Anatomical variations in coronary venous drainage: challenges and solutions in delivering cardiac resynchronisation therapy

Funding Acknowledgements

Type of funding sources: None.

Background

Cardiac resynchronisation therapy (CRT) is the cornerstone of heart failure management. Delivery of a left ventricular lead can occur in a small proportion of patients undermining the benefits of this treatment. Abnormal coronary venous anatomy is a contributing factor to this failure. Although epicardial lead placement is available, this patient cohort requiring CRT is subject to higher peri-operative morbidity and mortality than the general population; a transvenous approach is preferable.

Purpose

To investigate the abnormalities of the coronary venous system in candidates for cardiac resynchronization therapy (CRT) and describe methods for circumventing the resulting difficulties.

Methods

From 4 implanting institutes, data of all CRT implants between October 2008-October 2020 were screened for abnormal cardiac venous anatomy, defined as an anatomical variation not conforming to the accepted ‘normal’ anatomy. Patient demographics, procedural detail and subsequent left ventricle (LV) lead pacing indices were collected.

Results

From a total of 3548 CRT implants, 15 (0.42%) patients (80% male) of 72.2±10.6 years in age with a LV ejection fraction of 34±10.3% were identified to have had an abnormal cardiac venous anatomy over the study period. There were 13 cases of persistent left side superior vena cava (pLSVC), 5 of which had coronary sinus ostium atresia (CSOA) including 2 with an ‘unroofed’ coronary sinus (CS); 1 patient had a unique anomalous origin of the CS and 1 patient had an isolated CSOA. In total 14 patients (60% repeat attempt) had successful percutaneous implant under general anaesthesia (46.7%) via the cephalic vein (59.1%), using the femoral approach (53.3%) for levophase venography and/or pull-through, including 1 case of endocardial LV implant. Pacing follow-up over 37.64±37.6 months demonstrated LV lead threshold between 0.62-2.9 volts (pulsewidth 0.4-1.5 milliseconds) in all cases; 5 patients died within 2.92±1.6 years of successful implant.

Conclusion

CRT devices can be implanted percutaneously even in the presence of substantial abnormalities of coronary venous anatomy. Alternative routes of venous access may be required.

Oesophageal protection during AF ablation: real world registry data and mechanisms behind the therapeutic effect of tissue cooling

Funding Acknowledgements

Type of funding sources: None.

Background

Oesophageal protection using a dedicated device to provide controlled active thermal protection of the oesophagus during atrial fibrillation ablation has been shown to be effective at reducing endoscopically detected oesophageal lesions. Real world registry data of this device and established evidence on the effect of cooling on localized tissue after thermal injury have been under review.

Purpose

To determine the safety of an oesophageal temperature control device by a review of real-world registry data on its clinical use during catheter ablation procedures and to clarify basic mechanisms of its therapeutic action by a literature review of scientific studies on cooling in the context of thermal injury.

Methods

The United States Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE), FDA Medical and Radiation Emitting Device Recalls, the Medicines and Healthcare products Regulatory Agency (MHRA) Medical Device Alerts and SwissMedic records of Field Safety Corrective Actions (FSCA) databases were reviewed for any device-related adverse events. A systematic literature review was conducted to clarify the findings from studies investigating the physiological processes behind the therapeutic effect of cooling after tissue thermal injury.

Results

Of over 20,000 oesophageal temperature control devices clinically used, 7976 were recorded as having been used for the purpose of oesophageal protection during left atrial catheter ablations. No adverse events occurred related to its use during left atrial catheter ablations. No case of clinically significant oesophageal injury was reported in a patient who had been protected by the oesophageal temperature control device. 208 research articles retrieved from PubMed and MEDLINE that met the search criteria were reviewed. The common finding in all the studies was that cooling had an anti-inflammatory and restorative effect via modulation of several immune-mediated pathways, local cellular function and genetic expression.

Conclusions

There have been no adverse events reported to date in real world clinical use of an oesophageal temperature control device during left atrial catheter ablations, for the purpose of active thermal protection. Literature review data suggests that there are complex biophysical and cellular effects from cooling that leads to its therapeutic effect but further work is required to define the mechanisms of action of thermal protection in this specific context.

Randomised comparison of achieve and traditional circular mapping catheters in cryoballoon ablation: results at up to a decade

Funding Acknowledgements

Type of funding sources: None.

Background

A single-centre trial randomised patients to the use of the Achieve mapping catheter or a traditional circular mapping catheter during cryoballoon procedures for paroxysmal atrial fibrillation (AF) in 2011-2014. Long-term outcomes from the cohort were determined in 2021.

Purpose

To evaluate the determinants of long-term outcome of ablation for paroxysmal AF.

Methods

Patient and study procedure characteristics and clinical outcomes were determined, including mapping catheter assignment, model of cryoballoon used, AF recurrence, repeat ablations required, findings at repeat ablation long term survival of the patient.

Results

Of 102 patients in the original study, 98 had long-term (4.11+/-2.82 years) follow up data available. 35 patients (35.7%) had AF recurrence, giving a long-term success rate at 64.3% after 1 ablation, increasing to 81.6% after repeat ablation. Of the study cohort n=8 (8.16%) died at a median of 4.9 years after ablation (IQR:1.7-5.7). 25/98 (25.5%) patients had a second ablation and 7 (7.1%) had a third or more ablations. Those who had AF recurrence were older, with a higher prevalence of prior ischaemic heart disease and cardiac device implantation (p=0.02-0.03). After multi-variate analysis, a prior implanted cardiac device was the only significant predictor of recurrence (p=0.03).

Conclusion

Long-term outcomes after a 1st time PAF cryoablation were similar regardless of the type of mapping catheter used, the generation of cryoballoon, and traditional procedure endpoints. AF recurrences were more often detected in older patients with a history of ischaemic heart disease and implanted cardiac devices.

Transvenous lead revision for cardiac perforation: a single centre experience

Funding Acknowledgements

Type of funding sources: None.

Background

Cardiac perforation is an uncommon but life-threatening complication of cardiac implantable electronic device (CIED) implantation. Management strategy commonly relies on diagnostic Computed Tomography (CT) imaging and cardiac surgery. Emerging evidence has indicated a diversion from this approach. Transvenous culprit lead revision has been shown to be safe and efficacious in limited series.

We sought to evaluate the outcomes of transvenous lead revision in patients with cardiac perforation.

Method

Data was collected retrospectively of patients admitted to a single tertiary centre with CIED-related cardiac perforation between December 2013 – October 2019. Transvenous lead revision was performed as standard with cardiac surgery on standby. Patient demographics, use of CT imaging, method of removal and 30-day outcomes were recorded.

Results

Of the 46 recorded CIED-related cardiac perforations, the majority occurred in female patients (63%) and hypertensives (61%), whilst a proportion had cancer (20%) and ischaemic heart disease (30%). The culprit in most cases was a standard pacing lead (92%) of an active fixation (98%) in the right ventricle (80%) positioned at the ventricular apex (65%). The median time to presentation from implant was 14 days [IQR 4-50 days] with chest pain (44%); abnormal pacing indices was highly prevalent (95%) whilst a pericardial effusion was noted in the majority of cases (57%). CT scanning was performed in 19 cases (41%) for various indications but deemed essential in only 4, all of which had non-diagnostic pacing indices and imaging. Chest X-ray (CXR) found clear perforation, lead displacement or pleural effusion in 74% of cases, whilst an echocardiogram found these in 64% of cases. The culprit lead was replaced in the majority of cases (87%) under local anaesthesia (76%) with surgical backup. The median hospital stay was 7 days [IQR 3-10 days] with zero procedural and 30-day mortality.

Conclusion

Transvenous lead revision for CIED-related cardiac perforation is safe and efficacious. CT modality for diagnostic purposes is useful in providing incremental value in a minority of cases; patients with non-diagnostic pacing parameters and non-CT imaging benefit most from this.

A registry review of 2532 catheter ablations for atrial fibrillation using active thermal protection

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Dr Leung has received research support from Attune Medical (Chicago, IL). Dr Gallagher has received research funding from Attune Medical (Chicago, IL).

Background

  Thermal injury to the oesophagus causes a spectrum of adverse effects after ablation for atrial fibrillation (AF); at the most severe end, atrio-oesophageal fistula carries a high mortality rate. Controlled active thermal protection in the oesophagus during ablation is the most promising method of oesophageal protection. Randomized evidence from the IMPACT trial (NCT03819946) showed an 83.4% reduction in endoscopically detected oesophageal lesions compared to standard care when an oesophageal temperature control device was used to control the local temperature. The IMPACT patients who were randomized to the use of the device had no adverse event related to its use.  Real world registry data on applications of this device have not previously been available. 

Purpose

To determine the safety of an oesophageal temperature control device by review of real-world registry data on its clinical use and any reported device-related adverse events.

Methods

  We reviewed the following databases for any reported oesophageal temperature control device-related complications: The United States Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE), FDA Medical and Radiation Emitting Device Recalls, the Medicines and Healthcare products Regulatory Agency (MHRA) Medical Device Alerts and SwissMedic records of Field Safety Corrective Actions (FSCA). An internal registry (post-marketing follow up) database maintained by the manufacturer of the device was used to quantify the number used for each indication.  Reported events were reviewed and catalogued for description and identification of any events related to its use in the cardiac electrophysiology lab. The IMPACT study patients were reviewed for any device-related events.

Results

  Of the 13, 284 oesophageal temperature control devices used, 2532 were recorded as having been used for the purpose of oesophageal protection during catheter ablation for AF.  A total of 5 events associated with the device were identified, all from the MAUDE database.  Three were from 2017, one from 2018, and one from 2019.  All involved its use in critical care or trauma patients and were related to user error or contraindicated patient selection; none resulted in serious harm to the patient. No adverse events occurred related to its use in the cardiac electrophysiology lab. No case of clinically significant oesophageal injury was reported in a patient who had been protected by the oesophageal temperature control device.

Conclusions

Real world registry data has shown no adverse events reported to date in over 2500 uses of an oesophageal temperature control device in the cardiac electrophysiology lab, for the purpose of active thermal protection. This data supports the randomized trial evidence of its clinical effectiveness. Abstract Figure. Oesophageal active thermal protection

Advancement in our understanding of immune response against Encephalitozoon infection

Microsporidia are a group of obligate, intracellular, spore-forming eukaryotic pathogens, which predominantly infects immunocompromised individuals worldwide. Encephalitozoon spp. is one of the most prevalent microsporidia known to infect humans. Host immune system plays a major role in combating pathogens including Encephalitozoon spp. infecting humans. Both innate and adaptive arms of host immune system work together in combating Encephalitozoon infection. Researchers are conducting studies to elucidate the role of both arms of immune system against Encephalitozoon infection. In addition to cell-mediated adaptive immunity, role of innate immunity is also being highlighted in clearance of Encephalitozoon spp. from host body. Therefore, the current review will give a clear and consolidated update on the role of innate as well as adaptive immunity in protection against Encephalitozoon spp.

Long-Term Effects of Very Low Dose Particle Radiation on Gene Expression in the Heart: Degenerative Disease Risks

Compared to low doses of gamma irradiation (γ-IR), high-charge-and-energy (HZE) particle IR may have different biological response thresholds in cardiac tissue at lower doses, and these effects may be IR type and dose dependent. Three- to four-month-old female CB6F1/Hsd mice were exposed once to one of four different doses of the following types of radiation: γ-IR ¹³⁷Cs (40-160 cGy, 0.662 MeV), ¹⁴Si-IR (4-32 cGy, 260 MeV/n), or ²²Ti-IR (3-26 cGy, 1 GeV/n). At 16 months post-exposure, animals were sacrificed and hearts were harvested and archived as part of the NASA Space Radiation Tissue Sharing Forum. These heart tissue samples were used in our study for RNA isolation and microarray hybridization. Functional annotation of twofold up/down differentially expressed genes (DEGs) and bioinformatics analyses revealed the following: (i) there were no clear lower IR thresholds for HZE- or γ-IR; (ii) there were 12 common DEGs across all 3 IR types; (iii) these 12 overlapping genes predicted various degrees of cardiovascular, pulmonary, and metabolic diseases, cancer, and aging; and (iv) these 12 genes revealed an exclusive non-linear DEG pattern in ¹⁴Si- and ²²Ti-IR-exposed hearts, whereas two-thirds of γ-IR-exposed hearts revealed a linear pattern of DEGs. Thus, our study may provide experimental evidence of excess relative risk (ERR) quantification of low/very low doses of full-body space-type IR-associated degenerative disease development.

Patient outcomes after AF ablation using Ablation Index technology with oesophageal protection: insight from the IMPACT study

Background

Atrio-oesophageal fistula formation accounts for the majority of AF ablation-related morbidity and mortality. Thermal injury to the oesophagus can be significantly reduced by application of oesophageal cooling for protection during AF ablation. The effect of this method of oesophageal protection in patients receiving radiofrequency (RF) ablation guided by Ablation Index technology is currently unknown.

Objective

To investigate the ability of a temperature control device to protect the oesophagus from ablation-related thermal injury in patients receiving AF ablation guided by Ablation Index technology.

Methods

The IMPACT study is a single-centre, prospective, double-blind randomized controlled trial, which investigated the ability of a controlled method of oesophageal cooling to protect the oesophagus from ablation-related thermal injury. The EnsoETM device was used to deliver oesophageal cooling. This method was compared in a 1:1 randomization to a control group of standard practice utilizing a single-sensor temperature probe. In the study group, the device was used to keep the luminal temperature at 4°C during RF ablation. All participants received AF ablation using Ablation Index technology at posterior and anterior settings (30W at 350–400 and 40W at 450–500, respectively). Endoscopic examination was performed within 7 days post-ablation and oesophageal injury was graded. The patient and the endoscopist were blinded to the randomization. Structured clinical follow up occurred after 3 months post-ablation; both patient and follow up clinician were blinded.

Results

We recruited 188 patients, of whom 120 underwent endoscopic evaluation. Thermal injury to the mucosa was significantly more common in the control group than in those receiving oesophageal protection (12/60 versus 2/60; P=0.008). There was no difference between groups in RF time, lesion duration, force, power and combined ablation index (P value range= 0.2–0.9). Procedure and fluoroscopy duration were similar (P=0.97, P=0.91 respectively). The majority of those who passed through the 1st follow up evaluation (n=136) did not have gastrointestinal or chest pain symptoms post ablation and there was no difference between the randomized groups. Only 4.4% overall had severe symptoms and they were poorly correlated against those who sustained mucosal lesions. AF recurrence was similar in both groups (8% vs 8.8%). There were 2 cases of vascular trauma needing intervention in the control group and 1 case of conservatively managed pericardial effusion in the protected group only. Clinical and endoscopy findings did not report any EnsoETM device-related trauma.

Conclusion

Thermal protection of the oesophagus significantly reduces ablation-related thermal injury compared to standard care when ablation is performed using radiofrequency with Ablation Index technology. This method of oesophageal protection is safe and does not compromise the efficacy of the ablation procedure.

Endoscopy findings and patient symptoms.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): 1. Public hospital: St. George's NHS Foundation Trust; 2. Private company: Attune Medical (Chicago, IL)

Celiac Disease in Indian Children and Adolescents with Type 1 Diabetes

To estimate the time trend and prevalence of celiac disease in 208 children with type 1 diabetes by retrospective case review. Tissue transglutaminase (TTG IgA) levels were done within the first six months of diagnosis and annually on follow-up. Celiac disease was diagnosed in 35 (16.8%; 3 before diagnosis, 18 at initial screening and 14 on follow-up). 14 subjects with negative TTG serology at presentation, developed celiac disease after 3.9 (2.9) years (range 1.4 - 12.6 years, 85.7% within 5 years). Celiac disease is common in Indian children and adolescents with type I diabetes, developing in most within five years of diagnosis.

Macrophages of diverse phenotypes drive vascularization of engineered tissues

Macrophages are key contributors to vascularization, but the mechanisms behind their actions are not understood. Here, we show that diverse macrophage phenotypes have distinct effects on endothelial cell behavior, with resulting effects on vascularization of engineered tissues. In Transwell coculture, proinflammatory M1 macrophages caused endothelial cells to up-regulate genes associated with sprouting angiogenesis, whereas prohealing (M2a), proremodeling (M2c), and anti-inflammatory (M2f) macrophages promoted up-regulation of genes associated with pericyte cell differentiation. In 3D tissue-engineered human blood vessel networks in vitro, short-term exposure (1 day) to M1 macrophages increased vessel formation, while long-term exposure (3 days) caused regression. When human tissue-engineered blood vessel networks were implanted into athymic mice, macrophages expressing markers of both M1 and M2 phenotypes wrapped around and bridged adjacent vessels and formed vessel-like structures themselves. Last, depletion of host macrophages inhibited remodeling of engineered vessels, infiltration of host vessels, and anastomosis with host vessels.

Factors Associated With Cerebral Edema at Admission in Indian Children with Diabetic Ketoacidosis

OBJECTIVE

To evaluate the time course and predictors of cerebral edema in diabetic ketoacidosis (DKA).

METHODS

Review of hospital records of 107 episodes of DKA between January 2013 to March 2019.

RESULTS

Cerebral edema was identified in 26 (24.3%; 22 at presentation and 4 during treatment). Cerebral edema at presentation was associated with lower (<10 mmHg) arterial carbon dioxide (OR 3.6, 95% CI 1.0,12.7; P=0.04), prior fluid treatment (OR 4.7, 95% CI 1.8,12.7; P=0.001) and new onset diabetes (OR 3.5, 95% CI 1.1,11.1; P=0.03). Prior fluid was the only significant predictor on multivariate analysis (P=0.013). Cerebral edema resulted in a longer ICU stay [4.1 (2.3) vs 1.8 (0.9) d; P<0.001].

CONCLUSIONS

Cerebral edema at admission is common in Indian children with DKA and should be suspected with severe metabolic acidosis and inappropriate prior fluid treatment.

Use of Gonadotropin-Releasing Hormone Analogs in Children: Update by an International Consortium

This update, written by authors designated by multiple pediatric endocrinology societies (see List of Participating Societies) from around the globe, concisely addresses topics related to changes in GnRHa usage in children and adolescents over the last decade. Topics related to the use of GnRHa in precocious puberty include diagnostic criteria, globally available formulations, considerations of benefit of treatment, monitoring of therapy, adverse events, and long-term outcome data. Additional sections review use in transgender individuals and other pediatric endocrine related conditions. Although there have been many significant changes in GnRHa usage, there is a definite paucity of evidence-based publications to support them. Therefore, this paper is explicitly not intended to evaluate what is recommended in terms of the best use of GnRHa, based on evidence and expert opinion, but rather to describe how these drugs are used, irrespective of any qualitative evaluation. Thus, this paper should be considered a narrative review on GnRHa utilization in precocious puberty and other clinical situations. These changes are reviewed not only to point out deficiencies in the literature but also to stimulate future studies and publications in this area.

Cardiovascular protection in females linked to estrogen-dependent inhibition of arterial stiffening and macrophage MMP12

Arterial stiffening is a consequence of aging and a cholesterol-independent risk factor for cardiovascular disease (CVD). Arterial stiffening and CVD show a sex bias, with men more susceptible than premenopausal women. How arterial stiffness and sex interact at a molecular level to confer risk of CVD is not well understood. Here, we used the sexual dimorphism in LDLR-null mice to show that the protective effect of female sex on atherosclerosis is linked to reduced aortic stiffness and reduced expression of matrix metalloproteinase-12 (MMP12) by lesional macrophages. Deletion of MMP12 in LDLR-null mice attenuated the male sex bias for both arterial stiffness and atherosclerosis, and these effects occurred despite high serum cholesterol. Mechanistically, we found that oxidized LDL stimulates secretion of MMP12 in human as well as mouse macrophages. Estrogen antagonizes this effect by downregulating MMP12 expression. Our data support cholesterol-independent causal relationships between estrogen, oxidized LDL-induced secretion of macrophage MMP12, and arterial stiffness that protect against atherosclerosis in females and emphasize that reduced MMP12 functionality can confer atheroprotection to males.

The Role of Leukocytes in Diabetic Cardiomyopathy

Diabetes is predominant risk factor for cardiovascular diseases such as myocardial infarction and heart failure. Recently, leukocytes, particularly neutrophils, macrophages, and lymphocytes, have become targets of investigation for their potential role in a number of chronic inflammatory diseases such as diabetes and heart failure. While leukocytes contribute significantly to the progression of diabetes and heart failure individually, understanding their participation in the pathogenesis of diabetic heart failure is much less understood. The present review summarizes the role of leukocytes in the complex interplay between diabetes and heart failure, which is critical to the discovery of new targeted therapies for diabetic cardiomyopathy.

Effects of Non-thermal, Non-cavitational Ultrasound Exposure on Human Diabetic Ulcer Healing and Inflammatory Gene Expression in a Pilot Study

The purpose of this clinical study was to assess, in a limited patient population, the potential for a novel advanced wound care treatment based on low-frequency (20 kHz) low-intensity (spatial peak temporal peak intensity <100 mW/cm²; i.e., pressure amplitude of 55 kPa) ultrasound (LFLI-US), to affect wound closure rate in human diabetic foot ulcers (DFUs) and to effect changes in the relative expression of pro-inflammatory and anti-inflammatory genes. The ratio of expression of these genes, termed the M1/M2 score because it was inspired by the transition of macrophages from pro-inflammatory (M1) to anti-inflammatory (M2) phenotypes as wound healing progresses, was previously presented as a potential healing indicator for DFUs treated with the standard of care. We previously found that non-cavitational, non-thermal LFLI-US delivered with a pulse repetition frequency of 25 Hz was effective at improving wound healing in a pilot study of 20 patients with chronic venous ulcers. In this study, we assessed the potential for weekly LFLI-US exposures to affect wound healing in patients with diabetic ulcers, and we analyzed temporal changes in the M1/M2 score in debrided diabetic wound tissue. Although this was a limited patient population of only 8 patients, wounds treated with LFLI-US exhibited a significantly faster reduction in wound size compared with sham-treated patients (p < 0.001). In addition, the value of the M1/M2 score decreased for all healing diabetic ulcers and increased for all non-healing diabetic ulcers, suggesting that the M1/M2 score could be useful as an indicator of treatment efficacy for advanced DFU treatments. Such an indicator would facilitate clinical decision making, ensuring optimal wound management and thus contributing to reduction of health care expenses. Moreover, the results presented may contribute to an understanding of the mechanisms underlying ultrasonically assisted chronic wound healing. Knowledge of these mechanisms could lead to personalized or patient-tailored treatment.

Abstract 248: β2 Adrenergic Receptor Deletion Alters Leukocyte Subtype Inter Organ Localization and Survival Following Myocardial Infarction

Leukocytes are rapidly recruited to the heart following myocardial ischemia (MI) where they regulate a wide variety of cardiac remodeling responses including cardiomyocytes survival and infarct stabilization. We recently reported that mice lacking β2AR expression in cells of hematopoietic origin displayed 100% mortality via cardiac rupture associated with decreased post-MI leukocyte recruitment. Beyond a deficiency in recruitment, we hypothesized that β2AR expression in leukocytes is necessary to promote their survival in the milieu of ischemic cardiac tissue. To assess this, we generated chimeric wild-type (WT) mice harboring either WT or β2ARKO bone marrow via transplantation (BMT), subjected them to sham or MI surgery and assessed leukocyte sub-type localization and survival at different time points. At 1d post-MI there was an increase in TUNEL staining of both cardiomyocytes and CD45 + cells in β2ARKO BMT versus WT BMT hearts. To begin to identify the leukocyte populations that account for this increased death response, we performed flow cytometry analysis of cells isolated from bone marrow, blood, spleen and heart. Congruent with our previous findings, there was less accumulation of CD45 + and CCR2 + leukocytes, Ly6G + neutrophils and Ly6C + monocytes in the heart and peripheral blood 4d post-MI in β2ARKO BMT mice, with reciprocally increased levels of these populations in the spleen. Annexin V staining confirmed that despite fewer CD45 + cells being recruited to the heart post-MI, a proportionally higher number of these cells were apoptotic. Further, we detected a generalized enhancement in the apoptosis of CD45 + leukocytes, monocytes and neutrophils in particular, within the bone marrow and spleen. These data suggest that, in addition to decreasing the recruitment of leukocytes to the heart following MI, the absence of β2AR impairs their survival, exacerbating the loss of cardiomyocytes and cardiac repair.

Small molecule disruption of G protein βγ subunit signaling reprograms human macrophage phenotype and prevents autoimmune myocarditis in rats

The purpose of this study was to determine whether blocking of G protein βγ (Gβγ) signaling halts heart failure (HF) progression by macrophage phenotype manipulation. Cardiac Gβγ signaling plays a crucial role in HF pathogenesis. Previous data suggested that inhibiting Gβγ signaling reprograms T helper cell 1 (Th1) and Th2 cytokines, suggesting that Gβγ might be a useful drug target for treating HF. We investigated the efficacy of a small molecule Gβγ inhibitor, gallein, in a clinically relevant, experimental autoimmune myocarditis (EAM) model of HF as well as in human macrophage phenotypes in vitro. In the myocardium of HF patients, we observed that G protein coupled receptor kinase (GRK)2 levels were down-regulated compared with healthy controls. In rat EAM, treatment with gallein effectively improved survival and cardiac function, suppressed cardiac remodeling, and further attenuated myocardial protein expression of GRK2 as well as high mobility group box (HMGB)1 and its cascade signaling proteins. Furthermore, gallein effectively inhibited M1 polarization and promoted M2 polarization in vivo in the EAM heart and in vitro in human monocyte-derived macrophages. Taken together, these data suggest that the small molecule Gβγ inhibitor, gallein, could be an important pharmacologic therapy for HF as it can switch the phenotypic reprogramming from M1 to M2 phenotype in a rat model of EAM heart and in human macrophages.

Drug delivery strategies to control macrophages for tissue repair and regeneration

Tissue repair and regeneration is a complex process. Our bodies have an excellent capacity to regenerate damaged tissues in many situations. However, tissue healing is impaired in injuries that exceed a critical size or are exacerbated by chronic inflammatory diseases like diabetes. In these instances, biomaterials and drug delivery strategies are often required to facilitate tissue regeneration by providing physical and biochemical cues. Inflammation is the body's response to injury. It is critical for wound healing and biomaterial integration and vascularization, as long as the timing is well controlled. For example, chronic inflammation is well known to impair healing in chronic wounds. In this review, we highlight the importance of a well-controlled inflammatory response, primarily mediated by macrophages in tissue repair and regeneration and discuss various strategies designed to promote regeneration by controlling macrophage behavior. These strategies include temporally controlled delivery of anti-inflammatory drugs, delivery of macrophages as cellular therapy, controlled release of cytokines that modulate macrophage phenotype, and the design of nanoparticles that exploit the inherent phagocytic behavior of macrophages. A clear outcome of this review is that a deeper understanding of the role and timing of complex macrophage phenotypes or activation states is required to fully harness their abilities with drug delivery strategies.

Multimodal approach for diagnosis of bacterial etiology in brain abscess

BACKGROUND AND PURPOSE

Proton magnetic resonance spectroscopy (PMRS) has high sensitivity and specificity for the detection of pyogenic brain abscess and the categorization of bacteria. But the metabolite patterns failed to evaluate the etiology of disease when the culture results are sterile. The aim of the present study is to compare the multimodality techniques viz., conventional culture, MR spectroscopy and 16S rRNA PCR and sequencing for rapid diagnosis of etiology in brain abscess and evaluate the PMRS in culture sterile samples and also demonstrate the sensitivity and specificity of these techniques.

METHODS

Thirty five patients underwent MRI on a 3T MRI and in-vivo PMRS for the diagnosis and evaluation of various resonances of metabolites such as lipid (LIP), lactate (LAC), acetate (AC), amino acid (AC), succinate (SUC). Pus was collected for identification of etiologic agents by culture and molecular method.

RESULTS

In 35 samples, metabolite patterns were as follows: LIP/LAC/AA, n=17, LIP/LAC/AA/SUC with or without AC, n=17 and LIP/LAC/AA/AC, n=1. Culture showed bacterial growth in 22 samples (18 aerobic/facultative anaerobic, 9 anaerobic) whereas molecular method was detected 26 aerobic/facultative anaerobic, 13 anaerobic, 4 microaerophilic bacteria. Among the 13 sterile samples, molecular method detected 16 microorganisms along with 3 mixed infections and PMRS recognized metabolite patterns as LIP/LAC/AA, n= 5 and LIP/LAC/AA/SUC with or without AC, n=8. The sensitivity of in-vivo PMRS in sterile samples was 100% and 75%, and specificity was 75% and 100% for aerobic and anaerobic organisms respectively.

CONCLUSION

Based on metabolite resonances, PMRS can detect slow growing and fastidious organisms and classify them into aerobic and anaerobic bacteria which are difficult to culture by conventional method. It can categorize microorganisms even in culture sterile samples with rational sensitivity and specificity which may allow early choice of targeted therapy.

Unusual field dependence of remanent magnetization in granular CrO2: the possible relevance of piezomagnetism

We present low field thermoremanent magnetization (TRM) measurements in granular CrO(2) and composites of ferromagnetic (FM) CrO(2) and antiferromagnetic (AFM) Cr(2)O(3). TRM in these samples is seen to display two distinct timescales. A quasi-static part of remanence, appearing only in the low field regime, exhibits a peculiar field dependence. TRM is seen to first rise and then fall with increasing cooling fields, eventually vanishing above a critical field. Similar features in TRM have previously been observed in some antiferromagnets that exhibit the phenomenon of piezomagnetism. Scaling analysis of the TRM data suggest that presumably piezomoments generated in the AFM component drive the FM magnetization dynamics in these granular systems in the low field regime.

Estrogens and growth

Estrogen plays a key role in the regulation of growth in both genders, via its stimulation of the pubertal growth spurt and mediation of epiphyseal fusion. Mouse knockout models suggest a differential effect of oestrogen receptor (ER) alpha and beta on the growth plate, with ER beta possibly being more important in regulating epiphyseal fusion. Epiphyseal fusion may also depend on growth plate senescence, which is regulated by oestrogen. While molecular mechanisms for oestrogen's actions remain unclear, local production of oestrogen may be important for growth. Aromatase inhibitors appear to be effective in improving final height outcome in short stature, however long term safety data is lacking particularly in regards to reproductive function. Future studies are required to further understand the mechanisms by which ER alpha and ER beta affect growth plate function, while longer term studies of aromatase inhibitor usage, preferably utilising animal models, are required to verify the safety of these compounds.

Epidemiology and Economic Burden of Atrial Fibrillation

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Congenital adrenal hyperplasia presenting as hematuria and acute renal faliure

We present a neonate who presented with hematuria and acute renal failure. Classical 21 hydroxylase deficiency was diagnosed on the basis of features of salt wasting, response to treatment with corticosteroids and mineralocorticoids and a positive ACTH stimulation test. Renal vein thrombosis secondary to hemoconcentration due to salt wasting was attributed as the cause of hematuria. Follow-up revealed clinical improvement and normalization of renal parameters. This is the first report of congenital adrenal hyperplasia presenting as hematuria and renal failure to the best of our knowledge.

Patent ductus arteriosus in preterm neonates

Failure of the ductus arteriosus to close within 48-96 hours of postnatal age results in a left to right shunt across the ductus and overloading of the pulmonary circulation. This is more likely to happen in premature neonates with respiratory distress syndrome. Deterioration in the respiratory status on day 3-4 in a ventilated neonate and unexplained metabolic acidosis may be the earliest indicators of a patent ductus arteriosus (PDA). Indomethacin is the main stay of medical management of PDA in preterm neonates. Guidelines for administration of indomethacin have been described in the protocol. Restricted fluid therapy may be beneficial in the prevention of PDA in preterm neonates. Presence of PDA in a term neonate should be investigated to rule out an underlying congenital heart disease.

Successful treatment of Acanthamoeba meningitis with combination oral antimicrobials

Acanthamoeba was implicated as the causative agent of chronic meningitis in three apparently immunocompetent children. Diagnosis was established by cerebrospinal fluid wet mount examination and culture. Two children improved rapidly with combination oral therapy composed of trimethoprim-sulfamethoxazole, rifampin and ketoconazole.

Hypocalcemic heart failure masquerading as dilated cardiomyopathy

Hypocalcemia is a rare, but reversible, cause of congestive heart failure. We report a 4-month-old boy diagnosed as dilated cardiomyopathy who had prolonged QoTc with low blood levels of calcium, normal phosphate, elevated alkaline phosphatase and findings suggestive of rickets. In view of non response to calcium and vitamin D3, a possible diagnosis of VDDR I (Vitamin D-dependent rickets) was made and he was treated with calcium and calcitriol. The serum calcium levels normalised within 10 days, along with resolution of the signs and symptoms of heart failure, near normal left ventricular function and normalisation of QoTc. Pediatricians should be aware of the association of hypocalcemia with cardiac dysfunction and should keep it as a possible reversible cause of heart failure in children.

Evaluation of the diuretic activity of boerhaavia verticillata

The present investigation was undertaken to evaluate the potential diuretic activity of Boerhaavia verticillata . The ethanolic and aqueous extracts of B. verticillata were administered in doses of 50 and 100 mg/kg, i.p., to normal and adult albino rats, which were monitored over a period of 24 h. Experimental results confirmed that both the ethanol and aqueous extracts have diuretic properties, but the ethanol extract seems to have less diuretic and natriuretic activity than the aqueous extract.

Role of tyrosine phosphorylation of a cellular protein in adeno-associated virus 2-mediated transgene expression

The adeno-associated virus 2 (AAV), a single-stranded DNA-containing, nonpathogenic human parvovirus, has gained attention as a potentially useful vector for human gene therapy. However, the single-stranded nature of the viral genome significantly impacts upon the transduction efficiency, because the second-strand viral DNA synthesis is the rate-limiting step. We hypothesized that a host-cell protein interacts with the single-stranded D sequence within the inverted terminal repeat structure of the AAV genome and prevents the viral second-strand DNA synthesis. Indeed, a cellular protein has been identified that interacts specifically and preferentially with the D sequence at the 3' end of the AAV genome. This protein, designated the single-stranded D-sequence-binding protein (ssD-BP), is phosphorylated at tyrosine residues and blocks AAV-mediated transgene expression in infected cells by inhibiting the leading strand viral DNA synthesis. Inhibition of cellular protein tyrosine kinases by genistein results in dephosphorylation of the ssD-BP, leading not only to significant augmentation of transgene expression from recombinant AAV but also to autonomous replication of the wild-type AAV genome. Dephosphorylation of the ssD-BP also correlates with adenovirus infection, or expression of the adenovirus E4orf6 protein, which is known to induce AAV DNA replication and gene expression. Thus, phosphorylation state of the ssD-BP appears to play a crucial role in the life cycle of AAV and may prove to be an important determinant in the successful use of AAV-based vectors in human gene therapy.

Regulation of natural killer cell-mediated cytotoxicity by serine/threonine phosphatases: identification of a calyculin A-sensitive serine/threonine kinase

We have recently reported that Ser/Thr phosphatases play a key role in regulating natural killer (NK) cell lytic activity and that calyculin A and okadaic acid affect this activity differently [Bajpai and Brahmi (1994) J. Biol. Chem. 269, 18864-18869]. Here, we investigate a mechanism that might account for this differential action of calyculin A and okadaic acid on NK cells. Calyculin A specifically inhibited the lytic activity of YT-INDY, an NK-like cell line, and hyperphosphorylated 60 and 78 kDa proteins. The kinetics of appearance of these two proteins was correlated with the loss of lytic activity. In contrast, okadaic acid did not significantly affect either of these activities. The 78 kDa protein is localized in the cytosolic compartment whereas the 60 kDa protein is distributed equally between the membrane and the cytosolic fractions. Both proteins display a kinase activity and are phosphorylated mainly at serine and threonine residues but not at tyrosine residues. The activation of these kinases is specific to calyculin A treatment; it is independent of protein kinase C, protein kinase A, Ca2+, phosphotyrosine phosphatase and protein synthesis de novo. In conclusion, we have demonstrated that calyculin A, but not okadaic acid, hyper-phosphorylates two proteins with Ser/Thr kinase activity, thus explaining the differential regulation of NK cells by these two Ser/Thr phosphatase inhibitors.

Target cell-induced inactivation of cytolytic lymphocytes. Role and regulation of CD45 and calyculin A-inhibited phosphatase in response to interleukin-2

Cytolytic T lymphocyte (CTL) and natural killer cells (NK) lose their lytic potential after interaction with sensitive target cells that can be restored upon incubation with interleukin-2. In this study we observed that preincubation with Ser/Thr phosphatase inhibitor calyculin A inhibited both CTL and NK cell-mediated cytotoxicity (CMC) in a dose-dependent manner. In contrast, okadaic acid inhibited only CTL-CMC without significantly affecting NK-CMC. Incubation of CTL and NK cells with their sensitive TC inhibited both CTL-CMC by 74% and NK-CMC by > 80%. This loss in lytic activity was accompanied by a loss of 60% and > 80% in the cellular p-nitrophenyl phosphate phosphatase (pNPPase) activity in CTL and NK cells, respectively. When treated with 100 units/ml interleukin-2 for 16-18 h at 37 degrees C, inactivated CTL and NK cells recovered 70% and 100% of their lytic activity and approximately 60% and 100% of phosphatase activity, respectively. Analysis revealed that > 80% of the pNPPase activity was associated with membrane-bound CD45, and it is this phosphatase activity that was reversibly affected by target cell-induced inactivation/reactivation of CTL and NK cells. These results suggest that Ser/Thr phosphatases and CD45 play a key role in modulating the lytic activity of effector cells exposed to sensitive target cells.

Sulfhydryl reactive phenylarsine oxide inhibits signal transduction in NK and LAK cells: effect on zeta-chain phosphorylation and phosphatidylinositol level

The specific role of sulfhydryl groups in cell-mediated cytotoxicity (CMC) is still unknown. Here we demonstrate that natural killer cells and lymphokine-activated killer cells, when incubated with phenylarsine oxide (PAO), an organoarsenic compound showed a dose- and time-dependent inhibition of CMC and antibody-dependent cellular cytotoxicity (ADCC). PAO interacted directly with the effector cells (EC) without affecting the target cells (TC) or EC:TC conjugate formation. The loss of cytotoxicity was not due to lack of degranulation or to inhibition of serine esterases in PAO-treated cells. However, PAO inhibited the target-induced down regulation of phosphatidylinositol (PI) level in NK cells indicating that PAO blocked the cytolytic cascade at an early stage, upstream of PI. In addition, PAO also did not affect the disulfide link of the zeta-chain dimers, implicated in signal transduction in cytotoxic lymphocytes but did cause the rapid phosphorylation of the zeta chain. Finally, the effect of PAO on CMC was competitively blocked by dithiothreitol, a dithiol, but not by beta-mercaptoethanol, a mono-thiol. Taken together, these results indicate for the first time how sulfyhydryl groups may regulate CMC and ADCC.

Regulation of resting and IL-2-activated human cytotoxic lymphocytes by exogenous nucleotides: role of IL-2 and ecto-ATPases

In this investigation we studied the modulation of human NK- and CTL-mediated cytotoxicity in response to extracellular nucleotides. NK cell-mediated cytotoxicity (CMC) was inhibited in a dose-dependent manner by ATP/ADP, GTP/GDP, and by pentasodium triphosphate (PST), whereas MHC-restricted CTL were inhibited by GTP/GDP and PST, but not by ATP/ADP. Triphosphates were the most potent inhibitors, followed by diphosphates and monophosphates which were the least effective, suggesting that the inhibition was not due to the sugars nor adenosine and guanosine nucleotides, but rather to the increasing negative charges. Cultured CTL, fresh NK cells that had been incubated with IL-2 for 18 hr and IL-2-dependent NK 3.3 cells were all inhibited by GTP, but not by ATP. This differential regulation of fresh NK cells and CTL by exogenous nucleotides is dependent upon the presence of IL-2, but IL-4, IL-6, and IL-8 did not have any effect. Mouse CTL are resistant to ATP presumably because they contain high levels of ecto-ATPases. Different levels of ecto-ATPase activity in human CTL and NK cells may therefore explain the difference in the responses of these effector cells to extracellular nucleotides. To test this possibility we determined the levels of ecto-ATPases in human CTL and NK cells and showed that CTL contained five times more ecto-ATPases than NK cells. Incubation of NK cells with IL-2 or IL-4 did not significantly change the level of ecto-ATPase activity on NK cells. Treatment of NK cells with IL-2 also did not significantly change the substrate specificity of NK-ecto-ATPases toward the extracellular ATP and GTP. Furthermore, treatment of CTL and NK cells with a potent ecto-ATPase inhibitor, 5'-fluorosulfonylbenzoyladenosine (FSBA), did not significantly alter the effect of exogenous nucleotides on the lytic potential of CTL and NK cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Interactions of antisense peptides with ovine prolactin

Two antisense peptides were synthesized to a sense peptide corresponding to amino acid residues 23-35 of ovine prolactin. Both of the antisense peptides formed a saturable complex with the sense peptide and ovine prolactin. The sense peptide inhibited the interaction of ovine prolactin with the antisense peptides. Both of the antisense peptides have a common core sequence VMNV which can bind to ovine prolactin. The lactogenic hormones, rat prolactin and human growth hormone, compete with the binding of ovine prolactin to an antisense peptide whereas a nonlactogen, ovine growth hormone, does not compete indicating a degree of specificity in the interaction.

Rapid loss of perforin and serine protease RNA in cytotoxic lymphocytes exposed to sensitive targets

We have previously reported that cytotoxic lymphocytes, when exposed to sensitive target cells, temporarily lose their lytic potential. The mechanism leading to this loss of lytic activity is still unknown but it is reversible and the lytic potency can be recovered when the effector cells are incubated with interleukin-2 (IL-2) for 12-14 hr. In this study, we have investigated the regulation of RNA coding for perforin and for two serine proteases, HSP1 and HSP2, in cytotoxic lymphocytes exposed to sensitive targets. Perforin and the two serine proteases are contained in granules of major histocompatibility complex (MHC)-restricted and non-MHC-restricted cytotoxic lymphocytes, but their exact role in the lytic mechanism is still debated. Here we used four different human cytotoxic lymphocytes (CTL) as effector cells: an MHC-restricted CTL (SG-CTL), a non-MHC-restricted CTL (IE6), a natural killer (NK)-like cell line (3.3) and lymphokine-activated killer (LAK) cells. In all effector cells we observed a rapid loss of perforin and of serine protease RNAs within 5 min following the addition of sensitive targets. The effector cells recovered the RNA messages as early as 30 min, although the kinetics of recovery was faster with CTL than with NK-like or LAK effector cells. When we exposed the effector cells to resistant targets we did not detect any loss of perforin or serine protease RNAs. Incubation of the effector cells with cycloheximide, prior to the addition of sensitive targets, did not block message loss, indicating that de novo protein synthesis was not required in this process. Cycloheximide treatment, however, inhibited the recovery of perforin and serine protease RNAs. Taken together, our results indicate that the target-mediated loss of lytic activity in cytotoxic lymphocytes may be a consequence of the down-regulation of perforin or of serine protease transcripts, or both.