Comparison of droplet spread in standard and laminar flow operating theatres: SPRAY study group.

BACKGROUND: Reducing COVID-19 transmission relies on controlling droplet and aerosol spread. Fluorescein staining reveals microscopic droplets. AIM: To compare the droplet spread in non-laminar and laminar air flow operating theatres. METHODS: A 'cough-generator' was fixed to a theatre trolley at 45°. Fluorescein-stained 'secretions' were projected on to a series of calibrated targets. These were photographed under UV light and 'source detection' software measured droplet splatter size and distance. FINDINGS: The smallest droplet detected was ∼120 µm and the largest ∼24,000 µm. An average of 25,862 spots was detected in the non-laminar theatre, compared with 11,430 in the laminar theatre (56% reduction). The laminar air flow mainly affected the smaller droplets (<1000 µm). The surface area covered with droplets was: 6% at 50 cm, 1% at 2 m, and 0.5% at 3 m in the non-laminar air flow; and 3%, 0.5%, and 0.2% in the laminar air flow, respectively. CONCLUSION: Accurate mapping of droplet spread in clinical environments is possible using fluorescein staining and image analysis. The laminar air flow affected the smaller droplets but had limited effect on larger droplets in our 'aerosol-generating procedure' cough model. Our results indicate that the laminar air flow theatre requires similar post-surgery cleaning to the non-laminar, and staff should consider full personal protective equipment for medium- and high-risk patients.

The infralimbic cortex and mGlu5 mediate the effects of chronic intermittent ethanol exposure on fear learning and memory.

RATIONALE AND OBJECTIVES: Alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD) often occur comorbidly. While the incidence of these disorders is increasing, there is little investigation into the interacting neural mechanisms between these disorders. These studies aim to identify cognitive deficits that occur as a consequence of fear and ethanol exposure, implement a novel pharmaceutical intervention, and determine relevant underlying neurocircuitry. Additionally, due to clinical sex differences in PTSD prevalence and alcohol abuse, these studies examine the nature of this relationship in rodent models. METHODS: Animals were exposed to a model of PTSD+AUD using auditory fear conditioning followed by chronic intermittent ethanol exposure (CIE). Then, rats received extinction training consisting of multiple conditioned stimulus presentations in absence of the shock. Extinction recall and context-induced freezing were measured in subsequent tests. CDPPB, a metabotropic glutamate receptor 5 (mGlu5) positive allosteric modulator, was used to treat these deficits, and region-specific effects were determined using microinjections. RESULTS: These studies determined that CIE exposure led to deficits in fear extinction learning and heightened context-induced freezing while sex differences emerged in fear conditioning and extinction cue recall tests. Furthermore, using CDPPB, these studies found that enhancement of infralimbic (IfL) mGlu5 activity was able to recover CIE-induced deficits in both males and females. CONCLUSIONS: These studies show that CIE induces deficits in fear-related behaviors and that enhancement of IfL glutamatergic activity can facilitate learning during extinction. Additionally, we identify novel pharmacological targets for the treatment of individuals who suffer from PTSD and AUD.

Remote CB1 receptor antagonist administration reveals multiple sites of tonic and phasic endocannabinoid neuroendocrine regulation.

Endogenous cannabinoids (endocannabinoids, eCB) are expressed throughout the body and contribute to regulation of the hypothalamo-pituitary-adrenal (HPA) axis and general stress reactivity. This study assessed the contributions of CB1 receptors (CB1R) in the modulation of basal and stress-induced neural and HPA axis activities. Catheterized adult male rats were placed in chambers to acclimate overnight, with their catheters connected and exteriorized from the chambers for relatively stress-free remote injections. The next morning, the CB1R antagonist AM251 (1 or 2 mg/kg) or vehicle was administered, and 30 min later, rats were exposed to loud noise stress (30 min) or no noise (basal condition). Blood, brains, pituitary and adrenal glands were collected immediately after the procedures for analysis of c-fos and CB1R mRNAs, corticosterone (CORT) and adrenocorticotropin hormone (ACTH) plasma levels. Basally, CB1R antagonism induced c-fos mRNA in the basolateral amygdala (BLA) and auditory cortex (AUD) and elevated plasma CORT, indicating disruption of eCB-mediated constitutive inhibition of activity. CB1R blockade also potentiated stress-induced hormone levels and c-fos mRNA in several regions such as the bed nucleus of the stria terminalis (BST), lateral septum (LS), and basolateral amygdala (BLA) and the paraventricular nucleus of the hypothalamus (PVN). CB1R mRNA was detected in all central tissues investigated, and the adrenal cortex, but at very low levels in the anterior pituitary gland. Interestingly, CB1R mRNA was rapidly and bidirectionally regulated in response to stress and/or antagonist treatment in some regions. eCBs therefore modulate the HPA axis by regulating both constitutive and activity-dependent inhibition at multiple levels.

Is day-1 postoperative review necessary after pars plana vitrectomy?

PURPOSE: This study aimed to determine the proportion of patients requiring alteration in management based on the findings of the day-1 postoperative visit after pars plana vitrectomy, and to identify clinical characteristics that predict the need for unexpected intervention. PATIENTS AND METHODS: A retrospective case note review was conducted of all patients who underwent pars plana vitrectomy and who then attended for review on the first postoperative day. All patients received routine prophylactic anti-glaucoma medication. RESULTS: Two hundred and seventy-three patients examined on day 1 following vitrectomy were studied. Indications for surgery included retinal detachment, epiretinal membrane, macular hole, vitreous haemorrhage, diabetic eye disease, and floaters. Twenty-gauge (20G) vitrectomy was performed in 124 eyes (45%); 23-gauge (23G) vitrectomy was performed in 149 eyes (55%). Phacoemulsification was performed concurrently in 51/273 (19%) eyes. Ten patients (3.7%) required unexpected intervention on day 1 owing to intraocular pressure (IOP) >30 (2/273), IOP <6 (5/273), or unexpected return to theatre for anterior chamber washout (3/273). There was no difference in intervention rate or day-1 IOP between 20G and 23G cases. Hypotony was less common if gas tamponade was used (χ(2)-test, P<0.001). Patients undergoing combined phacoemulsification and 20G vitrectomy were significantly more likely to require intervention on day 1 than patients undergoing 20G vitrectomy alone (15.0 vs 1.9%, P=0.029, Fisher's exact test) but this was not the case for patients undergoing 23G vitrectomy (0 vs 4.2%, Fisher's exact test, P=0.58). CONCLUSIONS: The intervention rate on the first day after vitrectomy is low and day-1 postoperative review can be safely omitted in the majority of patients undergoing vitrectomy.

The incidence and distribution of iatrogenic retinal tears in 20-gauge and 23-gauge vitrectomy.

PURPOSE: The development of 23-gauge vitrectomy surgery has many benefits including a reduction in surgical time and faster postoperative rehabilitation; however, some have suggested that the complication rate is higher. To assess this we compared the incidence and distribution of iatrogenic retinal tears in 20- and 23-gauge surgery. METHODS: Fifty consecutive 23-gauge and 50 consecutive 20-gauge vitrectomy cases were selected; eyes with a history of previous vitreoretinal surgery were excluded. All surgery was performed by two surgeons (JL and RN). Entry-site breaks (ESB) were defined as any new vitreoretinal abnormality occurring within 1 clock hour of an entry site for which treatment with cryotherapy was deemed necessary. Data were collected by retrospective case note review. Statistical analysis was carried out using Fisher's exact and χ(2)-tests. RESULTS: ESB occurred in 24% (12/50) of cases in the 20-gauge group compared with 8% (4/50) in the 23-gauge group (P = 0.03); 88% (14/16) occurred superiorly on the same side as the surgeons' dominant hand. Iatrogenic breaks recorded elsewhere indicated an increased incidence in the 20-gauge group (9/50 compared with 6/50 in 23-gauge) but this did not achieve significance; the most common position was at 6 o'clock. CONCLUSIONS: 23-Gauge vitrectomy is associated with significantly fewer ESB when compared with conventional 20-gauge vitrectomy. The incidence of other iatrogenic breaks did not appear to be significantly different between the two groups.

Cannabinoid receptor type 1 antagonism significantly modulates basal and loud noise induced neural and hypothalamic-pituitary-adrenal axis responses in male Sprague-Dawley rats.

Altered regulation of the hypothalamic-pituitary-adrenal (HPA) axis is associated with stress-induced changes in cognitive, emotional, and physical health. Recent evidence indicates that the endogenous cannabinoid (eCB) system may modulate HPA-axis function both directly and more centrally, via regulation of limbic brain systems that control HPA-axis activity. The current study examines the contribution of cannabinoid type 1 (CB1) receptor modulation throughout the neuraxis on control and stress-induced HPA-axis activity. Adult male Sprague-Dawley rats were given intraperitoneal injections of either CB1 receptor antagonist (AM251, 2 mg/kg) or vehicle 30 min prior to a session of loud white noise stress (95 dBA for 30 min) or placement in a familiar sound-proof chamber. Immediately following stress and control treatments, rats were killed, the brains and pituitary glands were excised for subsequent immediate early gene (c-fos mRNA) measurement, and trunk blood was collected for subsequent determination of corticosterone (CORT) and adrenocorticotropic (ACTH) hormone levels. AM251 treatment resulted in a potentiated plasma ACTH response to loud noise stress. AM251 treatment also increased stress-induced plasma CORT levels, but that increase may be due to an increase in basal plasma CORT levels, as was evident in control rats. AM251 treatment produced three distinctive c-fos mRNA response patterns across the various brain regions examined. In cortical (prelimbic, infralimbic, somatosensory, and auditory) and some subcortical structures (basolateral amygdala and paraventricular nucleus of the hypothalamus), AM251 treatment produced a substantial increase in c-fos mRNA that was comparable with the elevated c-fos mRNA levels present in those brain regions of both vehicle and AM251-treated stressed rats. In some other subcortical structures (bed nucleus of the stria terminalis and medial preoptic area) and the anterior pituitary, AM251 treatment produced a c-fos mRNA response pattern that was similar to the response pattern of ACTH hormone levels, that is, no effect on no noise control levels, but an augmentation of stress-induced levels. Conversely, in the medial geniculate and ventral posterior thalamus, AM251 treatment inhibited stress-induced c-fos mRNA induction. These data indicate that disruption of eCB signaling through CB1 receptors results in potentiated neural and endocrine responses to loud noise stress, but also substantial increases in activity in various brain regions and the adrenal gland.

Use of Optomap for retinal screening within an eye casualty setting.

AIM: To compare nurse-guided Optomap retinal imaging with examination by an eye casualty officer, in detecting clinically significant peripheral retinal lesions in patients with retinal symptoms. METHODS: 219 patients presenting to eye casualty with retinal symptoms (flashing lights and floaters) were recruited. Retinal images were taken with the Optomap imaging system, and graded by an independent masked ophthalmologist. The findings from the Optomap and casualty officer were compared with a gold-standard examination with scleral indentation performed by a retinal specialist. We calculated the sensitivity and specificity of the Optomap and casualty officer. RESULTS: The final analysis included 205 eyes of 187 patients. The sensitivity of the Optomap for detecting retinal detachment (n = 7) was 100% (95% CI 59-100%), the same as the casualty officer. For retinal holes/tears (n = 18) the Optomap sensitivity was 33% (13-59%), compared with 67% (41-87%) for the casualty officer. Combining all retinal lesions (n = 52), the sensitivity was 62% (47-75%) and 73% (59-84%), with specificity 96% (92-99%) and 98% (94-100%) for the Optomap and casualty officer respectively. CONCLUSION: The Optomap detects retinal detachments successfully but, due to limitations in the optics, is not able to accurately detect retinal holes and tears.

Perinatal delta-9-tetrahydrocannabinol exposure disrupts social and open field behavior in adult male rats.

Marijuana is the most frequently used illegal drug among women of reproductive age, but little is known about the consequences of using marijuana during pregnancy. Delta-9-tetrahydrocannabinol (Delta9-THC), one of the active chemicals in marijuana, has been shown to cross the placental barrier easily. In this study, pregnant Long Evans rats were assigned to one of three treatment groups (Delta9-THC-exposed, vehicle control, and non-treated control) on day 1 of gestation. Drug exposure consisted of 2 mg/kg of natural Delta9-THC, administered twice daily by subcutaneous (s.c.) injection, from gestational day 1 through 22. Pups continued to receive drug exposure via s.c. injection from postnatal day 2 through 10. Male rats from each group were tested starting on postnatal day 90 in a battery of tests which included open field activity, active social interaction, and the forced swim test. There were no significant differences in weight gained by dams or weight of offspring when compared to controls. Delta9-THC-exposed rats showed decreased time in the inner part of the open field and an increase in investigation time in the test of social interaction compared to both control groups. There were no differences among groups in the forced swim test. Perinatal Delta9-THC exposure may result in increased susceptibility to anxious behavior and alter social functioning in adult offspring.

An analysis of the CFH Y402H genotype in AMD patients and controls from the UK, and response to PDT treatment.

AIM: Mutation in the complement factor H (CFH) gene is an important risk factor for age-related macular degeneration (AMD). In this study, we identified the strength of the CFH Y402H gene variant association in a UK AMD cohort and tested the hypothesis that this variant may influence the biological response of choroidal neovascularisation (CNV) following photodynamic therapy (PDT) for CNV. METHODS: A total of 557 cases with AMD and 551 normal controls were genotyped for the CFH Y402H (1277 C/T) variant using the 5' nuclease TaqMan assay for allelic discrimination. The CFH gene association for AMD, for the different CNV subtypes and for patients needing PDT was estimated. Twenty-seven PDT-treated patients were followed up for 15 months with ETDRS-derived vision, clinical examination, and fundus angiography. Individuals with different CFH genotypes were then analysed for any association with visual change following PDT. RESULTS: The risk association for AMD with the CFH CC genotype (odd ratio (OR)=3.62, Pc<0.0001) was similar to that reported in other Caucasian cohorts. The magnitude and strength of this association was stronger in AREDS stages 2-4 (ORs=4.48, 2.69, and 5.17). ORs for the risk of predominantly classic CNV were significantly raised for both the CC (OR=17.87, P<0.0001) and CT (OR=9.06, P=0.0002) genotypes. The number of patients carrying the high-risk C allele was 70.4% in those requiring PDT as compared to 52.3% in the non-PDT group (OR=2.16, P=0.011), and presence of the CC genotype significantly increased the risk of PDT (OR=5.48, P=0.015). The degree of visual loss following PDT was significantly higher in the CFH CC genotype group (P=0.038); 50% of CC cases (n=13) and 45% of the CT cases (n=12) lost 15 or more ETDRS letters at final follow-up. CONCLUSION: In this UK cohort of AMD patients, the CFH Y402H variant was significantly enriched in patients with predominantly classic CNV. Patients homozygous for the CFH Y402H genotype seem to have worse visual acuity after PDT.

Lentivirus-mediated downregulation of hypothalamic insulin receptor expression.

Regulation of feeding behavior and energy balance are among the central effects of insulin. For example, intracerebroventricular administration of insulin decreases food intake and body weight, whereas antisense oligodeoxynucleotide downregulation of insulin receptors (IRs) produces hyperphagia. To further examine the role of IRs in the central actions of insulin, we designed an IR antisense lentiviral vector (LV-IRAS) and injected this vector into the third ventricle to selectively decrease IR expression in the rat hypothalamus. Three weeks after LV-IRAS administration, the expression of IRs in the hypothalamus was significantly decreased, whereas no changes were observed in hippocampal IR levels. LV-IRAS administration decreased insulin-stimulated phosphorylation of hypothalamic IRs and translocation of the insulin-sensitive glucose transporter GLUT4 in the hypothalamus; no changes in IR signaling were observed in the hippocampus of LV-IRAS-treated rats. Lentivirus-mediated downregulation of IR expression and signaling produced significant increases in body weight, as well as increases in fat mass that were selective for the subcutaneous compartment. Conversely, lean muscle mass and water mass were not affected in LV-IRAS-treated rats compared to rats treated with control virus. Changes in peripheral adiposity were associated with increases in basal hypothalamic leptin signaling in the absence of changes in leptin receptor expression in LV-IRAS rats. Collectively, these data illustrate the important functional relationships between hypothalamic insulin and leptin signaling in the regulation of body composition and provide insight into the mechanisms through which decreases in IR expression and signaling dysregulates leptin activity, thereby promoting increases in peripheral adiposity.

Ocular morbidity associated with intravitreal triamcinolone acetonide.

AIM: To report on the complications associated with the use of intravitreal triamcinolone acetonide (IVTA) in a tertiary referral hospital setting. MATERIALS AND METHODS: A retrospective case series review of all IVTA injections carried out over a period of 30 months. RESULTS: One hundred and thirty IVTA injections were performed; nine with limited local follow-up were excluded. Thus, 121 injections (108 patients, 114 eyes) were included in the study. Triamcinolone (4 mg) was used in all cases. Indications were diabetic macular oedema (n=41 eyes), retinal vein occlusions (n=27), postoperative cystoid macular oedema (n=24), exudative age-related macular degeneration (n=16), and others (n=6). No intraoperative complications were recorded. Postoperative intraocular pressure (IOP) readings of 22, 28, 35, and 40 mmHg or higher were recorded in 46.5, 29.8, 12.3, and 7.9% of eyes, respectively. IOP elevation was treated with antiglaucoma medication in all but one eye (0.9%) that required trabeculectomy and one (0.9%) that required vitrectomy with cataract extraction for suspected phacoanaphylactic glaucoma. Two eyes (1.8%) developed retinal detachment; both had previously been treated for retinal breaks. One eye (0.9%) developed culture-positive endophthalmitis. CONCLUSIONS: Significant morbidity is associated with IVTA injection; clinicians should be aware when considering treatment options.

UK retinopathy of prematurity treatment survey.

BACKGROUND: Since the CRYO-ROP study showed the benefit of treating babies with ROP, a number of different treatment modalities have become available. Solid-state lasers have been extensively used in the treatment of ROP since their introduction some 10 years ago. Diode, argon and frequency-doubled YAG (FD-YAG) lasers have all been used to perform photocoagulation in ROP. We aimed to assess current treatment practices of ROP treatment in the UK. METHODS: A questionnaire survey was performed in June 2004 and sent to all consultants known to be involved in the treatment or screening of ROP patients. We asked about the number of patients treated in the last year, the treatment method, and whether there had been any serious complications. RESULTS: In all, 53 questionnaires were sent out, of which 42 were returned. Also, 30 respondents treated ROP. Of these 19 used transpupillary diode, 11 argon, and three FD-YAG. Cryotherapy and transscleral diode laser were used by two centres in particular cases. In all, 20 patients were treated with FD-YAG, 21 with argon laser, and 188 with diode laser. The number of burns per eye varied from 800 to 2500. Reported complications included hyphaema, retinal haemorrhage, and acute cataract formation; however, there was no significant difference in complications between different types of laser used. DISCUSSION: This survey of laser use in the treatment of ROP has shown that diode laser is now the most common mode of treatment in the UK. The incidence of complications was similar for centres using argon, diode, or FD-YAG laser.

Treatment of retinal breaks with large-spot diode laser photocoagulation.

A new technique is described for treating peripheral retinal breaks using large-spot, diode laser retinopexy. A large-spot (1.2 to 3.0 mm) diode laser (810 nm) was used to treat patients with breaks in attached retina. Powers between 800 and 1,200 mW produced a uniform retinal photocoagulation beyond the break margins. Patients were observed monthly until an adequate chorioretinal scar had formed. Eleven eyes were treated using this technique. Satisfactory retinopexy was obtained in all cases. The efficiency of large-spot diode laser photocoagulation for retinal breaks and its advantages over conventional laser and cryopexy techniques justifies further studies into this technique.