Long-term outcomes after pancreatoduodenectomy for ampullary cancer: The influence of the histological subtypes and comparison with the other periampullary neoplasms

BACKGROUND

Ampullary carcinoma (AC) is histologically classified as intestinal (In-AC), pancreaticobiliary (Pb-AC) or mixed-AC. The prognostic role of AC subtypes has been debated and remains unclear. The aims of this study were to evaluate outcomes after pancreatoduodenectomy (PD) for each subtype of AC and to compare these with pancreatic ductal adenocarcinoma [PDAC] and distal cholangiocarcinoma [DCC].

METHODS

PDs performed for AC between 2010 and 2018 were retrospectively evaluated. Histological subtype was obtained for all patients. One-year, 3-year and 5-year disease-free-survival (DFS) and overall survival (OS) rates were calculated. Kaplan-Meier survival analysis was performed to compare Pb-AC, In-AC and mixed-AC. Comparison with PDs performed for PDAC and DCC during the same period was also performed.

RESULTS

A total of 97 patients undergoing PD for AC were evaluated: 34 (35.1%) In-AC, 54 (55.7%) Pb-AC and 9 mixed-AC (9.3%). DFS and OS rates for Pb-AC were significantly lower compared to In-AC (p < 0.05 and p < 0.01), but similar to mixed-AC (p = 0.3 and p = 0.4). Adjuvant therapy was not associated with increased survival, regardless of the histological subtype (p > 0.05). During the same period, 337 and 53 PDs for PDAC and DCC, respectively, were performed. In-AC was associated with significantly better outcomes compared to PDAC and DCC (p < 0.001); DFS and OS rates for Pb-AC and mixed AC were significantly higher compared to PDAC (p < 0.001), but similar to DCC (p > 0.05).

CONCLUSIONS

Pb-AC has significantly worse survival compared to In-AC. Moreover, mixed-AC should be considered as Pb-AC. Pb-AC and mixed-AC seem to have better prognosis compared to PDAC, but similar to DCC.

Presence of gas in the refluxate enhances reflux perception in non-erosive patients with physiological acid exposure of the oesophagus

OBJECTIVE

The mechanisms underlying symptoms in gastro-oesophageal reflux disease, particularly in non-erosive reflux disease (NERD), remain to be fully elucidated. Weakly acidic reflux and the presence of gas in the refluxate could be relevant in the pathogenesis of symptoms.

METHODS

To assess the relationship between symptoms and weakly acidic, acid and mixed (liquid-gas) reflux, 24 h oesophageal pH-impedance monitoring was performed in 32 NERD and in 20 oesophagitis patients. In 12 NERD patients the study was repeated following 4 weeks treatment with a proton pump inhibitor (PPI). Impedance-pH data were compared with those of 10 asymptomatic controls. Heartburn and acid regurgitation were considered in the analysis of symptoms.

RESULTS

15 NERD patients showed a physiological acid exposure time (pH-negative). Weakly acidic reflux was significantly less frequent in patients (25% (2%), mean (SE)) than in controls (54% (4%), p<0.01). Gas was present in 45-55% of reflux events in patient groups and controls, and decreased following PPI treatment. In NERD pH-negative patients, weakly acidic reflux accounted for 32% (10%) (vs 22% (6%) in NERD pH-positive and 12% (8%) in oesophagitis patients) and mixed reflux for more than two-thirds of all symptom-related refluxes. Multivariate logistic analysis showed that in NERD pH-negative patients, the risk of reflux perception was significantly higher when gas was present in the refluxate (odds ratio, 3.2; 95% CI, 1.2 to 10; p<0.01).

CONCLUSIONS

The large majority of symptoms, in all patients, are related to acid reflux. In NERD patients, the presence of gas in the refluxate significantly enhances the probability of reflux perception. These patients are also more sensitive to less acidic reflux than oesophagitis patients.

Systematic review and meta-analysis of randomised clinical trials on topical treatments for vernal keratoconjunctivitis

AIMS

The aim of this study was to assess the efficacy of currently available topical drugs for vernal keratoconjunctivitis (VKC) through a meta-analysis of randomised clinical trials (RCTs).

METHODS

Twenty-seven RCTs (n = 2184 eyes) that had evaluated the efficacy of topical drugs for the treatment of VKC were selected according to the set criteria; 10 of these trials were suitable for statistical analysis and were enrolled in the meta-analysis. Articles published up to December 2005 were identified from the following

DATA SOURCES

Medline, Embase, Lilacs, the Cochrane Controlled Trials Register, and references from relevant articles. Articles in any language published with an English abstract, were screened, and those selected for inclusion were written in English, French, German, Italian, Portuguese or Spanish. The quality of the trials was assessed by the Delphi list. Statistical analysis was performed using STATA software.

RESULTS

A significant improvement in all signs and symptoms, except photophobia, was observed after topical treatment for active VKC, independent of the type of treatment. Comparison of the efficacy of different drugs was not possible due to a lack of standardised criteria among studies.

CONCLUSION

The currently available topical drugs are effective in treating acute phases of VKC. However, there is a lack of evidence to support the recommendation of one specific type of medication for treating this disorder. There is a need for standard criteria to assess diagnosis and therapy based on severity. There is also a need for RCTs assessing long-term effects of single drugs to control the disease and to prevent complications.

Dilated intercellular spaces and acid reflux at the distal and proximal oesophagus in patients with non-erosive gastro-oesophageal reflux disease

BACKGROUND

Acid exposure of proximal oesophagus and dilated intercellular space diameters of oesophageal epithelium are relevant in the perception of gastro-oesophageal reflux.

AIM

To explain the relationship between gastro-oesophageal reflux disease symptoms, acid exposure and intercellular space diameter along the oesophageal epithelium and to assess time-related variability of intercellular space diameter.

METHODS

Thirty-three non-erosive reflux disease (NERD), six erosive oesophagitis patients and 12 asymptomatic controls underwent oesophageal manometry and 24-h dual-channel oesophageal pH-monitoring following endoscopy. Biopsies were taken 5 cm above the LES and 10 cm below the UES, at comparable levels, as pH sensors. A total of 100 intercellular space diameters per patient/control were measured blindly at transmission electron microscopy. In 15 patients, the investigation was repeated after 1 year.

RESULTS

In all NERD patients, acid exposure was higher at mid-proximal oesophagus (P < 0.01) and mean intercellular space diameters, at distal and mid-proximal oesophagus, was three- and twofold higher (1.5 and 0.82 micro m, respectively) compared with controls. Intra-patient intercellular space diameter values were stable over time, not overlapping with those of controls.

CONCLUSIONS

Dilation of intercellular space diameter occurs along the distal and proximal oesophageal epithelium in NERD patients and could be responsible for the enhanced perception of proximal acid reflux. This finding appears to be time-reproducible and to represent a sensitive, histopathological marker of NERD.

Effect of hiatal hernia on proximal oesophageal acid clearance in gastro-oesophageal reflux disease patients

BACKGROUND

Proximal acid reflux is common in gastro-oesophageal reflux disease and is a determinant of symptoms. Patients with hiatal hernia complain of more symptoms than those without and are less responsive to proton-pump inhibitors.

AIM

To evaluate the role of hiatal hernia on spatiotemporal characteristics of acid reflux.

METHODS

Thirty seven consecutive gastro-oesophageal reflux disease patients underwent endoscopy, videofluoroscopy, manometry and multichannel 24-h pH test. Data were compared with those of 15 asymptomatic controls. Multivariate linear regression was used for statistical analysis.

RESULTS

At videofluoroscopy, hiatal hernia was found in 16 of 37 patients. The mean size of hiatal hernia was 3.4 cm. Patients showed significantly prolonged acid clearance time, both at proximal and distal oesophagus, compared with controls. Hiatal hernia patients showed a significantly delayed acid clearance, along the oesophageal body, compared with non-hiatal hernia patients. The prolonged acid exposure was maintained during upright and supine position. The presence of hiatal hernia significantly predicted acid clearance delay in the distal and proximal oesophagus [at 10 cm below upper oesophageal sphincter: Delta + 2.5 min (95% confidence interval: 0.4-4.5); P < 0.02].

CONCLUSIONS

The presence of hiatal hernia is a strong predictor of more prolonged proximal oesophageal acid exposure and clearance. Hiatal hernia is likely to play a role in the pathophysiology of gastro-oesophageal reflux disease symptoms, and should be taken into greater consideration in the treatment strategies of the disease.

[A serious complication in colorectal surgery: anastomotic leakage. Our experience]

Anastomotic leakage is a severe complication in colorectal surgery with a lot of generic and specific risk factors. There are still controversies about the possibility to prevent it or to limit its severity with the use of faecal diversions. We report our experience on 189 patients operated in five years on colon-rectum, in election and emergency, with manual or mechanical anastomoses in the last 20 cm from the anal verge. We have had 21 anastomotic leakages (11%), symptomatic in 10 cases (5.5%), and 5 deaths (2.6%), 3 directly correlated to the leakage. In the patients (n 98) with loop-ileostomy there wasn't anastomotic leakages reduction, but only of clinical impact. We prefer loop-ileostomy in cases of extraperitoneal anastomoses, always in emergency and in anastomoses at risk.

Nasal surgery and eustachian tube function: effects on middle ear ventilation

OBJECTIVES

To investigate the effect of nasal obstruction surgery on eustachian tube function and middle ear ventilation.

DESIGN

Prospective study.

SETTING

University Campus Bio-Medico of Rome.

PARTICIPANTS

Forty consecutive patients who underwent nasal surgery were evaluated for middle ear ventilation and tubal function.

MAIN OUTCOME MEASURES

Pre- and postoperative Valsalva and Toynbee tubal function tests, tympanometry and ear fullness sensation were evaluated for both ears of each patient.

RESULTS

Results of postoperative tubal function tests were significantly better than preoperative ones (90% versus 46%; P<0.001). No significant difference in tympanometric values was found. The majority (95%) of the patients reported a postoperative improvement of ear fullness sensation compared with preoperative (25%; P<0.001).

CONCLUSIONS

Surgery for chronic nasal obstruction significantly improves clinical tubal function but 1-month postoperative tympanometric findings remain almost the same.

Infliximab reverses growth hormone resistance associated with inflammatory bowel disease

BACKGROUND

Increasing evidence shows that inflammation plays a major role in the aetiology of catabolism and wasting observed in inflammatory bowel disease via growth hormone resistance.

AIM

To evaluate the effect of infliximab treatment on the growth hormone/insulin-like growth factor-1 axis.

METHODS

Fourteen adults with active Crohn's disease or ulcerative colitis underwent three infliximab infusions at a dose of 5 mg/kg for induction of remission, plus two maintenance infusions 8 weeks apart. Blood samples were collected for the analysis of serum growth hormone, insulin-like growth factor-1, insulin-like growth factor-binding protein-3 and acid labile subunit.

RESULTS

Serum insulin-like growth factor-1 and insulin-like growth factor-binding protein-3 concentrations, which were significantly lower in inflammatory bowel disease patients before treatment compared with controls (P < 0.01), significantly increased during the induction phase (+58% and +29%, respectively, after the second infusion, P < 0.01), and dropped to baseline levels during maintenance therapy. Both insulin-like growth factor-1 and insulin-like growth factor-binding protein-3 showed significant negative correlations with C-reactive protein (rho = -0.37, P = 0.002; rho = -0.35, P = 0.01, respectively). Growth hormone and acid labile subunit levels were not statistically different between controls and inflammatory bowel disease patients either at baseline or during treatment.

CONCLUSIONS

Infliximab induction treatment reverses growth hormone resistance observed in active inflammatory bowel disease through the suppression of systemic inflammation. The restored growth hormone/insulin-like growth factor-1 axis is impaired again following the prolonged interval between maintenance infusions, possibly because of the subclinical reactivation of the inflammatory process.

[Endocrine obesity: bioelectric profiles (biotypes) detected in the body composition]

136 patients were selected (16 men and 120 women with non-specific menstrual disturbances) with a BMI (Body Mass Index) between 25 and 45 kg/m2, which were diagnosed with "disendocrinia" (GH deficit, hyperadrenocorticism, hypothyroidsm, hyperandrogenism, menstrual cycle disorders). The proposed approach, based on the visualization of the value distribution of the electric measures in different graphics, is able to immediately explain the bioelectric state of the individual's lean-mass. Subjects with hypothyroidism present, along with their overweight, less bio-conducting mass, with an altered fluid intra/extra-cellular distribution. Patients with hyperadrenocorticism show instead an hyperhydratation of the body mass, especially in the extracellular level. Patients with menstrual disorders (amenorrea, polycystic ovary syndrome, anovulatory cycle etc...) present a lean mass reduction (elevated Rs) and an increase of the intra-cellular compartment (elevated-Xc). Patients with hyper-androgenism (and hirsutism) show a characteristic bioelectric "pattern", with low Rs levels and high Xc levels. Subjects with GH deficit (men and women), has a trend of documenting bioelectric measures with lower lean mass and higher fat-mass. Different electric biotypes seem to characterize the body composition in the several endocrine disorders.

[The reciprocal evaluation in the Learning Organization]

INTRODUCTION

The culture of the appraisal was introduced in the Italian Universities only five years ago and the collected data come from the evaluation nuclei in the university on the basis of grills structured, proposed from the national Observatory for the Appraisal, where data are dealt in comparative key.

MATERIALS AND METHODS

The Medicine faculty of the University Campus Bio Medico every year carries out an evaluation survey where the judgments from the students are compared with their didactic results. We utilise questionnaires to both inquire into the quality of the logistic and organizational aspects and into the didactic teacher competences and tutors, taking them in consideration singularly and as a whole, through the integrated course's analysis.

RESULTS

This study represents one further development regarding those already published in the previous years, because it compares every teacher's results of the last the five years and every student's academic career from the first moment the student entered into the faculty. The two evaluative lines have been discussed in meetings with students, teacher and administrative staff.

CONCLUSIONS

From the quantitative type of data gained through questionnaires, through the curves of performance of the students and through the interpretation that are in question observations for the improvement of the didactic quality are obtained.

[Malnutrition detected by "bioelectrical status" of total and segmental body mass to nutritional management of patients]

We examined 182 controls with Body Mass Index (BMI) between 20 and 25 kg/m2 and 246 hospitalised patients divided into 3 groups: the first one consisted of 70 severe malnourished with (BMI) < 20 kg/m2, the second one of 43 light malnourished with BMI between 20 and 25 kg/m2 and the last one of 133 obese with BMI > 25 kg/m2. The Resistance (Rs) and Reactance (Xc), with the Phase angle ((phi), are detected from total and segmental (Arm and "Trunk + Leg") body. We analysed electric parameters plotting them on 4 different graphs which reported the values of: 1) total Rs vs total Xc; 2) segmental Rs vs segmental Xc; 3) total Rs/height vs weight/ height; 4) total Xc/height vs weight/height. Rs and Xc were different in all groups: the severe malnourished patients (1st group) gave evidence of a paradoxical increase of Rs and a decrease of phi. The mean values decreased for the patient of the 2nd and 3rd group (the (phi reduced especially for the 2nd group). Referring to the segmental measures, "Trunk + Leg" biases total Rs and Xc much more than Arm. In addition the phi of "Trunk + Leg" is more similar to the total o than the Arm one. If compared with the total, this last one highly decreases in the patients of the 1st and 2nd group. We conclude that segmental bioelectrical values (Rs, Xc, phi) integrate the total one, because they allow to find out the correlation between total parameters and a specific body segment. Total and segmental Rs, Xc (and phi) values and segmental phi ratio are related to the malnutrition. The approach together with the analysis of the Graphics result to a prompt inspection of the individual bioelectrical status in subjects.

[Laparoscopic cholecystectomy for acute cholecystitis: our experience]

Laparoscopic cholecystectomy (LC) is now the gold standard in the treatment of cholelithiasis. LC is safe even in patients with acute cholecystitis. In our 118 cases there was 4 major complications as bile duct injuries (3%) and 13 minor complications (11%); conversion rate was 21% (24 patients), without mortality. Our experience confirms the validity of early LC in the treatment of acute cholecystitis, but laparoscopic procedure is associated with higher conversion rate (21% versus 3%) and complication rates compared to the treatment in non-acute patients.

Intra-oesophageal distribution and perception of acid reflux in patients with non-erosive gastro-oesophageal reflux disease

BACKGROUND

The majority of patients with gastro-oesophageal reflux disease do not present with erosive oesophagitis and make up a heterogeneous group. Patients with non-erosive gastro-oesophageal reflux disease are less responsive than patients with oesophagitis to acid-suppressive therapy.

AIM

To assess the role of acid reflux in gastro-oesophageal reflux disease symptoms.

METHODS

The spatio-temporal characteristics of reflux events were analysed and related to reflux perception in 45 patients with non-erosive gastro-oesophageal reflux disease and 20 patients with erosive oesophagitis.

RESULTS

Compared with healthy controls, all patients showed a higher intra-oesophageal proximal spread of acid, which was prominent in patients with non-erosive gastro-oesophageal reflux disease (> 50% of events lasting for 1-2 min). Irrespective of mucosal injury, the risk of reflux perception was very high when acid reached proximal sensors (odds ratio, 7.6; 95% confidence interval, 4.6-12.5), being maximal in patients with non-erosive gastro-oesophageal reflux disease with normal acid exposure time (odds ratio, 11; 95% confidence interval, 5.2-22.3).

CONCLUSIONS

Patients with non-erosive gastro-oesophageal reflux disease are characterized by a significantly higher proportion of proximal acid refluxes and a higher sensitivity to short-lasting refluxes when compared with patients with oesophagitis. The highest proximal acid exposure and highest perception occurred in patients with non-erosive gastro-oesophageal reflux disease presenting with a normal pH-metric profile. The assessment of acid distribution and its perception in the oesophageal body can better identify reflux patients who should benefit from acid-suppressive treatment.

Intra-oesophageal distribution and perception of acid reflux in patients with non-erosive gastro-oesophageal reflux disease

BACKGROUND

The majority of patients with gastro-oesophageal reflux disease do not present with erosive oesophagitis and make up a heterogeneous group. Patients with non-erosive gastro-oesophageal reflux disease are less responsive than patients with oesophagitis to acid-suppressive therapy.

AIM

To assess the role of acid reflux in gastro-oesophageal reflux disease symptoms.

METHODS

The spatio-temporal characteristics of reflux events were analysed and related to reflux perception in 45 patients with non-erosive gastro-oesophageal reflux disease and 20 patients with erosive oesophagitis.

RESULTS

Compared with healthy controls, all patients showed a higher intra-oesophageal proximal spread of acid, which was prominent in patients with non-erosive gastro-oesophageal reflux disease (> 50% of events lasting for 1-2 min). Irrespective of mucosal injury, the risk of reflux perception was very high when acid reached proximal sensors (odds ratio, 7.6; 95% confidence interval, 4.6-12.5), being maximal in patients with non-erosive gastro-oesophageal reflux disease with normal acid exposure time (odds ratio, 11; 95% confidence interval, 5.2-22.3).

CONCLUSIONS

Patients with non-erosive gastro-oesophageal reflux disease are characterized by a significantly higher proportion of proximal acid refluxes and a higher sensitivity to short-lasting refluxes when compared with patients with oesophagitis. The highest proximal acid exposure and highest perception occurred in patients with non-erosive gastro-oesophageal reflux disease presenting with a normal pH-metric profile. The assessment of acid distribution and its perception in the oesophageal body can better identify reflux patients who should benefit from acid-suppressive treatment.

[Radiology investment planning using the Break Even Point (BEP) method]

The health care financing decision are becoming increasingly complex in all health care environments. As a managed care becomes a greater percentage of overall business, accurate financial planning and decision making will be key components of viable organization. Therefore, the priority for health care systems is to manage their costs at the same time as maintaining the relationships they have with patients, providers, payors, and communities in order to have long term success and short term survival. Principal wedge to value an investment is to define a planning in order to identify the activities, to attribute costs to the activities, to fix a full cost for every performances and to examine fixed costs and variable costs. This is the key to achieve a economic balance.

[Manual colonic anastomosis with continuous single layer suture. Our experience]

The use of staplers has produced a reduction on operative times in the colorectal surgery without reduction of anastomotic complications. We present our experience about colonic anastomoses (ileo-colic, colo-colic and colo-rectal intraperitoneal anastomoses) with extramucosal one-layer continuous suture in synthetic slow absorbable one-filament. In the period January 2000-January 2003 we performed 157 operations on the large bowel, with 113 manual colonic anastomoses. Our results are similar to the best series of literature. The hand-sewn suture actually represents our common technique for the anastomoses of the large bowel.

[Teachers' education goes through students' evaluation as well]

OBJECTIVE

Students' opinion on the quality of the educational methods can represent an interesting factor useful to encourage teachers to reconsider their educational methodologies in view of the new planning required by changes in the study curricula.

MATERIALS AND METHODS

The paper considers the evaluation expressed by medical students of the "Campus Bio-Medico" University during three consecutive years, in order to perceive the dynamic sense and the evolving prospective of the educational quality as a whole. From a methodological point of view the evaluation of each year and of each course are related to a general median line. This is a significant indicator of the variations of educational methodologies considered as a whole. The relation between the general median line and the course one allows taking into consideration the relative and the absolute variation of the quality.

RESULTS

To be relevant the analysis of each course has to be put in relation with the progress of the previous year and with the overall state of the educational activities. While in the first case students evaluating the same course are not the same, in the second one the group of students is substantially stable and allows a better control of the evaluators' variable.

CONCLUSIONS

Students' judgements on the educational quality have to be put always into a constructive frame. They have to be involved in the process of improving the educational methodologies by means of orienting teachers' education, pointing out possible critical aspects or stressing each time the results they expect. The dynamic aspect of evaluation allows constant confrontation of the results obtained during a course with the criteria of the expected quality growth. That is, a course apparently static or even dropping, can be considered as such only because the students expectations have grown.

Expression of AP-2 transcription factor and of its downstream target genes c-kit, E-cadherin and p21 in human cutaneous melanoma

The AP-2 transcription factor plays a pivotal role in regulating the expression of several genes involved in tumor growth and progression of melanoma. We determined, by Western blot, variation in the level of expression of AP-2 and three of its downstream targets, c-kit, E-cadherin, and p21 in several human melanoma cell lines and, by immunohistochemistry, in a group of 99 histological samples including benign and malignant melanocytic lesions. A significant negative correlation between AP-2 expression level and tumor thickness was found. Moreover, AP-2 expression was positively associated with E-cadherin and c-kit expression. In contrast, there was a significant negative association between AP-2 and p21 expression levels. These findings suggest that p21 is independent of AP-2 transactivator function during the latest phases of melanoma progression. Finally, AP-2, c-kit, E-cadherin, and p21 expression levels did not show to be able to distinguish between dysplastic nevi and nevi without dysplasia. We conclude that changes in the expression of these proteins are involved in the later phases of melanoma progression, and may be responsible for the transition from local invasive melanoma to metastasis.

[Assessment of teaching quality: from normative aspects to the relapse of the formative project]

INTRODUCTION

To base the medical student's education on scientific evidence, we need to applied to medical education the same evidence-based methods characteristics of scientific research. Our goal is to change curricula, educational methods, teaching of clinical skills, in order to improve professional training of medical and nursing students. Our work highlights the student's point of view relative to changes of educational project, that is a constitutive aspect of best evidence medical education.

DESIGN

Every year, an evaluation test is submitted to all medical, nursing and nutritionist students of Università "Campus Bio-Medico". This test worked out by both teachers and students, is designed to explore student's perception of all aspects, educational and relational, related to the university. Data are been processed using explorative analysis of principal elements, and then using factorial analysis with "Varimax", data orthogonal rotation. A specific database in Microsoft Access, is been used for data entry, while statistical analysis is been performed using didactic software STATA (Stata Corporation).

RESULTS

According to data, we can claim that our students evaluate their teachers and tutors depending on two principal factors: on one hand educational skills, that include personal competence on teaching and getting in touch with the students; on the other hand managing and planning skills. These are very important to overcome the dangers related to integrated courses, composed by many different scientific matters and planned by many teachers: without a very good planning, students may not be allowed to achieve clear, synthetic and well-structured knowledge.

CONCLUSIONS

Students want to be regarded as adult learners, they wish to achieve a well structured knowledge, both composed by theoretical and practical skills and personal relations, in order to think of every activity according to an organic knowledge.

Free radical production by activated haem proteins: protective effect of coenzyme Q

The interaction of hydrogen peroxide with haem proteins leads readily to the formation of myoglobin and/or haemoglobin higher oxidation states (MbIV and/or HbIV), which are capable of promoting the oxidation of cellular costituents and are probably to blame for myocardic tissue damage in ischaemia/reperfusion. This study supports the evidence that the reduced form of Coenzyme Q, like other reducing agents, has an antioxidant activity exerted through the progressive reduction of ferryl forms (MbIV and/or HbIV) back to met and oxy forms (Mb and/or HbIIO2). Furthermore, the strong inactivation afforded by ferryl states of myoglobin on several enzymes, especially creatine kinase (CK), can be prevented by the addition of ubiquinol which protects the enzyme from the oxidative modifications. The ability of ubiquinol to recycle ferryl states of haem proteins provides a novel antioxidant mechanism for Coenzyme Q, besides its direct or indirect antiperoxidative activity, and may represent an important defense mechanism against oxidative tissue injury.

Antioxidant effect of coenzyme Q on hydrogen peroxide-activated myoglobin

In recent years increased attention has been focused on the reduced forms of coenzyme Q as antioxidant compounds inhibiting lipid peroxidation in model systems and in biological membranes, but in spite of extensive experimental evidences the molecular mechanisms responsible for the antioxidant activity of ubiquinones are still debated. Ferrylmyoglobin and/or its free radical form are regarded as powerful oxidizing agents capable of promoting oxidation of essential cellular constituents, particularly cell membranes. Therefore, we investigated the effects of ubiquinol on the formation and survival of ferryl species of myoglobin and on metmyoglobin itself. The addition of a threefold molar excess of hydrogen peroxide to a solution of metmyoglobin induces the rapid formation of a compound with the spectral characteristics of ferrylmyoglobin. The reaction is complete within 4 min, producing up to 76% of ferrylmyoglobin, which remains stable for at least 30 min. The addition of ubiquinol-1 to the same solution provokes a rapid and progressive reduction of ferrylmyoglobin to metmyoglobin and oxymyoglobin. Ubiquinol-1, furthermore, is also capable of protecting metmyoglobin against oxidation when added in the solution before hydrogen peroxide. Ubiquinol-1, indeed, is effective at both limiting the maximal ferrylmyoglobin level attained (59% inhibition) and accomplishing complete removal of the ferryl form (in about 15 min). The results demonstrate that ubiquinol is capable of reducing both ferrylmyoglobin and metmyoglobin to oxymyoglobin, providing a novel antioxidant mechanism for coenzyme Q.