Plant electrophysiology with conformable organic electronics: Deciphering the propagation of Venus flytrap action potentials

Electrical signals in plants are mediators of long-distance signaling and correlate with plant movements and responses to stress. These signals are studied with single surface electrodes that cannot resolve signal propagation and integration, thus impeding their decoding and link to function. Here, we developed a conformable multielectrode array based on organic electronics for large-scale and high-resolution plant electrophysiology. We performed precise spatiotemporal mapping of the action potential (AP) in Venus flytrap and found that the AP actively propagates through the tissue with constant speed and without strong directionality. We also found that spontaneously generated APs can originate from unstimulated hairs and that they correlate with trap movement. Last, we demonstrate that the Venus flytrap circuitry can be activated by cells other than the sensory hairs. Our work reveals key properties of the AP and establishes the capacity of organic bioelectronics for resolving electrical signaling in plants contributing to the mechanistic understanding of long-distance responses in plants.

Flexible Organic Electronic Ion Pump for Flow-Free Phytohormone Delivery into Vasculature of Intact Plants

Plant vasculature transports molecules that play a crucial role in plant signaling including systemic responses and acclimation to diverse environmental conditions. Targeted controlled delivery of molecules to the vascular tissue can be a biomimetic way to induce long distance responses, providing a new tool for the fundamental studies and engineering of stress-tolerant plants. Here, a flexible organic electronic ion pump, an electrophoretic delivery device, for controlled delivery of phytohormones directly in plant vascular tissue is developed. The c-OEIP is based on polyimide-coated glass capillaries that significantly enhance the mechanical robustness of these microscale devices while being minimally disruptive for the plant. The polyelectrolyte channel is based on low-cost and commercially available precursors that can be photocured with blue light, establishing much cheaper and safer system than the state-of-the-art. To trigger OEIP-induced plant response, the phytohormone abscisic acid (ABA) in the petiole of intact Arabidopsis plants is delivered. ABA is one of the main phytohormones involved in plant stress responses and induces stomata closure under drought conditions to reduce water loss and prevent wilting. The OEIP-mediated ABA delivery triggered fast and long-lasting stomata closure far away from the delivery point demonstrating systemic vascular transport of the delivered ABA, verified delivering deuterium-labeled ABA.

Benchmarking organic electrochemical transistors for plant electrophysiology

Plants are able to sense and respond to a myriad of external stimuli, using different signal transduction pathways, including electrical signaling. The ability to monitor plant responses is essential not only for fundamental plant science, but also to gain knowledge on how to interface plants with technology. Still, the field of plant electrophysiology remains rather unexplored when compared to its animal counterpart. Indeed, most studies continue to rely on invasive techniques or on bulky inorganic electrodes that oftentimes are not ideal for stable integration with plant tissues. On the other hand, few studies have proposed novel approaches to monitor plant signals, based on non-invasive conformable electrodes or even organic transistors. Organic electrochemical transistors (OECTs) are particularly promising for electrophysiology as they are inherently amplification devices, they operate at low voltages, can be miniaturized, and be fabricated in flexible and conformable substrates. Thus, in this study, we characterize OECTs as viable tools to measure plant electrical signals, comparing them to the performance of the current standard, Ag/AgCl electrodes. For that, we focused on two widely studied plant signals: the Venus flytrap (VFT) action potentials elicited by mechanical stimulation of its sensitive trigger hairs, and the wound response of Arabidopsis thaliana. We found that OECTs are able to record these signals without distortion and with the same resolution as Ag/AgCl electrodes and that they offer a major advantage in terms of signal noise, which allow them to be used in field conditions. This work establishes these organic bioelectronic devices as non-invasive tools to monitor plant signaling that can provide insight into plant processes in their natural environment.

Role of preoperative chemotherapy in squamous cell carcinoma of esophagus in kashmir, a cancer belt - a pilot study

BACKGROUND

Esophageal carcinoma is the fifth leading gastrointestinal malignancy and is one of the leading causes of cancer related death. Despite improvements in surgical technique over the last few decades, the outcome has been dismal, with overall 5 year survival not exceeding 15%-25%.

AIMS AND OBJECTIVES

To evaluate the effect of preoperative chemotherapy on resectability, complication rate and overall survival in patients with squamous cell carcinoma esophagus.

MATERIALS AND METHODS

50 patients with histologically confirmed squamous cell carcinoma (SCC), with localised or loco-regional disease (stage 4 excluded) were divided into 2 groups. Group A patients were subjected to 2-3 cycles of pre-operative chemotherapy (5FU-CDDP), whereas Group B patients were directly operated on.

OBSERVATIONS

3 (12%) patients in group A showed complete pathological response to chemotherapy and 18 (72%) showed a partial response, with four patients (16%) showing resistance to chemotherapy. There was no statistically significant difference in terms of response to chemotherapy with respect to degree of differentiation of tumor. There was no significant difference in the overall resectability rates between the two groups (p > 0.05), but R0 resection was achieved in 20 (80%) of group A and only 10 (40%) of group B, the difference being statistically significant (p < 0.05). The rate of overall complications was also much higher in the control group. Initially there was no significant difference in the survival between the two groups, but later (20 months) the study group showed a slight non-significant advantage.

CONCLUSION

Preoperative chemotherapy significantly increases the rate of R0 resection without significantly increasing postoperative morbidity and mortality in patients with squamous cell carcinoma of esophagus. However, to assess the impact on survival the study period needs to be extended.

Missile diaphragmatic injuries: kashmir experience

BACKGROUND

Importance of repairing a diaphragmatic tear due to a missile injury cannot be overemphasized. Even a small diaphragmatic rent should be repaired because of morbidity and mortality caused by subsequent herniation and strangulation.

METHODS

Fifty-three cases with diaphragmatic injuries caused by penetrating missiles were studied from January 1997 to January 2007. All the patients were primarily explored either for thoracic or abdominal penetrating trauma; the diaphragmatic injury was an associated incidental intraoperative finding. Thoracotomy was performed in 18 patients, Laprotomy in 33 patients and in two patients combined thorocoabdominal approach was utilised for managing associated visceral injuries.

RESULTS

Overall mortality was 37.7%. Mortality was dependent on associated injuries of thoracic and abdominal viscera. Most patients died due to associated injuries and septicaemia. None of the patients had any sequelae of diaphragmatic repair.

CONCLUSION

Immediate repair of diaphragmatic injury is of paramount importance to prevent subsequent complications of herniation and strangulation.

Atrial myxoma: trends in management

Myxomas are the most common type of cardiac tumours in all age groups accounting for one-third to one-half of cases at postmortum and for about three quarter of tumours treated surgically. Most atrial myxomas, whether left or right, arise from the atrial septum. About 10% have other sites of origin, particularly posterior wall, anterior wall and the appendages (in order of frequency). Myxomas are frequently located in left atrium and produce symptoms when they fragment and cause systemic emboli or when they interfere with cardiac valvular function and cause pulmonary congestion. Careful surgical management of these lesions should be curative with minimal early and late morbidity and mortality. Recurrence of atrial myxomas can occur most likely in about 3% of patients. However, extensive resection of the myxoma attached to atrial septum or atrial wall can reduce the likelihood of recurrence to a greater extent. Long term clinical and echocardiographic follow-up is mandatory.

Minimally invasive transthoracotomy–transphrenotomy for concurrent hepatic and pulmonary hydatid disease

Background

Combined liver and lung hydatid cysts are rare, but pose a challenge in terms of accessibility. The objective of the study was to find an alternative approach to conventional two-stage posterolateral thoracotomy and laparotomy or single-stage extensive thoracolaparotomy.

Methods

Twenty-five patients with right lung and liver hydatid disease underwent single-stage anterior minithoracotomy and phrenotomy. Primary diagnostic tools were chest radiography, ultrasonography and serology. The preferred mode of management of hydatid cysts was enucleation and partial or total capitonnage.

Results

Thirty-six (13·5 per cent) of 267 patients had concurrent hepatic and pulmonary hydatid cysts. Among the 25 patients who had anterior minithoracotomy and phrenotomy the male : female ratio was 2 : 1. Mean operating time was 75 min. Morbidity was negligible and postoperative recovery was prompt. All of the patients survived. The mean hospital stay was 5·2 days. Overall observations were encouraging.

Conclusion

This minimally invasive approach is associated with less morbidity and better cosmesis than conventional procedures. It represents an excellent alternative to other procedures in selected patients.

Sequence analysis of the nucleocapsid and phosphoprotein genes of avian pneumoviruses circulating in the US

Avian pneumovirus (APV) has recently been described as the cause of a new respiratory syndrome in turkey flocks in the United States. We here describe the complete sequence of the nucleocapsid (N) and phosphoprotein (P) genes of this emerging APV (APV/US). Our results show 59 and 61% nucleotide sequence identity of the APV/US N gene with N genes of previously described European APV subgroups A and B, respectively. The P gene of APV/US showed only 53% nucleotide sequence identity with the ortholog from APV subgroup A. Phylogenetic analyses of both N and P genes clearly demonstrate that the APV/US lineage is evolutionarily related but distinct from European APVs. Moreover, sequence analysis of the N and P genes from two laboratory adapted isolates of APV/US (APV/MN-1a and APV/MN-1b) and from ten clinical samples from APV-infected turkeys suggests only modest level of amino acid divergence in the N (0-0.3%) and P (0-1.4%) proteins. Taken together, the results of this study indicate support that APV/US represents a new subgroup (subgroup C) of APV and show that there is limited heterogeneity in the N and P genes of APV/US isolates.

PCR-based detection of an emerging avian pneumovirus in US turkey flocks

Avian pneumovirus (APV) or turkey rhinotracheitis virus (TRTV) is an important respiratory pathogen of domesticated poultry in many countries in Europe, Africa, and Asia. Until recently, the United States was considered free of APV. In late 1996, an atypical upper respiratory tract infection appeared in turkey flocks in Colorado and shortly thereafter in turkey flocks in Minnesota. An avian pneumovirus (APV-US) that was serologically distinct from the previously described TRTV was isolated as the primary cause of the new syndrome. The nucleotide sequence of a fragment of the APV-US fusion gene was determined and used to develop a polymerase chain reaction-based assay that specifically detects APV-US viral nucleic acid sequences in RNA extracts of tracheal swabs and turbinate homogenates. The assay is highly sensitive in that it can detect <0.01 TCID50 of APV. The availability of this assay enables the rapid and accurate determination of APV-US in infected poultry flocks.

A modified enzyme-linked immunosorbent assay for the detection of avian pneumovirus antibodies

Avian pneumovirus (APV) infection of turkeys in Minnesota was first confirmed in March 1997. Serum samples (n = 5,194) from 539 submissions to Minnesota Veterinary Diagnostic Laboratory were tested by a modified enzyme-linked immunosorbent assay (ELISA). Of these, 2,528 (48.7%) samples from 269 submissions were positive and 2,666 (51.3%) samples from 270 submissions were negative for APV antibodies. Most positive samples were from Kandiyohi, Stearns, Morrison, and Meeker counties in Minnesota. In addition, 10 samples from South Dakota were positive. The sensitivity and specificity of the ELISA test with anti-chicken and anti-turkey conjugates were compared by testing field and experimental sera. The ELISA test with anti-turkey conjugate was more sensitive than that with anti-chicken conjugate. The ELISA tests with antigens prepared with APV strains isolated from Colorado and Minnesota were also compared. No difference was detectable. Currently, the Minnesota Veterinary Diagnostic Laboratory uses an antigen prepared from the Colorado isolate of APV and a goat anti-turkey conjugate in the ELISA test.

Isolation of avian pneumovirus from an outbreak of respiratory illness in Minnesota turkeys

Antibodies to avian pneumovirus (APV) were first detected in Minnesota turkeys in 1997. Virus isolation was attempted on 32 samples (28 tracheal swabs, 4 pools of trachea and turbinates) that were positive for APV by reverse transcriptase polymerase chain reaction (RT-PCR). The cell cultures used were chicken embryo fibroblast (CEF), Vero cells, and QT-35 cells. Five virus isolates were obtained from these samples, and the identity of the isolates was confirmed by RT-PCR. Four isolates were obtained by inoculation of CEF cells, and 1 isolate was obtained in QT-35 cells after 3-7 blind passages in cell cultures. Vero cells did not yield any isolate on primary isolation; however, all 5 isolates could be adapted to grow in Vero cells following primary isolation in CEF or QT-35 cells. This is the first report of isolation of APV in Minnesota and also the first report of primary isolation of APV in QT-35 cells.

Comparison of immunohistochemistry, electron microscopy, and direct fluorescent antibody test for the detection of bovine coronavirus

Bovine coronavirus (BCV) is 1 of the major causes of calf diarrhea and has also been implicated in respiratory infections of young calves and winter dysentery of adult cattle. Currently, transmission electron microscopy (TEM), direct fluorescent antibody (DFA), and enzyme-linked immunosorbent assay (ELISA) techniques are considered standard methods for the diagnosis of BCV infection. However, these techniques are not useful if fresh tissues and intestinal contents are not available for examination. The detection of viral antigens in formalin-fixed, paraffin-embedded tissues using immunohistochemistry (IHC) is a suitable alternative. In the present study, 166 tissue specimens were tested by IHC for the presence of BCV. These tissues were from animals whose feces were positive for rotavirus and/or coronavirus by TEM. Some of these samples were also tested by DFA. Thus, TEM, DFA, and IHC were compared for the detection of BCV. There was 56% agreement among the 3 methods (overall kappa = 0.368). When IHC was compared with TEM, 78% agreement was observed (kappa = 0.475). Similarly, IHC and DFA had 64% agreement (kappa = 0.277). These kappa values indicate a moderate degree of agreement between IHC and TEM; agreement between IHC and DFA was fair. The results of this study indicate that IHC may be a suitable adjunct for the detection of BCV because of its simplicity, ease of use, and relatively close correlation with TEM results.