Determination of neutron flux parameters (f, α, φth and φe) of the irradiation sites of Isfahan MNSR reactor using empirical and MCNPX2.6 simulation approaches

Miniature Neutron Source reactors (MNSRs) are ideal for applications such as nuclear research, neutron activation analysis, etc., provided that their neutron flux parameters (φ_th, φ_e, f and α) are known. This paper present the results of the neutron flux parameters at inner and outer irradiation sites of Isfahan MNSR reactor determined through simulation with MCNPX2.6 code and experimentally using bare and cadmium-covered gold foils irradiation and bare triple (AuZr) monitor methods. In empirical approach, the obtained φ_th, φ_e, f [f_bare] and α-values were 5.02 × 10¹¹ ncm^-2s^-1 (±4.5%), 3.13 × 10¹⁰ ncm^-2s^-1 (±2.3%), 16.0 (±6.7%) [17.3 (±9.9%)] and -0.121 (±0.2%), for inner site; and 2.93 × 10¹¹ ncm^-2s^-1 (±2.3%), 6.48 × 10⁹ ncm^-2s^-1 (±3.1%), 45.2 (±5.4%) [42.5 (±7.1%)] and -0.011 (±1.8%), respectively, for outer site. In simulation approach, while, they were found to be 4.76 × 10¹¹ ncm^-2s^-1 (±0.9%), 2.00 × 10¹⁰ ncm^-2s^-1 (±2.2%), 23.8 (±3.1%) and -0.078 (±0.13%), for the inner site; and 2.67 × 10¹¹ ncm^-2s^-1 (±1.1%), 3.79 × 10⁹ ncm^-2s^-1 (±5.4%), 70.4 (±6.5%) and -0.017 (±0.4%) for the outer site, respectively. Comparison of empirical and simulation results clearly revealed that: the inner site's φ_th and f values correspond with those measured during the first startup of the reactor; the values of φ_th are more reliable than φ_e,-values, as are the inner site's f and α results in comparison with outer site's values; the inner site's φ_th and φ_e are ∼1.7 and 5 times, respectively, larger than those of outer site; and the inner site 's α and f-values are more than 4.8 and 2.4 times larger and less than the outer site's values, respectively.

The feasibility study of 177Lu production in Miniature Neutron Source Reactors using a multi-stage approach in Isfahan, Iran

Miniature neutron source reactors (MNSRs) are among the safest and economic research reactors with potentials to be used for neutron studies. This manuscript explores the feasibility of ¹⁷⁷Lu production in Isfahan MNSR reactor using direct production route. In this study, to assess the specific activity of the produced radioisotope, a simulation was carried out through the MCNPX2.6 code. The simulation was validated by irradiating a lutetium disc-like (99.98 chemical purity) at the thermal neutron flux of 5 × 10¹¹ ncm²s^-1 and an irradiation time of 4min. After the spectrometry of the irradiated sample, the experimental results of ¹⁷⁷Lu production were compared with the simulation results. In addition, factor from the simulation was extracted by replacing it in the related equations in order to calculate specific activity through a multi-stage approach, and by using different irradiation techniques. The results showed that the simulation technique designed in this study is in agreement with the experimental approach (with a difference of approximately 3%). It was also found that the maximum ¹⁷⁷Lu production at the maximum flux and irradiation time allows access to 723.5mCi/g after 27 cycles. Furthermore, the comparison of irradiation techniques showed that increasing the irradiation time is more effective in ¹⁷⁷Lu production efficiency than increasing the number of irradiation cycles. In a way that increasing the irradiation time would postpone the saturation of the productions. On the other hand, it was shown that the choice of an appropriate irradiation technique for ¹⁷⁷Lu production can be economically important in term of the effective fuel consumption in the reactor.

Effect of root canal rinsing protocol on dentin bond strength of two resin cements using three different method of test

Background

Different studies have used different tests to evaluate bond strength of resin cements to root dentin. In this in vitrostudy, three different tests were used to evaluate the bond strength of two resin cements to root dentin using two root dentin irrigation protocols.

Material and Methods

Ninety-six intact single-rooted teeth were selected for this study. Forty-eight teeth, with a root length of 15mm, were randomly divided into two groups and irrigated with normal saline or 2.5% sodium hypochlorite solutions during root canal preparation, respectively. For each 12 specimens from each group, fiber post #1 was bonded using an etch-and-rinse (Duo-Link) and a self-adhesive (BisCem) resin cement, respectively. After incubation, two specimens were prepared for the push-out test from the middle thirds of the roots. In another 24 teeth, after two 1.5-mm sections were prepared from the middle thirds of the prepared roots, sections of the post were bonded in two subgroups with each of the cements mentioned above and the samples were prepared for the pull-out test. For shear test, the crowns of 48 teeth were cut away, the dentin surfaces were prepared, the two irrigation solutions were used, and the resin cements were bonded. Data collected from the three tests were evaluated by ANOVA, post-hoc Tukey and Weibull tests (α=0.05).

Results

There were significant differences in the mean bond strength values between the three bond strength tests (P<0.001). Rinsing protocol and cement type resulted in similar variations in the mean bond strength in all tests (P>0.05).

Conclusions

Under the limitations of the present study, the method of the test used had an effect on the recorded bond strength between the resin cement and root dentin. Cement type and irrigation protocol resulted in similar variations with all the tests. Push-out and shear tests exhibited more coherent results.

Key words:Bond strength, endodontically treated tooth, fiber post, resin cement, sodium hypochlorite.

Socioeconomic determinants and metabolic syndrome: Results from the Isfahan Healthy Heart Program

Introduction: The prevalence of metabolic syndrome (MetS) is increasing in Iran. We assessed the relationship between socioeconomic status (SES) and Mets components in the Iranian population.

MATERIALS AND METHODS

The sample for this study comprised a random cross-section of men and women from two province districts who participated in the Isfahan Healthy Heart Program (IHHP) in 2007. Each participant completed a questionnaire, underwent anthropometric testing and blood pressure measurements, and provided a blood sample. Mets was defined based on ATPIII criteria. Several SES dimensions, such as education, occupation, and number of children, as well as home, car, and personal computer ownership, were assessed to determine the participant's SES.

RESULTS

A higher-than-average income, car ownership, owning or renting a private home, and having a computer are increasing towards increment in SES. All MetS components were more prevalent in participants defined as having a lower SES, while low HDL levels were more common in participants having an SES II (P>0.001). A multivariate analysis showed that having the lowest SES (I) increased the risk of MetS by 1.72 [1.44-2.07], whereas subjects having an SES III had a 1.23 [1.04-1.47] lower risk for MetS.

CONCLUSIONS

The relationship between SES and Mets is due largely to behavioural factors, such as practicing unhealthy eating habits. Given the high prevalence of Mets in Iran, we propose that regular health check-ups may be useful in the early detection of the syndrome and, consequently, in the prevention of its effects. In addition, the early detection of MetS may result in the early diagnosis and prevention of cardiovascular diseases.

Prevention of post-spinal hypotension using crystalloid, colloid and ephedrine with three different combinations: A double blind randomized study

Background:

The benefit of prophylactic combination therapy using crystalloid and colloid preload with ephedrine has not been cleared to prevent maternal hypotension after spinal anesthesia at cesarean delivery. This study evaluated the efficacy of three combinational methods to prevent hypotension following spinal anesthesia.

Materials and Methods:

In this prospective double blind trial, 150 candidates of elective cesarean delivery under spinal anesthesia were randomly allocated to three treatment groups; 1---Ringer's Lactate (RL) solution (15 ml/kg) plus Hemaxel (7 ml/kg) preload, 2---RL solution (15 ml/kg) preload plus ephedrine (15 mg, IV, bolus), 3---Hemaxel (7 ml/kg) preload plus ephedrine (15 mg, IV, bolus). Maternal hemodynamic changes during 60 min after spinal injection, nausea/vomiting, and neonatal condition were compared among the groups.

Results:

The cumulative incidence of hypotension was 44%, 40%, and 46% in groups 1 to 3, respectively. There were not significant differences in supplementary ephedrine requirement among groups which received or among groups which did not receive prophylactic ephedrine. Groups were not different in the incidence of hypertension and nausea or vomiting. There were no significant differences among groups in Apgar scores at 1 or 5 min and umbilical artery PH.

Conclusion:

Combination of preventive methods decreased the occurrence of hypotension following spinal anesthesia to an acceptable level. Overall, the most effective method was a combination of crystalloid preload with ephedrine.

Management of left ventricular distension during peripheral extracorporeal membrane oxygenation for cardiogenic shock

The application of peripheral veno-arterial extracorporeal membrane oxygenation in the management of inotrope-refractory cardiogenic shock has proven controversial because of concerns about sub-optimal drainage of the left heart, resulting in left ventricular distension and pulmonary oedema. In this article, we will discuss the pathophysiological basis and clinical implications of left ventricular distension following institution of peripheral extracorporeal life support. We will also review the clinical strategies used to circumvent left ventricular distension and pulmonary oedema in these patients.

A randomized comparative trial of combinational methods for preventing post-spinal hypotension at elective cesarean delivery

BACKGROUND

Various methods have been applied to prevent maternal hypotension after spinal anesthesia for cesarean delivery. We compared the efficacy of three combinational methods in this regard in the current study.

METHODS

In this randomized comparative trial, 150 candidates of elective cesarean delivery under spinal anesthesia were assigned to three groups: crystalloid preload and leg bandage, colloid preload and leg bandage, and ephedrine and leg bandage. Maternal hemodynamic changes during 60 minutes after spinal injection and neonatal condition were compared among the groups.

RESULTS

The cumulative incidence of hypotension was 54%, 64%, and 36% in groups 1 to 3, respectively (p = 0.018). Spinal injection to hypotension interval was similar among the groups (p = 0.828). Heart rate in group 3 was significantly lower at the most time measures after anesthesia compared with the other two groups (p < 0.05 to <0.001). Regarding neonatal outcomes, the interval between the birth and the first breath was longer and the Apgar score at minute 1 was lower in group 3 compared with the other groups (p < 0.001 and 0.038, respectively) but it was not clinically important. Umbilical cord blood pH was similar among the three groups (p = 0.248).

CONCLUSIONS

Among the three studied methods, administration of ephedrine plus bandage of the lower extremities was the most effective one in reducing the incidence of post-spinal hypotension. The groups were not clinically different concerning the effect of treatment on newborn health.

The impact of generic form of Clopidogrel on cardiovascular events in patients with coronary artery stent: results of the OPCES study

BACKGROUND

To compare the early and late cardiovascular events as well as side effects of Osvix, a generic form of Clopidogrel versus Plavix regimens in patients with chronic stable angina, undergoing bare metal stent (BMS) or drug eluting stent (DES) placement, this study was carried out.

METHODS

A total of 442 patients with chronic stable angina who were scheduled for elective percutaneous coronary intervention (PCI) were included in a randomized, double blind, multi-centric clinical trial being performed in 6 distinct university hospitals in 5 cities of Iran from March 2007 to November 2009. Baseline, demographic and history of risk factors were recorded using the patients' medical charts. Stenting procedure was performed via transfemoral approach using low osmolar contrast agents. Patients underwent BMS or DES placements based on the physician selection and were randomly assigned to Osvix or Plavix groups. Patients were followed by telephone in 0 and 6 months intervals regarding the major adverse cardiovascular events (MACE) including death, myocardial infarction, in-stent thrombosis, stroke, target lesion revascularization, and target vascular revascularization. Angina episodes, bleeding, liver enzymes, neutrophils and platelets count were also assessed in these intervals.

RESULTS

There was not any significant difference between these two groups regarding the baseline characteristics. In the DES group, the 6-month mortality rate and the incidence of MACE in Osvix and Plavix groups were 0.9% and 1.9% (p = 0.61) and 1.8% and 4.9% (p = 0.26), respectively. During the follow up period after DES or BMS placement, there wasn't any significant difference regarding neutrophil and platelet counts or liver enzymes between study groups.

CONCLUSIONS

Using Osvix and Plavix are followed by similar major cardiovascular events and side-effect profile in patients undergoing PCI.

Comparative study of two anesthesia methods according to postoperative complications and one month mortality rate in the candidates of hip surgery

BACKGROUND

Surgery for hip fractures can be done under general or neuraxial anesthesia. This study aimed to compare these two methods concerning their postoperative complications, duration of operation, hospitalization and the mortality rate within a period of one month after surgery.

METHODS

400 patients aged more than 30 years old and scheduled for elective operative fixation of fractured hip, randomly enrolled in two equal groups of general (GA) and neuraxial (NA) anesthesia. Hemoglobin level was measured before and 6 hours, 2, 3 and 5 days after the surgery. The intra and postoperative blood loss, duration of surgery, the severity of pain at the time of discharge from recovery and at the 2(nd), 3(rd) and 5(th) postoperative days were recorded. Statistical analysis was performed using SPSS version 12.0 by Mann-Whitney, chi-square, and t tests. P < 0.05 was considered significant.

RESULTS

Both groups were similar regarding age, weight, and gender ratio. There was no significant difference in baseline hemoglobin, duration of surgery, length of hospitalization before surgery and the type of surgery. The mean of intraoperative blood loss and visual analogue score (VAS) in recovery and at the 3(rd) postoperative day, and also the length of hospitalization after surgery were significantly less in neuraxial anesthesia group. Both groups showed a significant decrease in hemoglobin values on the 2(nd) and 3(rd) postoperative days comparing to the baseline (p < 0.001).

CONCLUSIONS

The morbidity and mortality rates of patients undergoing hip surgery were similar in both methods of anesthesia, but postoperative pain, blood loss, and duration of hospitalization were more in patients undergoing general anesthesia.

A study on the relationship of sexual satisfaction and common contraceptive methods employed by the couples

BACKGROUND

Sexual relationship is a basis for mental health and continuity of the healthy generation. Enjoying the healthy body and mind will cause the sexual relationships to run their normal course in life. One of the problems that couples are faced within their sexual relationships is the issue of employing family planning methods. Studies have revealed that contraceptive methods are in connection with the sexual function and health in different ways. This study was aimed to determine the mean and the relation of scores of sexual satisfaction of men and women with the common contraceptive methods.

METHODS

This was a descriptive-correlative study. Samples included 280 individuals (140 couples) to use the common contraceptive methods including withdrawal method, tubal ligation in women, oral contraceptive method, condom, vasectomy, IUD and injection contraceptive method. Tools for gathering the data were Female Sexual Function Index (FSFI) and the questionnaire provided by Dr. Abdo on sexual satisfaction in men in 2004. The validity and reliability of these questionnaires were approved by researches conducted in worldwide and Iran. Descriptive and inferential statistic methods were applied in analyzing the data.

RESULTS

The results suggested a significant statistic relation between scores of men's sexual satisfaction and separate contraceptive methods (p = 0.001) whereas this relation was not observed between the women's scores of sexual satisfaction and the contraceptive methods.

CONCLUSIONS

According to the results of the present study, training family planning counselors in relation to choose suitable contraceptive method, in view of its probable effects on the couple's sexual satisfaction, seems essential.

A comparison of two methods of removing zinc oxide-eugenol provisional cement residue from the internal surface of cast restorations

AIM

Remnants of provisional cement on the internal surface of cast restorations can have an adverse effect on the performance of the definitive luting agent. The purpose of this study was to evaluate the effect of eugenol-containing temporary cement removal by an ultrasonic or an organic solvent on the retentive strength of metallic rings cemented to amalgam cores using zinc phosphate cement.

METHODS AND MATERIALS

A total of 36 cylindrical amalgam cores measuring 5.9 x 6 mm were made by condensing amalgam in brass molds for use in this in vitro study. Thirty-six cylindrical spaces measuring 6 x 6 mm were machined in the center of cast rods of Rexillium III alloy to create simulated retainers. The amalgam cores were divided into two groups and provisionally cemented in these cylindrical spaces (retainers) using zinc oxide-eugenol cement. After separation of the cores from the retainers, one group was cleaned with an ultrasonic cleaning device with water and the other group was cleaned with Solitine organic solvent. All specimens were then cemented with zinc phosphate cement and the samples were stored at 100% humidity in a 37 degrees C water bath after which they were tested with a DARTEK testing machine at a 0.02 cm/minute cross head speed. The data were analyzed using the Independent t-test.

RESULTS

The statistical analysis revealed a significant difference between the two groups (p<0.0005) with the ultrasonic group having significantly higher separation forces than the Solitine group.

CONCLUSION

Specimens treated with the ultrasonic cleaner showed a higher mean separation force (282.2 MPa) than the solvent group (439.5 MPa).

CLINICAL SIGNIFICANCE

Despite the convenience of using an organic solvent for cleaning the internal surface of cast restorations, the ultrasonic cleaning method is more effective for removing zinc-oxide temporary cement.

Uric acid: a risk factor for coronary atherosclerosis?

BACKGROUND AND OBJECTIVES

It is uncertain whether high serum uric acid levels are a true independent risk factor for coronary atherosclerosis or whether the association is due to other confounding variables. We therefore studied the relationship between elevated serum uric acid levels and coronary atherosclerosis after adjustment was made for confounding factors such as age, gender, body mass index, smoking, lipid profile, blood pressure and blood glucose levels.

METHODS

A cross-sectional study was conducted on 240 patients referred for coronary angiography to heart centres in the Shahid-Chamran and Sina hospitals, Isfahan, Iran. Blood chemistry data as well as traditional risk factors and uric acid levels were measured at enrollment. We used vessel, stenosis and extent scores to indicate the degree of coronary artery involvement.

RESULTS

This study was conducted on 240 patients with a mean age of 56 +/- 10.9 years (66% male; 37% female) who underwent coronary angiography. Student's t-test analyses revealed that there were significant differences in the mean uric acid levels between male and female patients (p = 0.001). We found no statistically significant correlation between serum uric acid levels and coronary atherosclerosis (p > 0.05). In addition, multivariate logistic regression analyses, using coronary atherosclerosis as dependent variable and traditional risk factors and uric acid levels as independent variables, did not show any significant difference.

CONCLUSION

These findings indicated that uric acid is not associated with coronary atherosclerosis. Any correlation reported in other studies was probably due to the relationship between high serum uric acid levels and other cardiovascular risk factors.

Smooth muscle cell proliferation but not neointimal formation is dependent on alloantibody in a murine model of intimal hyperplasia

Transplant coronary artery disease is the pre-eminent cause of late cardiac allograft failure. It is primarily characterized by a concentric intimal hyperplasia, which we designate transplant intimal hyperplasia (TIH). Although the pathogenesis of TIH is predominately immune driven, the specific role of alloantibodies in the disease process remains undefined. In this study we investigated the contribution of alloantibodies to the development of TIH in a murine model. Orthotopic, carotid artery transplantation was performed between B10A(2R) (H-2(h2)) donor mice and B-cell deficient muMT(-/-) knockout or wild-type C57BL/6 (H-2(b)) recipients in the absence of immunosuppression. Grafts were harvested at 35 days and subjected to planimetry and immunohistochemistry. Alloantibodies were detectable in wild-type recipients within 7 days of transplantation and recipients developed marked TIH at 35 days. Allografts harvested from B-cell deficient recipient mice also developed TIH, which was comparable in severity with wild-type recipients. However, whereas allografts from wild-type recipients showed marked intimal smooth muscle cell (SMC) proliferation, the neointima in B-cell deficient recipients lacked SMCs. Post-transplantation administration of anti-donor serum to muMT(-/-) recipients restored neointimal SMC population but did not influence the severity of TIH. Significant neointimal formation occurs in the absence of alloantibodies but lacks a SMC component. Therefore, SMC migration and proliferation is antibody dependent.

Role of alloantibodies in the pathogenesis of graft arteriosclerosis in cardiac transplantation

Graft arteriosclerosis (GA) remains the leading obstacle to long-term survival of cardiac allografts. The pathogenesis of this chronic disease, though perceived to be multifactorial, is most likely immune-driven. Based on clinical and experimental observations, the humoral arm of the immune system has long been suspected to play a pivotal role in the disease process. In this article, we shall review the evidence generated from key clinical and experimental studies on the role of alloantibodies in GA. We will argue that although the strong correlation between the presence of anti-donor antibodies in clinical and experimental GA is highly suggestive of a pathogenic role for alloantibodies, a direct causal link between GA and the humoral arm of the alloresponse cannot yet be established based on the currently available evidence, and may in fact be one of a number of pathogenic processes that potentiate this vasculopathy. Finally, in this article, we shall discuss some of the potential mechanisms by which alloantibodies may exert their pathogenic effect in GA.

Association of IgM with IgG ANCA in patients presenting with pulmonary hemorrhage

ANCA are markers for systemic vasculitis such as Wegener's granulomatosis (WG) and microscopic polyarteritis (MPA) and are usually of the IgG isotype. However, IgM ANCA may rarely occur in isolation, and in these circumstances, we have found that they are associated clinically with a syndrome of pulmonary hemorrhage and systemic vasculitis. How frequently IgM ANCA may occur in conjunction with IgG has not previously been investigated. We report here a study of 24 consecutive patients with IgG ANCA-positive systemic vasculitis (14 WG, 10 MPA) in whom we determined whether IgM ANCA occurred in association with IgG ANCA, and if so, whether this had clinical importance. Eight patients were found to have IgM ANCA as well as IgG ANCA, and of these, seven presented with severe pulmonary hemorrhage. None of the IgM ANCA-negative patients presented with pulmonary hemorrhage. Although the occurrence of pulmonary hemorrhage in ANCA positive vasculitis was closely correlated with the presence of IgM ANCA, the antigen specificity of these IgM autoantibodies was variable, since both myeloperoxidase (4 patients), PR3 (3 patients), and an unknown ANCA antigen (1 patient) were found to be targets. We conclude that knowledge of ANCA isotype may have important clinical and therapeutic implications for the management of patients with systemic vasculitis.