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Objective: This study compared the efficacy of ultrasound-guided erector spinae plane block (ESPB) and wound infiltration (WI) for postoperative analgesia in patients who underwent lumbar spinal surgery with instrumentation., Methods: In this randomized controlled trial, 80 patients were divided into two groups: ESPB (n = 40) and WI (n = 40). Postoperative pain intensity was assessed via the visual analog scale (VAS) at multiple time points within 24 h. Additionally, opioid consumption, time to first rescue analgesia, incidence of postoperative nausea and vomiting (PONV), and patient satisfaction were evaluated., Results: Both ESPB and WI provided effective postoperative pain management, with no significant differences in VAS scores. However, the ESPB group demonstrated a significantly longer duration of analgesia, a shorter time to first rescue analgesia, and lower total tramadol consumption (50 ± 60 mg vs. 100 ± 75 mg; p = 0.010) than did the WI group. Furthermore, a trend toward reduced PONV incidence was observed in the ESPB group, likely due to its opioid-sparing effect., Conclusion: While both ESPB and WI provided effective postoperative pain management, ESPB demonstrated a distinct advantage by offering a longer duration of analgesia and significantly reducing opioid consumption. These findings suggest that ESPB is more effective than WI for postoperative analgesia in lumbar spinal surgeries, providing prolonged pain relief and improving patient outcomes. Further studies are warranted to explore its long-term benefits and cost-effectiveness., Trial Registration: ClinicalTrials.govPRS: NCT06567964 Date: 08/21/2024 Retrospectively registered., (© 2024. The Author(s).)

Objective: Carpal tunnel syndrome (CTS) is the most common type of entrapment neuropathy caused by compression of the median nerve in the carpal tunnel. Epilepsy is characterised by recurrent seizures caused by abnormal neuronal discharges in the brain.This study aimed to investigate whether there is a link between epilepsy and carpal tunnel and, if so, the underlying factors., Materials and Methods: Two hundred patients with epilepsy were included in this study. The patients' history of epilepsy, seizure type, and seizure frequency were assessed. The Tinel, Phalen, and Flick physical examination tests were performed on patients with complaints that matched those of median nerve neuropathy. Patients with epilepsy and clinically diagnosed carpal tunnel syndrome completed the Boston Carpal Tunnel Syndrome Questionnaire, and nerve conduction studies were performed. The relationship between seizure type and frequency in patients with carpal tunnel syndrome was compared., Results: Compared to focal-aware motor-onset seizures, the risk of detecting carpal tunnel syndrome was 88.7 times higher in focal-onset bilateral tonic-clonic seizures. Patients with a seizure frequency of one per month or more had a 0.704 times lower risk of CTS than those with a frequency of one per week or more (p = 0.026)., Discussion: Patients with epilepsy, especially those experiencing frequent seizures or specific seizure types, may be more susceptible to repetitive wrist flexion-extension postures. Therefore, during clinical follow-up, it is important to inquire about the presence of carpal tunnel syndrome in patients with epilepsy., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Background: Coronavirus disease 2019 (COVID-19) disrupted standard health policies and routine medical care, and thus, the management and treatment pathways of many clinical conditions have changed as never before. The negative impact of the pandemic rendered the systemic disease more complicated and accelerated mortality. For the last two years, clinicians have primarily focused on COVID-19 patients; however, the non-COVID-19 critically ill patients needed to be addressed from multiple perspectives. This study investigated the demographic and clinical characteristics of non-COVID-19 critical care patients admitted concurrently with a COVID-19 wave. The objective of this study was to identify the risk factors for mortality in critically ill non-COVID-19 patients., Methods: All consecutive cases admitted to the intensive care unit (ICU) were included in the study between January 1, 2021 and July 14, 2021. All data, including age, gender, admission characteristics, patient dependency, pre-existing systemic diseases, the severity of illness (Acute Physiology and Chronic Health Evaluation -APACHE-II), predicted death rate in ICU, life-sustaining medical procedures on admission or during ICU stay, length of stay, and admission time to the ICU, were obtained from the hospital's electronic database. The Charlson Comorbidity Index (CCI) was assessed for all patients., Results: A total of 192 patients were screened during the study period. Mortality was significantly increased in non-surgical patients, previously dependent patients, patients requiring mechanical ventilation, continuous renal replacement therapy, and patients requiring the infusion of vasoactive medications. The number of pre-existing diseases and the admission time had no impact on mortality. The mean CCI was significantly higher in non-survivors but was not a strong predictor of mortality as APACHE II., Conclusions: In this retrospective study, the severity of illness and the need for vasoactive agent infusion were significantly higher in non-survivors confirmed by multivariate analysis as predictive factors for mortality in critical non-COVID-19 patients., (© 2022 Kamuzu University of Health Sciences.)

Background: Carpal tunnel syndrome (CTS) is a common neurologic impairment caused by injury on the median nerve in the wrist, characterized by pain and loss of sensory. CTS usually occurs through three factors, such as a mechanical pressure on median nerve, immunologic changes, and oxidative stress. The aim of this study was to evaluate the influence of interleukin-1 receptor antagonist (IL-1Ra) and angiotensin-converting enzyme (ACE) I/D polymorphisms on the susceptibility of patients to the CTS., Methods: One hundred fifty-eight patients with CTS and 151 healthy controls were enrolled in this study. Each patient was analyzed according to diseases symptoms, such as gender, a positive Tinel's sign, a positive Phalen maneuver, disease sides, EMG findings, and clinical stage. We applied the polymerase chain reaction (PCR) to determine the polymorphisms of IL-1Ra and ACE I/D., Results: The statistically significant relation was not found between IL-1Ra, ACE I/D polymorphisms and CTS (respectively, P>.05; P>.05, OR: 1.51, CI: 0.82-1.61). Additionally, in the result of the statistical analysis compared with gene polymorphisms and clinical characteristics, we did not find any correlation (P>.05)., Conclusions: Our findings showed that there are no associations of IL-1Ra and ACE I/D polymorphisms with susceptibility of a person for the development of CTS. So, it means that these polymorphisms do not create a risk for the development of CTS. Further studies with larger populations will be required to confirm these findings in different study populations., (© 2017 Wiley Periodicals, Inc.)

Background: Although Alzheimer's disease (AD) is the most common age-related neurodegenerative disease and characterized by memory impairment, only symptomatic treatments are available., Objectives: Because recombinant human erythropoietin (rhEPO) has various neuroprotective effects and improves cognitive function in animal models of neurodegenerative disorders, we investigated the therapeutic effects of rhEPO in an intracerebroventricular (ICV)-streptozotocin (STZ) animal model of sporadic-AD., Material and Methods: A total of 24 Sprague-Dawley adult rats were divided into 4 groups of naive control (n = 6), sham-operated (n = 6), ICV-STZ + saline (n = 6) and ICV-STZ + rhEPO (n = 6). Twelve rats with Alzheimer's disease, induced by STZ injection (3 mg/kg) into both lateral ventricles using a stereotaxic frame (bilaterally ICV-STZ), were divided into 2 groups 5 days after the STZ injection: one treated with rhEPO 5000 (IU/kg/day, i.p.) and the other with 0.9% NaCl (1 mL/kg/day, i.p.) for 2 weeks. The sham-operated rats received bilaterally ICV-0.9% NaCl. No surgical operation or treatment was given to the naive-control animals. On day 20, a passive avoidance learning (PAL) test was used followed by sacrification and removal of the brain tissue in all animals. Brain TNF-α and ChAT levels were determined, and neurons in the hippocampal CA1 and CA3 regions were counted by Cresyl violet staining., Results: ICV-STZ was found to significantly shorten the latency time on the PAL, increase brain TNF-α level, and decrease brain ChAT activity and the number of neurons in the hippocampal CA1 and CA3 regions. On the other hand, rhEPO significantly attenuated all these detrimental effects induced by STZ., Conclusions: RhEPO treatment significantly prevented the ICV-STZ-induced memory deficit by attenuating the hippocampal neuronal loss, neuroinflammation and cholinergic deficit in rats. This result suggests that rhEPO may be beneficial for treating AD.

Here, we describe the clinical features of several members of the same family diagnosed with Friedreich ataxia (FRDA) and cerebral lesions, demyelinating neuropathy, and late-age onset without a significant cardiac involvement and presenting with similar symptoms, although genetic testing was negative for the GAA repeat expansion in one patient of the family. The GAA repeat expansion in the frataxin gene was shown in all of the family members except in a young female patient. MRI revealed arachnoid cysts in two patients; MRI was consistent with both cavum septum pellucidum-cavum vergae and nodular signal intensity increase in one patient. EMG showed demyelinating sensorimotor polyneuropathy in another patient. The GAA expansion-negative 11-year-old female patient had mental-motor retardation, epilepsy, and ataxia. None of the patients had significant cardiac symptoms. Description of FRDA families with different ethnic backgrounds may assist in identifying possible phenotypic and genetic features of the disease. Furthermore, the genetic heterogeneity observed in this family draws attention to the difficulty of genetic counseling in an inbred population and to the need for genotyping all affected members before delivering comprehensive genetic counseling.

Background: Montelukast is an antiinflammatory drug with an antioxidant property. In this study, we aimed to reveal whether montelukast has a preventive effect against seizures and post-seizure oxidative stress in pentylenetetrazol (PTZ)-induced seizures in rats., Material and Methods: Of the 48 male Sprague-Dawley rats used in the study, 24 were assigned to EEG recordings (group A) and 24 were assigned to behavioral studies (group B). In group A, the electrodes were implanted on dura over the left frontal cortex for EEG recording. After 10 days, in group A, i.p. saline, 25, 50, or 100 mg/kg montelukast+35 mg/kg PTZ was administered to the rats. EEG was recorded and spike percentage was evaluated. In group B, i.p. saline, 25, 50, or 100 mg/kg montelukast+70 mg/kg PTZ was administered to the rats. Racine's Convulsion Scale (RCS) and onset times of first myoclonic jerk (FMJ) was used to evaluate the seizures. Malondialdehyde (MDA) and superoxide dismutase (SOD) levels were determined in the brain tissue of animals., Results: Animals treated with 50 or 100 mg/kg montelukast had significantly lower RCS and significantly increased FMJ onset time compared to the saline-treated animals. Moreover, groups given 25, 50, or 100 mg/kg montelukast had significantly lower MDA and higher SOD levels compared to the saline-treated group. The differences were more pronounced in the 100 mg/kg montelukast-pretreated group (p<0.001)., Conclusions: Montelukast showed anticonvulsant action and led to amelioration of oxidative stress markers in PTZ-induced seizures in rats.

Aim: The aim of the present study was to investigate a possible association between the MIF -173G>C polymorphism and MS in Turkish patients., Materials and Methods: The study included 153 MS-patients and 210 controls. Genomic DNA was isolated and genotyped using PCR-RFLP assay for the MIF -173G>C promoter polymorphism (rs755622)., Results: There was no statistically significant difference in allele and genotype frequencies between MS-patients and controls (p=0.227 and p=0.157, respectively). Accordingly, no association was observed when the patients were compared against controls in terms of GG versus GC+CC genotypes and GG+GC versus CC genotypes (p=0.324 and p=0.179, respectively). Also, there was no statistically significant association between MIF-173G>C polymorphism and clinical and demographic characteristics of MS-patients. Conlusion: The results of the present study suggest no relation between MS susceptibility and MIF gene - 173G>C polymorphism in the examined Turkish population., (Copyright © 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)

Background: Moyamoya syndrome associated with protein S deficiency is rarely encountered and is usually reported in paediatric cases with cerebral ischaemia., Case Report: A 32-year-old woman had symptoms of sudden-onset severe headache, projectile vomiting, impaired consciousness, and slight neck stiffness. The computed tomography scan of her brain showed primary intraventricular haemorrhage, and the subsequent four vessel cerebral angiographies revealed stage 3 to 4 Moyamoya disease according to Suzuki and Takaku's angiographic classification. The coagulation profile showed the presence of protein S deficiency. The patient was treated with external ventricular drainage and conservative management until blood clot resolution. The patient was discharged with normal neurological examination findings after her initial impaired consciousness and orientation defect gradually recovered., Conclusion: This case report would alert physicians to the possible coexistence of Moyamoya syndrome and protein S deficiency, even in adult cases presenting with primary intraventricular haemorrhage.

The RNA-dependent RNA polymerases (RdRp) from Citrus tristeza virus (CTV) were tagged with HA and FLAG epitopes. Differentially tagged proteins were expressed either individually or concomitantly in Escherichia coli. Immunoprecipitation of the expressed proteins with anti-FLAG antibody followed by Western blot with anti-HA antibody demonstrated that molecules of RdRp from CTV interact to form oligomers. Yeast two-hybrid assays showed that molecules of RdRp interact in eukaryotic cells. Co-immunoprecipitation with anti-FLAG antibody of truncated HA-tagged RdRps (RdRpΔ1-166-HA, RdRpΔ1-390-HA, RdRp1-169-HA) co-expressed with full-length RdRp-FLAG showed that only RdRp1-169-HA interacted with the full-length FLAG-RdRp. Yeast two-hybrid assays with truncated RdRp constructs confirmed that the oligomerization site resides in the N-terminal region and that the first 169 aa of CTV RdRp are necessary and sufficient for oligomerization both in bacterial and yeast cells. Development of control strategies targeting viral RdRp oligomer formation may inhibit virus replication and prove useful in control of CTV., (© 2013 Elsevier Inc. All rights reserved.)

Background: Erectile dysfunction (ED), defined as the inability to achieve or maintain an erection sufficient for satisfactory sexual performance, is a common condition. The psychological, hormonal, neurogenic and arterial pathologies, medications, chronic diseases have been reported in the etiology of the ED. This paper aims to study sexual dysfunction in the male patients with migraine and Tension type headache (TTH)., Methods: 30 migraine cases (Group M), 31 TTH cases (Group T) and 30 control cases (Group C) were included in the study. Patients were evaluated with medical history, physical examination, body mass index (BMI), Beck Depression Inventory, biochemical analysis and hormone profiles. ED was evaluated via International Index of Erectile Function Scale (IIEF). In statistical analysis, variant analysis, post-hoc tukey test, Pearson correlation test, t-test, and fisher's exact chi-square test were used., Results: The patients' mean age was 34.96+/-1.30, 35.54+/-1.52 and 32.26+/-1.38 for group M,T and C, respectively. There was no significant difference between the groups in terms of testosterone levels. Mean IIEF scores was 19.83+/-2.2, 20.39+/-1.35 and 27.83+/-0.34 in groups M,T,C. When M and T groups were compared with group C, there were significant differences, and there was no statistical difference when T and M groups were compared to each other. Beck Depression Scores were not significantly different in groups M, T and C., Conclusion: In this study, it was shown that, migraine and TTH affects the sexual functions negatively in male patients. Chronic diseases may cause sexual disorders in patients because of despair, guilt, and fear of death or pain. Our results suggest that, along with the effect of chronic disease and pain, there must be other complicated factors exist causing the development of SD in patients with migraine and TTH.

The presence of Citrus tristeza virus (CTV) has previously been reported in citrus growing regions of Turkey. All serologically and biologically characterized isolates including Iğdır, which was the first identified CTV isolates from Turkey, were considered mild isolates. In this study, molecular characteristics of the Iğdır isolate were determined by different methods. Analysis of the Iğdır isolate by western blot and BD-RT-PCR assays showed the presence of MCA13 epitope, predominantly found in severe isolates, in the Iğdır isolate revealing that it contains a severe component. For further characterization, the coat protein (CP) and the RNA-dependent RNA polymerase (RdRp) genes representing the 3' and 5' half of CTV genome, respectively, were amplified from dsRNA by RT-PCR. Both genes were cloned separately and two clones for each gene were sequenced. Comparisons of nucleotide and deduced amino acid sequences showed that while two CP gene sequences were identical, two RdRp clones showed only 90% and 91% sequence identity in their nucleotide and amino acid sequences, respectively, suggesting a mixed infection with different strains. Phylogenetic analyses of the CP and RdRp genes of Iğdır isolate with previously characterized CTV isolates from different citrus growing regions showed that the CP gene was clustered with NZRB-TH30, a resistance breaking isolate from New Zealand, clearly showing the presence of severe component. Furthermore, two different clones of the RdRp gene were clustered separately with different CTV isolates with a diverse biological activity. While the RdRp-1 was clustered with T30 and T385, two well-characterized mild isolates from Florida and Spain, respectively, the RdRp-2 was most closely related to NZRB-G90 and NZRB-TH30, two well-characterized resistance breaking and stem pitting (SP) isolates from New Zealand confirming the mixed infection. These results clearly demonstrated that the Iğdır isolate, which was previously described as biologically a mild isolate, actually contains a mixture of mild and severe strains.

We present a premature infant with large intracardiac mass. She had a history of sepsis and umbilical venous catheterization in the neonatal period. Twenty-seven days after withdrawal of the catheter, a precordial murmur was noted. A large right atrial highly mobile mass suspected to be thrombus was detected by echocardiography. C-reactive protein was elevated. Three blood cultures were negative. Anticoagulation treatment was started. After one week, no resolution of the thrombus was observed. The mass was surgically resected and diagnosis of thrombus infected by fungi was made on histopathological examination. Early screening of cardiac chambers by echocardiography is recommended in all preterms with intravascular catheterization.

Paranasal schwannomas are uncommon lesions, representing less than 4% of all head and neck schwannomas. They give rise to nonspecific symptoms such as nasal obstruction, epistaxis, and anosmia. Imaging features are generally nonspecific. Here, we present the radiologic features of a benign schwannoma of the middle turbinate with dural invasion in a 71-year-old woman.

Purpose: To assess the frequency of abdominal computed tomography (CT) findings of continuous ambulatory peritoneal dialysis (CAPD)-related complications., Materials and Methods: CT examinations of 42 patients (23 females and 19 males; median age, 46.5 years; age range, 22-70 years) with end-stage renal disease receiving CAPD were investigated retrospectively. CT examinations were performed with a suspicion of CAPD-related complications who were admitted to dialysis unit with various complaints. Images were obtained from the level of the dome of the diaphragm to the pelvis with an 8-mm slice thickness before and after intravenous contrast injection. Oral contrast material was performed in 17 of these patients. CT peritoneography was performed in one patient., Results: Complications of CAPD detected on CT studies included peritoneal thickening (n = 19; 45.7%), peritoneal calcifications (n = 2; 4.7%), peritoneal enhancement (n = 2; 4.7%); intraperitoneal loculation of fluids (n = 16; 38.1%), dilatation of bowels secondary to adhesions (n = 3; 7.1%); leakage of dialysis fluid adjacent to the entry site of the CAPD catheter (n = 6; 14.3%)(leaked dialysis fluid was loculated near the catheter in 4 of these patients); abscesses (n = 3; 7.1%); hernias (n = 5; 11.9%); hematomas (n = 5; 11.9%); tuberculous lymphadenitis (n = 2; 4.7%); bowel perforation (n = 2; 4.7%); ischemic bowel disease (n = 1; 2.4%); acute pancreatitis (n = 2; 4.7%); and catheter malposition (n = 1; 2.4%)., Conclusion: CT of abdomen is useful in detection of CAPD-related complications. Peritoneal thickening and intraperitoneal loculation of fluids due to peritonitis were the most common complications of CAPD detected on abdominal CT.

The RNA dependent RNA polymerase of Sendai virus consists of a complex of the large (L) and phosphoprotein (P) subunits where L is thought to be responsible for all the catalytic activities necessary for viral RNA synthesis. We previously showed that the L protein forms an oligomer [Smallwood, S., Cevik, B., Moyer, S.A., 2002. Intragenic complementation and oligomerization of the L subunit of the Sendai virus RNA polymerase. Virology 304, 235-245] and mapped the L oligomerization domain between amino acids 1 and 174 of the protein [Cevik, B., Smallwood, S., Moyer, S.A., 2003. The oligomerization domain resides at the very N-terminus of the Sendai virus L RNA polymerase protein. Virology 313, 525-536]. An internal deletion encompassing amino acids 20 to 178 of the L protein lost polymerase activity but still formed an L-L oligomer. The first 25 amino acids of paramyxovirus L proteins are highly conserved and site-directed mutagenesis within this region eliminated the biological activity of the L protein but did not have any effect on P-L or L-L interactions. Moreover deletion of amino acids 2-18 in L abolished biological activity, but again the L-L binding was normal demonstrating that the oligomerization domain of L protein resides in two N-terminal regions of the protein. Therefore, sequences between both aa 2-19 and aa 20-178 can independently mediate Sendai L oligomerization, however, both are required for the activity of the protein.

Measles virus encodes an RNA-dependent RNA polymerase composed of the L and P proteins. Recent studies have shown that the L proteins of both Sendai virus and parainfluenza virus 3 form an L-L complex [Cevik, B., Smallwood, S., Moyer, S.A., 2003. The oligomerization domain resides at the very Nterminus of the Sendai virus L RNA polymerase protein. Virology 313, 525-536.; Smallwood, S., Moyer, S.A., 2004. The L polymerase protein of parainfluenza virus 3 forms anoligomer and can interact with the heterologous Sendai virus L, P and C proteins. Virology 318, 439-450.; Smallwood, S., Cevik, B., Moyer, S.A., 2002. Intragenic complementation and oligomerization of the L subunit of the Sendai virus RNA polymerase. Virology 304, 235-245.]. Using differentially tagged L proteins, we show here that measles L also forms an oligomer and the L-L binding site resides in the N-terminal 408 amino acids overlapping the P binding site in the same region of L. To identify amino acids important for binding P and L, site-directed mutagenesis of the L-408 protein was performed. Seven of twelve mutants in L-408 were unable to form a complex with measles P while the remainder did bind at least some P. In contrast, all of the mutants retained the ability to form the L-L complex, so different amino acids are involved in the L and P binding sites on L. Four of the 408 mutations defective in P binding were inserted into the full-length measles L protein and all retained L-L complex formation, but did not bind P. Full-length L mutants that did not bind P were also inactive in viral RNA synthesis, showing a direct correlation between P-L complex formation and activity.

The incidence of Citrus tristeza virus (CTV) was found to increase significantly in southern Florida within 2 years after the establishment of its most efficient vector, Toxoptera citricida (Kirkaldy). Increased incidence of both mild and severe strains was documented, with the incidence of severe strains increasing more than mild strains. Molecular probes capable of differentiating mild, quick decline and various types of stem-pitting strains demonstrated that trees often were infected with more than one strain of CTV, with trees containing up to five different strains. Some CTV strains detected in the southeast urban corridor of Florida and in commercial groves in southwest Florida were found to react with probes specific for stem-pitting strains known from elsewhere in the world. The implications of the presence of these CTV strains in Florida and their possible presence in citrus budwood scion trees are discussed.

To catalyze RNA synthesis, the Sendai virus P-L RNA polymerase complex first binds the viral nucleocapsid (NC) template through an interaction of the P subunit with NP assembled with the genome RNA. For replication, the polymerase utilizes an NP(0)-P complex as the substrate for the encapsidation of newly synthesized RNA which involves both NP-RNA and NP-NP interactions. Previous studies showed that the C-terminal 124 amino acids of NP (aa 401-524) contain the P-NC binding site. To further delineate the amino acids important for this interaction, C-terminal truncations and site-directed mutations in NP were characterized for their replication activity and protein-protein interactions. This C-terminal region was found in fact to be necessary for several different protein interactions. The C-terminal 492-524 aa were nonessential for the complete activity of the protein. Deletion of amino acids 472-491, however, abolished replication activity due to a specific defect in the formation of the NP(0)-P complex. Binding of the P protein of the polymerase complex to NC required aa 462-471 of NP, while self-assembly of NP into NC required aa 440-461. Site-directed mutations from aa 435 to 491 showed, however, that the charged amino acids in this region were not essential for these defects.

The Sendai virus RNA-dependent RNA polymerase is composed of the L and P proteins. We previously showed that the L protein gives intragenic complementation and forms an oligomer where the L-L interaction site mapped to the N-terminal half of the protein (S. Smallwood et al., 2002, Virology, 00, 000-000). We now show that L oligomerization does not depend on P protein and progressively smaller N-terminal fragments of L from amino acids (aa) 1-1146 through aa 1-174 all bind wild-type L. C-terminal truncations up to aa 424, which bind L, can complement the transcription defect in an L mutant altered at aa 379, although these L truncation mutants do not bind P. The fragment of L comprising aa 1-895, furthermore, acts as a dominant-negative mutant to inhibit transcription of wild-type L. N-terminal deletions of aa 1-189 and aa 1-734 have lost the ability to form the L-L complex as well as the L-P complex, although they still bind C protein. These data are consistent with the L-L interaction site residing in aa 1-174. Site-directed mutations in the N-terminal 347 aa, of L which abolish P binding, do not affect L-L complex formation, so while the L and P binding sites on L are overlapping they are mediated by different amino acids. The N-terminal portions of L with aa 1-424, aa 1-381, and to a lesser extent aa 1-174, can complement the transcription defect in an L mutant altered at aa 77-81, showing their L-L interaction is functional.

The RNA-dependent RNA polymerase of Sendai virus consists of two subunits, the L and P proteins, where L is thought to be responsible for all the catalytic activities necessary for viral RNA synthesis. Sequence alignment of the L proteins of a variety of negative-stranded RNA viruses revealed six regions of good conservation, designated domains I-VI, which are thought to correspond to functional domains of the protein. Analysis of a number of site-directed mutants within the six domains of L allowed us to conclude that the activities of the polymerase are not simply compartmentalized and that each domain contributes to multiple steps in viral RNA synthesis. Nevertheless these domains can function in trans since we demonstrate here that intragenic complementation between pairs of coexpressed inactive L mutants can restore viral RNA synthesis on an added template. Although intragenic complementation is typically very inefficient, complementation to restore leader RNA synthesis was surprisingly very efficient for some pairs and complementation of mRNA synthesis and genome replication was less, but still significant. Complementation occurred with L mutants in five of the six domains, the exception being a domain III mutant, and required the cotranslation of the two L mutants. C-terminal truncations deleting up to half of L were capable of restoring transcription of an inactive domain I L mutant at amino acid 379. Oligomerization of L in the polymerase complex was demonstrated directly by the co-immunoprecipitation of differentially epitope-tagged full-length and truncated L proteins. These data are consistent with L protein being an oligomer with multiple independent domains each of which exhibits several functions., (Copyright 2002 Elsevier Science (USA))