cells in Crus II of the cerebrocerebellum receive sensory-evoked phasic and spillover inhibition prior to mossy fiber excitation. This preceding inhibition reduces granule cell excitability and sensory-evoked spike precision, but enhances sensory response reproducibility across the granule cell population. Our findings suggest that neighboring granule cells and Golgi cells can receive segregated and functionally distinct mossy fiber inputs, enabling Golgi cells to regulate the size and reproducibility of sensory responses.

Inhibitory synaptic plasticity is important for shaping both neuronal excitability and network activity. Here we investigate the input and GABA(A) receptor subunit specificity of inhibitory synaptic plasticity by studying cerebellar interneuron-Purkinje cell (PC) synapses. Depolarizing PCs initiated a long-lasting increase in GABA-mediated synaptic currents. By stimulating individual interneurons, this plasticity was observed at somatodendritic basket cell synapses, but not at distal dendritic stellate cell synapses. Basket cell synapses predominantly express β2-subunit-containing GABA(A) receptors; deletion of the β2-subunit ablates this plasticity, demonstrating its reliance on GABA(A) receptor subunit composition. The increase in synaptic currents is dependent upon an increase in newly synthesized cell surface synaptic GABA(A) receptors and is abolished by preventing CaMKII phosphorylation of GABA(A) receptors. Our results reveal a novel GABA(A) receptor subunit- and input-specific form of inhibitory synaptic plasticity that regulates the temporal firing pattern of the principal output cells of the cerebellum.

The cerebellum plays a crucial role in the regulation of locomotion, but how movement is represented at the synaptic level is not known. Here, we use in vivo patch-clamp recordings to show that locomotion can be directly read out from mossy fiber synaptic input and spike output in single granule cells. The increase in granule cell spiking during locomotion is enhanced by glutamate spillover currents recruited during movement. Surprisingly, the entire step sequence can be predicted from input EPSCs and output spikes of a single granule cell, suggesting that a robust gait code is present already at the cerebellar input layer and transmitted via the granule cell pathway to downstream Purkinje cells. Thus, synaptic input delivers remarkably rich information to single neurons during locomotion.

Neuronal activity in primary motor cortex (M1) correlates with behavioral state, but the cellular mechanisms underpinning behavioral state-dependent modulation of M1 output remain largely unresolved. Here, we performed in vivo patch-clamp recordings from layer 5B (L5B) pyramidal neurons in awake mice during quiet wakefulness and self-paced, voluntary movement. We show that L5B output neurons display bidirectional (i.e., enhanced or suppressed) firing rate changes during movement, mediated via two opposing subthreshold mechanisms: (1) a global decrease in membrane potential variability that reduced L5B firing rates (L5Bsuppressed neurons), and (2) a coincident noradrenaline-mediated increase in excitatory drive to a subpopulation of L5B neurons (L5Benhanced neurons) that elevated firing rates. Blocking noradrenergic receptors in forelimb M1 abolished the bidirectional modulation of M1 output during movement and selectively impaired contralateral forelimb motor coordination. Together, our results provide a mechanism for how noradrenergic neuromodulation and network-driven input changes bidirectionally modulate M1 output during motor behavior., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)

Tonic inhibition is a key regulator of neuronal excitability and network function in the brain, but its role in sensory information processing remains poorly understood. The cerebellum is a favorable model system for addressing this question as granule cells, which form the input layer of the cerebellar cortex, permit high-resolution patch-clamp recordings in vivo, and are the only neurons in the cerebellar cortex that express the α6δ-containing GABA(A) receptors mediating tonic inhibition. We investigated how tonic inhibition regulates sensory information transmission in the rat cerebellum by using a combination of intracellular recordings from granule cells and molecular layer interneurons in vivo, selective pharmacology, and in vitro dynamic clamp experiments. We show that blocking tonic inhibition significantly increases the spontaneous firing rate of granule cells while only moderately increasing sensory-evoked spike output. In contrast, enhancing tonic inhibition reduces the spike probability in response to sensory stimulation with minimal effect on the spontaneous spike rate. Both manipulations result in a reduction in the signal-to-noise ratio of sensory transmission in granule cells and of parallel fiber synaptic input to downstream molecular layer interneurons. These results suggest that under basal conditions the level of tonic inhibition in vivo enhances the fidelity of sensory information transmission through the input layer of the cerebellar cortex.

Patients with complex needs are commonly admitted on the acute medical take and comprise a significant proportion of the workload for an acute physician. An innovative multi-professional approach to the assessment of this group of patients has been developed in Edinburgh; this paper summarises the results of a 4 week review of data collected on patients assessed by the multiprofessional team on the Medical Assessment Unit at Edinburgh Royal Infirmary.

Understanding the transmission of sensory information at individual synaptic connections requires knowledge of the properties of presynaptic terminals and their patterns of firing evoked by sensory stimuli. Such information has been difficult to obtain because of the small size and inaccessibility of nerve terminals in the central nervous system. Here we show, by making direct patch-clamp recordings in vivo from cerebellar mossy fibre boutons-the primary source of synaptic input to the cerebellar cortex-that sensory stimulation can produce bursts of spikes in single boutons at very high instantaneous firing frequencies (more than 700 Hz). We show that the mossy fibre-granule cell synapse exhibits high-fidelity transmission at these frequencies, indicating that the rapid burst of excitatory postsynaptic currents underlying the sensory-evoked response of granule cells can be driven by such a presynaptic spike burst. We also demonstrate that a single mossy fibre can trigger action potential bursts in granule cells in vitro when driven with in vivo firing patterns. These findings suggest that the relay from mossy fibre to granule cell can act in a 'detonator' fashion, such that a single presynaptic afferent may be sufficient to transmit the sensory message. This endows the cerebellar mossy fibre system with remarkable sensitivity and high fidelity in the transmission of sensory information.

Long-term plasticity typically relies on postsynaptic NMDA receptors to detect the coincidence of pre- and postsynaptic activity. Recent studies, however, have revealed forms of plasticity that depend on coincidence detection by presynaptic NMDA receptors. In the amygdala, cortical afferent associative presynaptic long-term potentiation (LTP) requires activation of presynaptic NMDA receptors by simultaneous thalamic and cortical afferents. Surprisingly, both types of afferent can also undergo postsynaptically induced NMDA-receptor-dependent LTP. In the neocortex, spike-timing-dependent long-term depression (LTD) requires simultaneous activation of presynaptic NMDA autoreceptors and retrograde signalling by endocannabinoids. In cerebellar LTD, presynaptic NMDA receptor activation suggests that similar presynaptic mechanisms may exist. Recent studies also indicate the existence of presynaptic coincidence detection that is independent of NMDA receptors, suggesting that such mechanisms have a widespread role in plasticity.

Purpose: To evaluate the outcome of orbital floor injection of betamethasone and methylprednisolone in the management of uveitis, with particular reference to its efficacy in avoiding increase in systemic immunosuppressive drugs., Methods: A sample of all patients attending the Uveitis Service at Moorfields Eye Hospital was carried out over a three-month period. All patients who had received one or more orbital floor injections of betamethasone (4 mg) and methylprednisolone (Depo-Medrone; 40 mg) in the management of their uveitis were identified and the case notes reviewed., Results: A total of 48 patients who had received 75 orbital floor injections were identified during the sample period. Most patients had either panuveitis (n = 24) or pars planitis (n = 14). One-month post-injection visual acuity (VA) had improved by at least one Snellen line after 33/75 injections (44%) and at least two lines after 11/75 (15%), was unchanged after 25 (33%), but had deteriorated in 14 (19%). VA was not recorded after 3/75 injections. The only complications recorded were periorbital haemorrhage (n = 1) and complaints of persistent pain after an injection (n = 1). Symptoms (pain and subjective vision) improved after 36/75 injections (47%), were unchanged after 24 (32%), and were reported as worse after five (7%). Additionally, three patients reported an improvement in symptoms which lasted less than one month. Signs other than VA were improved after 28/75 (37%), were unchanged after 38 (51%), and deteriorated after only one injection. Of the 31 patients given orbital floor injections to avoid systemic therapy, seven (23%) subsequently went on to require it, and the clinical course then improved in 45%., Conclusions: Combined orbital floor injection of betamethasone and methylprednisolone can result in improved visual acuity, symptoms, and signs of inflammation in uveitis, and may therefore avoid the necessity for increased systemic medication.

Purpose: Choroidal neovascularisation (CNV) occurs rarely following laser photocoagulation for macular oedema in diabetic retinopathy, and its management is not well established. We report the clinical course and visual outcomes in a series of patients who underwent surgical extraction of the CNV membrane., Methods: A retrospective review of 4 cases was carried out., Results: Two women and 2 men, mean age 59.5 (range 58-62) years, were reviewed. The CNV developed 2-24 (mean 11) months after laser coagulation and resulted in decreased visual acuity to between 6/60 and HM. All underwent pars plana vitrectomy, extraction of the CNV membrane and fluid-air exchange. Follow-up ranged between 9 and 48 months. In 2 patients, the vision improved by 4 and 1 Snellen lines respectively and remained stable, in 1 patient it improved by 1 line initially but then regressed to CF, and in 1 patient it remained unchanged. Recurrence of CNV occurred in only 1 patient. Histological characteristics were those of CNV without evidence of photoreceptors., Conclusions: This study shows that surgical removal of post-laser CNV is technically feasible despite the previous laser scars and may have beneficial outcome. This surgical approach may provide a therapeutic option in such patients.

A 29 year old myopic man sustained two separate giant retinal tears in his right eye following deliberate eye gouging during a rugby tackle. These were successfully repaired by vitrectomy and intraocular silicone oil injection. Although the postoperative course was complicated by pupil block glaucoma, he regained corrected visual acuity of 6/5 after oil removal. This injury highlights the potentially sight threatening nature of this type of rugby injury and the importance of early referral for specialist treatment.

Objective: This study investigates the clinical outcome of Acanthamoeba keratitis treated with polyhexamethyl biguanide (PHMB) and propamidine isethionate (Brolene)., Design: A retrospective review of all patients treated for Acanthamoeba keratitis between September 1992 and February 1995 was carried out. All patients were treated with PHMB 0.02% and propamidine 0.1% hourly for 3 days, the frequency reduced to four to six times daily according to clinical response., Main Outcome Measures: Age, gender, result of laboratory investigation, duration of disease before diagnosis, visual acuity (VA) pretreatment and post-treatment, need for keratoplasty, and presence of adverse reaction were measured., Results: One hundred eleven cases were identified in 105 patients (60 male, 45 female; mean age, 32). Ninety-two percent of infections were in contact lens wearers. The clinical diagnosis was confirmed by corneal culture or histopathology in 64 cases (57.7%). The diagnosis was made "early" (within 28 days) in 65 cases (58.6%). Twenty-one (18.9%) were "intermediate" (28 days-2 months) and 20 (18%) were "late" (> 2 months) diagnoses. Overall post-treatment VA was 6/12 or better in the majority (88/111, 79.3%) of cases, and 18 (16.2%) had VA of 6/36 or worse. The VA of > or = 6/12 was achieved by 90.8% of the early, 71.4% of the intermediate, and 65% of the late groups. Clinical relapses occurred in 19 patients on reducing the therapy. Treatment toxicity was never serious and consisted only of stinging or superficial punctate keratopathy. Keratoplasty was indicated in only ten patients, and disease activity was controlled adequately in all patients before grafting., Conclusions: Combined treatment with PHMB and propamidine is well tolerated, nontoxic, and effective. Typically, visual outcome is favorable and the requirement for keratoplasty reduced markedly.

Aim: To determine the clinical intervention rate during routine review after uncomplicated phacoemulsification., Methods: A review of case notes in 651 consecutive cases of uncomplicated phacoemulsification from 1994 (< or = 5.5 mm self sealing wound) was performed. The intervention rate at scheduled routine review visits and at unscheduled visits to the eye casualty service in the first 120 postoperative days was recorded. Interventions were defined as departures from predetermined postoperative care protocols., Results: Clinical interventions were reported in 2.8% (95% confidence interval 1.5 to 4.1%) of (n = 1652) routine follow up visits. Many of these interventions were avoidable or trivial; 90% of patients had no postoperative intervention at any visit. 7.3% of patients made unscheduled visits to the emergency service. The intervention rate in this group was 50% (35.9 to 64.1%)., Conclusions: The intervention rate in routine clinical review after uncomplicated modern cataract surgery is low. Alternatives to conventional postoperative review, including shared care with non-ophthalmologists and improved perioperative patient education with an open channel for self referral, should be evaluated.

Although phacoemulsification with only topical anaesthesia is possible, the level of any discomfort perceived by the patient is unknown. Topical anaesthesia eliminates any risk of inadvertent ocular or orbital injury. Twenty-four patients undergoing phacoemulsification under only topical anaesthesia (g. amethocaine 1%) were compared with 23 patients undergoing the same procedure with peribulbar anaesthesia (5 ml lignocaine 2%, 5 ml bupivacaine 0.5% and 75 units hyaluronidase). Perceived pain on administration of the anaesthesia, per-operatively and post-operatively was assessed by a nursing officer using a visual analogue scale (0-10). It was found that there was no difference in pain score between the two groups on induction of anaesthesia. Per-operatively and post-operatively scores were higher in the topical group than in the peribulbar group (p < 0.05, Mann-Whitney U-test), though most of these were within the range 0-3, ('no pain' to 'slight pain'). There was no difference in the amount of analgesia dispensed to the two groups on the ward post-operatively. In conclusion, topical anaesthesia provides adequate anaesthesia for phacoemulsification. Although a small increase in the level of discomfort was observed, the pain levels reported were small and may not be clinically significant when set against the reduced incidence of anaesthetic-related complications.

Data on the prevalence and causes of blindness and visual impairment in Polynesians are not readily available nor are they population based. This survey was designed to obtain an accurate estimate of blindness and its causes in Tonga. A sample of 4056 persons, aged 20 years and over, was selected by stratified cluster sampling. Participants received a screening, visual acuity examination, and, if visually impaired, were referred for detailed ophthalmic examination to determine the cause. The prevalence of bilateral blindness in the study population was 0.47% and all affected were aged over 50 years. It is estimated that the national prevalence of bilateral blindness, adjusted for the sample weight applied in the selection procedure, is 0.56% (95% confidence interval 0-1.13). Monocular blindness was three times more frequent. Cataract was responsible for 68.4% of bilateral and 30.3% of monocular blindness. Risk factors for life time experience of cataract included age and diabetes (self-reported). Neither smoking nor the presence of pterygium were independently associated with cataract. Increasing years of education were protective against cataract for women, but not men. Corneal opacity from infection or trauma, and diabetes were responsible for most of the remaining visual impairment. While these results do not represent a significant public health problem by world standards they do provide a basis for planning blindness prevention programmes in the region.

Cell culture methods that allow culture of Staphylococcus epidermidis biofilms at controlled growth rates were used to examine susceptibility to ciprofloxacin. Changes in biofilm susceptibility, dependent upon growth rate, were compared with those for suspended populations grown in chemostat, and also for newly-formed daughter cells shed from the biofilm during its growth and development. Susceptibility increased for intact and resuspended biofilms, and also for planktonic cultures, with increases in growth rate. The dependence of susceptibility upon growth rate was greatest for slow growing cells (mu, 0.01-0.15/h). At any particular growth rate, biofilms appeared more susceptible than their planktonic counterparts. Newly-formed daughter cells were relatively tolerant to ciprofloxacin at all rates of growth. Lack of growth rate dependency for the newly-formed cells suggested a role for the cell-division cycle in determining resistance. This was confirmed by examining the susceptibility of S. epidermidis throughout batch cultures with cell division synchronized. Perfusion of various steady-state biofilms with ciprofloxacin demonstrated killing of the adherent population even at much reduced rates of growth.

Biofilms of Staphylococcus epidermidis were cultured at various specific growth rates, and susceptibilities to tobramycin were compared with those of equivalent plank-tonic populations. In all instances, susceptibility increased significantly with increasing specific growth rate. However, resuspension of the biofilms increased susceptibility, suggesting some involvement of the glycocalyx in reducing antibiotic permeation of the biofilm. Cells that dispersed spontaneously from the biofilms at steady state were particularly susceptible to this agent. Since such cells correspond to newly-divided daughter cells, the relationship between tobramycin susceptibility and the phase in the division cycle was investigated. Susceptibility was enhanced in cultures dividing synchronously shortly before, during and shortly after cell separation. Perfusion of actively-growing S. epidermidis biofilms with tobramycin also demonstrated increased susceptibility with increasing growth rate, but also showed rapid recovery following removal of the agent.

Immunoperoxidase staining of samples of normal human retina and choroid was performed to demonstrate selected adhesion molecules in vivo. Intercellular adhesion molecule-1 (ICAM-1), lymphocyte function-associated antigen-3 (LFA-3) and endothelial leucocyte adhesion molecule-1 (ELAM-1) were expressed on retinal vascular endothelium and ICAM-1 and ELAM-1 in the region of the external limiting membrane. The very late antigen-2 (VLA-2) was found around the retinal ganglion cells and in the inner and outer fibre layers. The endothelium on the choriocapillaris showed moderate staining of ICAM-1, and slight staining of LFA-3 and ELAM-1. The presence of these molecules in this distribution strongly suggests they have an important role in the pathogenesis of immunologically mediated ocular conditions.

This study examines the expression of some selected adhesion molecules likely to be important in the migration of leucocytes across the blood-retinal and blood-aqueous barriers in samples of normal human retina and choroid by immunoperoxidase staining. ICAM-1, LFA-3 and ELAM-1 were expressed on retinal endothelium and ICAM-1, ELAM-1 and CD44 in the region of the external limiting membrane. VLA-2 was found around the retinal ganglion cells and in the inner and outer fibre layers and is likely to be important in maintaining the structural integrity of the retina. The endothelium on the choriocapillaris showed moderate staining of ICAM-1, and slight staining of LFA-3 and ELAM-1. These molecules may have an important functional role in the pathogenesis of many immunological ocular conditions, including uveoretinitis and corneal allograft rejection.

Surface hydrophobicity, surface electrokinetic potential and the ability to adhere to nitric-acid cleansed glass surfaces has been assessed throughout the growth, in batch culture, of Escherichia coli and Staphylococcus epidermidis. In both instances adhesiveness and surface hydrophobicity decreased in early- to mid-exponential phase. Cell surface charge, on the other hand became more electro-negative for E. coli but electro-neutral for Staph. epidermidis as the cells proceeded to divide. Adhesiveness correlated directly with surface electronegativity and hydrophobicity for Staph. epidermidis but inversely with surface electro-negativity for E. coli.

Diabetes mellitus was induced in rats by the administration of streptozotocin and observations have been made over a period of 2 months in 3 groups of animals: controls, untreated diabetics and diabetics treated with continuous subcutaneous insulin infusion (CSII) therapy, using a 14-day Alzet osmotic minipump. Optimal control of day-to-day and 24-h blood glucose levels was achieved in diabetic animals treated with CSII. Body weight and skeletal growth, assessed by measurements of tibial length, were decreased in untreated diabetic rats and were normalized by insulin treatment. The concentrations of glucose, sorbitol and fructose in the nerves of diabetic animals were significantly increased and that of myoinositol significantly decreased; CSII therapy normalized these levels to those of age-matched controls. External myelinated fibre diameter in the tibial nerve was significantly less in untreated diabetic rats as compared with age-matched controls. In the insulin-treated group, fibre diameter significantly increased as compared with untreated diabetics and there was no significant difference between insulin-treated and control animals. Teased fibre preparations from the tibial nerve revealed very few abnormal fibres in all the three groups and no significant difference was detected between any of the groups. Continuous subcutaneous insulin infusion therapy, therefore, corrected biochemical abnormalities and also normalized myelinated fibre diameter in the peripheral nerves of experimental diabetic animals. The paradoxical excess of axonal degeneration that has been reported with conventional insulin treatment was not observed.

Diabetes mellitus was produced in rats by the administration of streptozotocin and observations made over a period of 2 months. Four groups of animals were studied: onset and end controls, untreated diabetic rats and rats treated daily with a long-acting insulin preparation. Body weight increased in the end controls and insulin-treated diabetic animals to a similar degree over the observation period but was reduced in the untreated diabetic rats. Skeletal growth, assessed by measurements of tibial length, was also reduced in the untreated diabetic rats and partially corrected by insulin treatment. Myelinated fibre diameter in the tibial and sural nerves increased over the observation period in the controls, but the increase was less in the untreated animals and the growth deficit was not corrected by insulin treatment. Myelinated fibre numbers did not alter in the tibial or sural nerves between the onset and end controls. Numbers were significantly less in the tibial nerves of both the untreated and insulin-treated diabetic rats as compared with the two control groups; in the sural nerves, fibre numbers did not differ significantly between the four groups. Finally, the number of degenerating axons, assessed in teased fibre preparations, was very small in the control and untreated diabetic animals but was significantly increased in the insulin-treated group. Measurements of plasma glucose concentrations did not suggest that the axonal degeneration could be related to hypoglycaemia. The explanation for this paradoxical effect of insulin therapy is uncertain. It may be dependent upon fluctuations in blood glucose levels or other metabolic actions of insulin apart from its hypoglycaemic effect.

Four groups of male Sprague-Dawley rats aged 11 weeks and weighing approximately 450 g were studied over 16 weeks: onset and end controls, untreated diabetics and diabetics treated with a daily subcutaneous injection of Ultralente insulin. Good metabolic control was achieved in the insulin-treated group as judged by daily blood glucose estimations, glycosylated haemoglobin levels (HbA1c) and body weight. Cross-sectional myelinated fibre area significantly increased between onset and end controls; growth thus occurred. In the untreated diabetic rats the values were significantly less when compared with age matched controls and not different to onset controls. The values for the insulin-treated diabetic group did not show a significant increase when compared with untreated diabetics and onset controls and were intermediate between end controls and untreated diabetics without any significant difference when compared with either group. Cross-sectional axonal area was significantly less in the untreated diabetic group as compared with age matched controls and this was corrected by insulin therapy, as there was no difference between end controls and insulin-treated diabetic group. Insulin treatment corrects the reduction in axon size but total myelinated fibre size is not normalised. It seems that in addition to the axon, the myelin sheath and Schwann cells are also affected and these may be less influenced by insulin therapy.

Diabetes mellitus was induced in rats by streptozotocin. This gave rise to a loss of somatomedin activity in serum. The loss of somatomedin activity was due to the presence of inhibitors associated with serum proteins having mol wts of less than 1, 1-10, 30-50, and 300 K. Whereas less than 1, 1-10, and 30-50 kilodalton fractions were not inhibitory in control and insulin-treated animals, greater than 300 kilodalton fraction was inhibitory in control and insulin-treated animals; the inhibitory activity of this fraction in diabetic animals was significantly greater than that in controls and insulin-treated animals. The appearance of these inhibitors in diabetic animals was accompanied by reduced skeletal growth. Treatment of diabetic animals with insulin abolished the somatomedin-inhibitory activity of serum and corrected the skeletal growth deficit. Serum inhibitors of somatomedin may, therefore, be involved in the causation of some of the complications of diabetes, including impaired skeletal growth.

Trauma to the face may result in fracture of the maxillary floor and the passage of some of the ocular contents into the maxillary antrum. In some cases, the impaction of the extrinsic ocular musculature results in an annoying diplopia. In others, the maxillary fracture may involve not only the orbital floor, but also extend into the anterior maxilla with additional facial deformities. Surgical corrections of some of these fractures have utilized bone grafts from the anterior iliac crest to the orbital floor. In others, flat Teflon plates have been inserted along the line of the orbital floor fracture after any impacted orbital contents have been freed from the fracture. Both of these remedies suffer from disadvantages. The authors have utilized specially prepared and shaped plastic plates which have been inserted along both the bony orbital floor and the anterior maxilla. These reduce the possibility of displacement and extrusion of the implanted plastic prosthesis. Particularly in major osseous deformities, the functional and cosmetic results have been most gratifying. This technique may also be modified in patients who have coincidentally suffered the additional loss of the eyeball as a result of the injury and include an orbital implant.