Ultrathin, biodegradable polymer-coated everolimus-eluting stents for patients undergoing percutaneous coronary intervention: Final three-year results of the PERFORM-EVER registry

The registry reports 3-year safety and clinical performance of the ultrathin strut (60 μm) biodegradable polymer-coated Tetrilimus, an everolimus-eluting stent (EES) (Sahajanand Medical Technologies Limited, India), in 'real-world' patients with coronary artery disease. A total of 815 Tetrilimus EES were implanted in 735 lesions in 594 patients. At 3-year follow-up, primary endpoint (target lesion failure, TLF) was reported in 8.6 % patients, including 2.6 % cardiac deaths, 3.5 % myocardial infarction and 2.6 % target lesion revascularization. At three-year, no cases of definite stent thrombosis were reported. The final three-year results of PERFORM-EVER registry endorse the continuous safety and effectiveness Tetrilimus EES.

Effectiveness and safety of optical coherence tomography-guided PCI in Indian patients with complex lesions: A multicenter, prospective registry

BACKGROUND

Optical coherence tomography (OCT) is reported to be a feasible and safe imaging modality for the guidance of percutaneous coronary intervention (PCI) of complex lesions.

METHODS

This multicenter, prospective registry assessed the minimum stent area (MSA) achieved under OCT guidance. A performance goal of 24% improvement in MSA over and above the recommendation set by the European Association of Percutaneous Cardiovascular Interventions Consensus 2018 (4.5 mm2 MSA for non-left main and 3.5 mm2 for small vessels). The incidence of contrast-induced nephropathy was also assessed. Core lab analysis was conducted.

RESULTS

Five hundred patients (average age: 59.4 ± 10.1 years; 83% males) with unstable angina (36.8%), NSTEMI (26.4%), and STEMI (22%) were enrolled. The primary endpoint was achieved in 93% of lesions with stent diameter ≥2.75 mm (average MSA: 6.44 mm2) and 87% of lesions with stent diameter ≤2.5 mm (average MSA: 4.56 mm2). The average MSA (with expansion ≥80% cutoff) was 6.63 mm2 and 4.74 mm2 with a stent diameter ≥2.75 mm and ≤2.5 mm, respectively. According to the core lab analysis, the average MSA achieved with a stent diameter ≥2.75 mm and ≤2.5 mm was 6.23 mm2 and 3.95 mm2, respectively (with expansion ≥80% cutoff). Clinically significant serum creatinine was noted in two patients (0.45%). Major adverse cardiac events at 1 year were noted in 1.2% (n = 6) of the patients; all were cardiac deaths.

CONCLUSION

PCI under OCT guidance improves procedural and long-term clinical outcomes in patients with complex lesions not just in a controlled trial environment but also in routine clinical practice.

Post market surveillance registry (PIONEER) of the Yukon Choice PC-Elite Coronary Stent System for percutaneous coronary intervention in Indian acute coronary syndrome population

AIM

The aim of this study was to assess the safety and efficacy profile of a newer generation biodegradable DES, the Yukon Choice PC Elite with a temperature controlling mechanism, in patients with acute coronary syndrome (ACS).

METHODS

This prospective multi-center study (PIONEER Registry) was conducted in an Indian ACS population, therefore providing data in real world clinical practice. Patients with ACS underwent DES implantation in de novo native-vessel coronary lesions with the Yukon Choice PC Elite biodegradable polymer DES and were followed up for a year.

RESULTS

A total 999 patients were evaluated. The majority of patients were male (79.2%). A total of 6.7% of the patients had a history of prior myocardial infarction (MI) and 2.7% of patients had a history of previous coronary artery bypass graft. The clinical presentations of the patients included: unstable angina pectoris (UA) (46.4%), ST-segment elevation MI (STEMI) (38.1%), and Non-ST-segment elevation MI (NSTEMI) (15.4%). Implantation of the device was successful in 99.9% of cases. The median stent length and stent size were 21.0 mm (Range: 8.0-40.0 mm) and 2.8 mm (Range 2.0-4.0 mm), respectively. Through to one-year clinical follow-up after percutaneous coronary intervention, all-cause death occurred in 4 of 999 patients (Crude Percentage: 0.4%). Cardiac death, MI, TLR, and stent thrombosis were occurred in 1 (0.1%), 8 (0.8%), 12 (1.2%) and 1 (0.1%) patients, respectively.

CONCLUSION

The results of this post marketing surveillance registry suggest favorable safety and efficacy outcomes associated with the Yukon Choice PC Elite biodegradable DES in a real world Indian ACS population.

Safety and Clinical Performance of Biodegradable Polymer-Coated Ultra-Thin Everolimus-Eluting Stents in “Real-World” Patients: A Multicenter Registry (PERFORM-EVER)

Background:

Tetrilimus (Sahajanand Medical Technologies Limited, Surat, India) is a biodegradable polymer-coated everolimus-eluting stent with cobalt–chromium stent platform and ultra-thin (60 µm) strut thickness. We aimed to report 1-year safety and clinical performance of Tetrilimus everolimus-eluting stent in patients with coronary artery disease in “real-world” clinical practice.

Methods:

The PERFORMance of biodegradable polymer-coated ultra-thin EVERolimus-eluting stents was an observational, multicenter, single-arm, and investigator-initiated retrospective registry. All “real-world” patients who had received Tetrilimus everolimus-eluting stent between July-2015 and October-2016 at four study centers were analyzed. The data were collected retrospectively either by extraction from existing databases in consecutive fashion where index and follow-up data existed or the follow-up was obtained by telephonic contact. Primary endpoint was 1-year incidence of target lesion failure, which was defined as a composite endpoint of cardiac death, myocardial infarction, and target lesion revascularization by percutaneous or surgical methods. The Academic Research Consortium-defined stent thrombosis was assessed as additional safety endpoint.

Results:

During the study period, 815 Tetrilimus everolimus-eluting stents (1.4 ± 0.5 stent/patient) were implanted to treat 735 coronary lesions (1.1 ± 0.3 stent/lesion) in 594 patients (mean age: 55.6 ± 12.1 years). The cumulative incidence of target lesion failure at 1-year follow-up was 3.7%, which included 9 (1.5%) cardiac deaths, 8 (1.4%) myocardial infarctions, and 5 (0.8%) target lesion revascularizations. There were 5 (0.8%) cases of probable stent thrombosis and 4 (0.7%) cases of possible stent thrombosis at 1-year follow-up.

Conclusion:

Low incidences of target lesion failure and stent thrombosis at 1-year follow-up indicates that biodegradable polymer-coated ultra-thin Tetrilimus everolimus-eluting stents may have encouraging safety and efficacy in unselected real-world patients with coronary artery disease, including those with high-risk characteristics and complex lesions.

Guiding Principles for the Clinical Use and Selection of Microcatheters in Complex Coronary Interventions

The use of microcatheters as a coronary interventional tool for a therapeutic approach to complex coronary interventions like bifurcation lesions, ostial location, tortuous anatomy, angled takeoffs, coronary calcification, and chronic total occlusion (CTO) percutaneous coronary intervention (PCI) is growing among cardiologists across the country. During the treatment of such complex lesions, microcatheters play an essential part of the tool kit with both single-lumen and double-lumen microcatheters (DLMs) having their specific niche areas. The selection of microcatheters involves a detailed understanding of the microcatheter specification, lesion anatomy, lesion location, vessel tortuosity and trajectory, and crossing techniques. The selection of appropriate crossing techniques with different microcatheters increases success rates of PCI, reduces procedural time and contrast use, and lowers the radiation. However, the use of microcatheters and their technicalities have not yet fully realized by many operators and their true scope has not been fully explored. This article discusses and summarizes the thoughts and key opinions of experts in this field.

Mobile health technologies for the management of systemic lupus erythematosus: a systematic review

OBJECTIVE

We aimed to perform a standardized review of available mobile health (mHealth) applications (apps) for systemic lupus erythematosus (SLE) and to conduct a systematic review of the literature on mHealth technologies in SLE.

METHODS

Google Play and AppStore in the United States of America were queried and the quality of eligible mHealth apps was assessed using the Mobile App Rating Scale (MARS). Web of Science, EMBASE, Medline, and Cochrane databases were systematically searched from inception through June 2019.

RESULTS

Of 324 mHealth apps found, 20 were eligible for inclusion; 10 focused on education, 7 offered tools to track patient-reported symptoms, 5 included interactive online communities, and 1 enabled emoji sharing. The reviewed apps scored poorly on the MARS quality scale with a mean score 2.3 (0.6) out of 5. Of 1147 studies identified in the literature review, 21 were eligible for inclusion; 11 studies (52.4%) focused on the development and use of mHealth for providing patient information, while only 2 (9.5%) were randomized trials of mHealth interventions.

CONCLUSIONS

Although there is growing interest in the development of mHealth technologies to support SLE patients, currently available tools are of poor quality and limited functionality, and the literature examining this area is sparse.

Non-pharmacologic therapies for systemic lupus erythematosus

BACKGROUND

Non-pharmacologic therapies have been deemed as potentially beneficial for patients with systemic lupus erythematosus. We conducted an updated review to determine the effects of these therapies to inform practice.

METHODS

A literature search was performed using PubMed (MEDLINE), EMBASE, Cochrane, PsychINFO, the Cumulative Index to Nursing and Allied Health Literature, Web of Science, and Google Scholar from inception until August 2018. We included randomized controlled trials of non-pharmacologic therapies in systemic lupus erythematosus patients with sample size ≥10. Systemic lupus erythematosus was defined by 1982 or 1997 American College of Rheumatology criteria. Studies were synthesized separately by patient-reported outcomes and disease activity. Due to the heterogeneity of interventions and comparisons, a meta-analysis was not performed.

RESULTS

A total of 15 randomized controlled trials involving 846 participants met the inclusion criteria. Of the 15 trials, eight used exercise interventions, six used psychological interventions (one group psychotherapy, three cognitive behavioral therapies, one psychoeducation, one mindfulness-based cognitive therapy) and one used electro-acupuncture. Five of 15 studies utilized control groups consisting of usual medical care. Other studies included control interventions of relaxation, attention placebo, symptom monitoring support, education, minimal needling, isotonic and resistance exercise. Compared with the control conditions, non-pharmacological interventions were associated with a significant improvement in fatigue in three out of six studies. Three out of eight studies reported improved anxiety and depression, and one study reported improved pain after interventions. Seven out of 11 studies reported improvement in overall quality of life in at least one domain of the Short-Form Health Survey. Of note, no studies demonstrated an improvement in disease activity after 5-52 weeks of non-pharmacological therapies.

CONCLUSION

This review showed promising results for physical exercise and psychological interventions as adjuncts to traditional medical therapy for improvement in fatigue, depression, pain and quality of life for systemic lupus erythematosus. Further high-quality randomized controlled trials with longer follow-up periods are warranted.

Feasibility of Patient-Reported Outcomes Measurement Information System (PROMIS®) computerized adaptive tests in systemic lupus erythematosus outpatients

Objective

The aims of this study were to assess the feasibility of administering Patient-Reported Outcomes Measurement Information System (PROMIS®) computerized adaptive tests (CATs) to outpatients with systemic lupus erythematosus (SLE).

Methods

Adults with SLE were recruited during routine outpatient visits at an SLE Center of Excellence. Participants completed 14 PROMIS CATs and provided feedback on their experience. Differences in socio-demographic and clinical characteristics between participants and non-participants were evaluated.

Results

A total of 204 (86%) of 238 socioeconomically and racially diverse SLE patients completed PROMIS CATs. There were no significant differences between participants and non-participants. Time constraints were cited most frequently as reasons for non-participation. More than 75% of individuals submitted positive comments, including approval of the content and format of questions, and the survey’s promotion of self-reflection. A minority of participants cited challenges, most often related to question phrasing (8%) and technical difficulties (6%).

Conclusions

The administration of PROMIS CATs was feasible and positively received in a diverse cohort of SLE outpatients. Neither socio-demographic nor disease characteristics were significant barriers to successful completion of PROMIS CATs. PROMIS CATs have great potential for efficiently measuring important patient-centered outcomes in routine clinical care of a wide range of SLE patients.

A randomized placebo-controlled trial with amiodarone for persistent atrial fibrillation in rheumatic mitral stenosis after successful balloon mitral valvuloplasty

Objective

Atrial fibrillation is the most common sustained arrhythmia in patients with rheumatic heart disease (RHD). This study was conducted to determine the maintenance of sinus rhythm with amiodarone therapy following DC cardioversion (DCCV), early after successful balloon mitral valvuloplasty (BMV).

Methods

Patients were randomized to amiodarone group and placebo group and their baseline characteristics were recorded. DCCV was done 48 h after BMV. After cardioversion, oral amiodarone was started initially 200 mg three times a day for 2 weeks, then 200 mg twice daily for two weeks followed by 200 mg once daily for 12 months. Patients in placebo group received DCCV alone without preloading amiodarone. After DCCV, they were given placebo for 12 months.

Results

The 3 months follow-up period was completed by 77 patients (95%). Of them, 31 (77.5%) patients in amiodarone group and 14 (34.1%) in placebo group remained in sinus rhythm (SR). The 12 months follow-up period was completed by 73 patients (90.1%). Of them, 22 (55%) patients in amiodarone group and 7 (17.1%) in placebo group remained in SR.

Conclusion

We conclude that amiodarone is more effective than placebo in maintenance of SR at the end of 3 months following successful cardioversion and more patients continued to remain in SR even at the end of 12 months without major serious adverse effects.

Gene transfer of type 1 interleukin-1 receptor extracellular-domain complementary DNA into rabbit synovial cell line HIG-82 results in cellular blockade of interleukin-1 signal transduction

OBJECTIVE

To produce, by means of expression cloning, a soluble type 1 interleukin-1 receptor (sIL-1R), and to assess its inhibitory properties on the IL-1 pathway.

METHODS

High-affinity IL-1R sites were identified in a human chondrosarcoma cell line by means of 125I-IL-1beta binding. A 1-kilobase complementary DNA (cDNA) encoding the ligand-binding domain of the type 1 IL-1R was cloned by using polymerase chain reaction, and the cDNA was inserted into a mammalian expression vector pRc/CMV. The sIL-1R expression vector was transfected into a rabbit synovial cell line (HIG-82) and a stably transfected cell population was selected. The production of sIL-1R was confirmed in the medium of transfected cells using 125I-IL-1beta binding. 35S labeling of transfected cultures, followed by immunoprecipitation and gel electrophoresis, was used to characterize the size of the recombinant sIL-1R. Stromelysin and IL-1alpha steady-state messenger RNA (mRNA) levels were assessed by Northern blotting. Prostaglandin E2 (PGE2) release was measured by enzyme-linked immunosorbent assay.

RESULTS

IL-1R on the surface of HIG-82 cells bound 125I-IL-1beta with an equilibrium dissociation constant (Kd) of 67.3 +/- 7.8 pM (mean +/- SD). Transfection of the sIL-1R expression vector into a synovial cell line in vitro resulted in the appearance of an sIL-1R protein that bound 125I-IL-1beta with high affinity in the medium (Kd = 108 +/- 5 pM). Two protein bands (Mr 42 kd and 47 kd) were immunoprecipitated with an antibody against type 1 T cell-derived sIL-1R. Expression of sIL-1R was accompanied by a marked decrease in both stromelysin and IL-1alpha steady-state mRNA levels. In conjunction, there was a significant inhibition of basal and IL-1-stimulated PGE2 released by sIL-1R-producing cells.

CONCLUSION

The data suggest that gene transfer of type 1 sIL-1R into the synovium may be an effective means of inhibiting IL-1-induced metalloproteinase expression and inflammatory responses.

Metalloprotease-mediated cleavage secretion of pulmonary ACE by vascular endothelial and kidney epithelial cells

The pulmonary isozyme of angiotensin-converting enzyme (ACEP) is present in the body both as a cell-associated protein in endothelial, epithelial, and monocytic cells and as a soluble protein in various body fluids including serum. The mechanism by which soluble ACEP is produced in vivo is unknown. Using in vitro transfected cell culture systems, we previously demonstrated that the rabbit testicular isozyme of ACE (ACET), which shares extensive homology with ACEP, is first synthesized as a plasma membrane-anchored ectoprotein and then secreted to the culture medium by cleavage removal of its COOH-terminal membrane-anchored tail. Here, using in vitro cultures of arterial endothelial cells and acutely isolated renal epithelial cells, we demonstrate that ACEP is also cleavage secreted from their natural producer cells. Biochemical and immunological characterization of the in vitro secreted ACEP protein revealed that it is missing the COOH-terminal membrane-anchored region of the cell-associated ACEP. Similar analysis of ACEP proteins present in rabbit serum, lung, and kidney established that ACEP secretion in vivo is also caused by the cleavage removal of the COOH-terminal region of the cell-associated protein. To characterize the proteolytic enzyme responsible for ACEP secretion, we employed rabbit renal proximal tubular epithelial cells and demonstrated significant inhibition of secretion by compound 3, a hydroxamic acid-based inhibitor of specific metalloproteases. In contrast, the inhibitors of chymotrypsin, trypsin, serine, aspartate, and cysteine proteases were ineffective. These results indicate that soluble ACEP production by vascular endothelial and renal epithelial cells, both in vitro and in vivo, is achieved by cleavage removal of its membrane-anchoring COOH-terminal tail by a metalloprotease.

Role of glycosylation in the biosynthesis and activity of rabbit testicular angiotensin-converting enzyme

Angiotensin-converting enzyme (ACE) is a type I glycoprotein anchored in the plasma membrane by a hydrophobic domain near its carboxyl terminus. The enzymatically active extracellular domain of ACE is slowly released from the cell by cleavage-removal of its membrane-anchoring carboxyl-terminal region. In the present study, we investigated the role of N- and O-glycosylation in intracellular transport and extracellular cleavage-secretion of rabbit testicular ACE. For ACE expression, we used an in vitro translation system, a permanently transfected mouse cell line, and human and Chinese hamster cells transiently transfected with vaccinia virus-T7 RNA polymerase-driven expression vectors. Sugar modifications of ACE were analyzed by testing its sensitivity to specific glycosidases. Cellular protein glycosylation was inhibited by using chemical inhibitors and a mutant cell line defective in protein glycosylation. Our experiments demonstrated that newly synthesized ACE acquires both N- and O-linked sugars before its cleavage-secretion and complete blockage of glycosylation results in rapid intracellular turnover of underglycosylated ACE. However, ACE synthesized without N-linked complex sugars and O-linked sugars can undergo normal transport and cleavage-secretion, and the underglycosylated protein is enzymatically active.

Domain II of Pseudomonas exotoxin A arrests the transfer of translocating nascent chains into mammalian microsomes

The translocation of PE from the extracytosolic compartment to the cytosol during the intoxication of mammalian cells is mediated by domain II of the toxin. We have shown previously that within domain II amino acids 280-313 of PE promote their own export from mammalian microsomes following signal sequence-directed membrane insertion. In this study, we attempted to target full-length PE into mammalian microsomes using the preprocecropin signal sequence, but found that translocation was arrested to generate a transmembrane protein. "Stop transfer" required the presence of amino acids 280-313 of PE, and the first 313 amino acids of PE were sufficient to generate a transmembrane protein (N-terminus-in/C-terminus-out). The mechanism of stop transfer appears to be different from that described previously because amino acids 280-313 of PE are not highly hydrophobic and do contain many charged residues. In addition, the transmembrane segment appeared to be influenced by the cytoplasmic domain of the transmembrane proteins.

Mutations in two specific residues of testicular angiotensin-converting enzyme change its catalytic properties

Chemical modifications of 2 specific residues present in angiotensin-converting enzyme (ACE) result in its inactivation, thereby suggesting that these 2 residues may be important for its enzyme activity. We directly tested this hypothesis by substituting Tyr-236 with Phe and Lys-154 with Glu in rabbit testicular ACE (ACET) using site-directed mutagenesis of the corresponding cDNA. Wild type ACET, the two single mutants, and the double mutant were expressed in HeLa cells using the vaccinia virus-T7 polymerase expression system. The rate of synthesis, post-translational modifications, and cleavage secretion pattern of all four proteins were indistinguishable. The enzymatic properties of the two single mutants and the wild type enzyme were also very similar. In contrast, the double mutant had about a 20-fold lower specific activity although its Km was only 6-fold higher than that of the wild type protein. The double mutant also had a 100-fold higher Ki for lisinopril, a competitive inhibitor of ACET, and was 17-fold less sensitive to stimulation by NaCl, an activator of ACET. These results directly demonstrate that Tyr-236 and Lys-154 are indeed critical for the catalytic activity, lisinopril inhibition, and NaCl activation of ACET.

Insertion of constant region domains of human IgG1 into CD4-PE40 increases its plasma half-life

CD4-PE40 is a recombinant toxin containing the binding domain of CD4 and a mutant form of Pseudomonas exotoxin A from which the cell binding domain has been removed. To increase the serum half-life of CD4-PE40, we have inserted various portions of the constant domain of human IgG1 into CD4-PE40. The constructs made include CD4-CH2-PE40, CD4-CH3-PE40, CD4-CH1-CH2-PE40 and CD4-CH2-CH3-PE40. The fusion proteins were expressed and purified from E. coli. Insertion of various domains from the constant region of IgG1 did not alter the cytotoxic activity of CD4-PE40; all these molecules were equally cytotoxic to cells expressing gp120 on their surface. However, there was a marked increase in the serum mean residence time of CD4-CH2-PE40 which was 115 min as compared to 47 min for CD4-PE40. Insertion of other domains also increased the half-life of CD4-PE40, however, CD4-CH2-PE40 was found to have the longest mean residence time in the circulation. One possible explanation for the increase in plasma half-life is diminished susceptibility of proteins to proteolysis. It was found that CD4-CH2-PE40 was much more resistant to proteolysis by trypsin than CD4-PE40. We proposed that insertion of the CH2 domain into CD4-PE40 covers up the protease sensitive sites in the molecule, thereby making the molecule less susceptible to degradation. The increase in size and reduced sensitivity to proteases could both be responsible for the increased plasma half-life of CD4-CH2-PE40.

Alanine scanning mutagenesis identifies surface amino acids on domain II of Pseudomonas exotoxin required for cytotoxicity, proper folding, and secretion into periplasm

Pseudomonas exotoxin A (PE) is a single polypeptide chain that contains 613 amino acids and is arranged into three major structural domains. Domain Ia is responsible for cell recognition, domain II for translocation of PE across the membrane, and domain III for ADP-ribosylation of elongation factor 2. Recombinant PE can be produced in Escherichia coli and is efficiently secreted into the periplasm when an OmpA signal sequence is present. To investigate the role of the amino acids located on the surface of domain II in the action of the toxin against mammalian cells, we substituted alanine for each of the 27 surface amino acids present in domain II. Surprisingly, all 27 mutant proteins had some alteration in cytotoxicity when tested on human A431 or MCF7 cells or mouse L929 cells. Native PE has a compact structure and therefore is relatively protease resistant and very little ADP-ribosylation activity is detected in the absence of the denaturing agents like urea and dithiothreitol. Several of the mutations resulted in altered protease sensitivity of the toxin. Seven of the mutant molecules exhibited ADP-ribosylation activity without urea and dithiothreitol, indicating they are partially unfolded. Out of these seven mutants, six had increased cytotoxic activity on at least one of the target cell lines and the other retained its native cytotoxic potency.

Analysis of Vipera russelli venom using polyclonal antibodies prepared against its purified toxic phospholipase A2 VRV PL-V

Vipera russelli venom induces predominantly neurotoxic, myotoxic necrotic and hemorrhagic symptoms in experimental animals and has several hydrolytic enzyme activities. In this study, V. russelli venom is characterized both as a PLA2 and as a toxin. Anti PL-V Ig (antibodies to a toxic phospholipase A2 VRV PL-V of V. russelli venom) nullifies the toxicity of whole V. russelli venom to a great extent. The neurotoxic symptoms vanish completely in the presence of anti PL-V Ig. The cross reacting components of whole V. russelli venom were removed by precipitating them from whole venom by the addition of anti PL-V Ig. The non-cross reacting components present in the supernatant were checked for toxicity. There was a significant reduction in toxicity. The LD50 value of the supernatant had increased from 4.1 mg/kg body weight to 11.7 mg/kg body weight and it showed about 34% of the total venom phospholipase A2 activity. It had edema forming, hemorrhagic and hemolytic activity but failed to induce neurotoxic, anticoagulant and myotoxic effects.

Identification, isolation and purification of neurotoxic phospholipases A2 from Vipera russelli venom using polyclonal antibodies

All the neurotoxic phospholipases A2 present in whole Vipera russelli venom were precipitated selectively from other non-neurotoxic phospholipases A2 and non-phospholipases A2 fractions using antibodies (anti PL-V Ig) raised against one of the purified neurotoxic phospholipases A2 (VRV PL-V). These neurotoxins were identified and isolated in their homogeneous form by chromatographic and electrophoretic methods. The present report of selective isolation and purification of all the neurotoxic phospholipases A2 of V. russelli venom is first of its kind.

Structure-function relationships among neurotoxic phospholipases: NN-XIII-PLA2 from Indian cobra (Naja naja naja) and VRV PL-V from Russell's viper (Vipera russelli) venoms

Though venom phospholipases induce various pharmacological effects their mechanism of action is in some cases unclear. There may be separate pharmacological sites on the venom phospholipase molecule. In order to understand the structure-function relationships among venom phospholipases, studies on interaction of venom phospholipases with its antibodies and various alkaloids were carried out. The alkaloids aristolochic acid, ajmaline and reserpine were incapable of inhibiting the phospholipase A2 activity of NN-XIII-PLA2 but inhibited its edema inducing potency and partially inhibited the symptoms of neurotoxicity. The direct and indirect hemolytic activity remain unaffected. Polyclonal antibodies (anti PL-V Ig) to a neurotoxic PLA2 VRV PL-V neutralized the neurotoxic symptoms and lethality of VRV PL-V without affecting its in vitro phospholipase A2 activity when egg PC was used as the substrate. However, they inhibited the catalytic activity of VRV PL-V when synaptosomes were used as the substrate. Our results indicate the presence of multiple pharmacologically active sites apart from catalytic site.

The effect of menhaden oil on choline-deficiency-induced hepatic ornithine decarboxylase activity and hepatocyte insulin receptor binding

The effects of menhaden oil on the choline-deficient (CD) diet tumor promotion regimen-induced alterations in hepatocyte insulin receptors and the cellular ornithine decarboxylase (ODC) activity have been investigated in this study. Male Sprague-Dawley rats exposed to the tumor-promoting regimen of a CD diet for 10 days showed increases in hepatic ODC activity from 2.68 +/- 0.42 pmol 14CO2/mg protein/h in the animals fed basal control chow (C) to 13.54 +/- 2.38 (P less than 0.02) in the rats fed CD diet. These changes in ODC occur simultaneously with the alterations in hormone receptor binding as reported previously for insulin. Replacement of the lipid present in the control diet with 15% menhaden oil (CMO) had no significant effect on ODC activity (0.91 +/- 0.21), or on the number of insulin receptors (206,000 +/- 37,000) and the Kd (7.4 +/- 1.6). Sequential treatment with 10 days of CD diet and then 10 days of the C diet, resulted in a reversal in the elevated, CD-induced hepatic ODC activity to the control levels; however, substituting 15% menhaden oil for the fat present in the CD diet (CDMO) enhanced this enzymatic activity. In contrast, both sequential and CDMO treatments prevented the insulin receptor alterations induced by the CD diet. These data demonstrate that the CD diet-induced insulin receptor alterations occur concurrently with the induction of ODC activity. But insulin receptor changes and the increased ODC activity are affected differently by CDMO treatment, suggesting that their induction by the CD diet is through distinct mechanisms and only the receptor alterations correspond with the tumor-promoting action of CD diet regimen.

Antibodies to a phospholipase A2 from Vipera russelli selectively neutralize venom neurotoxicity

Polyclonal antibodies to a purified neurotoxic phospholipase A2 (PLA2), VRV PL-VIIIa, from Vipera russelli venom were raised in rabbits. Anti-PL-VIIIa-Ig (gamma-globulin fraction of rabbit antiserum injected with VRV PL-VIIIa) selectively neutralized the neurotoxicity of VRV PL-VIIIa, VRV PL-V, VRV PL-VI (neurotoxic PLA2 of V. russelli venom) and whole V. russelli venom without affecting their PLA2 activity, which clearly demonstrates that the catalytic site and the neurotoxic site (the site through which the PLA2 binds to the nervous system) are distinct on a PLA2 molecule. Anti-PL-VIIIa Ig did not have any effect on the oedema-inducing activity and indirect haemolytic activity of VRV PL-VIIIa, VRV PL-V and VRV PL-VI, which are attributed to the PLA2 activity of the peptide, but inhibited their anti-coagulant potency.

Detection, using antibodies, of pharmacologically active sites, apart from the catalytic site, on venom phospholipase A2

Polyclonal antibodies to a purified neurotoxic phospholipase A2 VRV PL-V from Vipera russelli venom were raised in rabbits. The gamma globulin fraction from the serum of the rabbits injected with VRV PL-V-toxoid (anti VRV PL-V antibodies) is termed anti PL-V Ig. Anti PL-V Ig neutralized the neurotoxic symptoms and lethal effects of neurotoxic PLA2s (VRV PL-V, VRV PL-VI and VRV PL-VIIIa) and neurotoxic symptoms of whole V. russelli venom, without affecting their phospholipase A2 activities. Their edema inducing activity was also unaffected. Anti VRV PL-V-antibodies inhibited the anticoagulant potencies of the neurotoxic PLA2s (VRV PL-V, VRV PL-VI and VRV PL-VIIIa) from V. russelli venom and VRV PL-V-toxoid. The myonecrotic activity of VRV PL-V, VRV PL-VIIIa and whole venom remain unaffected in presence of anti PL-V Ig. The hemoglobinuria induced in rabbits by injection of VRV PL-V-toxoid was inhibited by anti VRV PL-V antibodies. These results indicate the presence of multiple pharmacological sites apart from the catalytic site on V. russelli PLA2 molecules.

Purification and characterization of a major phospholipase A2 from Russell's viper (Vipera russelli) venom

A major phospholipase A2 (VRV PL-VIIIa) which constitutes 24% of the whole Vipera russelli venom was purified to homogeneity by CM-Sephadex C-25 column chromatography followed by gel filtration on Sephadex G-50. VRV PL-VIIIa is a basic protein with a molecular weight of 11,800 by SDS-PAGE. This enzyme contributes 45% of the total PLA2 activity of the venom, but it is least toxic compared to other purified basic PLA2 enzymes prepared from V. russelli venom. The LD50 value (i.p.) of VRV PL-VIIIa is 5.3 mg/kg body wt. It shows neurotoxic symptoms and damages vital organs such as lung, liver and kidney at LD50 doses. It induces myonecrosis when injected i.m. into the thigh muscle of mice and edema when injected into the foot pads.

Dissociation of catalytic activity and neurotoxicity of a basic phospholipase A2 from Russell's viper (Vipera russelli) venom

A neurotoxic phospholipase A2, VRV PL-V was purified from Vipera russelli venom in a single step by CM-Sephadex C-25 column chromatography. VRV PL-V is a basic PLA2 with a mol. wt of approximately 10,000. The lethal potency of VRV PL-V was greater than that of the crude V. russelli venom. VRV PL-V showed anticoagulant activity and induced edema in the foot pad of the mouse. VRV PL-V undergoes aggregation at pH 4.8. The size of the aggregate increased as the temperature at which the enzyme was incubated was raised. A highly aggregated form with a mol. wt of 53,100 was formed at 96 degrees C. This aggregate showed a two-fold increase in its catalytic activity, while its neurotoxic activity disappeared. The aggregate also showed a significant increase in its anticoagulant activity when compared to the monomeric form. Edema-inducing activity decreased upon association to higher molecular form.