The aim of this study is to investigate in the rat the properties of the pattern electroretinogram (ERG) and to assess whether it depends upon the functional integrity of ganglion cells. Flash and pattern ERG were recorded from urethane anaesthetized hooded rats. The pattern ERG was evoked by phase alternating gratings of various spatial frequencies and contrasts. In the first part of the study we determined how the amplitude of the main harmonic of the pattern ERG (2nd harmonic) varies as a function of stimulus parameters such as spatial and temporal frequency, contrast and mean luminance. In the second part of the study we investigated the effects of the retrograde degeneration of ganglion cells following optic nerve section on the amplitude of pattern ERG. We found that the section of the optic nerve leads to the progressive disappearance of the P-ERG which is almost complete 4 months after surgery. By this time only few axotomized ganglion cells are left. The flash ERG remained unaffected. Thus, the pattern electroretinogram seems to be a simple and sensitive tool to investigate the functional integrity of retinal ganglion cells in rats.

This study was undertaken to investigate the role of afferent spontaneous electrical activity in regulating death of target cells in the developing mammalian visual system. We show here that naturally occurring cell death in the rat superior colliculus is greatly augmented when the spontaneous firing of retinal ganglion cells is transiently blocked with TTX. An increased number of dying cells is already observed after 1 hr of afferent blockade. A 50% increase of cell death is reached after 3 hr of blockade, an effect that closely parallels increased cell death caused by eye enucleation after similar intervals of time. These results suggest that, during development, input cells exert a trophic action on target cells, which is prevented by silencing input electrical activity. A likely explanation of this effect is that the spontaneous firing of input cells causes the release by afferent fibers of a trophic agent promoting the survival of target cells.

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A lesion to the optic nerve of adult mammals leads to the retrograde degeneration and finally to the death of injured retinal ganglion cells. In this study, we have evaluated the effects induced by different sites of axotomy on the functional changes occurring in the retinal ganglion cells after optic nerve section. We have investigated the functional properties of retinal ganglion cells of adult rats by recording the retinal responses to patterned stimuli (pattern electroretinogram) after unilateral section of the optic nerve at two different levels: intraorbital and intracranial. The results show that the site of lesion of the optic nerve affects the time of disappearance of the pattern electroretinogram. The pattern electroretinogram takes longer to be degraded after an intracranial section than an intraorbital section.

Objectives To evaluate the accuracy of a new COVID‐19 prognostic score based on lung ultrasound (LUS) and previously validated variables in predicting critical illness. Methods We conducted a single‐center retrospective cohort development and internal validation study of the COVID‐19 Worsening Score (COWS), based on a combination of the previously validated COVID‐GRAM score (GRAM) variables and LUS. Adult COVID‐19 patients admitted to the emergency department (ED) were enrolled. Ten variables previously identified by GRAM, days from symptom onset, LUS findings, and peripheral oxygen saturation/fraction of inspired oxygen (P/F) ratio were analyzed. LUS score as a single predictor was assessed. We evaluated GRAM model's performance, the impact of adding LUS, and then developed a new model based on the most predictive variables. Results Among 274 COVID‐19 patients enrolled, 174 developed critical illness. The GRAM score identified 51 patients at high risk of developing critical illness and 132 at low risk. LUS score over 15 (range 0 to 36) was associated with a higher risk ratio of critical illness (RR, 2.05; 95% confidence interval [CI], 1.52‐2.77; area under the curve [AUC], 0.63; 95% CI 0.676‐0.634). The newly developed COVID‐19 Worsening Score relies on five variables to classify high‐ and low‐risk patients with an overall accuracy of 80% and negative predictive value of 93% (95% CI, 87%‐98%). Patients scoring more than 0.183 on COWS showed a RR of developing critical illness of 8.07 (95% CI, 4.97‐11.1). Conclusions COWS accurately identify patients who are unlikely to need intensive care unit (ICU) admission, preserving resources for the remaining high‐risk patients.

Background— The value of performing transthoracic echocardiography (TTE) as part of the clinical assessment of patients awaiting endovascular repair of the abdominal aorta is little evaluated. We aimed to estimate the prognostic importance of information derived from TTE on long-term all-cause mortality in a selected group of patients undergoing endovascular aneurysm repair. Methods and Results— This was a retrospective cohort study of 273 consecutive patients selected for endovascular aneurysm repair. All patients included in the analysis underwent TTE before their procedure. Multivariable Cox regression analysis was used to estimate the effect of TTE measures on all-cause mortality. Over a mean follow-up of 3.2±1.5 years, there were 78 deaths with a mean time to death of 1.28±1.16 years. A greater tubular ascending aorta (hazard ratio [HR] 5.6, 95% confidence interval [CI] 2.77–11.33), presence of mitral regurgitation (HR 8.13, 95% CI 4.09–12.16), lower left ventricular ejection fraction (HR 0.96, 95% CI 0.93–0.98), younger age (HR 0.97, 95% CI 0.95–0.99), and presence of diabetes mellitus (HR 1.46, 95% CI 1.24–1.89) were predictors of all-cause mortality. Conclusions— Echocardiography provides important long-term prognostic information in patients undergoing endovascular aneurysm repair. These TTE indices were more important at predicting outcome than standard conventional risk factors in this patient group. A greater tubular ascending aorta, presence of mitral regurgitation, reduced left ventricular ejection fraction, younger age, and diabetes mellitus were independently associated with long-term mortality.

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We have investigated the effectiveness of embryonal tectal tissue transplants in preserving the physiological activity of lesioned ganglion cells by recording the visual responses from the adult rat retina after section of the optic nerve, with or without transplants of embryonal nervous tissue on the stump. We have found that transplant of embryonal nervous tissue at the level of the optic nerve section has dramatic effects in preserving visual retinal responses to patterned stimuli for times as long as five months after surgery. By this time retinal responses to patterned stimuli have almost completely disappeared in control animals with optic nerve section alone.