Prospective Randomized Pilot Trial on the Effects of Mild Hypercapnia on Cerebral Oxygen Saturation in Patients Undergoing Off-Pump Coronary Artery Bypass Grafting

OBJECTIVE AND DESIGN

A single-center prospective randomized controlled study was conducted to assess the effect of targeted mild hypercapnia (TMH) on cerebral oxygen saturation (rSO2) in patients undergoing off-pump coronary artery bypass grafting (CABG).

SETTING AND PARTICIPANTS

A prospective randomized controlled study involving 100 patients undergoing off-pump CABG at U. N. Mehta Hospital, Ahmedabad, Gujarat, India.

INTERVENTION

Patients were randomized to either the TMH (PaCO2 45-55 mmHg) or the targeted normocapnia (TN; PaCO2 35-45 mmHg) group, containing 50 patients in each group.

MEASUREMENTS

Monitoring of rSO2, heart rate, mean arterial pressure (MAP), PaCO2, and peripheral oxygen saturation was done at baseline, after induction, after left internal mammary artery harvesting, at each grafting (distal and proximal), after protamine, and after shifting to the intensive care unit. The standardized minimental-state examination (SMMSE) was performed preoperatively and at 8, 12, and 24 hours postextubation. Data were analyzed using an independent sample t test.

RESULTS

The TMH group had higher MAP during grafting (p < 0.001) and higher rSO2 on both sides during distal and proximal grafting (p < 0.001) and after protamine (p < 0.05), as compared to the TN group. Compared to preoperative values, SMMSE scores in the TN group were significantly lower at 12 and 24 hours postextubation (p < 0.001).

CONCLUSION

TMH during grafting increased the cerebral blood flow and rSO2 when hemodynamic instability was very common. It has a protective role on the brain and helps maintain cognition postoperatively.

Outcome of obstructed total anamalous pulmonary venous connection (TAPVC) repair patients with milrinone versus milrinone and inhaled nitric oxide (INO): A prospective randomized observational study

Background

Obstructed total anomalous pulmonary venous connection (TAPVC) typically present with severe cardiovascular decompensation and requires urgent surgical management. Pulmonary arterial hypertension (PAH) is a major risk factor affecting mortality. Perioperative management focuses on providing inotropic support and managing potential pulmonary hypertensive episodes. Milrinone and inhaled nitric oxide (iNO) efficiently reduce pulmonary artery pressure (PAP) and help to improve the outcome. The aim was to determine the outcome of patients with high PAP with milrinone alone and a combination of iNO and milrinone.

Material and Method

After ethical committee approval, the study was conducted over a period of 3 years in 80 patients with obstructed TAPVC repair. A total of 80 patients having severe PAH (supra systemic arterial pressure) randomly divided into two groups with 40 patients in each (M & MN). Group M (milrinone) patients received milrinone and Group MN (milrinone & iNO) patients received both milrinone (after opening aortic cross clamp) and iNO (post operative ICU). Ventilation time, hospital stay, ICU stay, complications, in hospital mortality were compared between both groups.

Result

Ventilation time, Intensive Care Unit (ICU) stay, hospital stay for group M was 8.02 ± 5.74 days, 11.25 ± 7.33 day, 14.92 ± 8.55 days, respectively, and for group MN was 5.02 ± 1.78 days, 8.27 ± 3.24 days, 10.3 ± 3.18 days, respectively. In hospital mortality for group M and MN was 10% and 2.5%, respectively. P value for each variable was significant < 0.05 (except mortality).

Conclusion

Most of the patients with obstructed TAPVC had severe PAH. Management of severe PAH with a combination of milrinone with iNO had a better outcome than milrinone alone.

Assessment of the effect of two regimens of milrinone infusion in paediatric patients with pulmonary artery hypertension undergoing corrective cardiac procedure: A prospective observational study

Background

The aim of the study was to compare the effect of two different regimens of milrinone in pediatric patients with pulmonary artery hypertension (PAH) undergoing corrective procedure.

Materials and Methods

This randomized prospective study included 100 pediatric patients undergoing corrective cardiac surgeries. Group E: Milrinone was started as infusion 0.5 μg/kg/min without a loading dose after induction of anesthesia and continued as infusion 0.5-0.75 μg/kg/min in the pediatric cardiac surgical intensive care unit (PSICU). Group L: Milrinone was started as a loading dose 50 μg/kg over 10 min before weaning from cardiopulmonary bypass (CPB) followed by infusion 0.5-0.75 μg/kg/min in the PSICU. We compared heart rate, mean arterial blood pressure, central venous pressure, cardiac index (CI), mean pulmonary arterial pressure (MPAP), serum lactate level, urine output, vasoactive inotropic score, mechanical ventilation duration, and intensive care unit (ICU)- and hospital length of stay between the groups.

Results

There was an increase in mean arterial blood pressure, CI, and urine output in Group E compared to Group L (P < 0.05). MPAP, serum lactate level, and requirement of inotropes and vasopressors were lower in Group E compared to Group L (P < 0.05). Mechanical ventilation duration, ICU, and hospital length of stay were shorter in Group E than Group L (P < 0.05).

Conclusions

Early use of milrinone in patients with PAH undergoing corrective cardiac surgeries improved CI and mean arterial pressure, decreased MPAP, improved urine output, decreased serum lactate level, and decreased requirement of inotropes and vasopressors after weaning from CPB compared to the milrinone bolus group.

Predictors of cardiac implantable electronic device infection in the United States

Background

Cardiac implantable electronic devices (CIED) are important tools for managing arrhythmias, improving hemodynamics, and preventing sudden cardiac death. Device infection (DI) remains a significant complication of CIED and is associated with high morbidity, mortality, and healthcare cost.

Purpose

To analyze predictors of DI and its in-hospital outcomes.

Methods

National Inpatient Sample 2011–2018 database was analyzed for admissions for CIED implantation or DI. Baseline and hospital level characteristics were derived. The Chi-square test and student t-test were used for comparison of categorical and continuous variables respectively. Variables with p&lt;0.20 from univariate analysis were included in the multivariate logistic regression to identify independent predictors of DI.

Results

A total of 1,604,173 admissions for CIED implantations and 71,007 (4.4%) admissions for DI were reported during 2011–2018. There was no significant change in annual admissions for DI (range 8550 to 9307, p for trend=0.98). Those with DI were more likely to be male (69.3 vs 57%, p&lt;0.001) and had higher Charlson comorbidity index score ≥3 (46.6%-vs-36.8%, p&lt;0.001). Multivariate analysis identified post-procedural hematoma (odds ratio (OR)=3.96; 95% Confidence Interval (CI)=3.46–4.54), congestive heart failure (CHF; OR=2.80, 95% CI=2.66–2.96), age group 45–60 years (OR=2.46, 95% CI=2.30–2.63), malnutrition (OR=1.99, 95% CI=1.85–2.15), coagulopathy (OR=1.75, 95% CI=1.64–1.86), end-stage renal disease (OR=1.65, 95% CI=1.53–1.78), atrial fibrillation (OR=1.42; 95% CI=1.35–1.49), non-Hispanic race (OR=1.25; 95% CI=1.16–1.36), coronary artery disease (OR=1.21; 95% CI=1.15–1.26), and thyroid disease (OR=1.15; 95% CI=1.09–1.12) [all p&lt;0.001] as independent predictors of DI. Prevalence of CHF, malnutrition, and atrial fibrillation increased in those admitted with DI over the observation period as shown in Figure 1 (p for trend &lt;0.001). Prevalence of diabetes mellitus also increased during the observation period although it was not an independent predictor of DI (p for trend &lt;0.001). Pulmonary embolism and deep vein thrombosis were most common complications in those with DI (4.1 and 3.6% respectively). Annual in-hospital mortality ranged from 3.9 to 5.7% (mean 4.4%, p for trend=0.07).

Conclusion

DI is relatively common and continues to be associated with high morbidity and mortality. Prevalence of DI has not changed significantly despite technical and technological advances in device implantation. Evaluation of risk factors for DI and management of modifiable comorbidities may be needed to reduce the incidence of this important complication of CIED implantation.

Funding Acknowledgement

Type of funding sources: None.

Clinical outcomes in COVID-19 patients with in-hospital cardiac arrest – an insight from multi-centre data

Background

In general, rates of in-hospital cardiac arrest are reportedly 9 to 10 arrests per 1000 admissions, with survival rates of approximately 20–25%. Data regarding clinical characteristics and outcomes in patients with COVID-19 who received in-hospital CPR (cardiopulmonary resuscitation) are limited. This information can help guide end-of-life care conversations between families and health care workers based on real-world experience.

Purpose

To observe the outcomes (survival to discharged alive from the hospital) in critically sick COVID-19 patients who experienced in-hospital cardiac arrest.

Methods

This is a multi-centre institutional review board (IRB) approved retrospective study. The RT-PCR confirmed adult COVID-19 patients consecutively admitted from March 1st to April 30, 2020, were included. Data were extracted manually using the hospital's electronic medical record. The final date of follow-up to monitor clinical outcomes was January 2021.

Results

A total of 721 patients were admitted to the hospital. Of these, only 64 (8.87%) patients had “no CPR” orders.Cardiac arrest occurred in 141 (19.5%) patients. The mean duration of beginning of resuscitation was less than a minute and the mean duration of CPR was 19 minutes. The median age was 65 years; 62.4% were male. The most common co-morbidities were hypertension (66%) and diabetes mellitus (56%). The initial rhythm was non-shockable in 93.7% of patients [asystole in 48.4% and Pulseless Electrical Activity (PEA) in 45.3% of patients]. Only six (4.2%) patients had pulseless ventricular tachycardia and three (2.1%) patients had ventricular fibrillation. A total of eight patients (5.6%) survived and were discharged from the hospital; six (4.25%) had non-shockable and two (0.82%) had shockable initial rhythms. The median age of those who survived was 60 years (Figure 1).

Conclusions

Our study showed that critically sick patients with COVID-19 have a high rate of cardiac arrest and poor outcomes in those who received CPR. A non-shockable initial rhythm indicates that non-cardiac reasons might be playing a major role. These include acute respiratory insufficiency, severe sepsis, or multiorgan failure. These data should inform end-of-life care discussions between providers and patients' families.

Funding Acknowledgement

Type of funding sources: None.

Impact of gastrointestinal hemorrhage on hospital outcomes of patients with hypertrophic cardiomyopathy

Background

Patients with hypertrophic cardiomyopathy (HCM) may be at relatively high risk of gastrointestinal hemorrhage (GIH) due to acquired von Willebrand disease (aVWD) and anticoagulation for atrial fibrillation among others factors.

Purpose

We aimed to evaluate impact of GIH on in-hospital outcomes of patients with HCM.

Methods

The National Inpatient Sample reported 45,305 admissions for adults with HCM during a two-year period (2016–2017). Among them, 1,490 patients (3.3%) also had GIH. Baseline characteristics and in-hospital outcomes of the two groups were compared. Multivariable logistic regression analysis was used to assess the independent impact of GIH on in-hospital outcomes of HCM patients.

Results

Out of 45,305 HCM patients, 1490 (3.2%) also had concomitant diagnosis of GIH. HCM patients with GIH were older (70±9 vs 66±23 years), were more often male (64% vs 61%), and had higher prevalence of prior myocardial infarction (12% vs 7%, p&lt;0.001) and cirrhosis (7.1% vs 2.6%, p&lt;0.001) while being less often obese (15% vs 22%, p=0.01) or having a history of congestive heart failure (30% vs 36%, p=0.03) [Table 1]. Hospital mortality was significantly higher among those with GIH (6.4% vs 3.5%, p&lt;0.001). Multivariable logistic regression analysis identified GIH as an independent predictor of higher in-hospital mortality [adjusted odds ratio (aOR)=1.60, 95% confidence interval (CI)=1.02–2.63, p=0.001], hypovolemic shock (aOR=5.17, 95% CI=2.5–10.6, p&lt;0.001), mean length of stay (Δ +2.4 days, p&lt;0.001) and mean hospital cost (Δ +$21,162, p=0.004).

Conclusion

Adults with HCM and GIH are older, less often obese with higher prevalence of cirrhosis and prior myocardial infarction. Presence of GIH is an independent predictor of higher mortality, hypovolemic shock, length of stay and hospital cost in HCM adults admitted to hospital.

Funding Acknowledgement

Type of funding sources: None. Table 1

Impact of cardiac rhythm abnormality on hospital outcomes of patients with hypertrophic cardiomyopathy

Background

Serious cardiac arrhythmias [atrial fibrillation/flutter (AFF), and ventricular tachycardia/fibrillation (VTF)] are associated with adverse outcomes in general population of patients with hypertrophic cardiomyopathy (HCM).

Purpose

We aimed to evaluate the impact of such rhythm abnormalities on in-hospital outcomes of adults with HCM.

Methods

The National Inpatient Sample reported 45,305 admissions for adults with HCM during a two-year period (2016–2017). Among them, 21,220 patients (47%) also had AFF and/or VTF. Baseline characteristics and in-hospital outcomes of the two groups were compared. Multivariable logistic regression analysis was used to assess the independent impact of rhythm abnormalities on in-hospital outcomes of HCM patients.

Results

HCM patients with arrhythmias were older (68±26 vs 64±29 years), were more often male (43% vs 36%), and had higher prevalence of congestive heart failure (45% vs 28%), chronic kidney disease (27% vs 22%), hyperlipidemia (52% vs 48%), obstructive sleep apnea (17% vs 13%), chronic obstructive pulmonary disease (22% vs 18%) and thyroid disease (19% vs 16%) [Table 1, all p&lt;0.001]. Hospital mortality was significantly higher among those with arrhythmias (4.7% vs 2.7%, p&lt;0.05). Multivariate logistic regression analysis identified arrhythmias as an independent predictor of in-hospital mortality (adjusted odds ratio=1.51, 95% confidence interval=1.19–1.91, p=0.001), increased mean length of stay (Δ +0.75 days, p&lt;0.001) and increased mean total hospital cost (Δ +$18,263, p&lt;0.001).

Conclusion

Adults with HCM and AFF and/or VTF are older and have higher prevalence of comorbid conditions. Presence of such rhythm abnormalities is an independent predictor of higher mortality, length of stay and total cost in HCM adults admitted to hospital.

Funding Acknowledgement

Type of funding sources: None. Table 1

Rac1 activation can generate untemplated, lamellar membrane ruffles

BACKGROUND

Membrane protrusions that occur on the dorsal surface of a cell are an excellent experimental system to study actin machinery at work in a living cell. Small GTPase Rac1 controls the membrane protrusions that form and encapsulate extracellular volumes to perform pinocytic or phagocytic functions.

RESULTS

Here, capitalizing on rapid volumetric imaging capabilities of lattice light-sheet microscopy (LLSM), we describe optogenetic approaches using photoactivable Rac1 (PA-Rac1) for controlled ruffle generation. We demonstrate that PA-Rac1 activation needs to be continuous, suggesting a threshold local concentration for sustained actin polymerization leading to ruffling. We show that Rac1 activation leads to actin assembly at the dorsal surface of the cell membrane that result in sheet-like protrusion formation without any requirement of a template. Further, this approach can be used to study the complex morpho-dynamics of the protrusions or to investigate specific proteins that may be enriched in the ruffles. Deactivating PA-Rac1 leads to complex contractile processes resulting in formation of macropinosomes. Using multicolour imaging in combination with these approaches, we find that Myo1e specifically is enriched in the ruffles.

CONCLUSIONS

Combining LLSM and optogenetics enables superior spatial and temporal control for studying such dynamic mechanisms. Demonstrated here, the techniques implemented provide insight into the complex nature of the molecular interplay involved in dynamic actin machinery, revealing that Rac1 activation can generate untemplated, lamellar protrusions.

Rapid whole cell imaging reveals a calcium-APPL1-dynein nexus that regulates cohort trafficking of stimulated EGF receptors

The endosomal system provides rich signal processing capabilities for responses elicited by growth factor receptors and their ligands. At the single cell level, endosomal trafficking becomes a critical component of signal processing, as exemplified by the epidermal growth factor (EGF) receptors. Activated EGFRs are trafficked to the phosphatase-enriched peri-nuclear region (PNR), where they are dephosphorylated and degraded. The details of the mechanisms that govern the movements of stimulated EGFRs towards the PNR, are not completely known. Here, exploiting the advantages of lattice light-sheet microscopy, we show that EGFR activation by EGF triggers a transient calcium increase causing a whole-cell level redistribution of Adaptor Protein, Phosphotyrosine Interacting with PH Domain And Leucine Zipper 1 (APPL1) from pre-existing endosomes within one minute, the rebinding of liberated APPL1 directly to EGFR, and the dynein-dependent translocation of APPL1-EGF-bearing endosomes to the PNR within ten minutes. The cell spanning, fast acting network that we reveal integrates a cascade of events dedicated to the cohort movement of activated EGF receptors. Our findings support the intriguing proposal that certain endosomal pathways have shed some of the stochastic strategies of traditional trafficking and have evolved processes that provide the temporal predictability that typify canonical signaling.

Anesthetic and intensive care management of left main coronary artery to main pulmonary artery fistula diagnosed in postoperative case of tetralogy of fallot

Cases of coronary to pulmonary artery fistula are seen in patients of pulmonary atresia with ventricular septal defect (VSD). These fistulas are rarely seen in patients of Tetralogy of Fallot (TOF). In this case report, we have presented ICU management of a postoperative case of TOF, with missed diagnosis of left main coronary artery (LMCA) to main pulmonary artery (MPA) fistula.

Midterm Results of Mitral Valve Repair With Pericardial Leaflet Augmentation: A Single-Center Experience

In certain pathologies, mitral valve repair is complicated by a paucity of tissue caused by fibrosis or destruction. Utilization of autologous pericardium for leaflet augmentation may be the only option to repair these valves. We present the midterm results of mitral valve leaflet augmentation with glutaraldehyde-fixed autologous pericardium. One hundred thirty consecutive patients undergoing mitral valve repair with glutaraldehyde-fixed pericardial augmentation of leaflets were followed up clinically and by echocardiography at 6-month intervals. Mean age was 24.8 years (range 2-64). The etiology was rheumatic in 75.3%, indeterminate in 8.4%, and other in 16.1%. Out of the rheumatics, 57.1%, 24.4%, and 18.3% had combined mitral stenosis and mitral regurgitation, isolated mitral regurgitation, and mitral stenosis, respectively. About 21.5% had a recent history of rheumatic activity. Eight were operated emergently for intractable heart failure. Majority of the patients required repair of multiple components of the mitral valve apparatus. Leaflet peeling was done in 52.3%. Pericardial patch augmentation of anterior mitral leaflet, posterior mitral leaflet, or both were carried out in 61.5%, 34.6%, and 3.8% patients respectively. Sixty percent got chordal procedures, while 92.3% got annuloplasty. There were no deaths during the mean follow-up period of 28 months. Ninety-three percent of our patients were in New York Heart Association class I and II on follow-up. There were 11 repair failures. Seven patients underwent a reoperation, while 4 patients are being managed conservatively (reoperation rate 5.38%). Augmentation of mitral valve leaflets with autologous pericardium allows many significantly fibrosed and destroyed valves to be reliably repaired with good midterm durability and hemodynamics.

Effects of glargine insulin on glycemic control in patients with diabetes mellitus type II undergoing off-pump coronary artery bypass graft

Background:

The prevalence of diabetes mellitus in patients requiring coronary artery bypass grafting (CABG) is noticeably high (20%–30%). These patients have inferior perioperative outcome, reduced long-term survival, and high risk of recurrent episodes of angina. To improve perioperative outcome surgical unit defined satisfactory glycemic control is desired during this period. Hence, the aim of our study is to compare the efficacy of glargine insulin combination with continuous human insulin infusion for perioperative glycemic control in patients with diabetes undergoing CABG.

Materials and Methods:

Fifty Patients, who were posted for off-pump CABG with diabetes mellitus type II, were randomized in two group, Group I normal saline + human insulin infusion during the perioperative period, Group II (glargine group): Glargine + human insulin infusion during perioperative period.

Results:

During surgery and in the postoperative period, random blood sugar and human insulin requirement are significantly higher in control group than glargine group. Other infection, step-up antibiotics, intensive care unit (ICU) stay, and hospital stay were significantly higher in control groups in postoperative period.

Conclusion:

Our study results suggest that glargine effectively manages blood glucose level with significantly greater control over postoperative morbidity.

Management of a case of double aortic arch with tracheal compression complicated with postoperative tracheal restenosis

Tracheal stenosis in association with the double aortic arch (DAA) is uncommon; however, it carries a high risk of morbidity, mortality, and restenosis. Although surgery is the mainstay of managing a case of the DAA with tracheal stenosis, management of tracheal restenosis requires a multidisciplinary approach. In this case report, we present our successful experience in managing a child of DAA with tracheal stenosis who developed tracheal restenosis after sliding tracheoplasty of trachea.

Safe and easy method with little modification in technique is useful for successful internal jugular vein cannulation on the same side even after intra-arterial puncture without using ultrasound guidance in adult cardiac patients

Background:

The modification in technique is useful for successful right-sided internal jugular vein (IJV) cannulation on the same side even after intra-arterial puncture without using ultrasound guidance in adult patients.

Materials and Methods:

This study was carried out in total 160 adult patient from American Society of Anesthesiologists Grade II to III patients male (n = 95) and female (n = 65) who underwent cardiac surgery where cannulation was done on right sided by triple lumen catheter (7 French) using Seldinger technique.

Results:

Majority of patients were cannulated successfully by Seldinger technique with single or double attempt except for five patients in which arterial puncture occurred. All five patients were cannulated successfully on the same side with this modified technique without any significant major complications. They were managed by application of blocker at the end of arterial needle puncture without removing it. In our routine practice, we were used to removing this needle and applying compression for few minutes to prevent hematoma formation after an arterial puncture. In this study, cannula was used as a marker or guideline for the relocation of IJV on the same side and recannulation was performed by changing the direction of needle on same side lateral to the previous one and without going towards the same direction to prevent the arterial puncture again.

Conclusion:

Most simple and useful modified technique for institutes where the complications are most common with trainee doctors and in hospitals where there is no advanced facility like ultrasound-guided cannulation available. By this modification, it will be time saving, very comfortable, and user-friendly technique with high success rate.

Elective nasal continuous positive airway pressure to support respiration after prolonged ventilation in infants after congenital cardiac surgery

Background:

We sought to compare the effectiveness of oxygen (O₂) treatment administered by an O₂ mask and nasal continuous positive airway pressure (NCPAP) in infants after congenital cardiac surgery.

Methods:

In this retrospective observational study, 54 infants undergoing corrective cardiac surgery were enrolled. According to the anesthesiologist's preference, the patients ventilated for more than 48 h were either put on NCPAP or O₂ mask immediately after extubation. From pre-extubation to 24 h after treatment, arterial blood gas and hemodynamic data were measured.

Results:

After 24 h of NCPAP institution, the patients showed a significant improvement in oxygenation compared to O₂ mask group. Respiratory rate (per minute) decreased from 31.67 ± 4.55 to 24.31 ± 3.69 (P < 0.0001), PO₂ (mmHg) increased from 112.12 ± 22.83 to 185.74 ± 14.81 (P < 0.0001), and PCO₂ (mmHg) decreased from 42.88 ± 5.01 to 37.00 ± 7.22 (P < 0.0076) in patients on NCPAP. In this group, mean pediatric cardiac surgical Intensive Care Unit (PCSICU) stay was 4.72 ± 1.60 days, with only 2 (11.11%) patients requiring re-intubation.

Conclusion:

NCPAP can be used safely and effectively in infants undergoing congenital cardiac surgery to improve oxygenation/ventilation. It also reduces the work of breathing, PCSICU stay, and may reduce the likelihood of re-intubation.

Advances in the synthesis of acyclic peroxides

This review summarises the many developments in the synthesis of acyclic peroxides, with a particular focus on the past 20 years, and seeks to update organic chemists about these new approaches.

Chemodenitrification in the cryoecosystem of Lake Vida, Victoria Valley, Antarctica

Lake Vida, in the Victoria Valley of East Antarctica, is frozen, yet harbors liquid brine (~20% salt, >6 times seawater) intercalated in the ice below 16 m. The brine has been isolated from the surface for several thousand years. The brine conditions (permanently dark, -13.4 °C, lack of O₂ , and pH of 6.2) and geochemistry are highly unusual. For example, nitrous oxide (N₂ O) is present at a concentration among the highest reported for an aquatic environment. Only a minor ¹⁷ O anomaly was observed in N₂ O, indicating that this gas was predominantly formed in the lake. In contrast, the ¹⁷ O anomaly in nitrate (NO3-) in Lake Vida brine indicates that approximately half or more of the NO3- present is derived from atmospheric deposition. Lake Vida brine was incubated in the presence of ¹⁵ N-enriched substrates for 40 days. We did not detect microbial nitrification, dissimilatory reduction of NO3- to ammonium (NH4+), anaerobic ammonium oxidation, or denitrification of N₂ O under the conditions tested. In the presence of ¹⁵ N-enriched nitrite (NO2-), both N₂ and N₂ O exhibited substantial ¹⁵ N enrichments; however, isotopic enrichment declined with time, which is unexpected. Additions of ¹⁵ N-NO2- alone and in the presence of HgCl₂ and ZnCl₂ to aged brine at -13 °C resulted in linear increases in the δ¹⁵ N of N₂ O with time. As HgCl₂ and ZnCl₂ are effective biocides, we interpret N₂ O production in the aged brine to be the result of chemodenitrification. With this understanding, we interpret our results from the field incubations as the result of chemodenitrification stimulated by the addition of ¹⁵ N-enriched NO2- and ZnCl₂ and determined rates of N₂ O and N₂ production of 4.11-41.18 and 0.55-1.75 nmol L^-1  day^-1 , respectively. If these rates are representative of natural production, the current concentration of N₂ O in Lake Vida could have been reached between 6 and 465 years. Thus, chemodenitrification alone is sufficient to explain the high levels of N₂ O present in Lake Vida.

Medical students and interns' knowledge about and attitude towards homosexuality

Background and Rationale:

Medical professionals’ attitude towards homosexuals affects health care offered to such patients with a different sexual orientation. There is absence of literature that explores the attitudes of Indian medical students or physicians towards homosexuality.

Aim:

This study aimed to evaluate Indian medical students and interns’ knowledge about homosexuality and attitude towards homosexuals.

Materials and Methods:

After IEC approval and written informed consent, a cross-sectional study was conducted on a purposive sample of undergraduate medical students and interns studying in one Indian medical college. The response rate was 80.5%. Only completely and validly filled responses (N = 244) were analyzed. The participants filled the Sex Education and Knowledge about Homosexuality Questionnaire (SEKHQ) and the Attitudes towards Homosexuals Questionnaire (AHQ). SEKHQ consisted of 32 statements with response chosen from ‘true’, ‘false’, or ‘don’t know’. AHQ consisted of 20 statements scorable on a 5-point Likert scale. Multiple linear regression was used to find the predictors of knowledge and attitude.

Results:

Medical students and interns had inadequate knowledge about homosexuality, although they endorsed a neutral stance insofar as their attitude towards homosexuals is concerned. Females had more positive attitudes towards homosexuals. Knowledge emerged as the most significant predictor of attitude; those having higher knowledge had more positive attitudes.

Conclusion:

Enhancing knowledge of medical students by incorporation of homosexuality related health issues in the curriculum could help reduce prejudice towards the sexual minority and thus impact their future clinical practice.

Dumb-bell in the heart: rare case of biatrial myxoma with mitral regurgitation

Cardiac myxomas are rare intracardiac tumors, and the majority are benign myxomas involving the left atrium. We report a case of the very rare occurrence of biatrial myxoma associated with mitral regurgitation, which was successfully treated.

Effect of preoperative oral sildenafil on severe pulmonary artery hypertension in patients undergoing mitral valve replacement

Aim:

Long standing mitral valve disease is usually associated with severe pulmonary hypertension. Perioperative pulmonary hypertension is a risk factor for right ventricular (RV) failure and a cause for morbidity and mortality in patients undergoing mitral valve replacement. Phosphodiesterase 5 inhibitor-sildenafil citrate is widely used to treat primary pulmonary hypertension. There is a lack of evidence of effects of oral sildenafil on secondary pulmonary hypertension due to mitral valve disease. The study aims to assess the effectiveness of preoperative oral sildenafil on severe pulmonary hypertension and incidence of RV failure in patients undergoing mitral valve replacement surgery.

Materials and Methods:

A total of 40 patients scheduled for mitral valve replacement with severe pulmonary hypertension (RV systolic pressure (RVSP) ≥60 mmHg) on preoperative transthoracic echo were randomly treated with oral sildenafil 25 mg (N = 20) or placebo (N = 20) eight hourly for 24 h before surgery. Hemodynamic variables were measured 20 min after insertion of pulmonary artery catheter (PAC) under anesthesia (T1), 20 min at weaning from cardiopulmonary bypass (CPB) (T2) and after 1,2, and 6 h (T3, T4, T5, respectively) during the postoperative period.

Results:

Systolic and mean pulmonary artery pressure (MPAP) and pulmonary vascular resistance index (PVRI) were significantly lower (P < 0.0001) in sildenafil group at all times. Ventilation time and postoperative recovery room stay were significantly lower (P < 0.001) in sildenafil group.

Conclusion:

Sildenafil produces significant pulmonary vasodilatory effect as compared with placebo in mitral valve replacement patients with severe pulmonary hypertension. It also reduces ventilation time and intensive care unit (ICU) stay time as compared with placebo. It is concluded that sildenafil is effective in reducing pulmonary hypertension when administered preoperatively in patients with severe pulmonary hypertension undergoing mitral valve replacement surgery.

Transposition of great arteries with aortopulmonary window: our surgical experience

BACKGROUND

Transposition of the great arteries with aortopulmonary window is a rare congenital cardiac anomaly. An arterial switch operation with repair of the aortopulmonary window is the preferred operation in this subset. As the tissue between the great arteries is missing, it is considered to be a complex operation. The purpose of this study is to present our experience of a simple yet highly effective surgical technique for the management of this rare complex cardiac defect.

METHODS

We detail our experience of the surgery of this complex defect in 4 patients. Standard technique of an arterial switch operation with minor modification in excision of branch pulmonary arteries is all that is needed in approaching this complex subset. The moiety of tissue resulting from the absence of an aortopulmonary window was naturally covered by the proximal and distal neo-aortic flap tissue. The operative technique used in the 4 cases and their presentations are detailed in the text.

RESULTS

Four patients of ages 28 days, 35 days, 40 days, and 6 months were successfully operated. One patient expired on postoperative day 21. In this case, advanced age of presentation, severe pulmonary artery hypertension, and sepsis possibly caused the death. The remaining 3 patients are off medication now and are being regularly followed up.

CONCLUSIONS

In our experience early diagnosis and an arterial switch operation have been crucial in getting a favorable outcome in planning of this complex congenital heart disease.

Successful treatment of active haemorrhage from a duodenal diverticulum using surgicel (absorbable haemostat): a case report

Haemorrhage is one of the rare but serious complications of duodenal diverticula. Current methods of treatment include: endoscopy with injection therapy or hemoclip application and diverticulectomy. In this paper we present the case of a 61 year old man with life threatening haemorrhage who was managed successfully with gentle packing of a bleeding duodenal diverticulum using SURGICEL (Absorbable Haemostat). This appears to be a simple and effective way of dealing with the problem especially in situations where other methods are ineffective or inapplicable. Early surgical intervention before the development of any coagulopathy increases the chances of a successful outcome. It has not been possible to find a similar report from a thorough literature search.

Distinguishing nitrous oxide production from nitrification and denitrification on the basis of isotopomer abundances

The intramolecular distribution of nitrogen isotopes in N2O is an emerging tool for defining the relative importance of microbial sources of this greenhouse gas. The application of intramolecular isotopic distributions to evaluate the origins of N2O, however, requires a foundation in laboratory experiments in which individual production pathways can be isolated. Here we evaluate the site preferences of N2O produced during hydroxylamine oxidation by ammonia oxidizers and by a methanotroph, ammonia oxidation by a nitrifier, nitrite reduction during nitrifier denitrification, and nitrate and nitrite reduction by denitrifiers. The site preferences produced during hydroxylamine oxidation were 33.5 +/- 1.2 per thousand, 32.5 +/- 0.6 per thousand, and 35.6 +/- 1.4 per thousand for Nitrosomonas europaea, Nitrosospira multiformis, and Methylosinus trichosporium, respectively, indicating similar site preferences for methane and ammonia oxidizers. The site preference of N2O from ammonia oxidation by N. europaea (31.4 +/- 4.2 per thousand) was similar to that produced during hydroxylamine oxidation (33.5 +/- 1.2 per thousand) and distinct from that produced during nitrifier denitrification by N. multiformis (0.1 +/- 1.7 per thousand), indicating that isotopomers differentiate between nitrification and nitrifier denitrification. The site preferences of N2O produced during nitrite reduction by the denitrifiers Pseudomonas chlororaphis and Pseudomonas aureofaciens (-0.6 +/- 1.9 per thousand and -0.5 +/- 1.9 per thousand, respectively) were similar to those during nitrate reduction (-0.5 +/- 1.9 per thousand and -0.5 +/- 0.6 per thousand, respectively), indicating no influence of either substrate on site preference. Site preferences of approximately 33 per thousand and approximately 0 per thousand are characteristic of nitrification and denitrification, respectively, and provide a basis to quantitatively apportion N2O.

Isotopic ((13)C) analysis of dissolved organic carbon in stream water using an elemental analyzer coupled to a stable isotope ratio mass spectrometer

A technique for measurement of the stable isotope composition of dissolved organic carbon (DOC) in stream water, using an elemental analyzer (EA) coupled to an isotope ratio mass spectrometer (IRMS), is described. Stream water samples were concentrated by rotary evaporation, acidified to remove dissolved inorganic carbon (DIC), and dried in silver cups prior to analysis. Precision was evaluated with standards (alanine and humic acid), and with stream water samples with varying (13)C enrichment. Standards and samples were also prepared in sealed quartz tubes for high-temperature combustion (HTC) and analyzed by dual inlet for comparison. The delta(13)C values of natural abundance standards and samples measured by the two techniques differed by <or=0.3 per thousand. Isotopically enriched stream water samples analyzed using the EA and HTC methods had comparable delta(13)C and atom % values (differed by <or=6%). Expensive quartz vessels and the extensive time required for sample lyophilization, combustion and cryogenic separation of combustion products before isotopic analysis for the HTC method are eliminated with the EA method. Overall, the EA method is simpler, faster, and more economical than the HTC method, and it can be used for (13)C-enriched as well as natural abundance samples.

Nitrogen isotopomer site preference of N2O produced by Nitrosomonas europaea and Methylococcus capsulatus Bath

The relative importance of individual microbial pathways in nitrous oxide (N(2)O) production is not well known. The intramolecular distribution of (15)N in N(2)O provides a basis for distinguishing biological pathways. Concentrated cell suspensions of Methylococcus capsulatus Bath and Nitrosomonas europaea were used to investigate the site preference of N(2)O by microbial processes during nitrification. The average site preference of N(2)O formed during hydroxylamine oxidation by M. capsulatus Bath (5.5 +/- 3.5 per thousand) and N. europaea (-2.3 +/- 1.9 per thousand) and nitrite reduction by N. europaea (-8.3 +/- 3.6 per thousand) differed significantly (ANOVA, f((2,35)) = 247.9, p = 0). These results demonstrate that the mechanisms for hydroxylamine oxidation are distinct in M. capsulatus Bath and N. europaea. The average delta(18)O-N(2)O values of N(2)O formed during hydroxylamine oxidation for M. capsulatus Bath (53.1 +/- 2.9 per thousand) and N. europaea (-23.4 +/- 7.2 per thousand) and nitrite reduction by N. europaea (4.6 +/- 1.4 per thousand) were significantly different (ANOVA, f((2,35)) = 279.98, p = 0). Although the nitrogen isotope value of the substrate, hydroxylamine, was similar in both cultures, the observed fractionation (delta(15)N) associated with N(2)O production via hydroxylamine oxidation by M. capsulatus Bath and N. europaea (-2.3 and 26.0 per thousand, respectively) provided evidence that differences in isotopic fractionation were associated with these two organisms. The site preferences in this study are the first measured values for isolated microbial processes. The differences in site preference are significant and indicate that isotopomers provide a basis for apportioning biological processes producing N(2)O.

Effect of honey on the growth of and acid production by human intestinal Bifidobacterium spp.: an in vitro comparison with commercial oligosaccharides and inulin

Five human intestinal Bifidobacterium spp., B. longum, B. adolescentis, B. breve, B. bifidum, and B. infantis, were cultured in reinforced clostridial medium (control) and in reinforced clostridial medium supplemented with 5% (wt/vol) honey, fructooligosaccharide (FOS), galactooligosaccharide (GOS), and inulin. Inoculated samples were incubated anaerobically at 37degrees C for 48 h. Samples were collected at 12-h intervals and examined for specific growth rate. Levels of fermentation end products (lactic and acetic acids) were measured by high-pressure liquid chromatography. Honey enhanced the growth of the five cultures much like FOS, GOS, and inulin did. Honey, FOS, GOS, and inulin were especially effective (P < 0.05) in sustaining the growth of these cultures after 24 h of incubation as compared with the control treatment. Overall, the effects of honey on lactic and acetic acid production by intestinal Bifidobacterium spp. were similar to those of FOS, GOS, and inulin.

Growth and viability of commercial Bifidobacterium spp. in honey-sweetened skim milk

Two commercial Bifidobacterium bifidum (Bf-1 and Bf-6) were cultured in 12% (wt/vol) reconstituted nonfat dry milk (NDM) containing 5% (wt/wt) honey, sucrose, fructose, or glucose. Inoculated samples were incubated anaerobically at 37 degrees C for 48 h. Samples were collected at 12-h intervals and examined for (i) specific growth rate, (ii) pH, and (iii) levels of fermentation end products (lactic and acetic acids) as measured by high-performance liquid chromatography (HPLC). Viability of the organisms during 28 days of refrigerated storage at 4 degrees C was also assessed at 7-day intervals. Growth promotion and acid production were greatest when Bf-1 and Bf-6 were grown in the presence of honey. For both Bf-1 and Bf-6, retention of viability was greatest up to 14 days of refrigerated storageat 4 degrees C when they were grown and stored in the presence of honey compared to other sweeteners.

Polyclonal-antibody-based ELISA to detect milk alkaline phosphatase

Polyclonal antibodies (PAb) prepared against bovine milk alkaline phosphatase (ALP) were used to develop a competitive indirect (CI) ELISA. Anti-ALP PAb were specific for milk ALP and did not react with ALP from E. coli or bovine and calf intestinal mucosa. Anti-ALP PAb were 20% cross-reactive with bovine placenta ALP. The anti-ALP antibodies also did not recognize bovine serum albumin, acid glycoprotein, ovalbumin, ferritin, and casein, although some cross-reactivity was observed with whey protein isolate. Anti-ALP PAbs reacted with deglycosylated native ALP, but did not recognize ALP denatured at 100 degrees C in 2% SDS or deglycosylated denatured ALP. When buffered solutions of milk ALP were heated at 70 degrees C, ALP activity decreased at a faster rate than ALP content determined by CI-ELISA. The ELISA differentiated between native and heat denatured ALP. Further studies are warranted to determine if an ELISA can be used to verify pasteurization of fluid milk.