Raman-shifted wavelength-selectable pulsed fiber laser with high repetition rate and high pulse energy in the visible

A high-pulse-energy, diffraction-limited, wavelength-selectable, visible source, based on Raman frequency shifting of a frequency-doubled Yb-doped fiber laser, has been studied. The relative length-scaling laws of Raman gain and self-phase modulation push the design towards short fiber lengths with large core size. It is experimentally demonstrated that the Raman clean-up effect in a graded-index multi-mode fiber is not sufficient to obtain diffraction-limited beam quality in the short fiber length. Thus, a large-core photonic crystal fiber is used to maintain diffraction-limited performance and output pulse energies of ~1 μJ, at a 1-MHz repetition rate and 1.3-ns pulse-width are successfully achieved. This step-tunable visible source should find applications in photoacoustic microscopy.

Regional Anesthesia: Preferred Technique for Venodilatation in the Creation of Upper Extremity Arteriovenous Fistulae

Owing to the overall poor medical health of patients with end-stage renal disease, we have sought alternatives to the use of general anesthesia for access procedures. Furthermore, since local anesthesia (1) does not offer the motor block that is sometimes desired and (2) can be difficult to maintain when a large amount of vein needs to be transposed, we examined whether regional blocks can be useful for the creation of new arteriovenous fistulae (AVF).

From August 2002 to January 2005, 41 patients scheduled for AVF placement underwent a regional block with the use of a lidocaine and ropivacaine mixture using a nerve stimulator. Either axillary, interscalene, or infraclavicular blocks or a combination was used. Intraoperative duplex ultrasonography was used to assess the degree of venodilatation of the basilic and cephalic veins before and after the block. The site of each measurement was marked on the skin and selected by a clearly identifiable branch point. Each measurement was recorded three times and was made in the (1) native state, (2) after application of a tourniquet with opening and closing of the hand for 15 seconds, and (3) after placement of the block.

The average age of the patients was 65 ± 14 years (SD), with ages ranging from 33 to 91 years, and the prevalence of diabetes mellitus was 50%. Complete brachial plexus block was achieved in 34 patients (83%). Sensory block was accomplished within 10 to 15 minutes and usually lasted 4 to 6 hours. Motor block was accomplished in 10 to 25 minutes. Venodilatation was not noted in patients whose blocks did not work ( n = 7) or whose vein was found to be phlebitic on exploration ( n = 3). The degree of venodilatation noted as a percentage increase after application of the tourniquet compared with the native state for these 34 patients (in whom the block worked) was 37% for the distal cephalic, 31% for the midcephalic, and 32% for the midbasilic vein. The degree of venodilatation noted as a percentage increase after placement of the block compared with after tourniquet application for these 34 patients was 42% for the distal cephalic, 19% for the midcephalic, and 26% for the midbasilic vein. No instances of systemic toxicity, hematomas, or nerve injury from the block were noted. Accesses placed included 20 radiocephalic AVF, 8 brachiobasilic AVF, 8 brachiocephalic AVF, 2 arteriovenous grafts, 2 radiobasilic AVF, and 1 brachial vein AVF.

Regional block is a safe and, in our opinion, preferred technique for providing anesthesia for upper extremity vascular surgery. The venodilatation observed is augmented compared with that using a tourniquet and may allow more options for access placements.

ID: 25: SOCIAL DETERMINANTS OF PATIENT ANTIBIOTIC MISUSE IN HARYANA, INDIA

Background

Antibiotic resistance is recognized globally as an urgent health crisis. Multidrug resistant organisms lead to deadly hospital and community acquired infections and complicate patients' underlying health issues. In the United States, antibiotic resistance causes 23,000 deaths and direct healthcare costs of $20 billion a year. In the developing world, the costs are estimated to be even higher. In India alone, antibiotic resistance is responsible for an estimated 58,000 infant deaths annually. While its severity is agreed upon, the causes and solutions to antibiotic misuse are complex. Antibiotic dispensing laws are poorly enforced in many developing nations, including India. Patient and provider contributions are intertwined, thus confronting the problem requires a better understanding of the motivations of several populations.

Methods

We conducted a mixed methods study in the northern state of Haryana, India, between June and August 2015. We qualitatively assessed the antibiotic knowledge and use practices of 20 local community members using semi-structured interviews. We also completed 64 surveys of community members and healthcare workers. Both populations were given the same survey, which focused on the participant's experience obtaining antibiotics as a patient. The interviews and surveys were conducted in English and Hindi, as applicable, by bilingual members of the research team. Interview data was coded for themes using NVivo software, and quantitative survey responses were analyzed in SAS. We used DAGitty software to construct a directed acyclic graph to determine the minimally sufficient adjustment sets needed to block confounders of the relationship between antibiotic knowledge and antibiotic misuse.

Results

Over a third of survey participants reported antibiotic misuse, defined as purchasing medication from a pharmacy without a doctor's prescription (36.5%). Furthermore, none of the 20 community member interviewees were able to correctly define antibiotics without prompting. The interviews also revealed that limited health education, inadequate access to a doctor, and poverty all influence patients' antibiotic decision making. Participants with these characteristics were more likely to bypass doctors and seek medical care directly from a pharmacist.

The effect of antibiotic knowledge on antibiotic misuse was significant in our pilot survey data, even after adjusting for the variables in the minimally sufficient adjustment set: first vs. fourth quartile of knowledge, OR=72.09, p=0.014; second vs. fourth quartile, OR=44.09, p=0.006. The covariates in the model include age, income, healthcare occupation, education, having a doctor in the family, and having access to a doctor in your local community.

Discussion

This study highlights the need for public health education regarding antibiotics and the extensive health implications of their misuse. Local and national governments should consider social factors when enacting future antibiotic policies.

The Role of Selective Nerve Root Block in the Treatment of Lumbar Radicular Leg Pain

The objective of this retrospective study was to investigate the clinical effectiveness of nerve root blocks (i.e., periradicular injection of Lidocaine and triamcinolone) for lumbar monoradiculopathy in patients with a mild neurological deficit in National Institute of Traumatology & Orthopaedic Rehabilitation (NITOR), Dhaka, Bangladesh from March 2014 to December 2014. We Included 24 patients (32-74 years) with a minor sensory/motor deficit and an unequivocal MRI finding (18 disc herniations, 6 foraminal stenosis) treated with a selective nerve root block. Based on the clinical and imaging findings, surgery (decompression of the nerve root) was justifiable in all cases. Seventeen patients (87%) had rapid (1-4 days) and substantial regression of pain, four required a repeat injection. Sixty percent (60%) of the patients with disc herniation or foraminal stenosis had permanent resolution of pain, so that an operation was avoided over an average of 6 months (2-9 months) follow-up. Nerve root blocks are very effective in the non-operative treatment of minor monoradiculopathy and should be recommended as the initial treatment of choice for this condition.

Highly efficient Yb-free Er-La-Al doped ultra-low NA large mode area single-trench fiber laser

We demonstrate a 60µm core diameter Yb free Er-La-Al doped single-trench fiber having a 0.038 ultra-low-NA, fabricated using conventional MCVD process in conjunction with solution doping technique. Numerical simulations predict an effective single mode operation with effective area varying from 1,820µm(2) to 1,960µm(2) (taking bend-induced modal distortion into account) for different thicknesses of trenches and resonant rings at a constant bend radius of 25cm. Moreover, all solid structure favors easy cleaving and splicing. Experimental measurements demonstrate a robust effective single mode operation. Furthermore, with a 4%-4% laser cavity, this fiber shows a record efficiency of 46% with respect to the absorbed pump power.

High power, compact, picosecond MOPA based on single trench fiber with single polarized diffraction-limited output

We experimentally demonstrate an all-solid Yb-doped 30 μm core diameter single trench fiber. Measurements ensure a robust effective single-mode operation without the need of tight coiling as required for conventional fibers thanks to the ultralow NA (∼0.038) and resonant ring surrounding the core. All-solid and cylindrical design ensures the suitability for mass scale production with the added benefit of all-fiberized device structure. A compact master oscillator power amplifier (MOPA) has been built using this fiber delivering ∼23.5  ps pulses at 13.5 MHz repetition rate delivering up to ∼52  W of average output power corresponding to a pulse energy of ∼3.8  μJ and peak power of >160  kW, while maintaining ∼76% slope efficiency. The output beam exhibits a polarization extinction ratio of more than 15 dB and a M2 less than 1.15.

Review article: cytomegalovirus and inflammatory bowel disease

BACKGROUND

The association between ulcerative colitis and cytomegalovirus (CMV) has been recognised for over 50 years; and the role of CMV in ulcerative colitis in general, and steroid resistance in particular, remains a topic of ongoing controversy. The outcome for patients with CMV reactivation appears worse than that for patients without reactivation, but it is not entirely clear whether CMV is a contributor or a bystander and if treatment with anti-virals alters the course of inflammatory bowel disease (IBD).

AIM

To review the role of CMV associated with IBD, including epidemiology, clinical features, diagnosis and management strategies.

METHODS

By reviewing literature available on CMV associated with IBD in adult patients. A PubMed literature search was performed using the following terms individually or in combination: CMV colitis, cytomegalovirus colitis, IBD and CMV, CMV treatment.

RESULTS

Cytomegalovirus reactivation is common in patients with severe colitis, with a reported prevalence of 4.5-16.6%, and as high as 25% in patients requiring colectomy for severe colitis. The outcome for this group of patients appears worse than that for patients without reactivation; however, reported remission rates following treatment with anti-viral therapy are as high as 71-86%.

CONCLUSIONS

Evidence, although not conclusive, supports testing for CMV colonic disease in cases of moderate to severe colitis, by processing biopsies for haematoxylin and eosin staining with immunohistochemistry and/or, CMV DNA real-time polymerase chain reaction; and if present treating with ganciclovir.

Impact of killer immunoglobulin-like receptor-human leukocyte antigens ligand incompatibility among renal transplantation

Killer immunoglobulin-like receptor (KIR) gene shows a high degree of polymorphism. Natural killer cell receptor gets activated once they bind to self-human leukocyte antigens (HLAs) with specific ligand. KIR gene and HLA ligand incompatibility due to the presence/absence of KIR in the recipient and the corresponding HLA ligand in the allograft may impact graft survival in solid organ transplantation. This study evaluates the effect of matches between KIR genes and known HLA ligands. KIR genotypes were determined using sequence specific primer polymerase chain reaction. Presence of certain KIR in a recipient, where the donor lacked the corresponding HLA ligand was considered a mismatch. The allograft was considered matched when both KIR receptor and HLA alloantigen reveald compatibility among recipient and donor. The data revealed better survival among individuals with matched inhibitory KIR receptors and their corresponding HLA ligands (KIR2DL2/DL3-HLAC2, KIR3DL1-HLABw4). On the contrary, no adverse effect was seen for matched activating KIR receptors and their corresponding HLA ligands. One of the activating gene KIR2DS4 showed risk (P = 0.0413, odds ratio = 1.91, 95% confidence interval = 1.02-3.57) association with renal allograft rejection. We conclude that the presence of inhibitory KIR gene leads to better survival; whereas activating motifs show no significant role in renal allograft survival.

Maternal mortality in obstetrics and gynaecology in a tertiary care hospital

Maternal mortality is the leading causes of death and disability of reproductive age in the developing countries. Bangladesh is one of the developing countries where maternal mortality is very high. The purpose of the present study was to see the causes of maternal deaths at Obstetrics and Gynaecology ward. This retrospective study was carried out in the Department of Obstetrics and Gynaecology at Dhaka Medical College Hospital (DMCH). All maternal deaths were included in this study from July 2003 to June 2004 for a period of one year. The incidence of maternal death was 18.5/1000 live birth. Hypertensive disorder of pregnancy (41.84%) was the most common cause of maternal death followed by unsafe abortions (21.4%), PPH (10.2%), obstructed labour (8.2%). Among 98 patients 36(36.7%) cases are died due to eclampsia. Death due to pre-eclampsia (5.1%), unsafe Abortion (21.4%), Obstetric haemorrhage (18.4%) and obstructed labour (8.3%) were commonly found in this study. The study permits to conclude that Hypertensive disorder of pregnancy is the leading cause of pregnancy related deaths followed by unsafe abortions and obstetric haemorrhage. Other causes include obstructed labour, anaesthetic complications and others.

Improving the feeding value of straws with Pleurotus ostreatus

The high content of lignin in cell walls is the major limiting factor in the digestion and utilisation of cereal crop residues by ruminants. The aim of this study was to evaluate the effectiveness of the white rot fungus, Pleurotus ostreatus (P. ostreatus), to degrade lignin and to enhance the rumen degradability of maize stover, rice straw, wheat straw and their mixture in equal proportion on a dry-matter (DM) basis. Four samples of each substrate were incubated aerobically in triplicate with P. ostreatus for 0 (Control), 21, 28 and 35 days under solid-state conditions (temperature, 24°C; humidity, 70 ± 5%). The changes in chemical composition, DM and nutrient losses, and rumen fermentation characteristics using in vitro DM digestibility (DMD) and the in vitro gas-production (GP) technique were measured. The results showed that incubation with P. ostreatus decreased (P < 0.001) the contents of neutral detergent fibre and lignin with a concomitant increase (P < 0.001) in the contents of ash and crude protein. The losses of nutrients differed (P < 0.001) among the straw types, with rice straw and maize stover showing the largest (P < 0.05) lignin degradation compared to wheat and mixed straws. The DMD and 72-h cumulative GP increased (P < 0.001) consistently with increasing fungal incubation period and for all substrates the highest values of DMD and GP were measured after 35 days of incubation with P. ostreatus. The lignin degradation was strongly associated with hemicellulose degradation (r = 0.71) across the various straws. Results of the present study demonstrated that incubation of low-quality crop residues with P. ostreatus under solid-state conditions upgrades their feeding value by reducing the content of lignin and increasing the content of crude protein and ruminal degradation.

Processing of Polyetherimide/Cloisite 30B Nanocomposite by Vibration Casting Method

Vibration casting method was developed for making polyetherimide (PEI)/Cloisite 30B nanocomposite. Towards this, a vibration casting apparatus was designed and developed. Vibration casting apparatus provided vibrational energy and heat, simultaneously. The processing parameters were established for vibration casting in terms of frequency of vibration, temperature, time and viscosity of casting mixture. Casting mixture of PEI/Cloisite 30B/N,N-dimethyl acetamide (DMAc) was made by dissolving PEI in DMAc and then mixing Cloisite 30B in this solution. The viscosity of PEI/Cloisite 30B/DMAc mixture was optimized for casting by controlling the volume fraction of PEI in DMAc. Morphology of PEI/Cloisite 30B nanocomposite was examined by wide angle X-ray diffraction, transmission electron microscopy, scanning electron microscopy and contact angle measurement. Mechanical and thermal properties of PEI/Cloisite 30B nanocomposite were also compared with that of neat PEI to ascertain the efficacy of vibration casting method.

The Gonzalez hernia revisited: use of the ischiorectal fat pad to aid in the repair of rectovaginal and rectourethral fistulae

INTRODUCTION

During the development of the posterior sagittal approach to anorectal malformations a vital technical challenge was a precise midline dissection, which if off, allowed for the ischiorectal fat pad to bulge into the wound. This occurrence became affectionately known as a "Gonzalez hernia", after a trainee of Dr Pena's (and a co-author of this paper). We describe here an innovative use of the ischiorectal fat pad to aid in the repair of acquired rectovaginal and rectourethral fistulae.

METHODS

Patients with recurrent vaginal or urethral fistulae were selected for review. The ischiorectal fat pad was deliberately mobilized (via a posterior sagittal or transanal approach) and used to buttress the repair of the posterior vagina or urethra.

RESULTS

The ischiorectal fat pad technique was used in 9 patients. All had an acquired fistula (6 rectovaginal fistula, 3 rectourethral fistulas). We used the posterior sagittal approach in 7 and in 2 the transanal approach. Six patients had had at least two prior attempts at fistula repair. Six patients had a stoma, and 3 did not. There were no recurrences in greater than six month follow-up.

DISCUSSION

The ischiorectal fat pad is easily visualized and mobilized, either via a posterior sagittal or transanal approach, providing excellent coverage with native, well-vascularized tissue, in an area that is difficult to heal. It is an excellent option for recurrent rectovaginal and rectovaginal fistulae and may have other additional creative applications.

Infant robotic pyeloplasty: comparison with an open cohort

OBJECTIVE

To present our experience with infant pyeloplasty, comparing outcomes between robotic-assisted laparoscopic pyeloplasty (RALP) and open pyeloplasty (OP).

MATERIALS AND METHODS

A retrospective review was performed of all children <1 year of age who underwent unilateral dismembered pyeloplasty at a single pediatric institution since January 2007. Patients with standard laparoscopic pyeloplasty were excluded. Patient demographics, intraoperative details, narcotic usage, and complications were reviewed.

RESULTS

A total of 70 infants (51 boys and 19 girls) were identified, with nine RALP and 61 OP performed. Median age was 9.2 months (range, 3.7-11.9 months) for RALP and 4.1 months (range, 1.0-11.6 months) for OP (p = 0.005). Median weight was 8 kg (range, 5.8-10.9 kg) for RALP and 7 kg (range, 4-14 kg) for OP (p = 0.163). Median operative time was 115 min (range, 95-205 min) for RALP and 166 min (range, 79-300 min) for OP (p = 0.028). Median hospital stay was 1 day (range, 1-2 days) for RALP and 3 days (range, 1-7 days) for OP (p < 0.001). Median postoperative narcotic use of morphine equivalent was <0.01 mg/kg/day (range, 0-0.1 mg/kg/day) for RALP and 0.05 mg/kg/day (range, 0-2.2 mg/kg/day) for OP (p < 0.001). Median follow-up was 10 months (range, 7.2-17.8 months) for RALP and 43.6 months (3.4-73.8 months) for OP (p < 0.001). The success rate was 100% for RALP and 98% for OP.

CONCLUSIONS

Infant RALP was observed to be feasible and efficacious with shorter operative time, hospital stay, and narcotic utilization than OP.

The effect of an organophosphonite antioxidant on poly(ether ether ketone)/poly(ether imide) blend as studied by quasi-isothermal modulated differential scanning calorimetry and dynamic mechanical thermal analysis methods

In the present study, the effect of P-EPQ, an organophosphonite antioxidant, on the glass transition and the viscoelastic behavior of optimized poly(ether ether ketone) (PEEK)/poly(ether imide) (PEI; PEEK/PEI: 50/50) blend has been reported. For this, P-EPQ was added in various proportions to the PEEK/PEI blend and was studied by quasi-isothermal modulated differential scanning calorimetry (Qi-MDSC) and dynamic mechanical thermal analysis (DMTA) methods. The Qi-MDSC results clearly indicate a significant decrease in the glass transition temperature of the blend up to 1 wt% P-EPQ addition. The DMTA measurements revealed a decrease in tan δ peak temperature upon antioxidant addition in agreement with calorimetric results. The shift factors obtained using the time–temperature superposition of DMTA data exhibit Williams–Landel–Ferry behavior, and the fractional free volume of the blend increases with increase in antioxidant addition (up to 1 wt%). The “master curve” of storage modulus predicts high modulus for the blend with 1 wt% antioxidant, revealing its suitability for high-impact applications.