Effectiveness and safety of a new helmet CPAP configuration allowing tidal volume monitoring in patients with COVID-19

BACKGROUND

High generated tidal volumes (Vt) have been correlated with higher risk of self-induced lung injury and worse clinical outcome. This study aimed to evaluate the effectiveness and safety of a new helmet continuous positive airway pressure delivered (h-CPAP) configuration allowing Vt monitoring in patients affected by COVID-19.

METHODS

This prospective observational study was performed in the respiratory intermediate care unit of University Hospital in Turin, Italy, between March 24th, and June 15th, 2020. Included patients were treated with CPAP via a single-limb intentional leak configuration by a turbine-driven ventilator, provided with a dedicated patch. Effectiveness and safety of the configuration and healthcare workers safety were the outcomes of the study.

MAIN FINDINGS

Thirty-five patients were included in this study. Median age was 67 years (IQR 57-76 years), and 30 patients (85.7%) were men. Median value of overall leaks (intentional plus unintentional) was 68 L/min (IQR 63-75). Reliability of Vt measurements was 100%. An out of scale of Vt (above 50% compared to the previous values) was never recorded. Six patients (17.1%) needed more than two helmet replacements, due to leak test >10 l/min. Arm oedema and skin breakdowns were reported in sixteen (45.7%) and seven (20%) patients respectively. Among the 63 healthcare workers involved in the care of COVID-19 patients during the study only one was positive at RT-PCR nasopharyngeal swab testing.

CONCLUSIONS

The use of h-CPAP for treating COVID-19 in this configuration allowed for reliable Vt monitoring. Further studies evaluating this configuration in larger patients' cohorts are needed.

Identification of a β-arrestin-biased negative allosteric modulator for the β2-adrenergic receptor

Catecholamine-stimulated β2-adrenergic receptor (β2AR) signaling via the canonical Gs-adenylyl cyclase-cAMP-PKA pathway regulates numerous physiological functions, including the therapeutic effects of exogenous β-agonists in the treatment of airway disease. β2AR signaling is tightly regulated by GRKs and β-arrestins, which together promote β2AR desensitization and internalization as well as downstream signaling, often antithetical to the canonical pathway. Thus, the ability to bias β2AR signaling toward the Gs pathway while avoiding β-arrestin-mediated effects may provide a strategy to improve the functional consequences of β2AR activation. Since attempts to develop Gs-biased agonists and allosteric modulators for the β2AR have been largely unsuccessful, here we screened small molecule libraries for allosteric modulators that selectively inhibit β-arrestin recruitment to the receptor. This screen identified several compounds that met this profile, and, of these, a difluorophenyl quinazoline (DFPQ) derivative was found to be a selective negative allosteric modulator of β-arrestin recruitment to the β2AR while having no effect on β2AR coupling to Gs. DFPQ effectively inhibits agonist-promoted phosphorylation and internalization of the β2AR and protects against the functional desensitization of β-agonist mediated regulation in cell and tissue models. The effects of DFPQ were also specific to the β2AR with minimal effects on the β1AR. Modeling, mutagenesis, and medicinal chemistry studies support DFPQ derivatives binding to an intracellular membrane-facing region of the β2AR, including residues within transmembrane domains 3 and 4 and intracellular loop 2. DFPQ thus represents a class of biased allosteric modulators that targets an allosteric site of the β2AR.

Effects of hyperoxemia in patients with sepsis - A post-hoc analysis of a multicentre randomized clinical trial

BACKGROUND

Administration of supplemental oxygen is a life-saving treatment in critically ill patients. Still, optimal dosing remains unclear during sepsis. The aim of this post-hoc analysis was to assess the association between hyperoxemia and 90-day mortality in a large cohort of septic patients.

METHODS

This is a post-hoc analysis of the Albumin Italian Outcome Sepsis (ALBIOS) randomized controlled trial (RCT). Patients with sepsis who survived the first 48 h since randomization were included and stratified into two groups according to their average PaO₂ levels during the first 48 h (PaO_{2 0-48 h}). The cut-off value was established at 100 mmHg (average PaO_{2 0-48 h} >100 mmHg: hyperoxemia group; PaO_{2 0-48h}≤100: normoxemia group). The primary outcome was 90-day mortality.

RESULTS

1632 patients were included in this analysis (661 patients in the hyperoxemia group, 971 patients in the normoxemia group). Concerning the primary outcome, 344 (35.4%) patients in the hyperoxemia group vs. 236 (35.7%) in the normoxemia group had died within 90 days from randomization (p = 0.909). No association was found after adjusting for confounders (HR 0.87; CI [95%] 0.736-1.028, p = 0.102) or after excluding patients with hypoxemia at enrollment, patients with lung infection or including post-surgical patients only. Conversely, we found an association between lower risk of 90-day mortality and hyperoxemia in the subgroup including patients who had the lung as primary site of infection (HR 0.72; CI [95%] 0.565-0.918). Mortality at 28 days, ICU mortality, incidence of acute kidney injury, use of renal replacement therapy, days to suspension of vasopressor or inotropic agents, and resolution of primary and secondary infections did not differ significantly. Duration of mechanical ventilation and length of stay in ICU were significantly longer in patients with hyperoxemia.

CONCLUSIONS

In a post-hoc analysis of a RCT enrolling septic patients, hyperoxemia as average PaO₂>100 mmHg during the first 48 h was not associated with patients' survival.

LBMON186 Beta-agonist Profiling Reveals Novel Biased Signaling Phenotypes For The Beta 2-adrenergic Receptor With Implications In The Treatment Of Asthma

Asthma involves chronic airway inflammation and airway smooth muscle (ASM) cell contraction. Treatment include agonists of the beta 2-AR, a GPCR that induces the Gs/cAMP pathway leading to ASM relaxation. These agonists can also promote severe side effects which have been correlated with beta-arrestins (barr) activation. Therefore, biased ligands selective for the Gs/cAMP pathway over the barr-induced side effects should be beneficial. To test this, we have used high-throughput screening to identify Gs-biased agonists. The initial lead candidates were further analyzed for their ability to modulate Gs and Gi interaction, cAMP production, and barr interaction. We identified three compounds which showed minimal barr recruitment as well as decreased barr-mediated outputs including receptor internalization and ERK activation. They also showed reduced GRK-mediated phosphorylation of the receptor as well as decreased agonist-promoted receptor desensitization in human ASM cells. These Gs-biased agonists may contribute to develop more effective drugs for asthma and may help to determine the structure determinants of receptor mediated biased signaling.

Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

β2 -Adrenoceptor agonist profiling reveals biased signalling phenotypes for the β2 -adrenoceptor with possible implications for the treatment of asthma

BACKGROUND AND PURPOSE

β-Adrenoceptor agonists relieve airflow obstruction by activating β2 -adrenoceptors, which are G protein-coupled receptors (GPCRs) expressed on human airway smooth muscle (HASM) cells. The currently available β-adrenoceptor agonists are balanced agonists, however, and signal through both the stimulatory G protein (Gs )- and β-arrestin-mediated pathways. While Gs signalling is beneficial and promotes HASM relaxation, β-arrestin activation is associated with reduced Gs efficacy. In this context, biased ligands that selectively promote β2 -adrenoceptor coupling to Gs signalling represent a promising strategy to treat asthma. Here, we examined several β-adrenoceptor agonists to identify Gs -biased ligands devoid of β-arrestin-mediated effects.

EXPERIMENTAL APPROACH

Gs -biased ligands for the β2 -adrenoceptor were identified by high-throughput screening and then evaluated for Gs interaction, Gi interaction, cAMP production, β-arrestin interaction, GPCR kinase (GRK) phosphorylation of the receptor, receptor trafficking, ERK activation, and functional desensitization of the β2 -adrenoceptor.

KEY RESULTS

We identified ractopamine, dobutamine, and higenamine as Gs -biased agonists that activate the Gs /cAMP pathway upon β2 -adrenoceptor stimulation while showing minimal Gi or β-arrestin interaction. Furthermore, these compounds did not induce any receptor trafficking and had reduced GRK5-mediated phosphorylation of the β2 -adrenoceptor. Finally, we observed minimal physiological desensitization of the β2 -adrenoceptor in primary HASM cells upon treatment with biased agonists.

CONCLUSION AND IMPLICATIONS

Our work demonstrates that Gs -biased signalling through the β2 -adrenoceptor may prove to be an effective strategy to promote HASM relaxation in the treatment of asthma. Such biased compounds may also be useful in identifying the molecular mechanisms that determine biased signalling and in design of safer drugs.

Improved Survival and Quality of Life Through an Integrative, Multidisciplinary Oncological Approach: Pathophysiological Analysis of Four Clinical Cancer Cases and Review of the Literature

Objectives: According to the National Cancer Institute, the integrative medicine (IM) approach to medical care combines standard medicine with complementary and alternative medicine practices that have proved safe and effective.

Methods: We describe the clinical cases of four patients with malignant pleural mesothelioma (MPM), diffuse malignant peritoneal mesothelioma (DMPM), intrahepatic cholangiocarcinoma, and breast cancer (BC) who received supportive treatment (ST) according to an IM approach after the failure of standard cancer treatments or the appearance of serious adverse events caused by antiblastic chemotherapy. The critical role of complementary drugs in reducing the side effects of cancer treatments and normalizing the white cell count is especially apparent in the case of the patient with metastatic BC, who experienced prolonged neutropenia.

Results: The IM approach was well-tolerated and had no adverse side effects. It improved the quality of life (QoL) of all patients and in two cases extended overall survival.

Conclusion: The extended clinical and instrumental response to IM of the patients with malignant mesothelioma and the improved health-related QoL and good tolerance of the ST demonstrated in all cases support the value of this approach in patients whose cancer therapies have failed but who show a good performance status. Our data require confirmation in a well-designed prospective clinical trial.

Phenylalanine 193 in Extracellular Loop 2 of the β 2-Adrenergic Receptor Coordinates β-Arrestin Interaction

G protein-coupled receptors (GPCRs) transduce a diverse variety of extracellular stimuli into intracellular signaling. These receptors are the most clinically productive drug targets at present. Despite decades of research on the signaling consequences of molecule-receptor interactions, conformational components of receptor-effector interactions remain incompletely described. The β ₂-adrenergic receptor (β ₂AR) is a prototypical and extensively studied GPCR that can provide insight into this aspect of GPCR signaling thanks to robust structural data and rich pharmacopeia. Using bioluminescence resonance energy transfer -based biosensors, second messenger assays, and biochemical techniques, we characterize the properties of β ₂AR-F193A. This single point mutation in extracellular loop 2 of the β ₂AR is sufficient to intrinsically bias the β ₂AR away from β-arrestin interaction and demonstrates altered regulatory outcomes downstream of this functional selectivity. This study highlights the importance of extracellular control of intracellular response to stimuli and suggests a previously undescribed role for the extracellular loops of the receptor and the extracellular pocket formed by transmembrane domains 2, 3, and 7 in GPCR regulation that may contribute to biased signaling at GPCRs. SIGNIFICANCE STATEMENT: The role of extracellular G protein-coupled receptor (GPCR) domains in mediating intracellular interactions is poorly understood. We characterized the effects of extracellular loop mutations on agonist-promoted interactions of GPCRs with G protein and β-arrestin. Our studies reveal that F193 in extracellular loop 2 in the β₂-adrenergic receptor mediates interactions with G protein and β-arrestin with a biased loss of β-arrestin binding. These results provide new insights on the role of the extracellular domain in differentially modulating intracellular interactions with GPCRs.

Rationale and evidence on the use of tocilizumab in COVID-19: a systematic review

BACKGROUND

Tocilizumab is an IL-6 receptor-blocking agent proposed for the treatment of severe COVID-19. The aim of this systematic review was to describe the rationale for the use of tocilizumab for the treatment of COVID-19 and to summarize the available evidence regarding its efficacy and safety.

METHODS

MEDLINE, PubMed, EMBASE, pre-print repositories (bioRxiv and medRxiv) and two trial Registries were searched for studies on the use of tocilizumab in COVID-19 or SARS-CoV-2 infection, viral pneumonia, and/or sepsis until 20th June 2020.

RESULTS

We identified 3 indirect pre-clinical studies and 28 clinical studies including 5776 patients with COVID-19 (13 with a comparison group, 15 single-arm). To date, no randomized trials have been published. We retrieved no studies at low risk of bias. Forty-five ongoing studies were retrieved from trial registries.

CONCLUSIONS

There is insufficient evidence regarding the clinical efficacy and safety of tocilizumab in patients with COVID-19. Its use should be considered experimental, requiring ethical approval and clinical trial oversight.

Biased agonism at β-adrenergic receptors

The β-adrenergic receptors (βARs) include three subtypes, β₁, β₂ and β₃. These receptors are widely expressed and regulate numerous physiological processes including cardiovascular and metabolic functions and airway tone. The βARs are also important targets in the treatment of many diseases including hypertension, heart failure and asthma. In some cases, the use of current βAR ligands to treat a disease is suboptimal and can lead to severe side effects. One strategy to potentially improve such treatments is the development of biased agonists that selectively regulate a subset of βAR signaling pathways and responses. Here we discuss the compounds identified to date that preferentially activate a G_s- or β-arrestin-mediated signaling pathway through βARs. Mechanistic insight on how these compounds bias signaling sheds light on the potential development of even more selective compounds that should have increased utility in treating disease.

Biased signaling of the proton-sensing receptor OGR1 by benzodiazepines

GPCRs have diverse signaling capabilities, based on their ability to assume various conformations. Moreover, it is now appreciated that certain ligands can promote distinct receptor conformations and thereby bias signaling toward a specific pathway to differentially affect cell function. The recently deorphanized G protein-coupled receptor OGR1 [ovarian cancer G protein-coupled receptor 1 ( GPR68)] exhibits diverse signaling events when stimulated by reductions in extracellular pH. We recently demonstrated airway smooth muscle cells transduce multiple signaling events, reflecting a diverse capacity to couple to multiple G proteins. Moreover, we recently discovered that the benzodiazepine lorazepam, more commonly recognized as an agonist of the γ-aminobutyric acid A (GABAA) receptor, can function as an allosteric modulator of OGR1 and, similarly, can promote multiple signaling events. In this study, we demonstrated that different benzodiazepines exhibit a range of biases for OGR1, with sulazepam selectively activating the canonical Gs of the G protein signaling pathway, in heterologous expression systems, as well as in several primary cell types. These findings highlight the potential power of biased ligand pharmacology for manipulating receptor signaling qualitatively, to preferentially activate pathways that are therapeutically beneficial.-Pera, T., Deshpande, D. A., Ippolito, M., Wang, B., Gavrila, A., Michael, J. V., Nayak, A. P., Tompkins, E., Farrell, E., Kroeze, W. K., Roth, B. L., Panettieri, R. A. Jr Benovic, J. L., An, S. S., Dulin, N. O., Penn, R. B. Biased signaling of the proton-sensing receptor OGR1 by benzodiazepines.

Abnormal F-18 Fluorodeoxyglucose Uptake of the Lung in Immunocompromised Lymphoma Patients in Complete Remission: Report of Two Cases and Revision of Literature

Limited data suggest that F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) may have a role in diagnosing infection. Here we present two cases of lymphoma patients in complete response (CR) who presented during follow-up dry cough and fever. Physical examination and serum evaluations were negative for lymphoma while whole body FDG-PET showed lung uptake which posed a differential diagnosis between relapse of lymphoma and an atypical pneumonia due to persistent lymphopenia. In both cases, cytology examination of sputum suggested Pneumocystis Jiroveci pneumonia (PJP). After appropriate antibiotic treatment, the follow-up examination showed complete resolution of the lung changes revealed by FDG-PET. False-positive results on FDG-PET were supposed to be due to the high uptake of FDG in non-neoplastic inflammatory cellular elements such as macrophages and lymphocytes. Our findings suggest that in cases of FDG-PET positive images in immunocompromised patients with previous hematologic disease, caution must be used, and differential diagnosis might include infections such as PJP in addition to relapse of disease.

Molecular modeling approaches in the discovery of new drugs for anti-cancer therapy: the investigation of p53-MDM2 interaction and its inhibition by small molecules

The mdm2 oncogene product, MDM2, is an ubiquitin protein ligase that inhibits the transcriptional activity of the tumor suppressor p53 and promotes its degradation. About 50% of all human cancers present mutations or deletions in the TP53 gene. In the remaining half of all human neoplasias that express the wild-type protein, aberrations of p53 regulators, such as MDM2, account for p53 inhibition. For this reason, designing small-molecule inhibitors of the p53-MDM2 protein-protein interaction is a promising strategy for the treatment of cancers retaining wild-type p53. The development of inhibitors has been challenging. Although many small-molecule MDM2 inhibitors have shown potent in vitro activity, only a limited number of compounds have demonstrated to possess acceptable pharmacokinetic properties for in vivo evaluation. To date, the most studied chemotypes have been cis-imidazolines (such as nutlins), benzodiazepines, and spiro-oxindoles. The cis-imidazolines were the first discovered potent and selective small-molecule inhibitors of the p53-MDM2 interaction and they continue to show therapeutic potential. This review will focus on recent molecular modeling approaches (molecular dynamics, pharmacophore-based, molecular docking, structure-based design) used with the aim to better understand the behavior of these proteins and to discover new small-molecule inhibitors of the p53-MDM2 protein-protein interaction for the treatment of cancer.

Usefulness of 18FDG-positron emission tomography (FDG-PET) for early prediction of erlotinib (Eb) treatment outcome in non-small cell lung cancer (NSCLC) patients: Results of a pilot study

7568

Background: FDG-PET could be useful for early evaluation of tumor response to tyrosine kinase inhibitors (TKI). Glucose metabolic activity seems to closely reflect response to epidermal growth factor receptor (EGFR) TKI in vivo and in vitro (Su H et al, Clin Cancer Res 2006;12:5659–67). Thus, we attempted to assess the clinical value of FDG-PET for early prediction of tumor response to Eb an EGFR-TKI. Methods: Pts with NSCLC stage IV in progression after at least one line of chemotherapy and PS 0–1 were treated with Eb (150 mg orally once daily). FDG-PET was performed on days 0 and 2, after administration of 3 daily doses. FDG uptake was evaluated as the maximum standardized uptake value in the tumor (SUVmax). SUVmax was divided by SUV of the background region (liver) to produce the tumor:nontumor ratio (TNT). FDG-PET responses were evaluated by quantitative changes on TNT and classified according to the EORTC PET study group. PET response were compared with radiographic tumor response (RECIST criteria) assessment based on CT scan at baseline and on day 45. Results: From May 2007, 27 pts were enrolled and 23 were evaluable (4 not-evaluable: 2 BAC PET negative, 2 violations). FDG-PET revealed a metabolic partial response (PR) in 8 pts; subsequent CT scan assessment evidenced 4 PR and 4 long lasting stable disease (SD), respectively. Seven pts had metabolic progressive disease (PD) at PET scan and 8 had SD, all of them presented PD at CT scan. Metabolic PR was associated with a longer median progression-free survival (152 vs 45 days, p = < 0.0001) and longer overall survival (323 vs 128 days p=0.15). For radiological PD pts who presented metabolic SD or PD, survival time was respectively 220 and 117 days. EGFR gene mutation, gene copy number and protein expression are ongoing. Conclusions: FDG-PET using changes on TNT can very early predict (already 2 days after initiation) Eb treatment outcome. Particularly, pts with early metabolic PD are unlikely to benefit from Eb. Therefore, evaluation of the early metabolic response holds promise for assessment of pts selection. The two different behavior of FDG-PET observed on refractory pts, deserve biomolecular analysis for understanding mechanism of resistance.

No significant financial relationships to disclose.

[Chronic osteomyelitis: one-step treatment]

PURPOSE

Chronic osteomyelitis is a surgical disease that require significant dedication from surgeons to eradicate. Osteomyelitis can result from a variety of etiologies but most often is a consequence of trauma (open fractures) to a long bone. This type includes osteomyelitis secondary to a contiguous focus of infection (after trauma and its surgical treatment: osteosynthesis). Here we are reporting one case of post-traumatic chronic osteomyelitis of the humerus.

PATIENTS AND METHODS

A 34-years-old man presented with a post-traumatic chronic osteomyelitis due to an open fractur of the diaphysis humerus. We proposed a one-step surgical treatment, including fistulectomy, sequestrectomy, opening of the proximal and distal intramedullary canal. Antimicrobial therapy should be followed by close observation and treatment with appropriate antibiotics.

RESULTS

A clinical control at 30 days from the intervention revealed that: no secretion; negative cultured exam; second-intention healing of the skin.

CONCLUSIONS

Treatment requires isolation of the pathogens, significant debridement for removal of all infective and necrotic material, both of bone origin and soft-tissue one. Is is necessary not to close the foci: in this way we leave an external drainage, which is able to provide a tissues sterilization by secretion drainage and by the effects of the systemic antimicrobial therapy. Our results indicate that this long-term problem can be solved by a one-stage procedure that provide spontaneous second- healing of the skin defects, excluding the bony and soft tissue reconstruction.

Geographic variation in diapause incidence, life-history traits, and climatic adaptation in Drosophila melanogaster

In Drosophila melanogaster, exposure of females to low temperature and shortened photoperiod can induce the expression of reproductive quiescence or diapause. Diapause expression is highly variable within and among natural populations and has significant effects on life-history profiles, including patterns of longevity, fecundity, and stress resistance. We hypothesized that if diapause expression is associated with overwintering mechanisms and adaptation to temperate environments, the frequency of diapause incidence would exhibit a latitudinal cline among natural populations. Because stress resistance and reproductive traits are also clinal in this species, we also examined how patterns of fecundity and longevity varied with geography and how stress resistance and associated traits differed constitutively between diapause and nondiapause lines. Diapause incidence was shown to vary predictably with latitude, ranging from 35% to 90% among natural populations in the eastern United States Survivorship under starvation stress differed between diapause and nondiapause lines; diapause phenotypes were also distinct for total body triglyceride content and the developmental distribution of oocytes in the ovary following stress exposure. Patterns of longevity, fecundity, and ovariole number also varied with geography. The data suggest that, for North American populations, diapause expression is functionally associated with overwintering mechanisms and may be an integral life-history component in natural populations.

[Current trends and future perspectives in the therapy of the osteoporosis]

Osteoporosis is a pathology of considerable social impact for its high frequency in the elderly and for serious complications of the fragility fracture. Osteoporosis prevention requires high bone mass peak during growth age, adult and elder people must limit the bone loss by taking specific daily behavior and nutritional measures. The pharmacological treatment is based on drugs which are able to change bone metabolism, among which the bisphosphonates result to have a good efficacy with few collateral effects, the last generation (Alendronate and Risedronate) may be taken once a week. Promising for the next future is the Recombinante Parathormon, recently approved from the Food and Drug Administration for osteoporosis treatment. Leptin and l'Osteoprogerin are new experimental molecules under study able to act on the mechanism of central and local regulation of bone remodeling.

High fat fed hamster, a unique animal model for treatment of diabetic dyslipidemia with peroxisome proliferator activated receptor alpha selective agonists

Dyslipidemia, a major risk factor for cardiovascular disease, may be directly linked to diabetic hyperglycemia and insulin resistance. An appropriate dyslipidemic animal model that has diabetes would provide an important tool for research on the treatment of diabetic dyslipidemia. Ten days of high fat feeding in golden Syrian hamsters resulted in a significant increase in insulin resistance and baseline serum lipid levels accompanied by a pronounced dyslipidemia. Thirteen days of treatment with fenofibrate, a peroxisome proliferator-activated receptor alpha (PPARalpha) selective agonist, produced a dose-dependent decrease in serum lipid levels. The pattern observed was characterized by lowered very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) and raised high-density lipoprotein (HDL) cholesterol in a fashion similar to that seen in man. Diabetic conditions were also significantly improved by fenofibrate with a normalization of impaired glucose tolerance and an improvement of insulin sensitivity during an oral glucose tolerance test. These data suggest that fenofibrate may correct not only the dyslipidemia but also the insulin resistance caused by a high fat diet, and the high fat fed hamster may be a good animal model for research on the treatment of diabetic dyslipidemia with PPARalpha selective agonists.

PPARalpha agonists reduce 11beta-hydroxysteroid dehydrogenase type 1 in the liver

11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) is an enzyme that converts cortisone to the active glucocorticoid, cortisol. Cortisol-cortisone interconversion plays a key role in the regulation of glucose metabolism, since mice deficient in 11betaHSD1 are resistant to diet-induced hyperglycemia. Peroxisome proliferator activator receptors (PPAR) are key regulators of glucose and lipid homeostasis. We observed a striking downregulation of murine hepatic 11betaHSD1 expression and activity after chronic treatment of wild-type mice with PPARalpha agonists, while 11betaHSD1 in the livers of PPARalpha knockout mice, or in mice treated for only 7 h with PPARalpha agonists, was unaltered. Our results are the first to show PPARalpha agonists can affect glucocorticoid metabolism in the liver by altering 11betaHSD1 expression after chronic treatment. Regulation of active glucocorticoid levels in the liver by PPARalpha agonists may in turn affect glucose metabolism, consistent with reports of their antidiabetic effects.

Lack of prognostic value of 99mTc MIBI rest, 18F FDG and 201TL rest/redistribution on PTCA outcome of patients with moderate left ventricle dysfunction

BACKGROUND

The clinical work-out of patients undergoing coronary revascularization includes the assessment of myocardial viability. This approach has to be defined in the different classes of patients. The aim of this study was to evaluate the predictive prognostic value of different techniques on outcome following PTCA in patients with moderate left ventricle dysfunction (left ventricle EF > or = 40%).

METHODS

Seventeen patients with EF > or = 40% and undergoing PTCA were studied by 201Tl rest/redistribution, 18F-FDG and 99mTc-MIBI rest. Regional kinesis was scored by echo, dividing left ventricle in 11 segments. The echo evaluation was repeated at 1 and 6 months after revascularization.

RESULTS

Global EF was 52.5 +/- 7% and 69 segments had abnormal kinesis. Patients underwent stress/rest 99mTc-MIBI SPET, rest/redistribution 201Tl SPET and rest 18F-FDG PET. Among the 11 segments defined on echo-matched tomographic images, the one with the highest activity at stress was assumed as reference (activity = 100%). If > 50% of reference segment, 18F-FDG and 201Tl uptakes were considered significant. After PTCA, the echo-follow-up did not demonstrated significant improvement of left ventricle function at 30 days after PTCA (EF 56 +/- 6%) as well as at 6 months (EF 56 +/- 9%). The positive predictive value under these conditions resulted: 46.5% with 99mTc-MIBI rest, 47.4% with 201Tl rest-redistribution and 45.7% with 18F-FDG.

CONCLUSIONS

In summary, in the class of patients with moderately compromised function, considering as reference the improved regional kinesis after PTCA, 99mTc-MIBI at rest, 201Tl rest/redistribution and 18F-FDG do not exhibit a clear predictive value; patient population is then a highly relevant point to establish the accuracy of these diagnostic procedures.

[Correction measured by attenuation in tomographic heart studies with single photon emission with thallium 201. Comparison with positron- emission tomographic studies with ammonium marked with nitrogen]

PURPOSE

We investigated 201Tl myocardial uptake with(out) nonuniform attenuation compensation in ischemic myocardiopathy patients. The segmental patterns of the two types of SPECT images were compared with PET [13N]NH3 studies performed in the same patient. PET images were taken as reference and the diagnostic accuracy of SPECT with(out) attenuation correction was evaluated.

MATERIAL AND METHODS

During the SPECT study transmission and emission data were simultaneously recorded by a triple head gamma camera equipped with fan beam collimators and a 99mTc transmission line source (740MBq). SPECT and PET images, the former reconstructed with(out) attenuation correction, were corecorded and reoriented along the short axis. The left ventricular wall was divided into 11 segments and segmental activity normalized to maximum in each study.

RESULTS

Statistically significant differences were found between PET/(un)corrected SPECT ratios in posterior and septal segments. In these myocardial regions, attenuation correction compensates for attenuation artifacts, by correcting the underestimation of radioactivity concentration caused by radiation absorption. A statistically significant difference was also found in midventricular anterior and apical segments (p < .05). However, in these regions attenuation correction results in a decrease in corrected relative to uncorrected SPECT activity. The agreement rate with PET data is higher for corrected SPECT (mean differences were 3.12 +/- 11.51 and 2.19 +/- 8.63 for uncorrected versus corrected SPET). We had 50% positive and 77% negative predictive value without attenuation correction, versus up to 69% and 90%, respectively, with attenuation correction.

CONCLUSIONS

The attenuation correction procedure with simultaneous transmission-emission effectively reduces attenuation artifacts in SPECT myocardial imaging. While diagnostic accuracy increases in posterior and septal myocardial regions, anterior and apical data need careful interpretation because a relative decrease in radioactivity concentration can be observed after attenuation correction.