Effect of ocular magnification on macular measurements made using spectral domain optical coherence tomography

Aim:

The aim of the present study was to study the effect of ocular magnification on macular measurements made using spectral domain optical coherence tomography (OCT).

Materials and Methods:

One hundred and fifty-one subjects were included from the normative study of foveal morphology carried out at our hospital. Subjects underwent comprehensive eye examination and macular scanning using Cirrus high-definition OCT and axial length (AXL) measurement. Macular cube 512 × 128 scan protocol was used for scanning the macula. Automated measurements of the fovea namely foveal diameter, foveal slope (lateral measurements) and foveal depth (axial measurement) were taken. A correction factor for ocular magnification was done using the formula t = p × q × s, where “t” is the corrected measurement, “p” is the magnification of OCT, “q” is the ocular magnification, and “s” is the measurement on OCT without correction. The difference between corrected and uncorrected measurements was evaluated for statistical significance.

Results:

Mean AXL was 22.95 ± 0.78 mm. Refractive error ranged from −3D to +4D. Mean difference between measured and corrected foveal diameter, slope and depth was 166.05 ± 95.37 µm (P < 0.001), 0.81° ± 0.53° (P < 0.001) and 0.05 ± 0.49 µm (P = 0.178) respectively. AXL lesser than the OCT calibrated value of 24.46 mm showed an increased foveal diameter (r = 0.961, P < 0.001) and a reduced foveal slope (r = −0.863, P < 0.001) than the corrected value.

Conclusion:

Lateral measurements made on OCT varied with AXL s other than the OCT calibrated value of 24.46 mm. Therefore, to estimate the actual dimensions of a retinal lesion using OCT, especially lateral dimensions, we recommend correction for the ocular magnification factor.     

Pathophysiology,Diagnosis, and Management of Coronary No-Reflow Phenomenon

Coronary no-reflow phenomenon is a lethal mechanism of ongoing myocardial injury, following successful revascularization of an infarct-related coronary artery. Incidence of this phenomenon is high following percutaneous intervention, and is associated with adverse in-hospital and long-term outcomes. Several mechanisms such as ischemia-reperfusion injury and distal microthromboembolism in genetically susceptible patients and those with preexisting endothelial dysfunction have been implicated. However, the exact mechanism in humans is still poorly understood. Several investigative and treatment strategies within and outside the cardiac catheterization laboratory have been proposed, but have not uniformly shown success in reducing mortality or in preventing adverse left ventricular remodeling resulting from this condition. The aim of this article is to provide a brief and concise review of the current understanding of the pathophysiology, clinical predictors, and investigations and management of coronary no-reflow phenomenon.     

Differential effect of corticosterone deficiency on the expression of LH, prolactin and insulin receptors on rat Leydig cells

The adverse effects of glucocorticoid deficiency on the expression of genes encoding Leydig cell surface receptors and the response to LH/prolactin/insulin to produce testosterone production are yet to be recognized. Following metyrapone-induced corticosterone deficiency, serum corticosterone, testosterone and insulin levels decrease, whereas serum prolactin exhibits a significant increase and serum LH remains unaltered. LH binding and LH receptor mRNA expression were not altered, but a significant decrease in PRL and insulin binding and in the mRNA expressions of their receptors were observed in corticosterone-deficient rats in vivo. Corticosterone deficiency significantly decreases the Leydig cellular basal as well as hormone-stimulated testosterone production in vitro. Simultaneous administration of corticosterone prevented its deficiency-induced changes in Leydig cells both in vivo and in vitro. Our results show that metyrapone-induced corticosterone deficiency impairs Leydig cell insulin and prolactin receptors, and their mRNA expression and the response of Leydig cells to LH/PRL/insulin on testosterone production.     

Crystal structures of the copper and nickel complexes of RNase A: Metal-induced interprotein interactions and identification of a novel copper binding motif

We report the crystal structures of the copper and nickel complexes of RNase A. The overall topology of these two complexes is similar to that of other RNase A structures. However, there are significant differences in the mode of binding of copper and nickel. There are two copper ions per molecule of the protein, but there is only one nickel ion per molecule of the protein. Significant changes occur in the interprotein interactions as a result of differences in the coordinating groups at the common binding site around His-105. Consequently, the copper- and nickel-ion-bound dimers of RNase A act as nucleation sites for generating different crystal lattices for the two complexes. A second copper ion is present at an active site residue His-119 for which all the ligands are from one molecule of the protein. At this second site, His-119 adopts an inactive conformation (B) induced by the copper. We have identified a novel copper binding motif involving the α-amino group and the N-terminal residues.     

Embracing Technology for Capacity Building in Mental Health: New Path,Newer Challenges

Psychiatric Quarterly - Technology driven capacity building initiatives are the way to break the barrier of shortage of mental health human resources in India. This new path, while is a welcome...     

Effect of ventilator mode on sleep quality in critically ill patients

To determine whether sleep quality is influenced by the mode of mechanical ventilation, we performed polysomnography on 11 critically ill patients. Because pressure support predisposes to central apneas in healthy subjects, we examined whether the presence of a backup rate on assist-control ventilation would decrease apnea-related arousals and improve sleep quality. Sleep fragmentation, measured as the number of arousals and awakenings, was greater during pressure support than during assist-control ventilation: 79 +/- 7 versus 54 +/- 7 events per hour (p = 0.02). Central apneas occurred during pressure support in six patients; heart failure was more common in these six patients than in the five patients without apneas: 83 versus 20% (p = 0.04). Among patients with central apneas, adding dead space decreased sleep fragmentation: 44 +/- 6 versus 83 +/- 12 arousals and awakenings per hour (p = 0.02). Changes in sleep-wakefulness state caused greater changes in breath components and end-tidal CO2 during pressure support than during assist-control ventilation. In conclusion, inspiratory assistance from pressure support causes hypocapnia, which combined with the lack of a backup rate and wakefulness drive can lead to central apneas and sleep fragmentation, especially in patients with heart failure.     

Predictors of non-compliance in autologous hematopoietic SCT patients undergoing out-patient transplants

Non-compliance has received significant attention in medicine, yet few studies have examined its correlates in autologous hematopoietic SCT (AHSCT) patients. This study examined predictors of non-compliance in a sample of 151 AHSCT patients treated in an outpatient setting. Before AHSCT, participants completed a validated measure of mood and retrospective chart reviews were conducted to assess non-compliance during AHSCT, defined as refusal of oral hygiene, prescribed exercise programs, oral nutrition and/or prescribed medications. We found 121 patients (80%) were non-compliant with an aspect of the AHSCT regimen on 1 or more days; mean percentage of non-compliant days was 16.6 (s.d. 15.6). Men were more likely than women to be non-compliant (P<0.05); as were participants with an elevated depression score (P<0.05). Stepwise regression models identified significant predictors of non-compliance: gender, depression, global distress and nausea and vomiting severity (P-values all <0.01). Further analysis revealed that the interaction of the psychological variables with gender was a more robust predictor of non-compliance (P<0.001). For outpatient AHSCT, our findings suggest the need to broaden conceptualizations of risk factors for non-compliance and the importance of assessing patient barriers to compliance to ensure optimal treatment outcome.