Long-Term Therapy with Corticosteroids in Nasal Polyposis: A Bone Metabolism Assessment.

Chronic rhinosinusitis associated with nasal polyposis (RSCwNP) affects 4% of the general population. As chronic condition, it requires chronic pharmacological treatment, whereas the surgical approach becomes necessary in obstructive and/or complicated cases. Intranasal and systemic corticosteroids (CS) represent the "Gold Standard" treatment for RSCwNP. The present study aimed to evaluate the side effects of prednisone in a group of patients with RSCwNP treated with long-term CS. In particular, attention was focused on bone disorders (osteopenia and osteoporosis) and prospective fracture risk increase. Forty patients (26 females, mean age 55.70 ± 14.03 years) affected by RSCwNP have been enrolled. Control group included 40 healthy subjects (17 females, mean age 56.37 ± 13.03 years). Nasal endoscopy, skin prick tests, nasal cytology, and bone densitometry were evaluated in all subjects. The likelihood of impaired bone metabolism (osteopenia or osteoporosis) was superimposable in both groups. Within RSCwNP group, no parameter was statistically significant in predicting a metabolism alteration.

Idiopathic sudden sensorineural hearing loss and ménière syndrome: The role of cerebral venous drainage.

OBJECTIVES: To evaluate the influence of cerebral venous drainage on the pathogenesis of idiopathic sudden sensorineural hearing loss (ISSHL) and Ménière syndrome (MD). DESIGN: Observational, prospective, cohort study. SETTING: ENT and Cardiology Departments (University of Bari, Policlinico Hospital, Bari, Italy). PARTICIPANTS: We enrolled 59 consecutive patients (32 males, mean age 53.05 + 15.37 years): 40 ISSHL and 19 MD. MAIN OUTCOME MEASURE: All patients underwent physical examination, biochemical evaluation (glycemic and lipid profile, viral serology, C reactive protein, etc), audiometric (tonal, vocal, vestibular evoked myogenic potentials and auditory brainstem response test) and impedentiometric examination. The pure tone average (PTA) was calculated for the following frequencies: 250, 500, 1000, 2000, 3000, 4000, 8000. An echo-color Doppler evaluation of the venous cerebral veins, internal jugular (IJV) and vertebral veins (VV) at supine and 90° position was performed. RESULTS: No morphological alterations were found both in patients and controls. There were no signs of stenosis, blocked flow, membranes, etc. We found lower minimum, mean and maximum velocities in distal IJVs (P = .019; P = .013; P = .022; respectively) and left VVs (P = .027; P = .008; P = .001; respectively) in supine (0°) position in both MD and ISSHL patients as compared to controls. The same was for orthostatic position (90°). We found negative correlations between the velocities in extracranial veins and PTA values: therefore, the worst the audiometric performance of the subjects, the lower the velocities in the venous cerebral drainage. CONCLUSIONS: Idiopathic sudden sensorineural hearing loss and Ménière syndrome patients showed altered venous flow in IJVs and VVs as compared to controls, independently from posture. This different behavior of venous tone control can influence the ear performance and may have a role in the pathogenesis of both diseases.

Maternal depression and anxiety predicts the pattern of offspring symptoms during their transition to adulthood.

BACKGROUND: Episodes of depression and anxiety (D&A) during the transition from late adolescence to adulthood, particularly when persistent, are predictive of long-term disorders and associated public health burden. Understanding risk factors at this time is important to guide intervention. The current objective was to investigate the associations between maternal symptoms of D&A with offspring symptoms during their transition to adulthood. METHOD: Data from a large population-based birth cohort study, in South Brazil, were used. Prospective associations between maternal D&A and offspring risk of these symptoms during the transition to adulthood (18/19, 24 and 30 years) were estimated. RESULTS: Maternal D&A in adolescence was associated with offspring symptoms across the transition to adulthood, associations were consistently stronger for females than for males. Daughters whose mothers reported D&A were 4.6 times (95% confidence interval 2.71-7.84) as likely to report D&A at all three time-points, than daughters of symptom-free mothers. CONCLUSIONS: Maternal D&A is associated with persistent D&A during the daughter's transition to adulthood. Intervention strategies should consider the mother's mental health.

Bilateral diaphragmatic paralysis after kidney surgery.

A 57-year-old woman underwent an enucleoresection of her right kidney angiomyolipoma. Two weeks later she was admitted to our hospital because of dyspnea at rest with orthopnea. The chest x-ray showed the elevation of both hemidiaphragms and the measurement of the sniff transdiaphragmatic pressure confirmed the diagnosis of bilateral diaphragmatic paralysis. A diaphragm paralysis can be ascribed to several causes, i.e. trauma, compressive events, inflammations, neuropathies, or it can be idiopathic. In this case, it was very likely that the patient suffered from post-surgery neuralgic amyotrophy. To our knowledge, there are only a few reported cases of neuralgic amyotrophy, also known as Parsonage-Turner Syndrome, which affects only the phrenic nerve as a consequence of a surgery in an anatomically distant site.

Lipid analysis in Haematococcuspluvialis to assess its potential use as a biodiesel feedstock.

The lipid content and composition of Haematococcuspluvialis exposed to stress conditions were analyzed to assess the potential of this microalga as a biodiesel feedstock. The total lipid content of control cells was 15.61% dw, whereas that of cells exposed to continuous high light intensity with nitrogen-sufficient medium (A-stress condition) or under continuous high light intensity with nitrogen-deprivation medium (B-stress condition) was 34.85% dw and 32.99% dw, respectively. The fatty acid profile was similar under all conditions and indicated that the main components were palmitic, stearic, oleic, linoleic, linolenic and linolelaidic acids. The neutral lipid fraction increased about 2-fold under both stress conditions. The percentage of saturated fatty acids in the neutral lipid fraction was 30.36% and 29.62% in cultures grown under A-stress and B-stress, respectively, and 27.81% under control conditions. The monounsaturated fatty acid content was not significantly different in control and A-stress cultures (20.07% and 19.91%, respectively), but was 18.96% under B-stress. The content of polyunsaturated fatty acids was 47.23% under B-stress and 43.15% under A-stress. Growth-rate was higher under A-stress compared to B-stress. This is the first study of H.pluvialis that provides a detailed characterization of its lipid content in relation to bioenergy. The results indicate the potential of this microalga as a biodiesel feedstock; however, culture conditions still have to be improved in order to achieve an adequate energy balance in mass culture.

Mobile phones, in combination with a computer locator system, improve the response times of emergency medical services in central London.

INTRODUCTION: The aim of this study was to determine whether mobile phones and mobile phone locating devices are associated with improved ambulance response times in central London. PATIENTS AND METHODS: All calls from the London Ambulance Service database since 1999 were analysed. In addition, 100 consecutive patients completed a questionnaire on mobile phone use whilst attending the St Thomas's Hospital Emergency Department in central London. RESULTS: Mobile phone use for emergencies in central London has increased from 4007 (5% of total) calls in January 1999 to 21,585 (29%) in August 2004. Ambulance response times for mobile phone calls were reduced after the introduction of the mobile phone locating system (mean 469 s versus 444 s; P = 0.0195). The proportion of mobile phone calls made from mobile phones for life-threatening emergencies was higher after injury than for medical emergencies (41% versus 16%, P = 0.0063). Of patients transported to the accident and emergency department by ambulance, 44% contacted the ambulance service by mobile phone. Three-quarters of calls made from outside the home or work-place were by mobile phone and 72% of patients indicated that it would have taken longer to contact the emergency services if they had not used a mobile. CONCLUSIONS: Since the introduction of the mobile phone locating system, there has been an improvement in ambulance response times. Mobile locating systems in urban areas across the UK may lead to faster response times and, potentially, improved patient outcomes.

Infección por Helicobacter pylori: Asociación a Patologías gástricas y Métodos de diagnóstico / Infection by Helicobacter pylori: Association to `gastric` Pathologies and Methods of diagnosis

La infección por helicobacter pylori está distribuida a nivel mundial, la prevalencia es del 50%. Esta infección está asociada a enfermedades como las gastritis, úlceras, cancer gástrico y linfoma de MALT. El objetivo es describir la relación existente entre enfermedad e infección por helicobacter pylori.

Actividad anti-helicobacter pylori de Plantago major, Clinopodium bolivianum, Caléndula officinalis y Piper angustifolium por el método de difusión de disco / Activity anti-Helicobacter pylori of Plantago major, Clinopodium bolivianum, Calendula officinalis and Piper angustifolium by the method of dissemination of disk

Helicobacter pylori es una bacteria asociada a patologías gástricas como gastritis, ulceras, cancer y linfoma de MALT. De acuerdo a estudios realizados en la ciudad de La Paz-Bolivia aproximadamente el 50% de la población esta infectada por esta bacteria.

Effects of adding a preceding run-up on performance, blood lactate concentration and heart rate during maximal intermittent vertical jumping.

In this study, we examined the effects of a prior run-up on intermittent maximal vertical jump performance. Seven regionally ranked male volleyball players volunteered to participate in the study. They performed three randomized tests: (1) six repeated intermittent maximal jumps (jump condition), (2) six repeated intermittent run-ups (run-up condition), and (3) six repeated run-ups followed by maximal jumps (run-up plus jump condition). All performances were assessed and blood lactate concentration and heart rate were measured before and after each of the tests. Mean ( +/- ) jump performance (64.7 +/- 2.3 cm) increased significantly (P = 0.02) over the course of the jump condition and was significantly higher (P < 0.001) than for the run-up plus jump condition (58.0 +/- 3.2 cm), which tended to decrease with repetition. Blood lactate concentration was significantly higher in the run-up plus jump condition (3.73 +/- 0.24 mmol . l(-1)) than in the jump (2.61 +/- 0.26 mmol . l(-1), P = 0.02) and run-up (2.86 +/- 0.18 mmol . l(-1), P = 0.03) conditions. The increase in heart rate was significantly higher both in the run-up plus jump condition (33 +/- 6 beats . min(-1), P = 0.05) and run-up condition (33 +/- 4 beats . min(-1), P = 0.02) than in the jump condition (21 +/- 3 beats . min(-1)). The results indicate that the addition of run-ups probably impeded performance in the repetition of vertical jumps.

Time-of-day effects in maximal anaerobic leg exercise in tropical environment: a first approach.

The aim of this study was to establish the effect of time of day on maximal anaerobic leg power in a tropical environment (French West Indies). Twenty-three physical education students (15 males and 8 females) who trained 10.5 hours a week (SD 6) volunteered to participate in the study. Their mean age, height and body mass were 22.8 (SD 3) years, 172.6 (SD 8) cm, and 64.6 (SD 7) kg, respectively. The chronotype of all subjects was moderate or intermediate. Tests were scheduled at 08 : 00, 13 : 00 and 17 : 00 hours on separate days in random order and constant conditions (room temperature: 28.1 degrees C [SD 0.6], relative room humidity: 62.6 % [SD 3.4]). On test days, the subjects were first measured at rest for body mass, heart rate and rectal temperature and they then performed vertical jump tests and a force-velocity test. The results showed a time-of-day effect on rectal temperature, which was significantly (p < 0.005) higher by the afternoon (13 : 00 and 17 : 00) than the morning (08 : 00). However, our results failed to show any daytime variation in maximal anaerobic power under the influence of tropical climate, which suggests that a hot and humid environment may have blunted the time-of-day effect by a passive warm-up effect.

Does the use of the Advanced Medical Priority Dispatch System affect cardiac arrest detection?

BACKGROUND: Cardiac arrest is the most widely recognised prehospital event that early intervention can directly affect. Chance of survival from this event decreases every minute that passes without treatment. To deliver a rapid ambulance response to these patients the early detection of cardiac arrest by control room staff is crucial. To achieve this, the London Ambulance Service (LAS) uses the Advanced Medical Priority Dispatch System. What impact has AMPDS had on identifying patients in cardiac arrest? Does compliance with AMPDS protocol influence the identification of patients in cardiac arrest? METHODS: A two stage study was undertaken. The first, compared cases coded as "cardiac arrest" and found by the responding ambulance to be in cardiac arrest before the implementation of AMPDS. This was compared with cases triaged as "cardiac arrest" and found to be in cardiac arrest across three years after AMPDS implementation. The second stage compared AMPDS compliance, over a 32 month period against the percentage of cardiac arrest calls that were found to be cardiac arrest upon the ambulance arrival. The correlation coefficient was calculated and analysed for statistical significance. FINDINGS: AMPDS resulted in a 200% rise in the number of patients accurately identified as suffering from cardiac arrest. A relation was identified between identification and AMPDS compliance (r(2) = 0.65, p = 0.001). DISCUSSION: The implementation of AMPDS increased accurate identification of patients in cardiac arrest. Additionally, the relation between factors identified suggests compliance with protocol is an important factor in the accurate recognition of patient conditions.

Involvement of heterotrimeric G proteins in phagocytosis and recycling from the phagosomal compartment.

Phagocytosis is a receptor-mediated process by which specialized cell types engulf large extracellular particles. Phagosome maturation involves a series of intracellular membrane fusion and budding events resulting in the delivery of particles to compartments enriched in lysosomal hydrolases where they are digested. Substantial amounts of plasma membrane and many phagosomal proteins, such as receptors, rapidly recycle to the plasma membrane following phagosome formation. Despite the importance of this recycling pathway in phagosome maturation and in the retrieval of immunogenic peptides from phagosomes, the molecular machinery involved is largely unknown. To assess the participation of GTPases in phagocytosis and recycling from phagosomes we used aluminum fluoride (AIF(-)(4)), which activates the GDP-bound form of stimulatory and inhibitory trimeric G proteins. AlF(-)(4) inhibited both the uptake to and the recycling from the phagosomal compartment. Cholera toxin, which activates Galphas, and pertussis toxin, which uncouples Gi and Go from receptors, were effective inhibitors of phagocytosis. However, both toxins stimulated recycling from phagosomes. These results suggest that more than one GTP-binding protein participates either directly or indirectly not only in phagocytosis, but also in maturation and recycling from phagosomes, and thereby assign a role for heterotrimeric G proteins in controlling traffic through the phagocytic pathway.

Cardiovascular kinin-generating capability in hypertensive fructose-fed rats.

OBJECTIVE: The hypertensive state is often associated with metabolic abnormalities, including glucose intolerance. Tissue kallikrein, a potent kinin-generating enzyme, is present in the vascular wall and heart tissue. High dietary fructose consumption is reported to induce hyperinsulinemia, hypertriglyceridemia and hypertension. The objective of the present study was to examine the status of kallikrein in vascular and cardiac tissue from highly fructose-fed rats and to delineate the effect of kinins and the angiotensin converting enzyme inhibitor ramipril in this animal model of glucose intolerance. DESIGN AND METHODS: Male Wistar rats (350 g body weight) were divided into four groups of 10 rats each: (1) controls; (2) oral ramipril at 500 microg/kg per day for the last 2 study weeks; (3) fructose in drinking water as a 10% (w/v) solution for 4 weeks; and (4) fructose + ramipril, with fructose administered as in group 3 plus the administration of ramipril for the last 2 study weeks. Systolic blood pressure (tail-cuff method), glucose tolerance (2 g/kg body weight intraperitoneally) and metabolic parameters were recorded. Kallikrein activity in tail artery and heart tissue homogenates was estimated at the end of the 4th study week from measurements of kininogenase activity and kinins generated by a radioimmunoassay. RESULTS: The area under the curve for the glucose tolerance test increased from 1265 +/- 103 mmol/l after 120 min in the control and 1152 +/- 36 mmol/l in the ramipril group (NS) to 2628 +/- 143 mmol/l in the fructose group (P<0.01). The administration of ramipril to fructose-treated rats in group 4 improved glucose tolerance (2160 +/- 100 mmol/l; P<0.05 versus group 3). Blood pressure increased significantly in fructose-fed rats but fell markedly in fructose-fed rats treated with ramipril (P<0.01). Kallikrein activity measured in the heart and vessels increased as a consequence of fructose administration (P<0.05), but the administration of ramipril increased this parameter to a much greater extent (P<0.01 versus control group), which correlated closely with the decrease in blood pressure and the improvement in glucose tolerance observed in the fructose + ramipril group. CONCLUSIONS: The administration of fructose as a solution in the drinking water induced glucose intolerance and increased blood pressure. Treatment with the angiotensin converting enzyme inhibitor ramipril improved glucose tolerance and significantly diminished blood pressure. Cardiovascular kinin-generating capability increased in treated animals and this increase was even higher when rats were treated with ramipril, suggesting that kinins, acting as a paracrine hormonal system, can exert cardiovascular protection and contribute to the beneficial effects of angiotensin converting enzyme inhibitor.

Physicians' prescribing behaviour for diarrhoea in children: an ethnoepidemiological study in Southern Brazil.

With the aim of implementing an intervention program on physician's prescribing behaviour for diarrhoea in children under five, an ethnoepidemiological study was conducted in Pelotas (Brazil), from February to April 1993. Information on prescription of drugs was obtained through record review of 381 cases of diarrhoea provided by 33 medical doctors from eight health centres. Trained field workers observed a total of 54 clinical consultations due to diarrhoea. Brief exit interviews with the mothers were performed just after the observations. Twenty-seven open-ended home interviews were made with the mothers the day after they had been observed. After all observations had been completed, open-ended interviews were conducted with 21 physicians. The results showed that there is a misunderstanding of the role of ORS in the treatment of diarrhoea: mothers want something to "cut" diarrhoea and they notice that ORS does not act in this way and doctors do not explain the action of ORS in diarrhoea management. Comparing with record reviews, during observations a child had a lower probability of receiving an antibiotic or antidiarrheal drug prescription. This finding indicates that other variables than technical skills are involved in doctor's prescribing behaviour. A lack of ability or of motivation to deal with "anxious or difficult mothers" led some doctors to enhance antibiotic or other non-recommended drugs to manage diarrhoea. Therefore, efforts to improve the quality of case management of diarrhoea, through intervention programmes in the government health sector, are needed in Pelotas.

Enoxaparin plus compression stockings compared with compression stockings alone in the prevention of venous thromboembolism after elective neurosurgery.

BACKGROUND: Compression stockings are recommended for prophylaxis against venous thromboembolism in patients undergoing neurosurgery, but anticoagulant agents have not gained wide acceptance because of concern about intracranial bleeding. METHODS: In a multicenter, randomized, double-blind trial, we assessed the efficacy and safety of enoxaparin in conjunction with the use of compression stockings in the prevention of venous thromboembolism in patients undergoing elective neurosurgery. Enoxaparin (40 mg once daily) or placebo was given subcutaneously for not less than seven days beginning within 24 hours after the completion of surgery. The primary end point was symptomatic, objectively confirmed venous thromboembolism or deep-vein thrombosis assessed by bilateral venography, which was performed in all patients on day 8+/-1. Bleeding side effects were carefully assessed. RESULTS: Among the 307 patients assigned to treatment groups, 129 of the 154 patients receiving placebo (84 percent) and 130 of the 153 patients receiving enoxaparin (85 percent) had venographic studies adequate for analysis. An additional patient in the placebo group died before venography of autopsy-confirmed pulmonary embolism. In this analysis, 42 patients given placebo (32 percent) and 22 patients given enoxaparin (17 percent) had deep-vein thrombosis (relative risk in the enoxaparin group, 0.52; 95 percent confidence interval, 0.33 to 0.82; P=0.004). The rates of proximal deep-vein thrombosis were 13 percent in patients receiving placebo and 5 percent in patients receiving enoxaparin (relative risk in the enoxaparin group, 0.41; 95 percent confidence interval, 0.17 to 0.95; P=0.04). Two patients in the placebo group died of autopsy-confirmed pulmonary embolism on days 9 and 16. Major bleeding occurred in four patients receiving placebo (intracranial bleeding in all four) and four patients (intracranial bleeding in three) receiving enoxaparin (3 percent of each group). CONCLUSIONS: Enoxaparin combined with compression stockings is more effective than compression stockings alone for the prevention of venous thromboembolism after elective neurosurgery and does not cause excessive bleeding.

Method for cotemporal and coplanar comparison of magnetic resonance imaging and neuropathology of formalin-fixed human brains.

We describe the design and production of a mitre box that allows magnetic resonance imaging and pathological sectioning of a formalin-fixed brain so that the pathological and radiological slices are coplanar and therefore readily comparable.

Possible protective effects of kinins and converting enzyme inhibitors in cardiovascular tissues.

The main objective of this study was to determine if the components of the kallikrein-kinin system are released into the venous effluent from isolated perfused rat hearts. To assess the contribution of kinins and the vascular and cardioprotective effects of the ACE inhibitor ramipril, we determined the status of cardiac kallikrein (CKK), potent kinin-generating enzyme, in rats with right ventricular hypertrophy induced by chronic volume overload and left ventricular hypertrophy by aortic banding. CKK was measured as previously described (Nolly, H.L., Carbini, L., Carretero, O.A., Scicli, A.G., 1994). Kininogen by a modification of the technique of Dinitz and Carvalho (1963) and kinins were extracted with a Sep-Pak C18 cartridge and measured by RIA. CKK (169 +/- 9 pg Bk/30 min), kininogen (670 +/- 45 pg Bk/30 min) and immunoreactive kinins (62 +/- 10 pg Bk/30 min) were released into the perfusate. The release was almost constant over a 120 min period. Pretreatment with the protein synthesis inhibitor puromycin (10 mg i.p.) lowered the release of kallikrein (42 +/- 12 pg Bk/30 min, p < 0.001) and kininogen (128 +/- 56 pg Bk/30 min, p < 0.001). Addition of ramiprilat (10 micrograms/ml) increased kinin release from 54 +/- 18 to 204 +/- 76 pg Bk/30 min (p < 0.001). Aortic banding of rats increased their blood pressure (BP) (p < 0.001), relative heart weight (RHW) (p < 0.001) and CKK (p < 0.001). Ramipril treatment induced a reduction in BP (p < 0.05) and RHW (p < 0.005) while CKK remained elevated. Aortocaval shunts increased their ANF plasma levels (p < 0.05), RHW (p < 0.001) and CKK (p < 0.01). Ramipril treatment induced a reduction in RHW (p < 0.05), while CKK and ANF increased significantly (p < 0.05). The present data show that the components of the kallikrein-kinin system are continuously formed in the isolated rat heart and that ramipril reduces bradykinin breakdown with subsequent increase in bradykinin outflow. The experiments with aorta caval shunt and aortic banding show that cardiac tissues increase their kinin-generating activity and this was even higher in ramipril-treated animals. This may suggest that the actual level of kinins is finely tuned to the local metabolic demands. In this experimental model of cardiac hypertrophy. ACE inhibitors potentiate the actions of kinins and probably try to normalise endothelial cell function.

[Tuberculosis and immigrants. A study of its prevalence in the Umbria region]. / Tubercolosi ed immigrati. Uno studio di prevalenza nella Regione Umbria.

In 1995, 463 patients were admitted in the medical service of Perugia (Sanitary District n. 6). Only 20% of them were enrolled in the TBC programme. Mantoux was: < 10 mm in 35%, 10-15 mm in 25%, > 15 mm in 40%. Chest Rx in 30 subjects demonstrated: normality in 19; old TBC in 7, active TBC in 4 (miliary, bilateral upper lobe pneumonitis, left subapical upper lobe pneumonitis and right lobitis of the upper lobe). All patients were admitted in hospital and showed positive sputum culture for Mycobacterium Tuberculosis. They were treated with isoniazid, rifampin, pyrazinamide, ethambutol/streptomycin for 2 months and with isoniazid, rifampin for other 4-8 months. Two patients showed Mycobacterium tuberculosis with isoniazid resistance. Seven patients were treated with isoniazid chemoprophylaxis without side effects. Migrants should receive information about health care service and be encourage to register themselves with a general practitioner. Skin test screening and chest radiographs for those with positive results should be provided at a convenient location.

Transportation of curved canals prepared with canal master U, canal master U niti, and stainless steel K-type files.

The purpose of this study was to evaluate and to compare root canal configuration after preparation with three different hand instruments and techniques: the canal master U preparation technique (Brasseler, Savannah, GA.), using stainless steel or nickel-titanium canal master U instruments, and the step-back technique using precurved conventional stainless steel K-type files. Sixty-three simulated curved canals were divided in three groups of 21 each. Each group was prepared using one of the three instruments. Comparison of root canal configuration was evaluated with pre- and postoperative photographs that measured the difference in canal diameter and the mesial and distal transportation of the canal walls at the canal length and at levels 1, 2, 3, 4, 5, 6, 7, and 8 mm coronal to the canal length. Data obtained were analyzed statistically using an analysis of variance. Instrument breakage was also recorded. Results showed that the final diameter of the prepared canals as well as canal transportation were significantly different between both canal master U instruments and the stainless steel K file. Three stainless steel canal master U instruments separated during instrumentation whereas none in the nickel-titanium canal master U and stainless steel K-type file groups separated. The results of this study show that the canal master U instruments and technique provide a better canal configuration than K files using the step-back technique and that the nickel-titanium canal master U and stainless steel K-type file offers a greater safety factor against breakage than the stainless steel canal master U.