Vitamin D and type 2 diabetes mellitus.

WHAT IS KNOWN AND OBJECTIVE: The deleterious effect of vitamin D deficiency on bone health has long been known. More recent studies suggest a deleterious effect of low vitamin D (hypovitaminosis D) on general health. And specific studies propose an association between hypovitaminosis D and the aetiology and progression of type 2 diabetes (T2DM). Given a commonly assumed lack of toxicity of vitamin D, routine measurement of plasma vitamin D and supplementation is rapidly becoming accepted general practice. COMMENT: Authoritative practice guidelines have raised the level of vitamin D that is to be considered minimal for optimum health. This recommendation was based on a wealth of information and definitive evidence for skeletal benefits of vitamin D, but there was a lack of compelling evidence that hypovitaminosis D is causally related to extra-skeletal health outcomes such as diabetes. Hence, vitamin D supplementation for the purpose of achieving a level consistent with good health is evidence based, but measurement and supplementation for the purpose of preventing or treating T2DM is not. WHAT IS NEW AND CONCLUSION: Although the maintenance of adequate vitamin D levels is desirable for all patients, we conclude that routine measurement of vitamin D level in every patient or initiating high-dose supplementation for the purpose of preventing or treating T2DM is not evidence based.

The kidney as a new target for antidiabetic drugs: SGLT2 inhibitors.

WHAT IS KNOWN AND OBJECTIVE: A novel class of antidiabetic drugs - SGLT2 (Na(+) /glucose cotransporter type 2) inhibitors - target renal reabsorption of glucose and promote normal glucose levels, independent of insulin production or its action at receptors. We review this new mechanistic approach and the reported efficacy and safety of clinical testing of lead compounds. METHODS: Information was obtained from various bibliographic sources, including PubMed and others, on the basic science and the clinical trials of SGLT2 inhibitors. The information was then summarized and evaluated from the perspective of contribution to a fuller understanding of the potential and current status of the lead clinical candidates. RESULTS AND DISCUSSION: Diabetes mellitus is a spectrum of disorders that involves inadequate insulin function resulting in adverse health sequelae due to acute and chronic hyperglycaemia. Current antidiabetic pharmacotherapy primarily addresses either insulin production at the pancreatic ß-cells or insulin action at insulin receptors. These drugs have less than full clinical effectiveness and sometimes therapy-limiting adverse effects. The third major component of glucose balance, namely elimination, has not been a significant therapeutic target to date. SGLT2 inhibitors are a novel approach. WHAT IS NEW AND CONCLUSION: A sufficient number of clinical trials have been conducted on sufficiently chemically diverse SGLT2 inhibitors to reasonably conclude that they have efficacy (HbA1c reductions of 0·4-1%), and thus far, the majority of adverse effects have been mild and transitory or treatable, with the caveat of possible association with increased risk of breast cancer in women and bladder cancer in men.

Complications of augmentation procedures for dental implants in private practice, Victoria, Australia.

PURPOSE: This study audited complications associated with augmentation for dental implants, retrospectively over a 5-year period in a variety of private dental practices in Victoria (Australia). METHODS: Complications were categorized as surgical or biological and compared to a group not requiring augmentation. Implant factors underwent univariate and multivariate analysis. RESULTS: The study assessed 8486 implants with 26.9% undergoing augmentation. Augmentation had no effect on implant survival, however, a significant increase in complications for those implants requiring augmentation was found (P = <0.001). The hard tissue augmented group had significantly more cases of insufficient bone/dehiscences at implant placement (P < 0.001), and post-placement bone loss (P = 0.0014). These implants were grafted simultaneously (P < 0.05) with particulate autogenous bone and/or Bio-Oss (P < 0.05) with resorbable xenograft membrane (P < 0.001). There was significantly more bone loss in open sinus lifted cases than implants placed in native bone (1.90% v 0.30%; P = 0.009). CONCLUSIONS: The study demonstrated no increase in graft complications that could be related to any specific augmentation technique, suggesting that routine grafting procedures used in private practice were safe and appropriate. Previously augmented sites were found to be more likely to require further augmentation at implant placement.

Deliberating performance targets workshop: Potential paths for emerging PM2.5 and O3 air sensor progress.

The United States Environmental Protection Agency held an international two-day workshop in June 2018 to deliberate possible performance targets for non-regulatory fine particulate matter (PM2.5) and ozone (O3) air sensors. The need for a workshop arose from the lack of any market-wide manufacturer requirement for Ozone documented sensor performance evaluations, the lack of any independent third party or government-based sensor performance certification program, and uncertainty among all users as to the general usability of air sensor data. A multi-sector subject matter expert panel was assembled to facilitate an open discussion on these issues with multiple stakeholders. This summary provides an overview of the workshop purpose, key findings from the deliberations, and considerations for future actions specific to sensors. Important findings concerning PM2.5 and O3 sensors included the lack of consistent performance indicators and statistical metrics as well as highly variable data quality requirements depending on the intended use. While the workshop did not attempt to yield consensus on any topic, a key message was that a number of possible future actions would be beneficial to all stakeholders regarding sensor technologies. These included documentation of best practices, sharing quality assurance results along with sensor data, and the development of a common performance target lexicon, performance targets, and test protocols.

Demagnetizing fields in all-optical switching.

A model of demagnetizing fields and micromagnetic simulations are applied to examine the evolution of a demagnetized cylinder. In addition to three expected final magnetic structures, a fourth switched state is obtained over a range of magnetic energy densities. The switched state is absent when demagnetizing fields are neglected. The connection to all-optical switching of materials with perpendicular magnetic anisotropy is discussed.

Ultrafast demagnetization at high temperatures.

Time-resolved pump-probe measurements were made at variable heat accumulation in Co/Pd superlattices. Heat accumulation increases the baseline temperature and decreases the equilibrium magnetization. Transient ultrafast demagnetization first develops with higher fluence in parallel with strong equilibrium thermal spin fluctuations. The ultrafast demagnetization is then gradually removed as the equilibrium temperature approaches the Curie temperature. The transient magnetization time-dependence is well fit with the spin-flip scattering model.

Incorporation of the microencapsulated antimicrobial agent phytoncide into denture base resin.

BACKGROUND: This study aimed to fabricate a denture base resin (DBR) containing phytoncide microcapsules (PTMCs) and determine the mechanical properties of the resin and antifungal activity. METHODS: Fifty-four heat-cured rectangular DBR specimens (64 × 10 × 3.3 ± 0.2 mm) containing nine concentrations of PTMC between 0 and 5% (wt/wt) were fabricated and subjected to a three-point bending test. A phytoncide release bioassay was developed using DBR containing 0% and 2.5% PTMCs (wt/wt) in a 24 well-plate assay with incubation of Porphyromonas gingivalis at 37 °C for 74 h. The antifungal activity of PTMCs against Candida albicans, in a pH 5.5 acidic environment was determined in a plate assay. RESULTS: Flexural strength decreased with increasing PTMC concentration from 97.58 ± 4.79 MPa for the DBR alone to 53.66 ± 2.46 MPa for DBR containing 5.0% PTMC. No release of phytoncide from the PTMCs in the DBR was detected at pH 7.4. The PTMCs had a minimal inhibitory concentration of 2.6% (wt/vol) against C. albicans at pH 5.5. CONCLUSIONS: PTMCs can be added to DBR 2.5% (wt/wt) without adversely affecting flexural strength. PTMCs released the antimicrobial agent at pH 5.5 at concentrations sufficient to inhibit the growth of the C. albicans.

Gram-negative bacteraemia; a multi-centre prospective evaluation of empiric antibiotic therapy and outcome in English acute hospitals.

Increasing antibiotic resistance makes choosing antibiotics for suspected Gram-negative infection challenging. This study set out to identify key determinants of mortality among patients with Gram-negative bacteraemia, focusing particularly on the importance of appropriate empiric antibiotic treatment. We conducted a prospective observational study of 679 unselected adults with Gram-negative bacteraemia at ten acute english hospitals between October 2013 and March 2014. Appropriate empiric antibiotic treatment was defined as intravenous treatment on the day of blood culture collection with an antibiotic to which the cultured organism was sensitive in vitro. Mortality analyses were adjusted for patient demographics, co-morbidities and illness severity. The majority of bacteraemias were community-onset (70%); most were caused by Escherichia coli (65%), Klebsiella spp. (15%) or Pseudomonas spp. (7%). Main foci of infection were urinary tract (51%), abdomen/biliary tract (20%) and lower respiratory tract (14%). The main antibiotics used were co-amoxiclav (32%) and piperacillin-tazobactam (30%) with 34% receiving combination therapy (predominantly aminoglycosides). Empiric treatment was inappropriate in 34%. All-cause mortality was 8% at 7 days and 15% at 30 days. Independent predictors of mortality (p <0.05) included older age, greater burden of co-morbid disease, severity of illness at presentation and inflammatory response. Inappropriate empiric antibiotic therapy was not associated with mortality at either time-point (adjusted OR 0.82; 95% CI 0.35-1.94 and adjusted OR 0.92; 95% CI 0.50-1.66, respectively). Although our study does not exclude an impact of empiric antibiotic choice on survival in Gram-negative bacteraemia, outcome is determined primarily by patient and disease factors.

Managed care involvement by cardiovascular specialists: prevalence, attitudes and influence on practice.

OBJECTIVES: The purpose of this study was to determine the involvement in and attitudes toward managed care by cardiovascular specialists and the influence of such programs on their practices. BACKGROUND: No in-depth study has measured the impact of managed care on cardiovascular specialists. Therefore, we conducted a mail survey to determine the prevalence of managed care arrangements among cardiovascular specialists and variations among pediatric and adult cardiologists and cardiovascular surgeons; the types of managed care arrangements in which cardiovascular specialists are engaged; the reasons why those not participating in managed care have chosen not to do so; and the general attitudes among cardiovascular specialists with regard to various aspects of managed care. In addition, we evaluated the impact of managed care among several aspects of cardiovascular practice. METHODS: A questionnaire was mailed in the spring of 1993 to 4,577 practicing, domestic, American College of Cardiology (ACC) members selected at random from within each primary cardiovascular specialty group (adult cardiologists, pediatric cardiologists and cardiovascular surgeons). Additional data concerning practice characteristics were cross tabulated using results from the 1992 ACC membership profile survey. RESULTS: In total, 1,961 of the 4,577 members responded to the survey, representing a 43% response rate. Of all survey respondents, 76% reported entering into at least one relationship with a health maintenance organization (HMO) or preferred provider organization (PPO). Of those not participating in managed care arrangements, the most frequently mentioned reason was "concern over the quality of care." This reason was cited by 51% of those not entering into HMO relationships and 41% of those not participating in PPOs. The majority of respondents indicated that they do not strongly object to the gatekeeper approach to managing nonemergent patients, although more than half indicated concern that gatekeepers may not be appropriate in the management of cardiac emergencies. In addition, cardiovascular specialists report that under managed care, referrals have not increased, income has decreased, and managed care formularies have not substantially affected their ability to prescribe appropriate medication to their patients. CONCLUSIONS: Despite concerns over the quality of care and contract requirements and general philosophical opposition of cardiovascular specialists, most are becoming integrated into managed care environments.

Analysis of commonly reported medical conditions amongst patients receiving dental implant therapy in private practice.

BACKGROUND: The population seeking implants in private practice is a demographically and medically unique group. Understanding their medical needs can improve treatment planning and service delivery specifically for this population. METHODS: Privately practising dental clinicians from Victoria, Australia, participated in a five-year retrospective study. Data were collected from the medical histories of 4116 patients who met the inclusion criterion of at least one implant placed within the study period of 1 January 2005 to 31 December 2009. Descriptive statistics were used to describe patient demographics and commonly reported medical conditions. RESULTS: The most common age group to receive implant therapy was between 51 and 60 years (30.4% of patients). The patient population reported a broad range of co-morbidities including psychiatric disorders (83 patients), cardiovascular disorders (253 patients), gastrointestinal disorders (224 patients) and respiratory disorders (502 patients). Smoking was less prevalent amongst the study population compared to the general population. CONCLUSIONS: The population assessed in this study was a medically diverse group. Clinicians must be familiar with their target demographic and understand how the common co-morbidities amongst this patient group can influence clinical decision making and outcomes.

Survival rates and complication types for single implants provided at the Melbourne Dental School.

BACKGROUND: Single implants and implant-supported single crowns (ISSCs) have become popular treatment modalities for single tooth replacement. Studies have identified high implant survival rates, but also many complications. The aim of this five-year retrospective study was to assess the survival rates, complication types and occurrences for single implants and ISSCs at the Melbourne Dental School (MDS) in Victoria, Australia. METHODS: A search of the Royal Dental Hospital of Melbourne (RDHM) database was conducted for data on all implant treatment and reported complications during the period between 1 January 2005 and 31 December 2009. Complications were categorized into surgical, biological and restorative types. RESULTS: A total of 622 implant fixtures and 444 ISSCs were inserted into 406 patients. Seventeen implants failed during the mean follow-up time of 2.18 years, yielding a 2.7% failure rate and an estimated one- and five-year survival rate of 98.8% and 93.9%, respectively. The cumulative surgical, biological and restorative complication incidences were 11.9%, 17.6% and 14.1%, respectively. CONCLUSIONS: This study confirmed that single tooth replacement using implant therapy within a teaching environment had a high survival rate. However, complications frequently occurred. This article only provides a descriptive analysis. Correlation analysis between variables would provide greater insight into the causes of complications.

Patient perspectives on once-weekly fluoxetine.

BACKGROUND: Continuation therapy is recommended for 4 to 9 months following remission of symptoms of major depressive disorder. Long-term maintenance therapy is recommended for patients with severe, recurrent symptoms. However, most patients do not complete an adequate course of therapy. We investigated patient perceptions of antidepressant dosing to determine whether weekly dosing could provide an additional tool to help more patients remain compliant with antidepressant treatment. METHOD: Physicians were asked to complete an anonymous patient profile for 7 patients currently receiving antidepressant treatment and to give those patients a questionnaire that the patients could submit anonymously. In addition, clinically depressed patients in the United States and in France were surveyed by telephone. RESULTS: Patients surveyed by questionnaire agreed most strongly with statements indicating that they would like their doctor to involve them in the choice of antidepressant medication, that they did not want others to know they were taking antidepressant medication, and that they disliked the idea of taking daily medication. Patients in the telephone survey agreed most strongly with statements indicating that they considered once-weekly dosing more convenient than daily dosing, that they believed taking 1 pill a week would make them feel less dependent on pills, and that they perceived more advantages than disadvantages in taking 1 pill a week. CONCLUSION: Weekly antidepressant treatment may provide an effective tool in helping patients with depression. Positive patient perceptions of weekly dosing suggest that some patients may remain on continuation or maintenance therapy longer when they have the option of weekly dosing.

Treatment recommendations versus treatment realities: recognizing the rift and understanding the consequences.

Depression is a treatable disorder, although it often requires long-term therapy. To aid physicians in the effective long-term management of depression, treatment guidelines have been established by a number of organizations with minimum treatment duration recommendations. Unfortunately, numerous studies document a significant disparity between these recommendations and clinical practice realities. In particular, studies have shown that fewer than half of treated patients receive the recommended duration of 6 months of continuation therapy. Other clinical practice studies have reported that early discontinuation from therapy is associated with a substantial increase in the risk of relapse or recurrence. Long-term treatment of depression in clinical practice settings may benefit from a closer approximation to the conditions found in clinical trial settings.

The efficacy and safety of a new enteric-coated formulation of fluoxetine given once weekly during the continuation treatment of major depressive disorder.

BACKGROUND: A simple, once-weekly dosing regimen could be a convenient alternative for many patients during long-term treatment of depression. Such a strategy might also be effective for improving medication compliance and the outcome of continuation treatment. The safety and effectiveness of a new formulation of enteric-coated fluoxetine (90 mg) given once weekly was tested during the continuation treatment of major depressive disorder. METHOD: Patients meeting DSM-IV criteria for major depressive disorder with modified 17-item Hamilton Rating Scale for Depression (HAM-D-17) scores > or = 18 and Clinical Global Impressions-Severity of Illness scale (CGI-S) scores > or = 4 were treated 13 weeks with open-label 20 mg/day of fluoxetine in a multicenter U.S. study. Responders (N = 501) were randomly assigned to receive 20 mg of fluoxetine daily, placebo, or 90 mg of enteric-coated fluoxetine weekly for 25 weeks of double-blind continuation treatment. The primary efficacy measure was the percentage of patients who relapsed. Time to relapse was tested over the 25-week continuation period using log-rank analyses of the Kaplan-Meier estimates of relapse rates. Additional analyses of efficacy included comparison of change from baseline to endpoint for the HAM-D-17, CGI-S, and HAM-D-28 subscales by last observation carried forward (LOCF). Safety measures included comparison of treatment-emergent adverse events, both spontaneous and solicited (using the Association for Methodology of Documentation in Psychiatry-Module 5), vital signs, and laboratory measures. RESULTS: Relapse rates for patients assigned to fluoxetine, either 20 mg daily or 90 mg weekly, were significantly lower than for placebo by log-rank analysis and LOCF analyses of secondary efficacy measures. Efficacy did not significantly differ between the 2 active drug groups by these measures. Enteric-coated fluoxetine at a once-weekly dose of 90 mg was well tolerated, and its safety profile was similar to that of daily 20 mg of fluoxetine. CONCLUSION: The formulation of enteric-coated fluoxetine taken once weekly is effective, safe, and well tolerated for continuation treatment of depression in patients who responded to acute treatment with 20 mg/day of fluoxetine. Monitoring during long-term treatment for evidence of sustained remission is important regardless of dosing regimen.

A double-blind, multicenter study in primary care comparing paroxetine and clomipramine in patients with depression and associated anxiety. Paroxetine Study Group.

BACKGROUND: 60%-90% of patients with a primary diagnosis of depression also experience symptoms of anxiety, and such patients have a poorer prognosis than those with uncomplicated depression. The serotonin selective reuptake inhibitors have demonstrated efficacy in the treatment of both depression and certain anxiety states. Furthermore, in a metaanalysis of the paroxetine clinical trial database of 2963 patients in whom depression predominated, there was a concomitant reduction in the Hamilton Rating Scale for Depression anxiety factor. The purpose of the present study was to prospectively compare the efficacy of paroxetine and clomipramine in patients specifically selected for coexisting depression and anxiety. METHOD: This was a 12-week, double-blind, parallel-group trial comparing paroxetine 20-40 mg/day with clomipramine 75-150 mg/day in 1002 patients with a Montgomery-Asberg Depression Rating Scale (MADRS) score > or = 20 and a Clinical Anxiety Score (CAS) > or = 11 after a 3-7 day placebo run-in period. RESULTS: Both paroxetine and clomipramine reduced the MADRS and CAS ratings at 2, 6, and 12 weeks and at endpoint, with no significant differences between treatment groups at any time point. CGI severity of illness and global improvement ratings were also similar throughout the trial; however, there was a statistically significant difference in the CGI efficacy index at 6 weeks and at endpoint, favoring paroxetine (p = .015 and p = .015, respectively). Paroxetine resulted in fewer treatment-emergent adverse experiences and related withdrawals than clomipramine (p = .025 and p = .008, respectively). The number of serious adverse experiences was not significantly different in the paroxetine group compared with the clomipramine group (14 [2.8%] vs. 27 [5.4%]), but did approach statistical significance (p = .056). Anticholinergic-emergent adverse experiences were reported twice as frequently by patients in the clomipramine group as in the paroxetine group (36.1% vs. 18.6%). CONCLUSION: There was no evidence of any significant difference in efficacy between paroxetine and clomipramine in patients with coexisting depression and anxiety. However, paroxetine was better tolerated as shown by total treatment-emergent adverse experiences, anticholinergic adverse experiences, and withdrawals due to adverse experiences.

Fluoxetine versus sertraline and paroxetine in major depressive disorder: changes in weight with long-term treatment.

BACKGROUND: The effects of extended selective serotonin reuptake inhibitor (SSRI) treatment on weight are not well characterized. Also unknown is whether different agents have differential effects. To examine these questions, we assessed weight changes in patients randomly assigned to long-term treatment with fluoxetine, sertraline, or paroxetine. METHOD: Patients (N = 284) with major depressive disorder (DSM-IV) were randomly assigned to double-blind treatment with fluoxetine (N = 92), sertraline, (N = 96), or paroxetine (N = 96) for a total of 26 to 32 weeks. The mean percent change in weight was compared for each group, as was the number of patients who had > or = 7% weight increase from baseline. RESULTS: Patients (fluoxetine, N = 44; sertraline, N = 48; paroxetine, N = 47) who completed the trial were included in these analyses. Paroxetine-treated patients experienced a significant weight increase, fluoxetine-treated patients had a modest but nonsignificant weight decrease, and patients treated with sertraline had a modest but nonsignificant weight increase. The number of patients whose weight increased > 7% from baseline was significantly greater for paroxetine-treated compared with either fluoxetine-treated or sertraline-treated patients. CONCLUSION: Risk of weight gain during extended SSRI treatment differs depending on which SSRI is used.

The role of fluoxetine in the treatment of premenstrual dysphoric disorder.

Many women experience psychological and physical symptoms associated with the menstrual cycle, commonly referred to as premenstrual syndrome (PMS). For the 3% to 5% of women who meet Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for premenstrual dysphoric disorder (PMDD), symptoms are severe and impair social and occupational functioning. Although the etiology of PMDD is unknown, symptoms of dysphoria, including depression and anxiety, predominate and indicate a link to serotonergic neurotransmission. Pharmacotherapy trials have shown greater efficacy with serotonergic versus nonserotonergic compounds. We reviewed the published literature and found 7 controlled and 4 open-label clinical trials of fluoxetine, a selective serotonin reuptake inhibitor, in the treatment of PMDD. These trials demonstrate that PMDD symptoms decreased during treatment with fluoxetine. Preliminary findings suggest that intermittent luteal-phase fluoxetine dosing may also be a suitable treatment strategy for selected patients with PMDD. At 20 mg/d, adverse events were usually transient, rarely caused discontinuation, and were consistent with fluoxetine's known safety profile. Fluoxetine 20 mg/d is an effective and well-tolerated treatment for women with PMDD, a severe variant of PMS.

Discontinuation symptoms: comparison of brief interruption in fluoxetine and paroxetine treatment.

Abrupt interruption or cessation of selective serotonin reuptake inhibitor (SSRI) treatment may result in discontinuation or treatment interruption symptoms. Recent reports suggested these symptoms occur more frequently with shorter half-life SSRIs. Previous studies indicated a 5-8-day treatment interruption resulted in fewer discontinuation-emergent adverse events in fluoxetine-treated patients than in paroxetine-treated patients. This study examines the effects of shorter treatment interruption (3-5 days), as would occur if patients miss just a few doses of medication. Patients successfully treated for depression with fluoxetine or paroxetine underwent treatment interruption in a double-blind fashion. Treatment interruption-emergent symptoms were assessed using the Discontinuation-Emergent Signs and Symptoms checklist. Other assessments included the Montgomery-Asberg Depression Rating Scale, Clinical Global Impressions-Severity scale and a social functioning questionnaire. Of 150 patients enrolled, 141 completed the study. Following treatment interruption, fluoxetine-treated patients experienced fewer treatment interruption-emergent events than did paroxetine-treated patients. The paroxetine treatment group also experienced significant increases in depressive symptoms, clinical global severity scores and difficulty in social functioning; the fluoxetine treatment group did not. These results are consistent with reports suggesting abrupt interruption of treatment with paroxetine is more often associated with somatic and psychological symptoms than is abrupt interruption of fluoxetine. Patients treated with fluoxetine appeared to be protected by its longer half-life.

Spectroscopy and predissociation of the 3A2 electronic state of ozone 16O3 and 18O3 by high resolution Fourier transform spectrometry.

A high resolution Fourier transform spectrometry analysis of the rotational structure of the 2(0)1 absorption bands of the 3A2<--X1A1 Wulf transition for the isotopomers 16O3 and 18O3 of the ozone molecule is presented. These bands are very intense compared to the 0(0)0 bands but the predissociation is so strong that the main sub-bands appear as continuous contours. Isolated lines and band contour methods are used together to analyse these two rovibrational bands. The lines corresponding to the F2 component are generally the most intense and isolated. Our data sets for the (0 1 0) level of the 3A2 state are limited to about 102 weakly or unperturbed rotational lines for the 2(0)1 of 16O3 in the range 9620-10,140 cm(-1) and 123 weakly or unperturbed rotational lines for the same band of 18O3. Using for each of them the well-defined ground state parameters, we obtained a standard deviation of about 0.035 cm(-1) in the fit to the lines for 16O3 and 0.027 cm(-1) in the case of 18O3. The rotational constants A, B and C, the three rotational distortion terms deltaK, deltaJK and deltaJ, the spin-rotation constants a0, a and b have been successfully calculated for 16O3 and 18O3 while the spin-spin constants were fixed to their respective values obtained for the origin bands. As is the case for the 0(0)0 band, we have a partial agreement with the isotopic laws for the rotational constants. The geometrical parameters of the (0 1 0) level of 3A2 state for the two isotopomers are close, r = 1.357 A, theta = 100.7 degrees for 18O3 and r = 1.352 A and theta = 100.0 degrees for 16O3. The origin of the 2(0)1 band of 18O3 is red shifted by 7.06(4) cm(-1) with respect to 16O3 2(0)1 band and the two bending mode quanta are, respectively, 528.99(9) and 501.34(7) cm(-1). A preliminary qualitative analysis of the predissociation is given in the particular case of the F2 spin component of 16O3 for 0(0)0 and 2(0)1 bands by the measurement of shifts of positions of some rovibrational levels and the evolution of predissociation broadenings in (Q)Q2 branches. We justify the existence of perturbations in the rovibrational levels of 3A2 state through different interaction types: with the dissociation continuum of the same electronic state or with high vibrational repulsive or weakly bound levels of the ground state.

Contribution to the analysis of the predissociated rovibronic structure of the symmetric isotopomers 16O3 and 18O3 of ozone near 10,400 cm-1): [3A2(3(2)(0)) <-- X1A1(0(0)(0))] and 3B2 <-- X1A1.

The absorption spectrum of ozone was recorded at low temperatures (down to -135 degrees C) by high resolution Fourier transform spectrometry and intra cavity laser absorption spectroscopy (ICLAS) near 10,400 cm-1. A preliminary analysis of the rotational structure of the absorption spectra of 16O3 and 18O3 shows that this spectral region corresponds to a superposition of two different electronic transitions, one with a very broad rotational structure, showing for the first time the asymmetric stretching frequency mode nu3 of the electronic state 3A2, the other formed by a completely diffuse band, probably the 2(1)(0) band of a new transition due to the triplet electronic state 3B2. Predissociation effects induce large broadening of the rotational lines for the transition centered at 10,473 cm-1 identified as the 3(2)(0) band of the 3A2 <-- X1A1 electronic transition. The rotational structure cannot be analyzed directly but instead the band contour method was used to confirm the symmetry of the transition and to estimate the spectroscopic constants for the 16O isotopomer. The origin of the band is at 10,473 +/- 3 cm-1 and the value of the 16O3(3A2) antisymmetric stretching frequency mode is equal to 460 +/- 2 cm-1. We believe that the diffuse band is due to the 3B2 state and is located at about 10,363 +/- 3 cm-1 for 16O3 and 10,354 +/- 3 cm-1 for 18O3. The isotopic rules confirm the different results obtained for 18O3 and 16O3.