Francis Dubois

Preliminary Study of the Deposition of Aerosol in the Maxillary Sinuses Using a Plastinated Model

In spite of the widespread use of aerosols in respiratory diseases, very few studies have been performed in the field of ear, nose, and throat (ENT) disorders. The conditions for penetration of aerosols inside the sinus cavities are thus still not understood fully. The aim of this study was to investigate the penetration of aerosols inside maxillary sinuses in vitro, using plastinated models. Three plastinated specimens of the nose and sinuses were made from three different corpses. These specimens were validated by CT scans and were used to study deposition of aerosol in the maxillary sinuses. We performed scintigraphic images of the models in above, face, and profile views using a technetium (99mTc)-labelled solution to show aerosol deposition. We also counted the radioactivity deposited on gauze compresses placed inside the maxillary sinuses. In addition, we constructed a measuring unit with miniature humidity sensors placed inside the sinuses. We recorded the changes in relative humidity observed during nebulization. Results from these studies showed that scintigraphic images of the specimen, whatever the incidence of the views, were not accurate enough to differentiate the aerosol deposition in the maxillary sinuses from that in the nasal cavity. Using indirect counting on gauze compresses made possible the quantification of local aerosol deposition, and we found that aerosols entered into the sinuses. This confirmed that aerosols could reach the middle meatus, which is the main area for sinusitis disorders. The increased activity compared to background varied from 17 to 127%. The humidity sensors recorded changes in relative humidity during the nebulization. These humidity changes fitted a nonlinear model represented by the equation: y = b0 (1 - e(-b1t)), where b0 is the plateau and b1 is the speed to reach the plateau. These techniques may be useful in the future for in vitro characterization of aerosol penetration into the maxillary sinuses.

Evidence that 99mTc-(V)-DMSA uptake is mediated by NaPi cotransporter type III in tumour cell lines

In vivo studies have demonstrated that pentavalent technetium-99m dimercaptosuccinic acid [99mTc-(V)-DMSA] may be a useful tumour imaging agent. Several studies have suggested that 99mTc-(V)-DMSA uptake may be related to the structural similarity between the 99mTc-(V)-DMSA core and the PO43– anion. As phosphate ions enter cells via NaPi cotransporters, we investigated whether 99mTc-(V)-DMSA uptake is mediated by NaPi cotransporters. 99mTc-(V)-DMSA and phosphate uptake kinetics were compared in three cancer cell lines (MCF-7, G152 and MG-63) under several conditions (with and without sodium and NaPi cotransporter inhibitor and at different pH). Determination of molecular NaPi cotransporter mRNA expression was performed by reverse-transcriptase polymerase chain reaction (Rt-PCR) assay. Results obtained in the presence of NaPi inhibitor, in sodium-free medium and at alkaline pH showed that 99mTc-(V)-DMSA accumulation is linked to NaPi cotransporter functionality. MCF-7 and G152 exhibited the same tracer uptake, whereas MG-63 showed the highest phosphate accumulation and the lowest 99mTc-(V)-DMSA uptake. These results were in accordance with mRNA NaPi expression, i.e. all cell lines expressed NaPi type III but MG-63 also co-expressed NaPi type I. The total level of NaPi cotransporter was highly correlated with phosphate accumulation, while the level of type III was related to 99mTc-(V)-DMSA uptake. We have demonstrated that 99mTc-(V)-DMSA uptake is specifically mediated by NaPi type III in cancer cells.

Correlation between 99mTc-(V)-DMSA uptake and constitutive level of phosphorylated focal adhesion kinase in an in vitro model of cancer cell lines.

PurposeAlthough a number of prognostic indicators have been developed, it is still difficult to predict the biological behaviour of all cancer types. 99mTc-(V)-DMSA (V DMSA) uptake and focal adhesion kinase (FAK) expression and activation level could be potential agents for this purpose. We hypothesised the existence of a correlation between V DMSA, whose uptake is linked to phosphate ions, essential compounds for tumour growth and cell proliferation, and the adhesion protein FAK, whose elevated expression and level of constitutive activation are implicated in cancer progression. The aim of this study was to assess the relationship between V DMSA incorporation rate and FAK expression and activation by phosphorylation on tyrosine 397 residue.MethodsWe determined V DMSA uptake in six different cancer cell lines and we measured FAK expression and activation by using Western Blotting analysis. Correlations with factors known to be associated with poor prognosis, such as invasive potential, resistance to chemotherapy and proliferation rate, were also investigated. ResultsThe cell lines exhibited different V DMSA incorporation rates. In addition, these cells showed the same FAK expression, but various degrees of activation. A correlation was observed between V DMSA uptake and level of FAK phosphorylation and between V DMSA or constitutive FAK activation and proliferation rate. However, no correlation was shown between these parameters and the other factors tested, i.e. invasive potential and anticancer drug resistance.ConclusionThe results of this in vitro study clearly demonstrate that phosphorylation of FAK, proliferation rate and V DMSA uptake are closely related. Because proliferation and a high level of constitutive FAK activation are linked to cancer progression, it can be assumed that in vivo V DMSA uptake reflects tumour aggressiveness.

Contribution of cholescintigraphy to the early diagnosis of acute acalculous cholecystitis in intensive-care-unit patients

Abstract. Thirty-two intensive care unit patients (78% on long-term total parenteral nutrition) suspected of having acute acalculous cholecystitis (AAC) were studied prospectively. All of these patients underwent abdominal ultrasonography and cholescintigraphy with technetium-99m mebrofenin. Morphine sulphate (0.04 mg/kg) was administered only if the gallbladder was not visualised after 1 h (16 patients). The final diagnosis was reached after clinical improvement, or upon the discovery of another aetiology for the symptoms presented, or on the basis of histopathology following cholecystectomy (when this was performed). We analysed the contribution of individual cholescintigraphic findings (I: non-visualisation of the gallbladder during the first 60 min of the examination; II: persistent non-visualisation of the gallbladder 30 min following morphine administration; III: non-visualisation of the small bowel for at least 90 min) and their various combinations. We obtained a sensitivity of 79% and a specificity rate 100% using the interpretative criteria ”I and II or III”. Excluding obstructive syndrome (”I and II”), the sensitivity and specificity figures were 70% and 100% respectively (28 patients). We had no false-positive results in our patient population. Cholescintigraphy was found to complement ultrasonography, which had either good sensitivity (93%) and poor specificity (17%), when at least two of the three major signs were present (sludge, thickened wall, gallbladder distension), or poor sensitivity (36%) and good specificity (89%) when all three signs were present. We conclude that cholescintigraphy is a useful tool for early diagnosis of AAC in critically ill patients, in whom ultrasonography alone does not provide enough information to permit a sufficiently early decision regarding the use of surgery.

Could 99mTc-glucarate be used to evaluate tumour necrosis? In vitro and in vivo studies in leukaemic tumour cell line U937.

PurposeThe aim of this study was to determine whether 99mTc-glucarate (99mTc-GLA) is a powerful and discriminant tumour necrosis marker.Materials and methodsThe induction of apoptosis and secondary necrosis (by a chemotherapeutic agent) and necrosis (by intense hyperthermia) was studied on an in vitro and in vivo leukaemic cell line model (U937). The percentage of apoptosis/necrosis in vitro was determined by flow cytometry after staining cells with annexin-V-fluorescein/propidium iodide. The uptake of 99mTc-GLA was studied after treatments that produce an optimal of necrosis cells or apoptotic cells. Three populations of interest: viable, apoptotic and necrotic cells were sorted by flow cytometry. The uptake and the intracellular distribution of 99mTc-GLA on each population have been studied. We also investigated the influence of necrosis on 99mTc-GLA uptake in a model of U937 xenografts in nude mice.ResultsThe accumulation of 99mTc-GLA in untreated and apoptotic cells was lower than in necrotic cells. Cell sorting discriminated each cellular population and showed a 14% accumulation in necrotic cells and no more than a 3% in apoptotic cells. In apoptotic and viable cells, 99mTc-GLA is distributed between the cytosolic/membrane and the nucleus fractions. In necrotic cells, 99mTc-GLA is mainly found in the nucleus fraction. In vivo investigations showed a higher 99mTc-GLA uptake in necrotic tumour than in apoptotic and control ones.Conclusions99mTc-GLA may be a useful agent to specifically evaluate tumour necrosis and may be helpful for the follow-up of patients with cancer.

Sonic aerosol therapy to target maxillary sinuses

AIM Intranasal aerosol administration of drugs is widely used by ENT specialists. Although clinical evidence is still lacking, intranasal nebulization appears to be an interesting therapeutic option for local drug delivery, targeting anatomic sites beyond the nasal valve. The sonic nebulizer NL11SN associates a 100Hertz (Hz) sound to the aerosolization to improve deposition in the nasal/paranasal sinuses. The aim of the present study was: to evaluate in vivo the influence of associating a 100Hz sound on sinus ventilation and nasal and pulmonary aerosol deposition in normal volunteers, and; to quantify in vitro aerosol deposition in the maxillary sinuses in a plastinated head model. MATERIAL AND METHODS Scintigraphic analysis of (81m)Kr gas ventilation and of sonic aerosol ((99m)Tc-DTPA) deposition using the NL11SN was performed in vivo in seven healthy volunteers. In parallel, NL11SN gentamicin nebulization was performed, with or without associated 100Hz sound, in a plastinated human head model; the gross amount of gentamicin delivered to the paranasal sinuses was determined by fluorescence polarization immunoassay. RESULTS Associating the 100Hz sound to (81m)Kr gas ensured paranasal sinus ventilation in healthy volunteers. (99m)Tc-DTPA particles nebulized with the NL11SN were deposited predominantly in the nasal cavities (2/3, vs 1/3 in the lungs). In vitro, the use of NL11SN in sonic mode increased gentamicin deposition threefold in the plastinated model sinuses (P<0.002); the resulting antibiotic deposit would be sufficient to induce a local therapeutic effect. CONCLUSION The NL11SN nebulizer ensured preferential nasal cavity aerosol deposition and successfully targeted the maxillary sinuses.

Preoperative combined 18-fluorodeoxyglucose positron emission tomography and computed tomography imaging in head and neck cancer: does it really improve initial N staging?

Abstract Conclusion: In our experience PET-CT cannot yet reliably predict the need for surgical neck dissection in patients with N0 neck. According to the results of PET-CT the neck dissection should be extended towards unusual lymph node areas. Objective: To analyze the value of PET-CT for the initial N staging, comparing PET-CT data with histopathological results of the modified radical neck dissection. Methods: Fifty patients with previously untreated head and neck squamous cell carcinoma were eligible for inclusion in this study. Modified radical unilateral or bilateral neck dissection was performed in all patients. PET-CT findings and histological findings were compared to determine their diagnostic sensitivity, specificity, accuracy, positive predictive value, and negative predictive value. Results: In all, 105 levels had pathologically diagnosed metastases: PET-CT was positive in 87 levels and negative in 18 levels. Also, 399 levels had negative postoperative histology findings: PET-CT was positive in 24 levels and negative in 375 levels. The false-positive over-staged and the false-negative under-staged rates were 27% and 12%, respectively.

Involvement of the glutathione S-conjugate compounds and the MRP protein in Tc-99m-tetrofosmin and Tc-99m-sestamibi uptake in glioma cell lines

The objective of this study was to compare the accumulation of Tc-99m-tetrofosmin and Tc-99m-sestamibi in four grade IV glioma cell lines and to correlate their accumulation with the multidrug resistance of the cells. Tc-99m-tetrofosmin in all glioma cell lines showed slightly higher uptake and more efficient release beyond 150 min than Tc-99m-sestamibi and the retention of both tracers in the cells was to a certain extend inversely proportional to their degree of multidrug resistance. The results obtained showed that the efflux of both tracers was carried out only in part through the MRP/GS-X pump system. Tc-99m-tetrofosmin showed good potential as a marker of recurrent malignant glioma and in vivo studies are currently underway to confirm these observations.

The role of technetium-99m sestamibi single photon emission tomography in the follow-up of malignant melanoma and the detection of lymph node metastases.

Abstract. In the follow-up of patients with malignant melanoma treated by surgical resection of the cutaneous tumour, it is important to achieve early detection of possible lymph node metastasis. In many cases, clinical examination alone will not be sufficient. In our study, single-photon emission tomography (SPET) with technetium-99m sestamibi (MIBI) was used in the assessment of 30 patients with previously resected malignant melanoma when the clinical examination raised the suspicion of lymph node metastasis. Using MIBI, 16 out of 17 lymph node metastases were detected and confirmed by histology. No false-positive results were obtained during this prospective study. It is concluded that MIBI scintigraphy may be useful in the early detection of lymph node metastases of malignant melanomas. If our preliminary results are confirmed, early detection of lymph node metastasis of previously resected malignant melanoma by 99mTc-MIBI scintigraphy may have a significant impact on the management of these patients.

Spectrum of Radiopharmaceuticals in Nuclear Oncology

A major field of interest in nuclear medicine is in vivo tumor characterization and measurement of biological processes at cellular and molecular levels by means of positron emission tomography (PET) or single photon emission computed tomography (SPECT). Functional imaging with radiopharmaceuticals represents a useful noninvasive tool to evaluate the biological status of the tumor and its progression. The properties of radiopharmaceuticals are exploited for initial staging of cancer, assessment of recurrent or residual disease and, more recently, considerable progress has been made in the field of the evaluation of tumor response to treatment. PET and SPECT can both detect changes in tumor activity caused by therapy or disease progression before any detectable change in tumor volume. Measurement of tumor response to therapy using PET and SPECT is the subject of intense investigations because it may result in individualization of treatment and may have a prognostic value for long-term outcome. This review focuses on the various methods used to monitor anticancer therapy with a variety of clinically approved or investigational tracers. We summarize the mechanisms of radiopharmaceutical uptake based on certain physiological activities affected by treatment: proliferation, apoptosis, hypoxia, angiogenesis and multidrug resistance (MDR).