Antibody Binding Captures High Energy State of an Antigen: The Case of Nsp1 SARS-CoV-2 as Revealed by Hydrogen-Deuterium Exchange Mass Spectrometry

We describe an investigation using structural mass spectrometry (MS) of the impact of two antibodies, 15497 and 15498, binding the highly flexible SARS-CoV-2 Nsp1 protein. We determined the epitopes and paratopes involved in the antibody-protein interactions by using hydrogen-deuterium exchange MS (HDX-MS). Notably, the Fab (Fragment antigen binding) for antibody 15498 captured a high energy form of the antigen exhibiting significant conformational changes that added flexibility over most of the Nsp1 protein. The Fab for antibody 15497, however, showed usual antigen binding behavior, revealing local changes presumably including the binding site. These findings illustrate an unusual antibody effect on an antigen and are consistent with the dynamic nature of the Nsp1 protein. Our studies suggest that this interaction capitalizes on the high flexibility of Nsp1 to undergo conformational change and be trapped in a higher energy state by binding with a specific antibody.

Biochemical and HDX Mass Spectral Characterization of the SARS-CoV-2 Nsp1 Protein

A major challenge in defining the pathophysiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is to better understand virally encoded multifunctional proteins and their interactions with host factors. Among the many proteins encoded by the positive-sense, single-stranded RNA genome, nonstructural protein 1 (Nsp1) stands out due to its impact on several stages of the viral replication cycle. Nsp1 is the major virulence factor that inhibits mRNA translation. Nsp1 also promotes host mRNA cleavage to modulate host and viral protein expression and to suppress host immune functions. To better define how this multifunctional protein can facilitate distinct functions, we characterize SARS-CoV-2 Nsp1 by using a combination of biophysical techniques, including light scattering, circular dichroism, hydrogen/deuterium exchange mass spectrometry (HDX-MS), and temperature-dependent HDX-MS. Our results reveal that the SARS-CoV-2 Nsp1 N- and C-terminus are unstructured in solution, and in the absence of other proteins, the C-terminus has an increased propensity to adopt a helical conformation. In addition, our data indicate that a short helix exists near the C-terminus and adjoins the region that binds the ribosome. Together, these findings provide insights into the dynamic nature of Nsp1 that impacts its functions during infection. Furthermore, our results will inform efforts to understand SARS-CoV-2 infection and antiviral development.

Oropouche orthobunyavirus infection is mediated by the cellular host factor Lrp1

Oropouche orthobunyavirus (OROV; Peribunyaviridae) is a mosquito-transmitted virus that causes widespread human febrile illness in South America, with occasional progression to neurologic effects. Host factors mediating the cellular entry of OROV are undefined. Here, we show that OROV uses the host protein low-density lipoprotein-related protein 1 (Lrp1) for efficient cellular infection. Cells from evolutionarily distinct species lacking Lrp1 were less permissive to OROV infection than cells with Lrp1. Treatment of cells with either the high-affinity Lrp1 ligand receptor-associated protein (RAP) or recombinant ectodomain truncations of Lrp1 significantly reduced OROV infection. In addition, chimeric vesicular stomatitis virus (VSV) expressing OROV glycoproteins (VSV-OROV) bound to the Lrp1 ectodomain in vitro. Furthermore, we demonstrate the biological relevance of the OROV-Lrp1 interaction in a proof-of-concept mouse study in which treatment of mice with RAP at the time of infection reduced tissue viral load and promoted survival from an otherwise lethal infection. These results with OROV, along with the recent finding of Lrp1 as an entry factor for Rift Valley fever virus, highlight the broader significance of Lrp1 in cellular infection by diverse bunyaviruses. Shared strategies for entry, such as the critical function of Lrp1 defined here, provide a foundation for the development of pan-bunyaviral therapeutics.

AB0042 OPTIMAL CONDITIONS FOR THE DETECTION OF INFLAMMASOME ACTIVATION IN CD14+ CD16- MONOCYTES FROM HUMAN BLOOD BY FLOW CYTOMETRY

Background

The inflammasome activation is linked to the aggregation of the adaptor protein ASC into a multimeric structure, known as the ASC speck. The aggregation of cytosolic ASC into ASC specks is therefore used as a readout parameter for inflammasome activity. The direct detection of ASC speck formation on a single cell basis through flow cytometry, can analyze inflammasome activated cells. This allows the investigation of inflammasome activity in a clinical setting.

Objectives

Investigating the optimal conditions for a reliable identification of inflammasome activated ASC speck positive cells ex vivo using flow cytometry.

Methods

Freshly donated blood from five different healthy donors was used for all experiments. The choice of anticoagulant, storage time and storage temperature were examined. PBMCs were isolated from blood collecting tubes with ethylenediaminetetraacetic acid (EDTA) or lithium heparin (LH). PBMCs were also isolated from LH blood stored at 4 °C, room temperature (RT), 37 °C and after different storage times. After isolation, PBMCs were fixed immediately and stained for flow cytometric analysis. ASC speck positive CD14+ CD16- monocytes and THP-1 cells can be generated through incubation with nigericin in PBS.

Results

We adapted a method for flow cytometric analysis of ASC specks, with was previously described by Sester et al. [1]. As expected, we observed ASC speck formation after inflammasome activation, in CD14+ CD16-monocytes through a decrease in ASC fluorescent pulse width and an increase in ASC fluorescent pulse area. Monocytes in PBMCs collected from tubes with EDTA compared with LH showed significantly higher numbers of unspecific ASC speck positive cells. Blood storage at RT for 24 h can lead to an unspecific ASC speck formation. Storage at 37 °C resulted in contamination of the PBMC interface with erythrocytes, while blood stored at 4 °C resulted in severe cell clumping. Since storing LH blood for 24 h at RT lead to unspecific ASC speck formation in CD14+ CD16- cells, but not monocytes from freshly isolated PBMCs, the determination of the time until unspecific ASC speck signals occur was investigated. A significant increase in ASC speck positive CD14+CD16- monocytes was detected after 4 h storage at RT compared to directly processed samples and the number of ASC speck positive monocytes further accumulated over time. The incubation with nigericin in PBS leads to a significant increase in ASC speck positive CD14+ CD16- monocytes and THP-1 cells compared to incubation in RPMI media.

Conclusion

The flow cytometric detection of ASC specks is adapted for practical clinical usability. To reduce background signals, LH- instead of EDTA blood collecting tubes are recommended. The LH blood should be processed within 2 h after blood collection and be stored at RT. To avoid nonspecific activation and formation of ASC specks, the PBMCs should be isolated directly after venipuncture and fixed immediately. It is also possible to freeze the PBMCs until further usage. However, this will cause some loss of ASC speck positive cells. With these settings, clinical samples can now be examined.

References

[1]Sester, D.P et al. A novel flow cytometric method to assess inflammasome formation. J. Immunol. 2015, 194, 455–462.

Acknowledgements

We thank all healthy donors who participated in this study. The authors thank Jana Gramenz (University Medicine Greifswald, Pediatric Rheumatology and Immunology, Greifswald, Germany) for excellent technical assistance.

Disclosure of Interests

None declared

Development of Monoclonal Antibodies to Detect for SARS-CoV-2 Proteins

The COVID-19 pandemic caused by SARS-CoV-2 infection has impacted the world economy and healthcare infrastructure. Key reagents with high specificity to SARS-CoV-2 proteins are currently lacking, which limits our ability to understand the pathophysiology of SARS-CoV-2 infections. To address this need, we initiated a series of studies to generate and develop highly specific antibodies against proteins from SARS-CoV-2 using an antibody engineering platform. These efforts resulted in 18 monoclonal antibodies against nine SARS-CoV-2 proteins. Here we report the characterization of several antibodies, including those that recognize Nsp1, Nsp8, Nsp12, and Orf3b viral proteins. Our validation studies included evaluation for use of antibodies in ELISA, western blots, and immunofluorescence assays (IFA). We expect that availability of these antibodies will enhance our ability to further characterize host-viral interactions, including specific roles played by viral proteins during infection, to acquire a better understanding of the pathophysiology of SARS-CoV-2 infections.

Lrp1 is a host entry factor for Rift Valley fever virus

Rift Valley fever virus (RVFV) is a zoonotic pathogen with pandemic potential. RVFV entry is mediated by the viral glycoprotein (Gn), but host entry factors remain poorly defined. Our genome-wide CRISPR screen identified low-density lipoprotein receptor-related protein 1 (mouse Lrp1/human LRP1), heat shock protein (Grp94), and receptor-associated protein (RAP) as critical host factors for RVFV infection. RVFV Gn directly binds to specific Lrp1 clusters and is glycosylation independent. Exogenous addition of murine RAP domain 3 (mRAP_D3) and anti-Lrp1 antibodies neutralizes RVFV infection in taxonomically diverse cell lines. Mice treated with mRAP_D3 and infected with pathogenic RVFV are protected from disease and death. A mutant mRAPD3 that binds Lrp1 weakly failed to protect from RVFV infection. Together, these data support Lrp1 as a host entry factor for RVFV infection and define a new target to limit RVFV infections.

Non-canonical proline-tyrosine interactions with multiple host proteins regulate Ebola virus infection

The Ebola virus VP30 protein interacts with the viral nucleoprotein and with host protein RBBP6 via PPxPxY motifs that adopt non-canonical orientations, as compared to other proline-rich motifs. An affinity tag-purification mass spectrometry approach identified additional PPxPxY-containing host proteins hnRNP L, hnRNPUL1, and PEG10, as VP30 interactors. hnRNP L and PEG10, like RBBP6, inhibit viral RNA synthesis and EBOV infection, whereas hnRNPUL1 enhances. RBBP6 and hnRNP L modulate VP30 phosphorylation, increase viral transcription, and exert additive effects on viral RNA synthesis. PEG10 has more modest inhibitory effects on EBOV replication. hnRNPUL1 positively affects viral RNA synthesis but in a VP30-independent manner. Binding studies demonstrate variable capacity of the PPxPxY motifs from these proteins to bind VP30, define PxPPPPxY as an optimal binding motif, and identify the fifth proline and the tyrosine as most critical for interaction. Competition binding and hydrogen-deuterium exchange mass spectrometry studies demonstrate that each protein binds a similar interface on VP30. VP30 therefore presents a novel proline recognition domain that is targeted by multiple host proteins to modulate viral transcription.

Systems approach for assessment of maternal deaths in Rajasthan: A feasibility study

Background

High maternal mortality in the state like Rajasthan, which is at second rank in terms of high Maternal Mortality Ratio (MMR) in India, require concentrated efforts in this direction The objectives of this study were to assess the magnitude and trend of maternal death and underlying factors contributing to maternal deaths in Rajasthan and to identify barriers and challenges in reporting maternal deaths in Rajasthan.

Methods

Data related to maternal deaths, cause of deaths and live births were retrieved from official Government sources and MMR was calculated. To find out the underlying factors contributing to maternal deaths, Verbal Autopsies were conducted through household surveys. In-depth interviews of health care staff were conducted to carry out the 'SWOT' analysis in order to identify the barriers in reporting maternal deaths. Data was analysed using SPSS version 23.

Results

A total of 7185 maternal deaths were reported from Rajasthan in last five years. The mean age of mothers was 25.18±4.98 years. Haemorrhage were reported as most common cause of maternal death (17%) followed by Severe hypertension or fits (8%) and obstructed labour (2%). The median duration of hospital stay was 23 hours (IQR=7.5-70). Maximum deaths were reported during post-partum period (61%), while around one fourth of the deaths happened during delivery.

Conclusions

The discrepancies were observed in the reporting of number and causes of maternal deaths. The trend and forecasted figures were quite different from the published National and State level reports in this regard.

Key messages

need to streamline and strengthen the Maternal Deaths Surveillance and Response to track the number of deaths and get the exact information about the underlying factors contributing to them. Effective strategies can be developed to reduce the Maternal Deaths in the State.

Dual activity of amphiphilic Zn(II) nitroporphyrin derivatives as HIV-1 entry inhibitors and in cancer photodynamic therapy

Two Zn(II) nitro porphyrin derivatives bearing combinations of meso-4-nitrophenyl and meso-4-methylpyridinium moieties and their free-base precursors were synthesized through one-pot microwave process, purified and characterized. The biological activity of these nitroporphyrins was assessed under both photodynamic and non-photodynamic conditions to correlate their structure-activity relationship (SAR). Unlike, the free-base precursors, Zn(II) complexes of these nitroporphyrins displayed nearly complete inhibition in the entry of lentiviruses such as HIV-1 and SIVmac under non-photodynamic conditions. In addition, the Zn(II) complexes also exhibited a higher in vitro photodynamic activity towards human lung cancer cell-line A549 than their free-base precursors. Our results strongly suggest that incorporation of Zn(II) has improved the antiviral and anticancer properties of the nitroporphyrins. To the best of our knowledge, this is the first report demonstrating the dual activity of nitroporphyrin-zinc complexes as antiviral and anti-cancer, which will aid in their development as therapeutics in clinics.

G protein-coupled and ATP-sensitive inwardly rectifying potassium ion channels are essential for HIV entry

The high genetic diversity of Human Immunodeficiency virus (HIV), has hindered the development of effective vaccines or antiviral drugs against it. Hence, there is a continuous need for identification of new antiviral targets. HIV exploits specific host proteins also known as HIV-dependency factors during its replication inside the cell. Potassium channels play a crucial role in the life cycle of several viruses by modulating ion homeostasis, cell signaling, cell cycle, and cell death. In this study, using pharmacological tools, we have identified that HIV utilizes distinct cellular potassium channels at various steps in its life cycle. Members of inwardly rectifying potassium (Kir) channel family, G protein-coupled (GIRK), and ATP-sensitive (KATP) are involved in HIV entry. Blocking these channels using specific inhibitors reduces HIV entry. Another member, Kir 1.1 plays a role post entry as inhibiting this channel inhibits virus production and release. These inhibitors are not toxic to the cells at the concentration used in the study. We have further identified the possible mechanism through which these potassium channels regulate HIV entry by using a slow-response potential-sensitive probe DIBAC4(3) and have observed that blocking these potassium channels inhibits membrane depolarization which then inhibits HIV entry and virus release as well. These results demonstrate for the first time, the important role of Kir channel members in HIV-1 infection and suggest that these K+ channels could serve as a safe therapeutic target for treatment of HIV/AIDS.

Effect of homoeopathic treatment on filariasis

A single blind follow-up study was undertaken to assess the effect of homeopathic treatment on microfilarial clearance and frequency of filarial fevers in an endemic village, India, State of Orissa. Homoeopathic treatment effectively reduced the frequency of filarial fevers by 20 per cent (P<0.05) among amicrofilaraemic cases, with a higher reduction in cases with genital involvement (36%) and mastitis (57%). However, among symptomatic microfilaraemia cases, the frequency of filarial fever (attack) had doubled (p<0.05) following treatment. There was no additional effect on microfilaria clearance in asymptomatic carriers.

Homœopathic treatment of filariasis

A single-blind study was conducted to assess the effect of homœopathic treatment on cases of bancroftian filariasis. Based on the predominant symptom, the filariasis cases were grouped as adenitis, genitalia involvement, lymphoedema and mastitis. Effect of treatment with homœopathic drugs were assessed by comparing with groups treated with placebo. Filiariasis cases treated with homœopathic medicines showed a better improved/not improved ratio (2.0) compared with cases treated with placebo (0.46). The results indicate that the improvements derived from homœopathic medicines are statistically highly significant (p<0.001).

Human APOBEC3B interacts with the heterogenous nuclear ribonucleoprotein A3 in cancer cells

Human APOBEC3B (A3B), like other APOBEC3 members, is a cytosine deaminase which causes hypermutation of single stranded genome. Recent studies have shown that A3B is predominantly elevated in multiple cancer tissues and cell lines such as the bladder, cervix, lung, head and neck, and breast. Upregulation and activation of A3B in developing tumors can cause an unexpected cluster of mutations which promote cancer development and progression. The cellular proteins which facilitate A3B function through direct or indirect interactions remain largely unknown. In this study, we performed LC-MS-based proteomics to identify cellular proteins which coimmunoprecipitated with A3B. Our results indicated a specific interaction of A3B with hnRNP A3 (heterogeneous nuclear ribonucleoprotein). This interaction was verified by co-immunoprecipitation and was found to be RNA-dependent. Furthermore, A3B and hnRNP A3 colocalized as evident from immunofluorescence analysis.

Syncytial Hepatitis of Tilapia ( Oreochromis niloticus L.) is Associated With Orthomyxovirus-Like Virions in Hepatocytes

Using transmission electron microscopy (TEM), the presented work expands on the ultrastructural findings of an earlier report on "syncytial hepatitis," a novel disease of tilapia (SHT). Briefly, TEM confirmed the presence of an orthomyxovirus-like virus within the diseased hepatocytes but not within the endothelium. This was supported by observing extracellular and intracellular (mostly intraendosomal), 60-100 nm round virions with a trilaminar capsid containing up to 7 electron-dense aggregates. Other patterns noted included enveloped or filamentous virions and virion-containing cytoplasmic membrane folds, suggestive of endocytosis. Patterns atypical for orthymyxovirus included the formation of syncytia and the presence of virions within the perinuclear cisternae (suspected to be the Golgi apparatus). The ultrastructural morphology of SHT-associated virions is similar to that previously reported for tilapia lake virus (TiLV). A genetic homology was investigated using the available reverse transcriptase polymerase chain reaction (RT-PCR) probes for TiLV and comparing clinically sick with clinically normal fish and negative controls. By RT-PCR analysis, viral nucleic acid was detected only in diseased fish. Taken together, these findings strongly suggest that a virus is causally associated with SHT, that this virus shares ultrastructural features with orthomyxoviruses, and it presents with partial genetic homology with TiLV (190 nucleotides).

Cation exchange synthesis of uniform PbSe/PbS core/shell tetra-pods and their use as near-infrared photodetectors

In this work we explore the preparation of complex-shaped semiconductor nanostructures composed of different materials via a cationic exchange process in which the cations of the original semiconductor nanostructure are replaced by cations of different metals with preservation of the shape and the anionic framework of the nanocrystals. Utilizing this cation exchange method, we synthesized two new tetrapods for the first time: Cu2-xSe/Cu2-xS and PbSe/PbS, both prepared from CdSe/CdS tetrapods as 'templates'. We also fabricated near-infrared (NIR) photodetectors with a very simple architecture comprising a PbSe/PbS tetrapod layer between two Au electrodes on a glass substrate. When illuminated by a NIR laser, these devices are capable of achieving a responsivity of 11.9 A W(-1) without the use of ligand-exchange processes, thermal annealing or hybrid device architecture. Transient absorption spectroscopy was carried out on these PbSe/PbS tetrapods, the results of which suggest that the branched morphology contributes in part to device performance. Investigation of the charge dynamics of the PbSe/PbS tetrapods revealed an extremely long-lived exciton recombination lifetime of ∼17 ms, which can result in enhanced photoconductive gain. Overall, these heterostructured tetrapods showcase simultaneously the importance of nanoparticle shape, band structure, and surface chemistry in the attainment of NIR photodetection.

Negative feedback circuit for toll like receptor-8 activation in human embryonic Kidney 293 using outer membrane vesicle delivered bi-specific siRNA

Background

TLR8 assists in antiviral approach by producing Type 1 INF via MyD88 dependent IRF7 pathway. However, over expression of INFα/β molecule poses threat by developing tolerance in chronic infection cases and enhancing inflammatory response. Here we report a bi-specific siRNA based complex which differentially activates and silences the TLR8 and MYD88 respectively in a negatively regulated fashion.

Results

Outer membrane vesicle from Escherichia coli used for siRNA delivery was observed more efficient when attached with invasive protein Ail along with OmpA (P < 0.001) in HEK293-TLR8 cell line. siRNA complexed with p19 protein was efficient in activating TLR8, confirmed by the increment of INFβ molecules (P < 0.001) in HEK293-TLR8 compared to its counterpart. Fusion of lipid bilayer of endosomal compartment was significant at pH 4.5 when fusogenic peptides (diINF-7) were incubated in membrane vesicle, thus facilitating the escape of siRNA complex to the host cytoplasm in order to silence MyD88 transcript (P < 0.001).

Conclusions

We investigated the activation of TLR8 by bi-specific si-RNA for the production of INFβ. In the same setting we showed that bi-specific si-RNA was able to silence MyD88 transcript in a delayed manner. For the cases of auto immune disease and inflammation where over activation of endosomal TLRs poses serious threat, bi specific siRNA could be used as negative feedback controlled system.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-015-0109-9) contains supplementary material, which is available to authorized users.

Molecular mechanism of in vitro transformation of mammalian cells by chemical carcinogens

BHK21 clone 13 cells transformed by dimethylnitrosamine (DMN) or nitrosomethylurea (NMU) ("alkylating" chemical carcinogens) appear to be restricted by temperature in the expression of their transformed phenotype. When grown at 38.5 degrees C, they exhibit a transformed phenotype (clonal morphology and ability to plate in agar), when grown at 32 degrees C, their phenotype is normal. Conversion from the normal to the transformed phenotype and the reverse is possible by temperature shifts. Conversely of the BHK21 clone 13 cells, of the rat fibroblasts (R111) transformed by 4-nitroquinoline-N-oxide (NQN), some exhibit a transformed phenotype restricted by temperature while others are not restricted by temperature in the expression of transformation. A working hypothesis is proposed suggesting that the phenotype of cells transformed by chemical carcinogens may be determined by the nature of the chemical reaction with the cell DNA. "Alkylating" carcinogens cause prevalently point mutation in bacteria (of the base substitution kind); in the case of transformation of mammalian cells temperature-sensitive phenotypes will be obtained. "Frameshift" carcinogens cause frameshift mutation in bacteria and cells transformed by this class of carcinogens will exhibit a transformed phenotype unrestricted by temperature.

Prevalence of torus palatinus and torus mandibularis among Malay population

The aims of this study were to determine the prevalence, size, shape, and location of torus palatinus (TP) and torus mandibularis (TM), and to assess their sex-related and age-related differences in the Malay population. Sixty-five subjects were assessed for the presence of both tori at the School of Dental Sciences University Sains Malaysia. The prevalence of TP was 38–63% and that of TM was 1–10%. TP was frequently more common in females than males (90.9% versus 9.1%; P < 0.05) and was frequently found in medium sizes, spindle shaped, and was often located at the combined premolar to molar areas. The prevalence of TM was not significantly different in males and females (33.3% versus 66.7%; P = 0.523), occurred most commonly in bilateral multiple form, and was often located at the canine to premolar area.

Intraosseous acinic cell carcinoma

Acinic cell carcinoma is an uncommon low-grade malignant tumor of salivary glands. It was first described by Nasse in 1892, arising in parotid salivary gland. Salivary gland tumors are also known to develop within jaw bones, arising within the jaw as a primary central lesion, and are extremely rare with only a few cases reported. We present a rare case report of 65-year-old woman with intraosseous acinic cell carcinoma of left side of the mandible.

Genetic variety of bovine viral diarrhea virus 1 strains isolated from sheep and goats in India

Antigenic and genetic typing of pestiviruses isolated from Indian sheep and goats was carried out. Testing of 1777 sheep and 1026 goat blood samples collected between 2004 and 2008 resulted in isolation of twelve pestiviruses, seven from sheep and five from goats. All of them were antigenically typed as bovine viral diarrhea virus 1 (BVDV-1). Both the partial 5ʹ-UTR and entire non-structural autoprotease (Npro) gene of the pestiviruses were amplified by RT-PCR and sequenced. The phylogenetic analysis confirmed all twelve sheep and goat pestiviruses as BVDV-1 and they were further classified into two subtypes, BVDV-1b (seven) and BVDV-1c (five). This is for the first time that BVDV-1c was detected in sheep and goats. However, no association between the subtype and geographic area of origin was observed. Although closely related, BVDV-1b and BVDV-1c isolates of sheep and goats were placed in a different clade than previously reported Indian BVDV-1b/BVDV-1c isolates. This study confirmed widespread prevalence of BVDV-1 in Indian sheep and goats that has significance in the epidemiology of bovine viral diarrhea.

KEYWORDS

bovine viral diarrhea virus; BVDV-1; goat; Npro; genetic typing; sheep; 5ʹ-UTR.

Quercetin modulates Na(+)/K(+) ATPase and sodium hydrogen exchanger in type 2 diabetic erythrocytes

Quercetin has been reported to possess many important biological properties. We undertook in vitro studies to examine the effect of quercetin on erythrocyte Na(+)/K(+) ATPase and sodium hydrogen exchanger (NHE) activity in normal and type 2 diabetic subjects. A significant (p<0.02) increase in the activities of Na(+)/K(+) ATPase and a decrease (p< 0.01) in NHE were observed in type 2 diabetic subjects compared to normal. In vitro treatment with quercetin caused inhibition of both Na(+)/K(+) ATPase and NHE. The inhibitory effect of quercetin was concentration dependent. The effect of quercetin on Na(+)/K(+) ATPase and NHE may be explained due to a direct effect of this compound on plasma membrane leading to a change in membrane fluidity. The data obtained in this study may help to explain the anti—diabetic and anti—carcinogenic role of quercetin.

Laparoscopic vertical sleeve gastrectomy after open gastric banding in a patient with situs inversus totalis

While several equivalent alternatives are available in the bariatric algorithm, more recently the laparoscopic sleeve gastrectomy (SG) has been gaining traction as an effective means of weight loss in patients with morbid obesity. We present the case of a 39-year-old woman with situs inversus totalis, who was taken to the operating room for laparoscopic SG. The patient had previously undergone a failed open gastric banding procedure 20 months earlier. Awareness of the inherited condition before performing the operation allows for advanced planning and preparation. Subsequent modifications to the standard trocar placement help make the procedure more technically feasible. To our knowledge, this is the first published report of a laparoscopic SG after open gastric banding in a patient with situs inversus totalis. After encountering the initial disorientation, we believe experienced laparoscopic surgeons can perform this procedure successfully and safely.

Increased zymogen activity of thrombin-activatable fibrinolysis inhibitor prolongs clot lysis

BACKGROUND AND OBJECTIVES

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a zymogen that can be activated by proteolytic cleavage into the active enzyme TAFIa. Hydrolysis of the C-terminal lysines on fibrin by TAFIa results in a down-regulation of fibrinolysis. Recent studies demonstrated that the zymogen also exerts an intrinsic enzymatic activity. Our objective was to identify and characterize zymogen-stimulatory nanobodies.

METHODS AND RESULTS

The screening of 24 nanobodies against TAFI revealed that two nanobodies (i.e. Vhh-TAFI-a51 and Vhh-TAFI-i103) were able to stimulate the zymogen activity 10- to 21-fold compared with the baseline zymogen activity of TAFI. The increase in catalytic efficiency can be attributed mainly to an increased catalytic rate, as no change in the K(M) -value was observed. The stability, the susceptibility towards PTCI and GEMSA and the kinetics of the stimulated zymogen activity differ significantly from those of TAFIa activity. Epitope mapping revealed that both Asp(75) and Thr(301) are major determinants in the binding of these nanobodies to TAFI. Localization of the epitope strongly suggests that this instability is as a result of a disruption of the stabilizing interactions between the activation peptide and the dynamic flap region (residues 296-350). In TAFI-depleted plasma reconstituted with a non-activatable variant of TAFI (TAFI-R92A), clot lysis could be prolonged by nanobody-induced stimulation of its zymogen activity as well as by increasing its concentration.

CONCLUSIONS

Increasing the zymogen activity of TAFI results in an antifibrinolytic effect.

Antibacterial photodynamic therapy on Staphylococcus aureus and Pseudomonas aeruginosa in-vitro

Photodynamic therapy (PDT) involves the use of drugs or dyes known as photosensitizers, and light source which induces cell death by the production of cytotoxic reactive oxygen species (ROS). This principle of cell death can be utilized to kill bacteria in vitro. We propose the use of blue light emitting diodes (LEDs) and Riboflavin as the light source and photosensitizer for in vitro killing of Staphylococcus aureus and Pseudomonas aeruginosa. Circularly arranged 65-blue LED array was designed as the light source to fit exactly over 7cm culture plate. Riboflavin having non-toxic properties and nucleic acid specificity was used as a photosensitizer. Clinical isolates of Staphylococcus aureus and Pseudomonas aeruginosa were used in our study. Effect of PDT on viability on these species of bacteria was compared with control samples that included: control untreated, control treated with light only and control treated with riboflavin only. Statistical analysis was done using one-way ANOVA test. PDT against Pseudomonas aeruginosa and Staphylococcus aureus was significantly (p < 0.05) effective compared to all control samples. Combination of blue LEDs and Riboflavin in PDT against these bacterial species has been successfully demonstrated in-vitro. Therefore, PDT has promising applications in the process of treating superficial wound infections.

Changing trends of services used as first contact by patients with mental health problems

BACKGROUND

In the past, traditional faith healers and practitioners of alternative medicine have often been reported to be the first source of contact for Indian patients with mental health problems. However, over the past few decades, this trend seems to be changing.

METHOD

Using a semi-structured questionnaire, we assessed 200 new patients at a psychiatric outpatient service in a general hospital for the first service contact used by them for their mental health problems.

RESULTS

Psychiatrists, non-psychiatric physicians, traditional faith healers and practitioners of alternative medicine were the first service contact for 91 (45.5%), 88 (44%), 16 (8%) and 5 (2.5%) patients, respectively. Patients suffering from severe mental illnesses were more likely to choose a psychiatrist as the first contact, whereas those with neurotic, stress-related and organic mental disorders contacted a non-psychiatric physician.

CONCLUSION

In the current scenario, psychiatrists and nonpsychiatric physicians serve as the first service contact for most patients with mental health problems in India, though traditional faith healers and practitioners of alternative medicine are contacted by a minority.