Three novel mutations in CYBA among 22 Iranians with Chronic granulomatous disease.

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency caused by defect in one of the components of nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase enzyme. The enzyme is at least composed of membrane-bound subunits gp91-phox and p22-phox (also named cytochrome b558 ), and cytosolic ones p40-phox, p47-phox and p67-phox. A defect in the enzyme activity leads to impaired intracellular killing of phagocytic cells. The CYBA gene encoding p22-phox is located on chromosome 16q24. In this study, new genetic changes of CYBA gene in 22 Iranian patients with autosomal recessive-CGD (AR-CGD) were identified. Twenty-two patients with CGD were referred to Immunology, Asthma and Allergy Research Institute (IAARI) and enrolled in this study based on defect in NADPH oxidase activity, demographic data and clinical histories. All patients had p22-phox deficiency based on Western blotting. Genomic DNA was extracted from peripheral blood mononuclear cells (PBMCs), and PCR followed by direct sequencing was performed to find p22-phox mutations. Mutation analysis of CYBA revealed 12 different mutations, including three novel mutations: one was deletion of exon 1, and two were point mutations in exon 3 (c.136G>A (p.Gly46Ser)), and exon 6 (c.388C>T (p.Gln130X)). Three new mutations of CYBA gene in four of 22 Iranian patients with AR-CGD were found. These three novel mutations can partly complete the database of Human Gene Mutation Database (HGMD) and other related ones. It can also be helpful for further prenatal diagnosis in the affected families. Given that currently bone marrow transplantation is considered to be the curative treatment for patients with CGD, finding mutations will also be useful for timely decision-making in bone marrow transplantation.

Clinical, Laboratory, and Molecular Findings for 63 Patients With Severe Combined Immunodeficiency: A Decade´s Experience.

BACKGROUND: Severe combined immunodeficiency (SCID) is a life-threatening pediatric disease. We report on the clinical evaluation, immunological assessment, molecular analysis, and outcomes of SCID patients in a tertiary referral center in Iran. METHODS: From January 2006 to December 2015, we performed a prospective cohort study in which initial screening and advanced immunological tests were carried out on patients suspected of having SCID. Genetic analysis was also performed to confirm the diagnosis. RESULTS: A total of 63 patients were diagnosed with SCID (43 male [68.3%]). The median age at onset and diagnosis and diagnostic delay were 40 and 110 and 60 days respectively. A total of 49 patients (77.8%) had a history of BCG vaccination, and of these, one-third experienced BCG-associated complications. The most common clinical manifestations were pneumonia, recurrent oral candidiasis, chronic diarrhea, and failure to thrive. Of the thirteen patients who underwent hematopoietic stem cell transplantation, 8 survived and 5 died before they could receive the transplant. Most patients (34.9%) were classified as having T-B-NK+ SCID and had a mutation in the RAG2 or RAG1 gene. CONCLUSIONS: Autosomal recessive SCID is the most common type in Iranian patients. Providing high-quality training to physicians and patients' families to reduce the diagnostic delay should be prioritized. It is also important to raise awareness of live vaccination and to expand stem cell donor registries to speed up the transplantation process.

Single nucleotide polymorphisms of IL-2, but not IL-12 and IFN-γ, are associated with increased susceptibility to chronic spontaneous urticaria.

BACKGROUND: A clear picture of interaction of Th1/Th2 cytokines in pathogenesis of chronic spontaneous urticaria (CSU), remains elusive. Impaired IFN-γ production and decreased levels of IL-2 have been reported. The aim of this study was to evaluate the association of Th1 cytokines; IL-2, IL-12 and IFN-γ polymorphisms with CSU. METHODS: 90 patients with CSU and 140 age-sex matched subjects were included in this study. DNA samples were evaluated through PCR-SSP assay in order to detect single nucleotide polymorphisms of IL-12 (A/C -1188) or (rs3212227), IFN-γ (A/T UTR5644) or (rs2069717) and IL-2 (G/T -330 and G/T +166) or (rs2069762 and rs2069763). RESULTS: G allele at -330 at promoter region of IL-2 gene was overrepresented in CSU. Heterozygotes (GT) at this locus and heterozygotes at +166 of IL-2 gene (GT) were more prevalent in CSU group. Additionally, the haplotype GT for loci -330 and +166 of IL-2 gene was powerfully associated with CSU (OR (95%CI)=57.29 (8.43-112.7)). CONCLUSIONS: SNP at position -330 and +166 of IL-2 gene are differently expressed in CSU. The haplotype GT of IL-2 at -330 and +166 might confer vulnerability to a number of immunological disorders in Iranian region.

FLG single nucleotide polymorphisms in chronic idiopathic urticaria.

BACKGROUND: Filaggrin (FLG), which is formed from profilaggrin protein during epidermal terminal differentiation, is a prerequisite to squame biogenesis and thus for perfect formation of the skin barrier. Yet, the relationship between genetic polymorphisms of FLG and chronic idiopathic urticaria (CIU) has not been investigated. METHODS: The study population consisted of 93 CIU patients and 93 healthy control subjects without a history of allergic, autoimmune or any other systemic disease. Five single nucleotide polymorphisms (SNPs) of FLG were investigated: rs2485518, rs3126065, rs2786680, rs3814300, and rs3814299. RESULTS: For all the investigated polymorphisms, 100% of both CIU patients and control subjects exhibited one given allele and consequently one given genotype as following: A/A genotype for two SNPs, rs3126065 and rs2786680, C/C genotype for two SNPs, rs2485518 and rs3814300, and G/G genotype for one SNP rs3814299 of FLG, and hence no association was found between either allele frequencies or genotype distributions of FLG SNPs and CIU in an Iranian population. CONCLUSIONS: The present study examined the possible relationship between SNPs of FLG and CIU for the first time, and demonstrated that none of five investigated SNPs (rs2485518, rs3126065, rs2786680, rs3814300, and rs3814299) are correlated with CIU in an Iranian population. Further investigations are required to address whether ethnicity/race impacts on relationship between SNPs of FLG and CIU.

Gene polymorphisms of interleukin-10 and transforming growth factor beta in allergic rhinitis.

BACKGROUND: Allergic rhinitis (AR) is a polygenic inflammatory disorder of the upper respiratory airway with an increasing prevalence worldwide. Interleukin-10 (IL-10) and transforming growth factor-beta (TGF-ß), as two cytokines with pleiotropic effects on both innate and adaptive immunity, play important roles in allergic responses. Therefore, this study was performed to evaluate the associations of five polymorphisms of IL-10 and TGF-ß genes with AR. MATERIALS AND METHODS: Ninety-eight patients with AR along with 140 healthy volunteers with no history of AR and with the same ethnicity of the patients were recruited in this study. Genotyping was done for three polymorphisms in promoter region of IL-10 gene (rs1800896, rs1800871, rs1800872), and two polymorphisms in the exonic region of TGF-ß1 gene (rs1982037, rs1800471) using PCR sequence-specific-primers method. RESULTS: A allele and AA genotype in rs1800896 of IL-10 and TT genotype in rs1982037 in TGF-ß were significantly less frequent in the patients than in controls. While the C allele and the CG genotype in rs1800471 in TGF-ß1 were associated with a higher susceptibility to AR. C/C and T/C haplotypes (rs1982037, rs1800471) in TGF-ß1 gene and A/C/A, A/T/C and G/C/A haplotypes (rs1800896, rs1800871, rs1800872) in IL-10 gene were found with higher frequencies in patients than controls. Patients with CC genotype in rs1800871 in Il-10 had significantly lower levels of IgE. CONCLUSION: We found that certain genetic variants in IL-10 and TGF-ß polymorphisms were associated with susceptibility to AR as well as some clinical parameters in the patients with AR.

Primary Antibody Deficiency in a Tertiary Referral Hospital: A 30-Year Experiment.

BACKGROUND: Primary antibody deficiency (PAD) is the most common group of primary immunodeficiency disorders (PID), with a broad spectrum of clinical features ranging from severe and recurrent infections to asymptomatic disease. OBJECTIVES: The current study was performed to evaluate and compare demographic and clinical data in the most common types of PAD. MATERIALS AND METHODS: We performed a retrospective review of the medical records of all PAD patients with a confirmed diagnosis of common variable immunodeficiency (CVID), hyper IgM syndrome (HIgM), selective IgA deficiency (SIgAD), and X-linked agammaglobulinemia (XLA) who were diagnosed during the last 30 years at the Children's Medical Center, Tehran, Iran. RESULTS: A total number of 280 cases of PAD (125 CVID, 32 HIgM, 63 SIgAD, and 60 XLA) were enrolled in the study. The median (range) age at the onset of disease in CVID, HIgM, SIgAD, and XLA was 2 (0-46), 0.91 (0-9), 1 (0-26), and 1 (0-10) years, respectively. Gastrointestinal infections were more prevalent in CVID patients, as were central nervous system infections in XLA patients. Autoimmune complications were more prevalent in HIgM patients, malignancies in CVID patients, and allergies in SIgAD patients. The mortality rate for CVID, HIgM, and XLA was 27.2%, 28.1%, and 25%, respectively. No deaths were reported in SIgAD patients. CONCLUSIONS: SIgAD patients had the best prognosis. While all PAD patients should be monitored for infectious complications, special attention should be paid to the finding of malignancy and autoimmune disorders in CVID and HIgM patients, respectively.

Interleukin-6 and tumor necrosis factor-alpha gene polymorphisms in chronic idiopathic urticaria.

BACKGROUND: This study was performed to evaluate association of gene polymorphisms among proinflammatory cytokines and susceptibility to chronic idiopathic urticaria (CIU). METHODS: Ninety patients with prolonged urticaria more than 6 weeks were included as case group. Single nucleotide polymorphisms (SNPs) of IL-6 (G/C -174, G/A nt565) and TNF-α (G/A -308, G/A -238) were evaluated, using polymerase chain reaction (PCR); and the results were compared to the control group. RESULTS: G allele was significantly higher in the patients at locus of -238 of promoter of TNF-α gene (p<0.001). Frequency of following genotypes were significantly lower in patients with CIU, compared to controls: AG at -308 and GA at -238 of TNF-α gene (p<0.05 and p<0.001, respectively), CG at -174 and GG at +565 of IL-6 gene (p<0.05). Additionally, following genotypes were more common among patients with CIU: GG at -308 and -238 of TNF-α gene (p<0.05 and p<0.001, respectively), GG at -174 and GA at +565 of IL-6 gene (p<0.05). CONCLUSIONS: Pro-inflammatory cytokine gene polymorphisms can affect susceptibility to CIU. TNF-α promoter polymorphisms as well as IL-6 gene polymorphisms are associated with CIU.

Single-nucleotide polymorphisms of TNFA and IL1 in allergic rhinitis.

BACKGROUND: Allergic rhinitis is a complex polygenic disorder of the upper respiratory tract. Given that proinflammatory cytokines such as tumor necrosis factor (TNF) and interleukin (IL) 1 seem to play a role in the development of allergic rhinitis, we evaluated the associations between various single-nucleotide polymorphisms (SNPs) of the TNF and IL1 genes in a case-control study. METHODS: The study population comprised 98 patients with allergic rhinitis. Genotyping was performed using polymerase chain reaction with sequence-specific primers for 2 TNFA promoter variants (rs1800629 and rs361525), 1 variant in the promoter region of IL1A (rs1800587), 2 SNPs in the IL1B gene (rs16944 and rs1 143634), 1 variant in the IL1 receptor (rs2234650), and 1 in IL1RA (rs315952). RESULTS: Patients who were homozygous for the T allele of rs16944 in IL1B had an 8.1-fold greater risk of allergic rhinitis than those with the C allele. In TNFA, a significant relationship was also detected between rs1800629 and rs361525 and allergic rhinitis. Except for rs1800587 in IL1A and rs315952 in IL1RA, significant differences were found between the patient and control groups for all other SNPs. CONCLUSIONS: We found that allelic variants in the TNFA and IL1 genes were not only associated with the risk of developing allergic rhinitis, but also affected disease course and severity.

Autoimmune phenotype in patients with common variable immunodeficiency.

BACKGROUND AND OBJECTIVE: Autoimmune disorders occur with a higher incidence in common variable immunodeficiency (CVID) patients than in the general population. To describe the clinical features of the autoimmune phenotype in patients with CVID. METHODS: The hospital records of all diagnosed CVID patients referred to the Children's Medical Center Hospital in Tehran, Iran between 2000 and 2010 were reviewed. Patients were also classified according to the presence or absence of autoimmune disease. RESULTS: Of 52 patients studied, 26.9% (n=14) had shown at least 1 autoimmune manifestation during the study period. Autoimmune cytopenias and juvenile rheumatoid arthritis were the most common form of autoimmunity in our series. Autoimmunity was significantly associated with polyclonal lymphocytic infiltrative disorders (P = .017), increased serum Immunoglobulin (Ig) M levels (P < .001), decreased IgE values (P = .04) and diminished switched memory B-cell count (P < .001). CONCLUSIONS: Because autoimmunity is one of the first manifestations in CVID, humoral immune system tests should be considered in autoimmune patients with a history of recurrent infection. The presence of polyclonal lymphocytic infiltrative disorders and decreased switched memory B-cells may predispose CVID patients to autoimmunity.

Study on fungal flora of tap water as a potential reservoir of fungi in hospitals in Sari city, Iran.

OBJECTIVE: The aim of the present investigation was to evaluate the fungal flora of tap water from university hospitals of Sari city, Iran. MATERIALS AND METHODS: During a 1-year period, 240 water samples were collected from four university hospitals. All water samples were collected in sterile polystyrene bottles. A volume of 100ml of the samples passed through sterile 0.45-micrometer filters. The filters were placed directly on malt extract agar and incubated at 27°C for 3 to 7 days. Routine mycological techniques were applied to identification of grown fungi. RESULTS: Out of 240 plates, 77.5% were positive for fungal growth. Twelve different genera were identified. Aspergillus (29.7%), Cladosporium (26.7%) and Penicillium (23.9%) were the most common isolated. Among Aspergillus species, A. flavus had the highest frequency. Highest colony counts were found in autumn. Aspergillus predominated in autumn, Cladosporium in winter and spring and Penicillium in summer. CONCLUSION: The results of our study showed that hospital water should be considered as a potential reservoir of fungi particularly Aspergillus.

Polymorphisms in IL4 and iLARA confer susceptibility to asthma.

BACKGROUND: Asthma is a complex disease that is caused by genetic and environmental factors. The production of interleukin (IL)-4, which can influence mast cell responsiveness to immunoglobulin (Ig) E--mediated signaling, could be modified by genetic variants in the IL-4 promoter. OBJECTIVE: To investigate the association between the IL-4 and IL-4RA promoter polymorphisms and asthma in a sample of Iranian patients. METHODS: We used polymerase chain reaction with sequence-specific primers to investigate the allele and genotype frequencies of 2 polymorphic genes coding for IL-4 and IL-4RA in 59 Iranian patients with asthma and 139 healthy controls. RESULTS: The most frequent genotypes in the patient group were IL-4TC (-590), IL-4TC (-33), IL-4 GT (-1098), and IL-4RA GA (+1902). In contrast, the frequencies of IL-4 CC (-590), IL-4 CC (-33), IL-4TT (-1098), and IL-4RAAA (+1902) were significantly lower in the patient group than in the control group. The most frequent haplotypes in our patients were IL-4 TCT and GTC at positions -1098,-590,-33. The mean total serum IgE level in patients with the TTT/GCC genotype was 258.8 IU/mL, which was significantly higher than the 95.4 IU/mL observed for other genotypes. CONCLUSION: We showed a strong association between the polymorphisms of the IL-4 gene promoter at positions -590, -33 and -1098 and bronchial asthma. We also demonstrated an association between their haplotypes and serum total IgE.

Adverse reactions of prophylactic intravenous immunoglobulin; a 13-year experience with 3004 infusions in Iranian patients with primary immunodeficiency diseases.

Intravenous immunoglobulin (IVIG) replacement therapy improves health-related quality of life in patients with a primary immunodeficiency disease, although there have been reports of adverse reactions associated with its regular administration. The study population was composed of 99 patients with primary antibody deficiencies. All the patients were diagnosed with a primary immunodeficiency disease and received at least 4 infusions of IVIG at the Children's Medical Center Hospital, Tehran, Iran over a 13-year period (1995-2007). A total of 3004 infusions were recorded, and 216 (7.2%) of these were associated with adverse reactions in 66 patients. Adverse reactions were classified as mild (172 reactions), moderate (41 reactions), and severe (3 reactions). The rate of adverse reaction varied by diagnosis from 3.35% in patients with X-linked agammaglobulinemia to 17.4% in IgG subclass deficiency. There were no age-related differences in the rates of adverse reactions. Adverse reactions to IVIG infusions are occasionally encountered; therefore, physicians and nurses should be aware of these reactions in order to manage and prevent them.

A new selective optode for the determination of iron(III) based on the immobilization of morin on triacetylcellulose: A combined experimental and computational study.

Accurate and fast measurement of the iron ion in biological, pharmaceutical and medical samples is of great applied importance. In this work, a novel optical sensor (optode) for the Fe(III) ion is fabricated based on the immobilization of morin (2',3,4',5,7-pentahydroxyflavone) on a triacetylcellulose membrane. Chemical binding of the Fe(III) ion with the immobilized morin is monitored spectrophotometrically at 334 nm. The prepared optode shows excellent response over a wide range of concentrations from 1.06 × 10-10 to 4.73 × 10-5 M with a detection limit of 4.23 × 10-11 M Fe(III). Effects of the factors determining sensitivity of the optode are studied and optimized. The prepared optical sensor shows good selectivity toward the Fe(III) ion in the presence of a number of other metal ions. The developed sensor is applied successfully and satisfactorily for the determination of iron in three pharmaceutical, one plasma and two serum samples. In addition, concentration of the Fe(III) ion in two tap water samples is measured using standard addition method. Density functional theory (TD) B3LYP/6-311++G** method is used to investigate structure and binding characteristics, and calculate the UV-Vis spectrum of the Fe(III)-morin complex.

Antibacterial Susceptibility Pattern of the Pseudomonas aeruginosa and Staphylococcus aureus after Exposure to Electromagnetic Waves Emitted from Mobile Phone Simulator.

BACKGROUND: The increasing use of telecommunication devices such as Wi-Fi modems and mobile phones in the recent years can change the cellular structure of microorganisms so the generation of electromagnetic waves has led to concern in the community whenever be exposed to these fields and may have harmful effects on human health. MATERIAL AND METHODS: In this experimental study, standard strains of bacteria were prepared on Mueller-Hinton agar for bacterial growth to obtain 0.5 McFarland turbidity (1.5 × 108 CFU) of bacteria. Antibiotic susceptibility test using the Kirby-Bauer disk diffusion method was done. For Staphylococcus aureus and Pseudomonas aeruginosa, antibiotics susceptibility test was conducted. The test group was exposed to electromagnetic waves emitted by mobile phone simulator with a frequency of 900 MHz and the control group were not exposed. RESULTS: The results revealed that increasing duration of exposure to electromagnetic waves emitted by the mobile simulators with a frequency of 900 MHz especially after 24 h of exposure, can increase bacterial resistance in S. aureus, and P. aeruginosa. CONCLUSION: Several factors can cause bacterial resistance against antibiotics. One of these factors is the electromagnetic waves emitted from mobile simulator with a frequency of 900 MHz, which can increase the permeability of the cell wall of bacteria.

Molecular diagnosis of X-linked chronic granulomatous disease in Iran.

Chronic granulomatous disease (CGD) is an inherited disorder of pathogen killing by phagocytic leukocytes caused by mutations in NADPH oxidase subunits. Patients with CGD have life-threatening bacterial and fungal infections. Children's Medical Center at Tehran University is the referral center for immunodeficiency in Iran. During 2 years of study, 11 non-consanguineous families with clinically diagnosed CGD were referred to this center. In functional assays performed on neutrophils from affected children and their mothers; no activity or strongly decreased oxidase activity was detected in the patients' cells. In oxidase tests that scored this activity on a per-cell basis, a mosaic pattern was detected in the neutrophils from all 11 mothers. Western blot analysis revealed an X91 degrees phenotype in all patients. Mutation screening in the CYBB gene encoding gp91(phox) by SSCP analysis followed by sequencing showed nine different mutations, including two novel mutations. The present survey is the first study aimed to analyze the clinical features and the molecular diagnosis of X-CGD in Iranian patients.

Observation period for asymptomatic penetrating chest trauma: 1 or 3 h?

BACKGROUND: Current recommendations for evaluation and safe discharge of penetrating chest trauma patients regarding pneumothorax (PTX) include a Chest X Ray (CXR) at the Emergency Department (ED) upon arrival and second CXR after 3 h if the first one is negative. PURPOSE: To compare CXRs taken at the first and third hours of ED arrival and evaluate a 1 h period of observation instead of 3 h for safe discharge of patients with penetrating chest trauma. METHODS: In this cross-sectional study, all asymptomatic patients with penetrating chest trauma referred to a level 1 trauma center with negative initial Postero-Anterior (PA) CXRs (hour 0) were enrolled. Those with intoxication, tube thoracostomy, chest computed tomography, evidence of abdominal penetration, an overall elapsed timed of more than 1 h for admission to the ED, and refusal to take part in the study were excluded. Patients underwent subsequent PA CXRs at hours 1 and 3. A phone call follow up after 24 h was organized for each patient. RESULTS: A total of 68 patients were enrolled. There was 100 % concordance among CXRs performed at hours 1 and 3 in the study population. None of the patients showed clinical deterioration or PTX in CXR at hour 1 if remained asymptomatic during the first hour of observation. CONCLUSION: Asymptomatic patients with penetrating chest trauma, negative initial PA CXR, no signs of intoxication, and no deterioration during the first hour of observation may be considered for discharge. Further evidence is required to make recommendations based on these findings.

A Study on Performance and Safety Tests of Defibrillator Equipment.

INTRODUCTION: Nowadays, more than 10,000 different types of medical devices can be found in hospitals. This way, medical electrical equipment is being employed in a wide variety of fields in medical sciences with different physiological effects and measurements. Hospitals and medical centers must ensure that their critical medical devices are safe, accurate, reliable and operational at the required level of performance. Defibrillators are critical resuscitation devices. The use of reliable defibirillators has led to more effective treatments and improved patient safety through better control and management of complications during Cardiopulmonary Resuscitation (CPR). MATERIALS AND METHODS: The metrological reliability of twenty frequent use, manual defibrillators in use ten hospitals (4 private and 6 public) in one of the provinces of Iran according to international and national standards was evaluated. RESULTS: Quantitative analysis of control and instrument accuracy showed the amount of the obtained results in many units are critical which had less value over the standard limitations especially in devices with poor battery. For the accuracy of delivered energy analysis, only twelve units delivered acceptable output values and the precision in the output energy measurements especialy in weak battry condition, after activation of discharge alarm, were low. CONCLUSION: Obtained results indicate a need for new and severe regulations on periodic performance verifications and medical equipment quality control program especially for high risk instruments. It is also necessary to provide training courses on the fundumentals of operation and performane parameters for medical staff in the field of meterology in medicine and how one can get good accuracy results especially in high risk medical devices.

Pulmonary complications in primary hypogammaglobulinemia: a survey by high resolution CT scan.

BACKGROUND: Primary hypogammaglobulinemia disorders are a group of heterogeneous immunodeficiency syndromes with an increased susceptibility to pulmonary complications. METHODS: The aim of this study was to evaluate the extent of lung abnormalities in primary hypogammaglobulinaemic patients by high resolution computed tomography (HRCT) scan and pulmonary function test (PFT). HRCT and PFT were performed in 22 Iranian patients with primary hypogammaglobulinemia. RESULTS: Pathological bronchial findings were observed in thirteen patients: three patients showed only peribronchial thickening and the remaining ten patients suffered from both bronchiectasis and peribronchial wall thickening. Mild type of bronchiectasis and peribronchial wall thickening were the most common type, predominantly observed in the right middle and both right and left lower lobe segments of lungs. Although bullae were not found, emphysema, air-trapping, and collapse/consolidation were observed in two patients. Bronchial involvement was mostly limited to 1 up to 5 bronchopulmonary segments; only one HRCT indicated bronchial involvement in more than nine bronchopulmonary segments. Pathological bronchial findings mostly observed in the proximal bronchi; meanwhile the involvement of the distal bronchi was less common. Decreasing FEVI and FVC were observed in 65% and 55% of patients, respectively. There was a significant correlation between the HRCT score and the predicted values by PFT. The delay of diagnosis in patients with bronchiectasis was significantly higher than those without bronchiectasis. CONCLUSIONS: It seems that the majority of hypogammaglobulinaemic patients suffer from the mild type of bronchiectasis, which is mostly observed in the proximal bronchi of the lower lobe segments. The delay of diagnosis plays an important role in the occurrence of this complication in these patients.