Right heart failure in acute respiratory distress syndrome: An unappreciated albeit a potential target for intervention in the management of the disease

Mortality from acute respiratory distress syndrome (ARDS) has gone down recently. In spite of this trend, the absolute numbers continue to be high even with improvements in ventilator strategies and a better understanding of fluid management with this disease. A possible reason for this could be an under-recognized involvement of the pulmonary vasculature and the right side of the heart in ARDS. The right heart is not designed to function under situations leading to acute elevations in afterload as seen in ARDS, and hence it decompensates. This brief review focuses on the magnitude of the problem, its detection in the intensive care unit, and recognizes the beneficial effect of prone-positioning on the pulmonary vasculature and right heart.

Design and development of a low-cost biphasic charge-balanced functional electric stimulator and its clinical validation

Functional electric stimulators that produce near-ideal, charge-balanced biphasic stimulation waveforms with interphase delay are considered safer and more efficacious than conventional stimulators. An indigenously designed, low-cost, portable FES device named InStim is developed. It features a charge-balanced biphasic single channel. The authors present the complete design, mathematical analysis of the circuit and the clinical evaluation of the device. The developed circuit was tested on stroke patients affected by foot drop problems. It was tested both under laboratory conditions and in clinical settings. The key building blocks of this circuit are low dropout regulators, a DC-DC voltage booster and a single high-power current source OP-Amp with current-limiting capabilities. This allows the device to deliver high-voltage, constant current, biphasic pulses without the use of a bulky step-up transformer. The advantages of the proposed design over the currently existing devices include improved safety features (zero DC current, current-limiting mechanism and safe pulses), waveform morphology that causes less muscle fatigue, cost-effectiveness and compact power-efficient circuit design with minimal components. The device is also capable of producing appropriate ankle dorsiflexion in patients having foot drop problems of various Medical Research Council scale grades.

Batf3 deficiency proves the pivotal role of CD8α+ dendritic cells in protection induced by vaccination with attenuated Plasmodium sporozoites

Increasing evidence indicates that hepatic CD8α⁺ dendritic cells (DCs) are important antigen cross-presenting cells (APC) involved in the priming of protective CD8⁺ T-cell responses induced by live-attenuated Plasmodium sporozoites. Experimental proof for a critical role of CD8α⁺ DCs in protective pre-erythrocytic malaria immunizations has pivotal implications for vaccine development, including improved vectored subunit vaccines. Employing Batf3^-/- mice, which lack functional CD8α⁺ DCs, we demonstrate that deficiency of these particular APCs completely abolishes protection and corresponding signatures of vaccine-induced immunity. We show that in wild-type, but not in Batf3^-/- , mice CD8α⁺ DCs accumulate in the liver after immunization with live irradiation-attenuated P. berghei sporozoites. IFN-γ production by Plasmodium antigen-specific CD8⁺ T cells is dependent on functional Batf3. In addition, our results demonstrate that the dysfunctional cDC-CD8+ T-cell axis correlates with MHC class II upregulation on splenic CD8α^- DCs. Collectively, these findings underscore the essential role of CD8α⁺ DCs in robust protection induced by experimental live-attenuated malaria vaccines.

Expression of microRNA-155 correlates positively with the expression of Toll-like receptor 7 and modulates hepatitis B virus via C/EBP-β in hepatocytes

Effective recognition of viral infection and successive activation of antiviral innate immune responses are vital for host antiviral defence, which largely depends on multiple regulators, including Toll-like receptors (TLRs) and microRNAs. Several early reports suggest that specific TLR-mediated immune responses can control hepatitis B virus (HBV) replication and express differentially with disease outcome. Considering the versatile function of miR-155 in the TLR-mediated innate immune response, we aimed to study the association between miR-155 and TLRs and their subsequent impact on HBV replication using both a HBV-replicating stable cell line (HepG2.2.15) and HBV-infected liver biopsy and serum samples. Our results showed that miR-155 was suppressed during HBV infection and a subsequent positive correlation of miR-155 with TLR7 activation was noted. Further, ectopic expression of miR-155 in vitro reduced HBV load as evidenced from reduced viral DNA, mRNA and subsequently reduced level of secreted viral antigens (HBsAg and HBeAg). Our results further suggested that CCAAT/enhancer-binding protein-β (C/EBP-β), a positive regulator of HBV transcription, was inhibited by miR-155. Taken together, our study established a correlation between miR-155 and TLR7 during HBV infection and also demonstrated in vitro that increased miR-155 level could help to reduce HBV viral load by targeting C/EBP-β.

A Dynamic Programming Algorithm for Finding the Optimal Placement of a Secondary Structure Topology in Cryo-EM Data

The determination of secondary structure topology is a critical step in deriving the atomic structures from the protein density maps obtained from electron cryomicroscopy technique. This step often relies on matching the secondary structure traces detected from the protein density map to the secondary structure sequence segments predicted from the amino acid sequence. Due to inaccuracies in both sources of information, a pool of possible secondary structure positions needs to be sampled. One way to approach the problem is to first derive a small number of possible topologies using existing matching algorithms, and then find the optimal placement for each possible topology. We present a dynamic programming method of Θ(Nq(2)h) to find the optimal placement for a secondary structure topology. We show that our algorithm requires significantly less computational time than the brute force method that is in the order of Θ(q(N) h).

Unusual presentation of listerial myocarditis and the diagnostic value of cardiac magnetic resonance

Listeria monocytogenes is an infrequent cause of bacterial myocarditis. Myocarditis without evidence of endocarditis is even rarer. Management in such cases involves early diagnosis, antibiotic therapy, and emergency treatment of arrhythmias. We report the case of a 47-year-old man who presented with features of acute ST-segment-elevation myocardial infarction complicated by ventricular tachycardia that necessitated urgent electrical cardioversion. Contrast-enhanced cardiac magnetic resonance images revealed hypertrophy, necrosis, and a mass that was determined to be an abscess caused by L. monocytogenes. Antibiotic treatment led to resolution of the listerial myocarditis. In addition to reporting our patient's case, we discuss the comparative advantages of cardiac magnetic resonance versus transthoracic echocardiography in characterizing myocarditis, upon presentation and in follow-up evaluation.

ISQuest: finding insertion sequences in prokaryotic sequence fragment data

MOTIVATION

Insertion sequences (ISs) are transposable elements present in most bacterial and archaeal genomes that play an important role in genomic evolution. The increasing availability of sequenced prokaryotic genomes offers the opportunity to study ISs comprehensively, but development of efficient and accurate tools is required for discovery and annotation. Additionally, prokaryotic genomes are frequently deposited as incomplete, or draft stage because of the substantial cost and effort required to finish genome assembly projects. Development of methods to identify IS directly from raw sequence reads or draft genomes are therefore desirable. Software tools such as Optimized Annotation System for Insertion Sequences and IScan currently identify IS elements in completely assembled and annotated genomes; however, to our knowledge no methods have been developed to identify ISs from raw fragment data or partially assembled genomes. We have developed novel methods to solve this computationally challenging problem, and implemented these methods in the software package ISQuest. This software identifies bacterial ISs and their sequence elements-inverted and direct repeats-in raw read data or contigs using flexible search parameters. ISQuest is capable of finding ISs in hundreds of partially assembled genomes within hours, making it a valuable high-throughput tool for a global search of IS elements. We tested ISQuest on simulated read libraries of 3810 complete bacterial genomes and plasmids in GenBank and were capable of detecting 82% of the ISs and transposases annotated in GenBank with 80% sequence identity.

CONTACT

abiswas@cs.odu.edu.

Interaction of α-crystallin with some small molecules and its effect on its structure and function

BACKGROUND

α-Crystallin acts like a molecular chaperone by interacting with its substrate proteins and thus prevents their aggregation. It also interacts with various kinds of small molecules that affect its structure and function.

SCOPE OF REVIEW

In this article we will present a review of work done with respect to the interaction of ATP, peptide generated from lens crystallin and other proteins and some bivalent metal ions with α-crystallin and discuss the role of these interactions on its structure and function and cataract formation. We will also discuss the interaction of some hydrophobic fluorescence probes and surface active agents with α-crystallin.

MAJOR CONCLUSIONS

Small molecule interaction controls the structure and function of α-crystallin. ATP and Zn+2 stabilize its structure and enhance chaperone function. Therefore the depletion of these small molecules can be detrimental to maintenance of lens transparency. However, the accumulation of small peptides due to protease activity in the lens can also be harmful as the interaction of these peptides with α-crystallin and other crystallin proteins in the lens promotes aggregation and loss of lens transparency. The use of hydrophobic probe has led to a wealth of information regarding the location of substrate binding site and nature of chaperone-substrate interaction. Interaction of surface active agents with α-crystallin has helped us to understand the structural stability and oligomeric dissociation in α-crystallin.

GENERAL SIGNIFICANCE

These interactions are very helpful in understanding the mechanistic details of the structural changes and chaperone function of α-crystallin. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.

Therapeutic effects of functional electrical stimulation on motor cortex in children with spastic Cerebral Palsy

In the present study we have evaluated the electroencephalogram (EEG) signal recorded during ankle dorsal and plantar flexion in children with spastic Cerebral Palsy (CP) after Functional Electrical Stimulation (FES) of the Tibialis Anterior (TA) muscles. The intervention group had 10 children with spastic diaplegic/hemiplegic CP within the age group of 5 to 14 years of age who received both FES for 30 minutes and the conventional physiotherapy for 30 minutes a day, while the control group had 5 children who received only conventional physiotherapy for 60(30 + 30) minutes a day only. Both group were treated for 5 days a week, up to 12 weeks. The EEG data were analyzed for Peak Alpha Frequency (PAF), sensorimotor rhythm (SMR), mu wave suppression and power spectral density (PSD) of all the bands. The results showed a decrease in SMR and mu wave suppression in the intervention group as compared to the control group, indicating a positive/greater improvement in performance of motor activities. Therefore, from this study we could conclude that FES combined with conventional physiotherapy improves the motor activity in children with spastic CP.

A novel fibrinogen γ chain frameshift deletion (c.637delT) in a patient with hypodysfibrinogenemia associated with thrombosis

Inherited fibrinogen (FG) disorders are rare and result in quantitative or/and qualitative FG deficiency. While the majority of patients with clinically relevant FG deficiencies demonstrate a bleeding phenotype, a subset of patients are at increased risk of thrombosis.

PATIENTS AND METHODS

We report a 54-years old man presenting with a thrombophilic phenotype characterized by two episodes of unprovoked venous thrombosis and a deep vein thrombosis several weeks after myocardial infarction. Recently, he developed A. carotis communis thrombosis and died. Coagulation tests were done using standard procedures. FG genes were screened using direct sequencing. Effect on fibrin clot structure was analyzed by scanning electron microscopy (SEM) and FG chain polymerization was analysed using SDS-PAGE.

RESULTS

While thrombophilia testing was negative, we found a decreased concentration of clottable FG (126-148 mg/dl) compared to FG antigen (182-194 mg/dl of normal). The thrombin time was slightly prolonged, while aPTT and reptilase time were within the normal range. A novel deletion in FGG gene (c.637delT) resulting in a frameshift and the premature termination of the γ chain at amino acid position p.228 was identified. SDS-PAGE showed a time-shift in γ-γ and α-α cross linking. SEM showed no statistically significant differences between the patient´s and a healthy control´s fibrin clot structure.

CONCLUSIONS

In addition to the reduction of FG concentration expected by the nature of the mutation also a functional defect (hypodysfibrinogenemia) was found. Moreover this mutation seems to increase the risk of thrombosis warranting long term anticoagulation possibly in a combination with antiplatelet drugs.

Neoplasm-induced bleeding in inherited, heterozygous FXIII-A deficiency

Inherited mild factor XIII deficiency belongs to one of the most underdiagnosed bleeding disorders so far. This is, because most patients do not develop bleeding complications in daily life.

A man (age: 64 years) without a history of bleeding presented with painful swelling of neck, weight loss, anemia and episodic bleeding from the right tonsil necessitating tonsillectomy. Histologic and immunohistochemical evaluation revealed cytokeratinpositive epitheloid angiosarcoma. Blood coagulation status showed significantly elevated D-dimer and decreased FXIII levels (FXIII-activity 35%, FXIIIA-Ag 16–26%). Plasma mixing studies excluded neutralizing antibodies against FXIII.

A novel heterozygous F13A1 gene nonsense mutation (p.Glu103Ter, c.307G>T) was found confirming heterozygous FXIII-A deficiency. The same mutation was detected in two further asymptomatic relatives. For further clinical management the patient was transfused with FXIII-concentrate and showed an adequate increase of FXIII ruling out FXIII deficiency to be induced by increased turnover. Despite this haemostatic management and antifibrinolytic treatment the patient had to undergo several revisions due to delayed, Hb relevant bleeding after cervical lymph nodes extirpation and resection of tonsil. Two chemotherapy cycles with paclitaxel and palliative radiotherapy of the neck area were performed, but the patient died unfortunately two months after diagnosis.

It is a unique case showing the combination of a highly aggressive angiosarcoma and presence of inherited FXIII deficiency. It is also a rare example demonstrating the benefit of FXIII genotyping besides the expected acquired FXIII deficiency possibly due to neoplasm induced increased consumption by elevated crosslinking of fibrin fibers.

Novel point mutation in fibrinogen (Innsbruck; BβArg44Gly). Phenotypic differences compared to another mutation (fibrinogen Nijmegen) at the same position

This is a report of a novel fibrinogen point mutation (fibrinogen Innsbruck), a C/G point mutation at position 220 of exon two of the fibrinogen Bβ-chain leading to BβArg44Gly. The heterozygous mutation was found in a 16-year-old adolescent, hospitalized for the management of juvenile depression, who suffered from multiple epistaxis episodes during his stay at the university hospital in Innsbruck, Austria. Fibrinogen (based on the Clauss method) and fibrinogen antigen levels were highly discrepant (86 vs. 223 mg/dl) with thrombin time and reptilase time being in the respective upper reference ranges. Densitometric analysis of electrophoretic band pattern showed a reduction of α-polymers, indicating an impaired fibrin polymerization. This is in agreement with structural analysis, which showed a disturbance of the flexibility and structure of the region surrounding the fibrinoeptide B cleavage site. Fibrinogen Nijmegen, a mutation at the same position, is causative for thrombosis, whereas fibrinogen Innsbruck appears to lead to a bleeding tendency, illustrating that even mutations at the same position can cause contrary symptoms.

Novel point mutation in fibrinogen (Innsbruck; BβArg44Gly)

This is a report of a novel fibrinogen point mutation (fibrinogen Innsbruck), a C/G point mutation at position 220 of exon two of the fibrinogen B|-chain leading to B|3Arg44Gly. The heterozygous mutation was found in a 16-year-old adolescent, hospitalized for the management of juvenile depression, who suffered from multiple epistaxis episodes during his stay at the university hospital in Innsbruck, Austria. Fibrinogen (based on the Clauss method) and fibrinogen antigen levels were highly discrepant (86 vs. 223 mg/dl) with thrombin time and reptilase time being in the respective upper reference ranges. Densitometric analysis of electrophoretic band pattern showed a reduction of a-polymers, indicating an impaired fibrin polymerization. This is in agreement with structural analysis, which showed a disturbance of the flexibility and structure of the region surrounding the fibrinoeptide B cleavage site. Fibrinogen Nijmegen, a mutation at the same position, is causative for thrombosis, whereas fibrinogen Innsbruck appears to lead to a bleeding tendency, illustrating that even mutations at the same position can cause contrary symptoms.