Machine learning based identification potential feature genes for prediction of drug efficacy in nonalcoholic steatohepatitis animal model.

BACKGROUND: Nonalcoholic Steatohepatitis (NASH) results from complex liver conditions involving metabolic, inflammatory, and fibrogenic processes. Despite its burden, there has been a lack of any approved food-and-drug administration therapy up till now. PURPOSE: Utilizing machine learning (ML) algorithms, the study aims to identify reliable potential genes to accurately predict the treatment response in the NASH animal model using biochemical and molecular markers retrieved using bioinformatics techniques. METHODS: The NASH-induced rat models were administered various microbiome-targeted therapies and herbal drugs for 12 weeks, these drugs resulted in reducing hepatic lipid accumulation, liver inflammation, and histopathological changes. The ML model was trained and tested based on the Histopathological NASH score (HPS); while (0-4) HPS considered Improved NASH and (5-8) considered non-improved, confirmed through rats' liver histopathological examination, incorporates 34 features comprising 20 molecular markers (mRNAs-microRNAs-Long non-coding-RNAs) and 14 biochemical markers that are highly enriched in NASH pathogenesis. Six different ML models were used in the proposed model for the prediction of NASH improvement, with Gradient Boosting demonstrating the highest accuracy of 98% in predicting NASH drug response. FINDINGS: Following a gradual reduction in features, the outcomes demonstrated superior performance when employing the Random Forest classifier, yielding an accuracy of 98.4%. The principal selected molecular features included YAP1, LATS1, NF2, SRD5A3-AS1, FOXA2, TEAD2, miR-650, MMP14, ITGB1, and miR-6881-5P, while the biochemical markers comprised triglycerides (TG), ALT, ALP, total bilirubin (T. Bilirubin), alpha-fetoprotein (AFP), and low-density lipoprotein cholesterol (LDL-C). CONCLUSION: This study introduced an ML model incorporating 16 noninvasive features, including molecular and biochemical signatures, which achieved high performance and accuracy in detecting NASH improvement. This model could potentially be used as diagnostic tools and to identify target therapies.

Advanced 3D Face Reconstruction from Single 2D Images Using Enhanced Adversarial Neural Networks and Graph Neural Networks.

This paper presents a novel framework for 3D face reconstruction from single 2D images and addresses critical limitations in existing methods. Our approach integrates modified adversarial neural networks with graph neural networks to achieve state-of-the-art performance. Key innovations include (1) a generator architecture based on Graph Convolutional Networks (GCNs) with a novel loss function and identity blocks, mitigating mode collapse and instability; (2) the integration of facial landmarks and a non-parametric efficient-net decoder for enhanced feature capture; and (3) a lightweight GCN-based discriminator for improved accuracy and stability. Evaluated on the 300W-LP and AFLW2000-3D datasets, our method outperforms existing approaches, reducing Chamfer Distance by 62.7% and Earth Mover's Distance by 57.1% on 300W-LP. Moreover, our framework demonstrates superior robustness to variations in head positioning, occlusion, noise, and lighting conditions while achieving significantly faster processing times.

Pediatric kidney transplantation in Egypt: Results of 10-year single-center experience.

Pediatric kidney transplantation is a multidisciplinary therapy that needs special consideration and experience. In this study, we aimed to present CUCH experience; over a 10-year period, as a specialized center of kidney transplantation in children. We studied 148 transplantations performed at a single center from 2009 to 2018. Pretransplant and follow-up data were collected and graft/patient survival rates were evaluated. A total of 48 patients developed at least one rejection episode during 688 patient-years of follow-up. Infections, recurrence of original disease, and malignancy were the most important encountered medical complications (20%, 2%, and 1.4%, respectively). One-year patient survival was 94.1%, while graft and patient survival was 91.9%. Graft/patient survival at 5, 7, and 9 years was 90%, 77%, and 58%, respectively. Infections were the main cause (69%) of mortality. Death with a functioning graft and CR were the main causes of graft loss (48% and 33%, respectively). Pediatric kidney transplantation in Egypt is still a challenging yet successful experience. Rejections and infections are the most frequent complications. Short-term outcomes surpass long-term ones and graft survival rates are similar to the international standard.

Intensive Early Rehabilitation in the Intensive Care Unit for Liver Transplant Recipients: A Randomized Controlled Trial.

OBJECTIVE: To validate the feasibility and tolerance of an intensive rehabilitation protocol initiated during the postoperative period in an intensive care unit (ICU) in liver transplant recipients. DESIGN: Prospective randomized study. SETTING: ICU. PARTICIPANTS: Liver transplant recipients over a period of 1 year (N=40). INTERVENTIONS: The "usual treatment group" (n=20), which benefited from the usual treatment applied in the ICU (based on physician prescription for the physiotherapist, with one session a day), and the experimental group (n=20), which followed a protocol of early and intensive rehabilitation (based on a written protocol validated by physicians and an evaluation by physiotherapist, with 2 sessions a day), were compared. MAIN OUTCOME MEASURES: Our primary aims were tolerance, assessed from the number of adverse events during rehabilitation sessions, and feasibility, assessed from the number of sessions discontinued. RESULTS: The results revealed a small percentage of adverse events (1.5% in the usual treatment group vs 1.06% in the experimental group) that were considered to be of low intensity. Patients in the experimental group sat on the edge of their beds sooner (2.6 vs 9.7d; P=.048) and their intestinal transit resumed earlier (5.6 vs 3.7d; P=.015) than patients in the usual treatment group. There was no significant difference between the 2 arms regarding length of stay (LOS), despite a decrease in duration in the experimental group. CONCLUSIONS: The introduction of an intensive early rehabilitation program for liver transplant recipients was well tolerated and feasible in the ICU. We noted that the different activities proposed were introduced sooner in the experimental group. Moreover, there is a tendency to decreased LOS in the ICU for the experimental group. These results now need to be confirmed by studies on a larger scale.

Vascular access challenges in hemodialysis children.

BACKGROUND: Hemodialysis (HD) success is dependent mainly on vascular access (VA). The aim of this study is to share the experience of Pediatric Nephrology Unit (PNU), Cairo University Children's Hospital (CUCH), with VA-related obstacles in end stage kidney disease (ESKD) HD children. METHODS: This is a retrospective analysis of VA related data of 187 ESKD children received regular HD over 3 year duration (2019-2021). Kaplan-Meier curves were used to present arteriovenous fistula (AVF) and cuffed catheters survivals. RESULTS: Uncuffed central venous catheter (CVC) was the primary VA for HD in up to 97.3% with 2.7% of patients had AVF performed and attained maturation before initiation of regular HD. Fifty-six (29.9%) patients have inserted 120 tunneled CVCs. AVFs & AV grafts (AVF) were performed in 79 (42.2%) and 6 (3.2%) patients respectively. There were 112 uncuffed CVCs implanted beneath the screen in Rt internal jugular vein (IJV) (44%) Lt IJV (17%), right internal mammary vein (2.7%) while Trans hepatic (TH) technique was used to place 39 uncuffed CVCs (34%) in the inferior vena cava (IVC). Catheter-related bacteremia (CRB) was the most frequent complication in uncuffed and cuffed CVCs (2.58 / 100 catheters day and 10.1 /1000 catheter days respectively). AVFs achieved a high success rate (83%) after 757.71 ± 512.3 functioning days. CONCLUSION: Native AVF is the preferred VA for pediatric HD but its creation is limited by the small sized vessels where non-cuffed CVC could be a reasonable relatively long-term alternative. Challenging situations (occluded central veins) could benefit from TH technique of CVC insertion in IVC.

Predictors of the unfavorable outcomes in acute ischemic stroke patients treated with alteplase, a multi-center randomized trial.

Worldwide, stroke is a leading cause of long-term disability in adults. Alteplase is the only approved treatment for acute ischemic stroke (AIS) and results in an improvement in a third of treated patients. We evaluated the post-stroke unfavourable outcome predictors in alteplase-treated patients from Egypt and Saudi Arabia. We assessed the effect of different risk factors on AIS outcomes after alteplase in Egypt and Saudi Arabia. Our study included 592 AIS alteplase-treated patients. The relationship between risk factors, clinical presentation, and imaging features was evaluated to predict factors associated with poor outcomes. An mRS score of three or more was used to define poor outcomes. Poor outcome was seen in 136 patients (23%), and Patients with unfavourable effects had significantly higher admission hyperglycaemia, a higher percentage of diabetes mellitus, cardioembolic stroke, and a lower percentage of small vessel stroke. Patients with higher baseline NIHSS score (OR 1.39; 95% CI 1.12-1.71; P = 0.003), admission hyperglycaemia (OR 13.12; 95% CI 3.37-51.1; P < 0.001), and post-alteplase intracerebral haemorrhage (OR 7.41; 95% CI 1.69-32.43; P = 0.008) independently predicted unfavourable outcomes at three months. In AIS patients treated with alteplase, similar to reports from other regions, in patients from Egypt and Saudi Arabia also reveal that higher NIHSS, higher serum blood sugar, and post-alteplase intracerebral haemorrhage were the predictors of unfavourable outcomes three months after ischemic stroke.Trial registration: (clinicaltrials.gov NCT06058884), retrospectively registered on 28/09/2023.

Ventilator-associated pneumonia and ICU mortality in severe ARDS patients ventilated according to a lung-protective strategy.

INTRODUCTION: Ventilator-associated pneumonia (VAP) may contribute to the mortality associated with acute respiratory distress syndrome (ARDS). We aimed to determine the incidence, outcome, and risk factors of bacterial VAP complicating severe ARDS in patients ventilated by using a strictly standardized lung-protective strategy. METHODS: This prospective epidemiologic study was done in all the 339 patients with severe ARDS included in a multicenter randomized, placebo-controlled double-blind trial of cisatracurium besylate in severe ARDS patients. Patients with suspected VAP underwent bronchoalveolar lavage to confirm the diagnosis. RESULTS: Ninety-eight (28.9%) patients had at least one episode of microbiologically documented bacterial VAP, including 41 (41.8%) who died in the ICU, compared with 74 (30.7%) of the 241 patients without VAP (P = 0.05). After adjustment, age and severity at baseline, but not VAP, were associated with ICU death. Cisatracurium besylate therapy within 2 days of ARDS onset decreased the risk of ICU death. Factors independently associated with an increased risk to develop a VAP were male sex and worse admission Glasgow Coma Scale score. Tracheostomy, enteral nutrition, and the use of a subglottic secretion-drainage device were protective. CONCLUSIONS: In patients with severe ARDS receiving lung-protective ventilation, VAP was associated with an increased crude ICU mortality which did not remain significant after adjustment.

Next-generation sequencing in identification of pathogenic variants in primary hyperoxaluria among 21 Egyptian families: Identification of two novel AGXT gene mutations.

BACKGROUND: Primary hyperoxaluria (PH) is a rare heterogeneous, autosomal recessive disorder of glyoxylate metabolism. It is characterized by excessive hepatic production of oxalate resulting in a wide spectrum of clinical, imaging, and functional presentation. The characteristic features of PH comprise of recurrent urolithiasis, renal stones, and/or nephrocalcinosis. Three known types of PH have been identified PH1, PH2, and PH3. Pathogenic variants in AGXT, GRHPR, and HOGA1 cause the phenotypic expression of PH. METHODS: In this study, we describe the clinical and genetic findings of 22 patients from 21 unrelated Egyptian families with the distinctive clinical features of PH. A thorough clinical evaluation followed by an NGS custom panel of AGXT, GRHPR, and HOGA1 genes was done. RESULTS: Two novel mutations (p.Gly27Glu and p.Gln256Serfs*17) and six previously reported mutations (p.Lys12Glnfs*156, p.Lys12Argfs*34, p.Ile244Thr, p.Asn22Ser, p.Pro11Leu, and p.Ile340Met) were identified in AGXT gene. The NGS panel results were validated thereafter using Sanger sequencing. CONCLUSION: Our results extend the number of AGXT mutations identified so far and emphasize the important role of genetic testing in providing proper counseling and patients management.

A Comparative Study of Levetiracetam and Phenobarbital for Neonatal Seizures as a First Line Treatment.

Objectives: We aimed to evaluate the use of intravenous levetiracetam as the first-line treatment of neonatal seizures compared with phenobarbital. Methods: The study was conducted on 104 neonates (0-28 days) with clinical seizures after inclusion criteria. They were assigned in equal ratio into 2 groups; 1 included neonates who received phenobarbitone, and the other included neonates who received levetiracetam. Neonates were loaded with 20 mg/kg of intravenous drug-A (phenobarbitone) or drug-B (levetiracetam). In persistent seizures, a second loading dose of the same drug was given. Crossover to other drugs occurred if seizures persisted after the second dose of the same drug. The proportion of neonates who achieved cessation of seizures following the first or second loading dose of either drug-A or drug-B (PB or LEV) was the main outcome measure provided that they remained free of seizure for the following 24 hours. Results: After 1 or 2 doses of Levetiracatam or Phenobarbitone, clinical seizures stopped (and remained seizure-free for 24 hours) in 41 (78.84%) and 34 (65.38%) patients, respectively (P = .01). Neonates in the LEV group showed better seizure control than neonates in the PB group (RR = 0.57; 95% CI (0.17, 0.80). We did not report any adverse drug reactions in the LEV group. However, 12 (23.07%) neonates developed adverse drug reactions in the PB Group. Conclusion: Levetiracetam is considered an effective and safe drug as a first-line AED in neonatal seizures.

The Impact of Vitamin D3 Supplementation to Topiramate Therapy on Pediatric Migraine Prophylaxis.

Background:There is still a need for more studies to evaluate the role of vitamin D3 in pediatric migraine prophylaxis. Objectives: We aimed to evaluate the effects and safety of vitamin D3 supplementation to topiramate on pediatric migraine. Methods: A double-blinded prospective clinical trial was conducted on 5- to 14-year-old children with migraine. They were randomly assigned in a 1:1 ratio into 2 groups, one with vitamin D3 supplementation (the supplementation group) and the other without vitamin D supplementation (the placebo group). The supplementation group received topiramate plus one 5000-IU dose of vitamin D3 daily for 4 months. The placebo group received topiramate with a placebo capsule without any effective substances. The primary outcomes were a monthly frequency of headache attacks, a good response to intervention, and reduction in migraine severity, duration, and disability before and after treatment. Fifty-six children completed the trial. Vitamin D3 supplementation to topiramate was more effective than the placebo group in the reduction of monthly frequency (6231.31 vs 9792.24 times, P = .01) and disability score for migraines (17 566.43 vs 25 187.65, P = .04). A good response was observed in 76.13% of patients in the vitamin D3 supplementation group and 53.5% of patients in the placebo group, and vitamin D3 supplementation was significantly more effective than placebo (P = .01). Side effects were observed in 13.3% and 20% of the intervention group and placebo groups, respectively, P = .5. Conclusion: Vitamin D3 supplementation in pediatric migraine prophylaxis could be a well-tolerated, safe, and effective strategy.

Primary hyperoxaluria type 1 in children: Clinical classification, renal replacement therapy, and outcome in a single centre experience.

Primary hyperoxaluria type 1 (PH1) is a rare disease that is challenged by the overproduced oxalate and commonly presented with radiopaque renal stones or obstructive uropathy. This study aimed to report clinical presentations, renal replacement therapy (RRT), and outcome of PH1 in end stage kidney disease (ESKD) children. This is an observational cohort study. Data of 22 patients with ESKD due to PH1 were analyzed at Pediatric Nephrology Unit, Faculty of Medicine Cairo University. Infantile onset patients (n = 10) had worst renal outcome (80% with ESRD at presentation, p = 0.019) and worse patient outcome (mortality 40%, p = 0.016) than juvenile (n = 9) and late onset (PH1 n = 3) patients. RRT modalities include peritoneal dialysis (PD) in 7 (31.8%), hemodialysis (HD) in 11 (50%), and combined liver kidney transplantation (CLKT) in 4 (18.2%) patients. Infectious complications were encountered in 42.8% of PD patients. Better HD adequacy was observed with frequent HD (n = 6) and/or HD via arteriovenous fistula (AVF) than with infrequent dialysis (n = 5) and/or via central venous line (CVL) (p = 0.0001 and 0.0047, respectively). Morbidity and mortality (infection related) rates of the whole cohort were 63.6% and 31.8%, respectively. Clinical presentation of PH1 varies according to the age of onset (infantile onset being the most aggressive form). Aggressive HD (better through AVF) is needed to achieve acceptable HD adequacy, PD was challenged by infection. Infection found to be the main cause of mortality even after successful CLKT.

Analysis of the interacting surface of maurotoxin with the voltage-gated Shaker B K(+) channel.

Maurotoxin (MTX) is a 34-residue toxin that was isolated initially from the venom of the scorpion Scorpio maurus palmatus. Unlike the other toxins of the α-KTx6 family (Pi1, Pi4, Pi7, and HsTx1), MTX exhibits a unique disulfide bridge organization of the type C(1) C(5) , C(2) C(6) , C(3) C(4) , and C(7) C(8) (instead of the conventional C(1) C(5) , C(2) C(6) , C(3) C(7) , and C(4) C(8) , herein referred to as Pi1-like) that does not prevent its folding along the classic α/ß scaffold of scorpion toxins. MTX(Pi1) is an MTX variant with a conventional pattern of disulfide bridging without any primary structure alteration of the toxin. Here, using MTX and/or MTX(Pi1) as models, we investigated how the type of folding influences toxin recognition of the Shaker B potassium channel. Amino acid residues of MTX that were studied for Shaker B recognition were selected on the basis of their homologous position in charybdotoxin, a three disulfide-bridged scorpion toxin also active on this channel type. These residues favored either an MTX- or MTX(Pi1) -like folding. Our data indicate clearly that Lys(23) and Tyr(32) (two out of ten amino acid residues studied) are the most important residues for Shaker B channel blockage by MTX. For activity on SKCa channels, the same amino acid residues also affect, directly or indirectly, the recognition of SK channels. The molecular modeling technique and computed docking indicate the existence of a correlation between the half cystine pairings of the mutated analogs and their activity on the Shaker B K(+) channel. Overall, mutations in MTX could, or could not, change the reorganization of disulfide bridges of this molecule without affecting its α/ß scaffold. However, changing of the peptide backbone (cross linking disulfide bridges from MTX-like type vs MTX(Pi1) -like type) appears to have less impact on the molecule activity than mutation of certain key amino acids such as Lys(23) and Tyr(32) in this toxin.

Risk Factors of Intractable Epilepsy in Children with Cerebral Palsy.

OBJECTIVES: We aimed to investigate the risk factors predicting the development of intractable epilepsy in children with cerebral palsy (CP), with an emphasis on perinatal characteristics, seizure semiology, imaging, and EEG findings. MATERIALS & METHODS: Following a descriptive, retrospective, case-control design, 106 children with CP and epilepsy from 2015 to 2020 were studied (46 children with CP and intractable epilepsy and 60 with CP and controlled epilepsy). Data were retrieved from medical records of participants (i.e., demographics, clinical characteristics, perinatal history, etiology of seizure and CP, seizure semiology, intellectual functions, therapeutic options, brain imaging, and EEG findings). RESULTS: We established a model of the most important risk factors that can predict intractable epilepsy in children with CP. The model included the additive effect of a poor Apgar score at 5 minutes, the presence of neonatal seizures, focal epilepsy, and focal slowing on the EEG background (Area under the receiver operating characteristic of 0.810). CONCLUSION: The findings can be used to identify intractable epilepsy in children who suffer from CP with further support by offering early therapeutic interventions intended to reduce the burden of refractory seizures.

Omega-3 supplementation in children with ADHD and intractable epilepsy.

BACKGROUND: Omega-3 may have a role in the treatment of drug- resistant epilepsy. OBJECTIVES: To evaluate omega-3 supplementation in seizure control in children with attention deficit hyperactivity disorder (ADHD) and intractable epilepsy. PATIENTS AND METHODS: Sixty children with ADHD and intractable epilepsy were enrolled. They were randomly assigned in a double-blind fashion in a 1:1 ratio into the omega-3 supplementation group or the placebo group in addition to risperidone and antiepileptic drugs. All patients were assessed for the frequency and severity of the epileptic attacks at baseline, monthly, and at 6 months from the beginning of the study; 30 children received omega-3 and the other 30 children received placebo. RESULTS: At baseline, the median number of seizures per month was 5 in both groups. After one month, this median decreased to 3 and became 2 after two months of supplementation with omega-3 in the supplementation group while it remained 5 in the control group. After 3 months and till the end of the study, this median decreased to 0 while it remained 5 in the control group throughout the study period. Children who were supplemented with omega-3 showed a significant decrease in the monthly frequency of seizure attacks after six months of supplementation compared to the baseline before supplementation (P < 0.05) There was no significant decrease in the severity of the seizures attacks among our patients with omega-3 supplementation (P > 0.05). CONCLUSION: Omega 3 may help in achieving good seizure control in children with ADHD and intractable epilepsy.

Mycophenolate mofetil monotherapy in membranous nephropathy: a 1-year randomized controlled trial.

BACKGROUND: Treatment of patients with membranous glomerulonephritis (MGN) is controversial because of the lack of clear benefit of the immunosuppressive regimens on patient or renal survival. The objective of this study is to evaluate the efficacy and safety of mycophenolate mofetil (MMF) for patients with MGN. STUDY DESIGN: 1-year prospective, randomized, and controlled clinical trial. SETTING & PARTICIPANTS: 36 patients with biopsy-proven idiopathic MGN and nephrotic syndrome. INTERVENTION: 19 patients received MMF (2 g/d) for 12 months and 17 patients were in the control group. All patients had the same conservative treatment based on renin-angiotensin blockers, statins, low-salt and low-protein diet, and diuretics in case of edema. OUTCOMES & MEASUREMENTS: End points were the mean proteinuria over creatinuria ratio in mg/g throughout the study and numbers of complete and partial remissions at 1 year (month 12). Data were analyzed on an intention-to-treat analysis. RESULTS: Mean proteinuria over creatinuria ratio was stable in both groups throughout the study (P = 0.1). Mean proteinuria over creatinuria ratio was 4,690 +/- 2,212 mg/g in the MMF group and 6,548 +/- 4,601 mg/g in the control group (95% confidence interval of the difference, -619 to +4,247; P = 0.1). Remission was complete in 3 patients (1 in the MMF group, 2 in the control group; P = 0.5) and partial in 11 patients (6 in the MMF group, 5 in the control group; P = 0.9). The probability of complete or partial remission did not differ between the 2 groups after 12 months (relative risk, 0.92; 95% confidence interval, 0.48 to 1.75; P = 0.7). Kidney function was stable in the 2 groups according to estimated glomerular filtration rate and serum creatinine level. LIMITATIONS: The small number of patients and short follow-up prevent generalizations. CONCLUSIONS: A 12-month regimen of MMF did not decrease mean proteinuria over creatinuria ratio or increase partial and complete remissions. Serious adverse effects were observed in 4 patients (20%) receiving MMF.

[A case-control study of health benefits in patients with moderate renal failure]. / Une étude cas-témoin évaluant les prestations de santé dans une population de malades insuffisants rénaux modérés.

In order to evaluate medical management in patients with renal failure before dialysis, we conducted a case-control study to analyze the health benefits in 914 moderate renal failure patients with Cockcroft clearance between 30 and 60 ml/min. Health benefits reimbursed by the Social Security in this population were compared with those in 1828 controls randomly chosen in the Social Security files but matched by age and gender. Mean age of the participants was 73+/-11 year-old, 67% were women, Cockcroft clearance was 48+/-8 ml/min. Number of hospitalizations and hospitalization durations were not different between the two populations. Conversely, cases had more specialized outpatients' clinics in cardiology but not in nephrology or urology. Cases had more biological tests and radiological exams and had taken more medicines. For biology, cases had more often renal function tests and markers of renal dysfunction tests than controls. Cases had taken more medicines than controls for erythropoietin, diuretics, renin-angiotensin blockers, hypoglycemic drugs, and anticoagulants. Patients with mild renal failure had higher health benefits than controls for outpatients' clinics in cardiology, for biological tests, for radiological exams, and for some medicines.

An interspecies conserved motif of the mouse immune system-released activating agent (ISRAA) induces proliferative effects on human cells.

We have recently described an immune system-released activating agent (ISRAA) as a nervous system-induced factor that stimulates immune responses in the mouse spleen. However, the human ISRAA has not yet been identified. In this study, we examined the effects of the mouse ISRAA protein on human peripheral blood mononuclear cells (PBMCs), to observe if the biological activity of this molecule is consistent between the two different species. Mouse ISRAA demonstrated dose-dependent dualistic effects on human cells, as 5 µg exhibited positive apoptosis and 50 pg exhibited significant proliferation (P<0.05). Furthermore, immunosuppressed cells from patients undergoing immunosuppressive therapy demonstrated significant proliferation to 50 pg ISRAA (P<0.05). Studies to compare sequences in different species revealed a preserved motif, exhibiting 72% similarity with the interspecies conserved signal peptide motif of tumor necrosis factor receptor 1 (TNFR1). A mutant ISRAA lacking this motif was produced and tested for its biological effects. The mutant ISRAA demonstrated neither apoptotic nor proliferative effects compared with wild type. Therefore, an interspecies conserved domain of ISRAA constitutes the active site of the molecule, and its effects on immunocompromised cells should be investigated for future therapies in the treatment of immunosuppressive disorders.

Modelling of the III-IV loop, a domain involved in calcium channel Ca(v)2.1 inactivation, highlights a structural homology with the gamma subunit of G proteins.

We have modelled the conformation of the III-IV loop of the Ca(v)2.1 subunit of P/Q calcium channels, a loop that is implicated in fast voltage-dependent inactivation. Change in channel inactivation requires its direct interaction with the I-II loop. This interaction occurs with an affinity in the order of 70 nm. Intracellular injection of a 40-mer III-IV loop-derived peptide produces an increase in the rate of fast inactivation. This alteration in channel kinetic is also accompanied by a hyperpolarizing shift in the steady-state voltage-dependence of inactivation. None of these effects are observed in the presence of a beta subunit, suggesting the existence of a competitive mechanism of action between the beta subunit and the III-IV loop. Amino acid sequence comparison using BLAST reveals that the III-IV loop shares 53% identity with the gamma subunit of G proteins. Because of the pivotal contribution of the III-IV loop to inactivation, an atomic model of the III-IV loop was generated by both homology modelling and molecular mechanics calculations. Using the X-ray structures of the betagamma dimer of the heterotrimeric G-proteins as templates, the III-IV loop is predicted to contain a well-structured alpha-helix at the amino-terminus with both the N- and C-termini having the same orientation in the plane of the inner lipid bilayer. We provide a hypothetical working model in which we propose that the III-IV loop interacts with the I-II loop via its Gbetagamma binding domain.

Synthesis, 3-D structure, and pharmacology of a reticulated chimeric peptide derived from maurotoxin and Tsk scorpion toxins.

Maurotoxin (MTX) is a 34-mer scorpion toxin cross-linked by four disulfide bridges that acts on both Ca(2+)-activated (SK) and voltage-gated (Kv) K(+) channels. A 38-mer chimera of MTX, Tsk-MTX, has been synthesized by the solid-phase method. It encompasses residues from 1 to 6 of Tsk at N-terminal, and residues from 3 to 34 of MTX at C-terminal. As established by enzyme cleavage, Tsk-MTX displays half-cystine pairings of the type C1-C5, C2-C6, C3-C7 and C4-C8 which, contrary to MTX, correspond to a disulfide bridge pattern common to known scorpion toxins. The 3-D structure of Tsk-MTX, solved by (1)H NMR, demonstrates that it adopts the alpha/beta scaffold of scorpion toxins. In vivo, Tsk-MTX is lethal by intracerebroventricular injection in mice (LD(50) value of 0.2 microg/mouse). In vitro, Tsk-MTX is as potent as MTX, or Tsk, to interact with apamin-sensitive SK channels of rat brain synaptosomes (IC(50) value of 2.5 nM). It also blocks voltage-gated K(+) channels expressed in Xenopus oocytes, but is inactive on rat Kv1.3 contrary to MTX.