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Epiretinal prostheses are being developed to bypass a degenerated photoreceptor layer and excite surviving ganglion and inner retinal cells. We used custom microfabricated multielectrode arrays with 200-[micro]m-diameter stimulating electrodes and 10-[micro]m-diameter recording electrodes to stimulate and record neural responses in isolated tiger salamander retina. Pharmacological agents were used to isolate direct excitation of ganglion cells from excitation of other inner retinal cells. Strength-duration data suggest that, if amplitude will be used for the coding of brightness or gray level in retinal prostheses, shorter pulses (200 [micro]s) will allow for a smaller region in the area of the electrode to be excited over a larger dynamic range compared with longer pulses (1 ms). Both electrophysiological results and electrostatic finite-element modeling show that electrode-electrode interactions can lead to increased thresholds for sites half way between simultaneously stimulated electrodes (29.4 [+ or -] 6.6 nC) compared with monopolar stimulation (13.3 [+ or -] 1.7 nC, p < 0.02). Presynaptic stimulation of the same ganglion cell with both 200- and 10-[micro]m-diameter electrodes yielded threshold charge densities of 12 [+ or -] 6 and 7.66 [+ or -] 1.30 nC/[cm.sup.2], respectively, while the required charge was 12.5 [+ or -] 6.2 and 19 [+ or -] 3.3 nC. Index Terms--Microelectrodes arrays, retinal electrophysiology, retinal prosthesis.

As microelectrodes gain widespread use for electrochemical sensing, biopotential recording, and neural stimulation, it becomes important to understand the dependence of electrochemical impedance on microelectrode size. It has been shown mathematically that a disc electrode, coplanar in an insulating substrate and exposed to a conducting media, exhibits an inhomogeneous current distribution when a potential step is applied. This distribution is known as the primary distribution, and its derivation also yielded an analytic solution for electrical resistance of the conducting media ([R.sub.s]), between the disc surface and a distant ground, which is inversely proportional to disk radius [[R.sub.s] = 1/(4kr), where h is media conductivity and r is disk radius]. The dependence of spectral impedance on microelectrode radius, however, has not been explored. We verify the analytical solution for resistance using high-frequency (100 kHz) electrochemical impedance data from microelectrodes of varying radius (11-325 [micro]m). For all disc radii, as we approach a lower frequency ([right arrow] 10 Hz), we observe a transition from radial to area dependence (e.g., 1/r [right arrow] 1/[r.sup.2]). We hypothesize that this transition is driven by the fact that the derivation of the primary distribution ignores concentration gradients, but that these gradients cannot be ignored at lower frequencies. Index Terms--Electrochemical sensing, impedance spectroscopy, microelectrode, neural stimulation, primary current distribution.

With applied potential, the current distribution at the surface of a disk electrode is spatially nonuniform and time dependent. This distribution is important to control in applications that desire a uniform current density profile or minimal corrosion. We examine the current density profile of a capacitive disk electrode subjected to a voltage-step using finite element analysis software to solve the system of partial differential equations. In detailed analyses we show quantitatively that the current density shifts from peripheral enhancement to near-uniformity following 1/2 of the lumped element time constant. As charging continues, the current density is slightly enhanced in the central region. We present curves for the evolution of local 'time constants' as time progresses and calculate their effective values. The model is intended to be the basis of future work to control the corrosion profile of biologically implantable electrodes of arbitrary shape. Data suggest a means to control corrosion by retarding the edges of a stimulus pulse. Additionally, smaller electrodes may be more effective in fully utilizing surface area for charge transfer due to their shorter time constants. Index Terms--Current density, double layer, electrochemical processes, implantable electrodes, microelectrodes.

This paper proposes a hybrid algorithm based on artificial immune systems and ant colony optimization for distribution system reconfiguration, which is formulated as a multi-objective optimization problem. The algorithm maintains a population of candidate solutions called antibodies. The search space is explored by means of the hypermutation operator that perturbs existing antibodies to produce new ones. A table of pheromones is used to reinforce better edges during hypermutation. An added innovation is the use of the pheromones to obtain quick solutions to restore the distribution system under contingency situations. The hybrid approach has been successfully implemented on two test networks. The results obtained demonstrate the efficacy of the algorithm. Index Terms--Ant colony optimization, artificial immune system, distribution system reconfiguration, Pareto optimality, power system restoration.

Objectives: Solid organ transplant recipients (SOTR) receiving post‐transplant immunosuppression show increased COVID‐19‐related mortality. It is unclear whether an additional dose of COVID‐19 vaccines can overcome the reduced immune responsiveness against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) variants. Methods: We analysed humoral immune responses against SARS‐CoV‐2 and its variants in 53 SOTR receiving SARS‐CoV‐2 vaccination. Results: Following the initial vaccination series, 60.3% of SOTR showed no measurable neutralisation and only 18.9% demonstrated neutralising activity of > 90%. More intensive immunosuppression, antimetabolites in particular, negatively impacted antiviral immunity. While absolute IgG levels were lower in SOTR than controls, antibody titres against microbial recall antigens were higher. By contrast, SOTR showed reduced vaccine‐induced IgG/IgA antibody titres against SARS‐CoV‐2 and its delta variants and fewer linear B‐cell epitopes, indicating reduced B‐cell diversity. Importantly, a third vaccine dose led to an increase in anti‐SARS‐CoV‐2 antibody titres and neutralising activity across alpha, beta and delta variants and to the induction of anti‐SARS‐CoV‐2 CD4+ T cells in a subgroup of patients analysed. By contrast, we observed significantly lower antibody titres after the third dose with the omicron variant compared to the ancestral SARS‐CoV‐2 and the improvement in neutralising activity was much less pronounced than for all the other variants. Conclusion: Only a small subgroup of solid organ transplant recipients is able to generate functional antibodies after an initial vaccine series; however, an additional vaccine dose resulted in dramatically improved antibody responses against all SARS‐CoV‐2 variants except omicron where antibody responses and neutralising activity remained suboptimal. [ABSTRACT FROM AUTHOR]

Introduction: As the “Science of Medicine” is getting advanced day-by-day, need for better pedagogies & learning techniques are imperative. Problem Based Learning (PBL) is an effective way of delivering medical education in a coherent, integrated & focused manner. It has several advantages over conventional and age-old teaching methods of routine. It is based on principles of adult learning theory, including student’s motivation, encouragement to set goals, think critically about decision making in day-to-day operations. Above all these, it stimulates challenge acceptance and learning curiosity among students and creates pragmatic educational program. Aim and objectives: To measure the effectiveness of the “Problem Based Learning” as compared to conventional theory/ didactic lectures based learning. Material and Methods: The study was conducted on 72 medical students from Dayanand Medical College & Hospital, Ludhiana. Two modules of problem based sessions designed and delivered. Pre & Post-test score’s scientific statistical analysis was done. Student feed-back received based on questionnaire in the five-point Likert scale format. Results: Significant improvement in overall performance observed. Feedback revealed majority agreement that “Problem-based learning” helped them create interest (88.8 %), better understanding (86%) & promotes self-directed subject learning (91.6 %). Substantial improvement in the post-test scores clearly reveals acceptance of PBL over conventional learning. Conclusion: PBL ensures better practical learning, ability to create interest, subject understanding. It is a modern-day educational strategy, an effective tool to objectively improve the knowledge acquisition in Medical Teaching.

PURPOSE: Reports of morning glory disc anomaly (MGDA) in India have mostly been case reports. The aim of this study was to describe the demographic and clinical profile of patients with MGDA in South India. MATERIALS AND METHODS: A retrospective review of the medical records of patients with MGDA seen at a tertiary eye hospital in South India over a period of 8 years was carried out. The patients' demographic and clinical data were extracted from the case files and were entered into Epi Info reporting software version 7.2.3.0 and then analyzed. RESULTS: There were 51 eyes of 44 patients with MGDA comprised 25 (56.8%) males and 19 (43.2%) females. Seven (15.9%) patients had bilateral MGDA. The mean age for females was 5.8 years (standard deviation [SD]: 5.8) and for males, 11.2 years (SD: 12.1). This difference was not statistically significant with a P = 0.07. The most common ocular associations were strabismus, refractive error, and retinal detachment, whereas the most common systemic associations were cleft lip and cleft palate. Fifty-one percent of eyes were blind at presentation. CONCLUSION: Patients with MGDA in India tend to present late with poor visual prognosis. Early diagnosis and prompt treatment of blinding complications are crucial in reducing the risk of irreversible visual loss. Associated systemic abnormalities highlight the importance of a multidisciplinary approach in the management of patients with this condition. [ABSTRACT FROM AUTHOR]

Objective: To find out whether there exists a correlation between the quantum of energy used and the amount of rise of intraocular pressure (IOP) following neodymium: yttrium aluminum garnet (Nd: YAG) laser capsulotomy. Materials and Methods: A total of 110 patients who had undergone Nd: YAG laser posterior capsulotomy for the management of posterior capsule opacification with a minimum of 3 months following cataract surgery were enrolled after taking written informed consent. After detailed history and ocular examination, Nd: YAG laser capsulotomy was performed. Prelaser IOP was noted. Nd: YAG laser posterior capsulotomy was performed. Laser energy used was noted following which postlaser IOP was also recorded after 1, 2, and 4 h postprocedure. Paired t-test was used for the comparison of means of IOP and energy levels. Receiver operating characteristic analysis was used to predict the cut-off value of energy on the basis of change of IOP from baseline. Results: The mean energy used in the Nd: YAG laser posterior capsulotomy procedure for all patients was 58.57 ± 34.63 mJ. The mean IOP at 1st h follow-up was 15.32 ± 2.91 mmHg, at 2nd h follow-up was 16.24 ± 3.23 mmHg, and at 4th h follow-up was 16.18 ± 3.35 mmHg. At all three follow-ups, the mean change in IOP was found to be statistically significant (P < 0.001). Conclusion: Postlaser IOP rise is minimal and transient; it varies with the amount of energy used. [ABSTRACT FROM AUTHOR]

PURPOSE: The purpose of this study was to determine the incidence, severity, and associated risk factors of retinopathy of prematurity (ROP) in a district in South India. METHODS: This was a prospective, observational, cohort study involving babies at risk of ROP conducted in five Neonatal Intensive Care Units in a district in Tamil Nadu, South India. All babies with gestational age at birth of ≤36 weeks and a birth weight (BW) of ≤1900 g with a follow‑up period of at least 6 months were enrolled for the study. Neonatal and maternal risk factors were assessed and univariate and multivariate logistic regression analysis performed to examine the predictors of ROP. RESULTS: A total of 325 infants were screened. ROP was identified in 210 eyes of 106 (32.6%) babies with severe ROP (stage ≥3 ROP) occurring in 14 (13.2%) babies. Low BW (LBW) was the only significant risk factor for ROP on multivariate logistic regression analysis. The mean BW was 1285 and 1452 g for babies with and without ROP, respectively. Treatment was indicated in 22 eyes of 14 (13.2%) infants. CONCLUSIONS: The incidence of ROP was fairly high and strongly associated with LBW. A relatively low incidence of severe ROP was, however, observed. More effort is, therefore, required towards the prevention of preterm births while the present gains in neonatal care should be sustained to reduce the incidence of ROP and thus childhood blindness in the country. [ABSTRACT FROM AUTHOR]

Introduction: Increasing incidence of obesity in Indian population has led to an exponential rise in the number of bariatric operations performed annually. Laparoscopic Sleeve Gastrectomy (LSG) has been proposed to cause rapid remission of Type 2 Diabetes Melitus (T2DM) and metabolic syndrome in a weight loss independent manner. Aim: To evaluate the effects of LSG on metabolic syndrome and central obesity in morbidly and severely obese Indian adults. Material and Methods: Study was conducted on 91 morbidly obese [Body Mass Index (BMI)>40 kg/m2] and severely obese (BMI>35 kg/m2) individuals who were suffering from diabetes, hypertension or dyslipidemia. The patients were followed up for six months and the trends of glycaemic control, mean blood pressure, lipid profile, weight loss parameters and changes in parameters of central obesity were studied. Results: Weight loss was significant at three months postsurgery and was sustained through six months. There was significant improvement in glycaemic control leading to reduction in need for oral hypoglycaemic agents or insulin in majority of them and even discontinuation of these medications in few patients. Hypertension and dyslipidemia also showed an improving trend through six months postsurgery. There was a significant impact on reduction of central obesity in these patients as marked by significant reduction in waist to hip ratio. Conclusion: LSG produces sustainable weight loss with significant improvement in glycaemic status and control of metabolic syndrome in severe to morbidly obese patients. LSG is also efficacious in reducing central obesity in Indian population which is a major depressive ailment amongst obese individuals. [ABSTRACT FROM AUTHOR]

This paper proposes an algorithm based on hybridization of pheromones derived from ant colony optimization with crossover operator and is applied to minimize real losses in distribution systems using reconfiguration. The algorithm maintains a population of candidate solutions and a table of pheromones to reinforce better edges during search process. Exploration for better solutions is performed by means of crossover operator directed by the information stored in the pheromone table. The hybrid approach has been successfully implemented on three test networks. The efficacy of the algorithm has been demonstrated by presenting a comparison between results obtained using uniform crossover operator and pheromone directed crossover and also by comparing with the results published in the literature for the test systems considered. [ABSTRACT FROM PUBLISHER]

Objective: To evaluate the feasibility of a new technique for the implantation of ultrathin substrates containing stem cell-derived retinal pigment epithelium (RPE) cells into the subretinal space of retina-degenerate Royal College of Surgeon (RCS) rats. Methods: A platform device was used for the implantation of 4-μm-thick parylene substrates containing a monolayer of human embryonic stem cell-derived RPE (hESC-RPE). Normal Copenhagen rats (n = 6) and RCS rats (n = 5) were used for the study. Spectral-domain optical coherence tomography (SD-OCT) scanning and histological examinations were performed to confirm placement location of the implant. hESC-RPE cells attached to the substrate before and after implantation were evaluated using standard cell counting techniques. Results: SD-OCT scanning and histological examination revealed that the substrates were precisely placed in the rat's subretinal space. The hESC-RPE cell monolayer that covered the surface of the substrate was found to be intact after implantation. Cell counting data showed that less than 2% of cells were lost from the substrate due to the implantation procedure (preimplantation count 2,792 ± 74.09 cells versus postimplantation count 2,741 ± 62.08 cells). Detailed microscopic examination suggested that the cell loss occurred mostly along the edges of the implant. Conclusion: With the help of this platform device, it is possible to implant ultrathin substrates containing an RPE monolayer into the rat's subretinal space. This technique can be a useful approach for stem cell-based tissue bioengineering techniques in retinal transplantation research. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Epiretinal prostheses for the blind bypass diseased photosensitive cells in the retina, directly stimulating retinal neurons electrically and evoking signals that are relayed to the brain. Current clinical implants have few electrodes and provide limited visual acuity. Acuity may be improved by identifying electrode array design features and operational details that enhance or interfere with visual percept formation. We labeled all retinal ganglion cells in whole mount retina with a calcium reporter and then measured the number and pattern of cells responding, over a range of electrode diameters and stimulus durations. Span of the response scaled with electrode diameter for electrodes 60 \mum and larger. Short stimulation pulse widths selectively activated cells nearest the electrode. Our measurements in the salamander retina suggest that the spatial resolution is 150 \mum, which on a human retina is equivalent to 0.55^\circ of human visual field and corresponding Snellen acuity of 20/660. Reading large print could be possible with such a prosthesis. [ABSTRACT FROM PUBLISHER]

Splenic infarctions have been reported in cirrhotic patients with comorbidities (e.g., primary biliary cirrhosis), but there is little to no mention of spontaneous splenic infarction in alcoholic hepatitis. This condition is notable, as splenic function has been shown to decrease in alcoholic liver disease, but the exact pathophysiology has been unclear. We describe a relatively young cirrhotic woman who developed splenic infarctions in the setting of alcoholic hepatitis. [ABSTRACT FROM AUTHOR]

Reports on the development of a hippocampal-cortical neural prostheses by researchers from the U.S. Use of the novel medical apparatus to restore lost cognitive function; Safety and efficacy of replacing the CA3 region of the hippocampal slice with the biomimetic device; Characterization and mathematical modeling of the nonlinear dynamic properties of the region.

We present a case of an 18-year old female with intraocular cysticercosis in the form of a freely mobile cyst in the anterior chamber of the right eye, that was successfully removed by viscoexpression. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to assess the severity of the erectile (ED) dysfunction among type 2 diabetic men. For subjective information patients were asked to fill up the IIEF questionnaire. This study was also done to correlate ED with other variables like age, obesity, duration of diabetes, degree of diabetic control and complications of diabetes. Neuropathy was assessed objectively by using the Vibration Perception Threshold (VPT). Material and Methods: This study was conducted on 348 patients. Age range of these subjects was 25 years to 75 years. All patients underwent routine clinical examinations which included recording of duration of diabetes, type of diabetes, Body Mass Index, previous HbA1c tests and VPT measurement. Results and Conclusion: In the present study, it was observed that there was a significant association of ED with age, duration of diabetes, glycemic control and BMI. In fact, VPT emerged as a strong predictor of ED. We conclude that adding objectivity of VPT measurement improves the subjective predictive value of IIEF-5. [ABSTRACT FROM AUTHOR]

Introduction: Acute generalised peritonitis coming forth due to underlying intestinal perforation is a critical & life-threatening medical condition. It is a common surgical emergency most of the times across the world. Misleading data on crude morbidity and mortality due to the condition usually contaminates substantially the very purpose of medical audit. Thus, early prognostic evaluation is not only desirable but mandate to much extent. High-risk patients require timely & aggressive treatment especially in severe peritonitis & to select them reasonably well, evaluation through prognostic scoring is an approach of choice. Well sought after & reasonably reliable APACHE II scoring system is used for the purpose & scores are correlated well to accentuate & measure the various factors needed for better management of condition. Material and Methods: The study was conducted over the period of 18 months (Jan 2010 to June 2011) on 50 patients with confirmed diagnosis of intestinal perforation. APACHE II score was calculated and correlated with their symptoms & clinical outcomes regarding morbidity and mortality. Results: APACHE II score correlated well with the outcome of the study, showing score affects of two major aspects in the treatment outcome & management.1.) APACHE II score of less than 10 included 30 low risk group patients discharged in a satisfactory gratifying manner. Three out of four in high risk group with APACHE II score >20, shown adverse outcomes. 2.) Mean ICU stay of 9.75 days was found in patients with APACHE II score 20 or more compared to those with mean ICU stay of 0.13 days in patients with APACHE II score 10 or less. Conclusion: Acute generalized peritonitis being life-threatening medical emergency requires careful consideration in its management that needs to be economically viable, acceptably feasible and outcome oriented with better allocation & utilization of ICU resources that needs meticulous case analysis & prioritization. This present study helps the clinicians in three major ways: a) To take better decisions on case to case basis; b) To design strategies in order to prevent adverse outcomes; c) Last but not least, to make better use of ICU resources. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 48-year old woman who experiences a dull pain in the left flank and recurrent urinary tract infections. Microscopic examination of her urine reveals pus cells while preoperative retrograde pyelography and ureteroscopy revealed ureteral obstruction. She was diagnosed with aspergillosis and underwent an ureteroscopy to remove the Aspergillus fungal balls from her ureter. It mentions that itraconazole and amphotericin B were also administered to the patient.