Validation of a dendron concept to tune colloidal stability, MRI relaxivity and bioelimination of functional nanoparticles

A dendritic coating induces colloidal stability of nanoparticles through electrostatic and steric interactions.

Multi-luminescent hybrid gadolinium oxide nanoparticles as potential cell labeling

This manuscript analyses the use of newly developed hybrid gadolinium oxide nanoparticles as cell-labeling tracers. The nanoparticles are core-shell particles composed of a core of gadolinium oxide of [2-4] nm and a protecting shell of polysiloxane [1-3 nm] where different organic dyes (fluoresceine isothiocyanate (FITC) or rhodamine B isothiocyanate (RBITC)) are embedded. They are functionalized with poly(ethylene glycol)bis(carboxymethyl) to ensure their colloidal stability in biological buffers. These particles are potential multi-labeling tracers (magnetic and optical). In this paper, we show by optical imaging that they can be efficiently internalized in cells without cell alteration. The in-vitro uptake of the nanoparticles was followed in two cell lines (human fibroblasts and a human adenocarnima cell lines MCF7 cells). Nanoparticles distribution within cells was analysed by confocal analysis, and gadolinium concentration within cells was quantified by mass spectrometry (ICP-MS analysis). Nanoparticles uptake is found to be fast and efficient for both cell lines, with fluorescent labeling visible after 10 min of incubation whatever the nature of the fluorophore. The fluorescent intensity is mainly found as concentrated dots in the perinuclear region of the cells and decreases with the number of days in culture, but is still easily detectable after 3 days in culture. No significant effect on cell growth was detected. Finally, we show in this study the protective effect of the polysiloxane layer: encapsulation of RBITC within the polysiloxane shell, leads to a better photostability of this low cost dye than Cy3 and even reach a level comparable to Alexa 595. With their high photostability and long-lasting contrast properties, these hybrid luminescent nanoparticles appears thus as a versatile solution to assess multiple cell fate both in in-vitro cell model as well as in-vivo.

Apport de la tomographie par émission de positons pour le diagnostic de sarcoïdose au cours d'une myopathie granulomateuse

INTRODUCTION

Granulomatous myositis is a rare condition that has been described in association with sarcoidosis. In the absence of sarcoidosis or other underlying disease, a diagnosis of isolated granulomatous myositis is considered.

OBSERVATION

A 61-year-old African man presented with progressive limitation in running and proximal atrophy of the lower limbs for the past year. Quadricipital muscle biopsy revealed non-caseating epithelioid granulomas and multinuclear giant cells. Whole body fluorodeoxyglucose positron emission tomography ((18)FDG-PET) revealed hypermetabolic activity of salivary and lachrymal glands, and mild hypermetabolism in the mediastinal lymph nodes. Minor salivary gland biopsy was consistent with sarcoidosis.

CONCLUSION

To our knowledge, this is the first reported case of sarcoid myopathy demonstrating the diagnostic usefulness of (18)FDG-PET.

[Feasibility and technical problems of sentinel node analysis in melanoma]

BACKGROUND

Development of the sentinel lymph node (SLN) biopsy the last 10 years has changed surgical approach of solid tumor treatment and particularly of melanoma. The aim of our study was to analyze in our hospital, the feasibility of the SLN biopsy technique in order to define a better prognostic classification of melanomas.

PATIENTS AND METHODS

Between July 1999 and October 2003, 97 patients were included in this study in our center. Criteria for inclusion were cutaneo-mucosal melanoma of Breslow >or=1,5 mm, and/or Clarck >or=IV, and/or ulceration, and/or signs of regression, before any surgical margins.

RESULTS

Lymphoscintigraphy (LS) identified at least 1 SLN in 94 cases/97 (97%), thus permitting intraoperative SLN mapping and sentinel node biopsy of at least 1 lymph node in 88 cases/94 (94%). Failure of the SLN procedure was noted in 9 cases: in 3 cases, no lymph node was individualized by LS, in 1 patient, intraoperative SLN mapping failed to find the previously identified SLN and in 5 cases, a SLN was identified by LS and intraoperative mapping but could not be removed because of its deep location and difficulty of dissection. In 17 patients, removal of one or two "non sentinel lymph node(s)" was (were) made by the surgeon because of its (their) suspected aspect (black or large). Among the 88 patients who had dissection of at least 1 SLN, a micrometastasis was detected by standard histological evaluation and/or immunohistochemical stains in 14 cases (16%) and into a "non SLN" in 2 cases (2,3%). The median follow up of patients was 16 months (1- 48 months). Among the 14 patients with positive SLN, 6 (43%) relapsed. The other eight were in complete remission of their melanoma with a mean follow up of 11,44 months . Among the 74 patients with negative SLN, 7 (9,5%) developed a recurrence. Among the 9 patients in whom any sentinel lymph node have been removed, 3 had a relapse (one in transit than on lymph nodes, and two on lymph nodes).

CONCLUSION

Our results are in accordance with the literature, and confirm the feasibility of SLN mapping and of SLN histological analysis in our center. We described in this study technical problems we encountered. Our study also show the prognostic value of this technique. However, advantage in global survey of sentinel node dissection and regional lymph node dissection in cases of micrometastases has still to be demonstrated.

Cell internalization of anionic maghemite nanoparticles: quantitative effect on magnetic resonance imaging

Anionic iron oxide nanoparticles are efficiently internalized into macrophages where they concentrate within micrometric endosomes, conferring on them a high magnetic susceptibility. The uptake of anionic maghemite nanoparticles by macrophages was quantified by an electron spin resonance (ESR) experiment. MR spin-echo sequences were performed with various TEs and TRs. The contrast enhancement was compared between two types of agarose phantoms with the same equivalent ferrite concentrations but containing either dispersed isolated nanoparticles or magnetically labeled macrophages. It is shown that the intracellular confinement of maghemite nanoparticles within micrometric endosomes results in a significant decrease of the longitudinal relaxivity and a moderate decrease of the transverse relaxivity compared to the relaxivities of the dispersed isolated nanoparticles. As a consequence, the signature of endosomal magnetic labeling consists of a negative contrast on T(1)-weighted images in the whole ferrite concentration range, whereas the presence of extracellular isolated nanoparticles can result in a positive enhancement.

Intracellular uptake of anionic superparamagnetic nanoparticles as a function of their surface coating

A new class of superparamagnetic nanoparticles bearing negative surface charges is presented. These anionic nanoparticles show a high affinity for the cell membrane and, as a consequence, are captured by cells with an efficiency three orders of magnitude higher than the widely used dextran-coated iron oxide nanoparticles. The surface coating of anionic particle with albumin strongly reduces the non specific interactions with the plasma membrane as well as the overall cell uptake and at the same time restores the ability to induce specific interactions with targeted cells by the coadsorption on the particle surface of a specific ligand. Kinetics of cellular particle uptake for different cell lines are quantitated using two new complementary assays (Magnetophoresis and Electron Spin Resonance).

In vivo model mimicking natural history of dog prostate cancer using DPC-1, a new canine prostate carcinoma cell line

BACKGROUND

Dog prostate cancer is usually considered to be highly relevant to human prostate cancer. We report the isolation of a new canine prostate cancer epithelial cell line designated DPC-1.

METHODS

Primary cultures were established from a canine poorly differentiated prostatic adenocarcinoma. Population doubling time was determined by counting nuclei after cell lysis. Tumorigenicity was assessed in nude mice and in one adult immunodeficient dog. Immunoscintigraphy was performed in both models using a monoclonal antibody (mAb) raised against the [44-62] sequence of human PSMA.

RESULTS

DPC-1 cells have a rapid growth in vitro (doubling time, 27 hr) which is not stimulated by androgens. In addition, DPC-1 displays immunoreactivity to human PSA and PSMA. DPC-1 was found to be highly tumorigenic not only in nude mice but also for the first time after orthotopic seeding in an immunodeficient dog. This allograft mimicked, in a compressed form, the aggressive biological behavior of spontaneous dog prostate adenocarcinoma. Immunoscintigraphy using a (131)Iodine-labeled PSMA mAb clearly visualized induced tumors in nude mice and in the dog allograft.

CONCLUSIONS

This study suggests that DPC-1 may constitute a powerful model for assessing new diagnostic and/or therapeutic tools in the management of prostate cancer.

Reoperation for secondary uremic hyperparathyroidism: are technical difficulties influenced by initial surgical procedure?

BACKGROUND

Parathyroid surgery in patients with uremia and secondary hyperparathyroidism is performed either by subtotal parathyroidectomy or total parathyroidectomy with immediate reimplantation. The aim of this study was to compare the results of reoperation for persistent or recurrent hyperparathyroidism after parathyroidectomy according to which initial operative procedure was used.

PATIENTS AND METHODS

Eighty-nine patients had reoperation for persistent (28 patients) or recurrent (61 patients) hyperparathyroidism after 53 subtotal parathyroidectomies and 36 total parathyroidectomies with immediate reimplantation. Results of the reoperation were assessed in terms of success rate, morbidity, and operative findings.

RESULTS

The success rate of reoperation in patients with persistent hyperparathyroidism was 89% and was independent of the initial type of surgery. Success rates of reoperation for recurrent hyperparathyroidism after initial subtotal parathyroidectomy and total parathyroidectomy with immediate reimplantation were 87% and 70%, respectively (P = .02). Hypertrophy of the parathyroid remnant was the main cause of recurrence after subtotal parathyroidectomy. After total parathyroidectomy with immediate reimplantation, recurrence was located in the graft in half the patients, while hyperplastic tissue was found in the neck or the mediastinum in the other half.

CONCLUSIONS

Subtotal parathyroidectomy provides the best conditions for successful reoperation in case of recurrent hyperparathyroidism and should become the surgical treatment of choice for secondary hyperparathyroidism.

Successful surgical removal of occult metastases of medullary thyroid carcinoma recurrences with the help of immunoscintigraphy and radioimmunoguided surgery

Patients with recurrent or metastatic medullary thyroid carcinoma (MTC) were referred for pretargeted immunoscintigraphy (Affinity Enhancement System; AES) and radioimmunoguided surgery (RIGS). Data collected from 13 patients establish that whole-body AES immunoscintigraphy revealed metastases < 360 mg and RIGS detected micrometastases (5-15 mg). All tissue samples removed by the surgeon were diagnosed by histology and immunohistochemistry of calcitonin to check the accuracy of IS and RIGS results. AES immunoscintigraphy is very sensitive. Of 34 metastases or recurrences detected, 22 had escaped physical examination or conventional imaging. The accuracy of RIGS was 86%, its sensitivity 75%, and its specificity was 90% (n = 208). IS and RIGS detected occult tumors that would have escaped surgery, clearly demonstrating clinical benefit. Serum calcitonin (normal, 10 pg/ml) and carcinoembryonic antigen (normal, 5 ng/ml) of two patients were restored to normal. In patients whose tumors were discovered, progression of their disease was slowed, as evidenced by the large decrease in serum calcitonin and carcinoembryonic antigen, an important prognostic factor. Surgery was canceled in one case where IS detected distant metastases out of surgical reach. Thus, AES immunoscintigraphy and RIGS might be of valuable help for the surgical management of medullary thyroid carcinoma.

Cervicomediastinal magnetic resonance imaging in persistent or recurrent papillary thyroid carcinoma: clinical use and limits

Cervicomediastinal magnetic resonance imaging (MRI) was evaluated in 13 consecutive persistent or recurrent papillary thyroid carcinoma (PTC) patients, previously treated by total thyroidectomy and radioiodine ablation. All had elevated thyroglobulin (Tg) levels and were therefore submitted to a new therapeutic radioiodine dose followed by a posttherapeutic whole-body scan (131I-WBS) and subsequent MRI. Patients with known distant metastases were excluded from the study. Group 1 included 7 patients with a negative 131I-WBS, whereas cervical and/or mediastinal 131I-uptake was evidenced in the other 6 patients (group 2). MRI was thus compared to 131I-WBS, and additionally in 8 reoperated cases, to histology. MRI was positive in 11 of 13 (85%) patients, corresponding to 23 of 55 (41.8%) histologically confirmed sites. In group 1, MRI was positive in 5 of 7 patients, with a sensitivity of 47% (15/32 histologically positive sites), allowing appropriate indication of surgery: 4 neck surgery, and 1 mediastinal dissection because of too distant lymph node foci. In group 2, MRI always showed more localization than 131I-WBS; histology was obtained in 3. Because all the foci located in the mediastinal area (0.8 to 1.8 cm) were histologically confirmed (7/7 sites), MRI avoided underestimation of surgery in the 8 reoperated patients. However, additional images were also observed corresponding to a normal thymus, a small neuroma or inflammatory lymph nodes, but pretracheal and very small nodes (less than 0.5 cm) were missed. In conclusion, although less specific than radioiodine scintigraphy, MRI can detect local persistent or recurrent PTC, and seems particularly effective for evaluation of mediastinal involvement.

[Bilateral scrotal panniculitis in a prepubescent child]

Scrotal panniculitis or scrotal fat necrosis is an uncommon acute scrotal pathology. We report a case of scrotal fat necrosis in a 9 1/2 year-old over-weight boy with bilateral tender scrotal masses, located beneath the tests. Pathologic findings were those of subcutaneous fatty indurated masses with lipogranulomatous foci. The etiology of scrotal fat necrosis is unknown. A similar condition has been described in young children exposed to cold. In obese prepubescent boys, a greater sensitivity to cold and a higher saturated fatty acid concentration of the scrotal adipose tissue would induce fat necrosis. Our study of fatty acid composition by gas-liquid chromatography showed an elevation of stearic acid. The spontaneous resolution of scrotal fat necrosis is always the rule and allows symptomatic treatment without surgical investigation.

Epidemiological data in polycythaemia vera: a study of 842 cases

An epidemiological study of 842 polycythaemic patients (entered between 1980 and 1997 in the French investigational prospective protocols) is presented. The global incidence is approximately 0.8-1.5/100,000/year in the reference area (Ile-de-France and surrounding areas). It increases linearly with age until 80, which suggests that several mutational somatic events are necessary. There was a slight male excess (sex-ratio 1.2, after correction for the percentage of male and female French people still living at risk). We did observe a slight excess of PV in the population of Jewish ancestry. A surprising excess of former blood donors (20.7% of the PV cases, compared to 8% estimated in the reference population) was observed. Only a few cases of familial myeloproliferative diseases and occurence of leukemia in the family of our patients have been observed; even if slight, this excess is statistically significant. In contrast, no excess of carcinomas was observed either in the family or in the patients' antecedents. We did not find any excess of radiation exposure in our cases. When analysing the previous occupation of our patients a possible excess of physicians and of patients previously working in occupations using solvents and glues was found, but this finding needs confirmation.

[Radioimmunotherapy of lymphomas and leukemias]

Radioimmunotherapy offers an exciting new therapeutic modalities for patients with recurrent hematologic malignancies or resistant to conventional chemotherapy. Clinical trials involving hematologic malignancies have produced more impressive results than these involving solid tumors. In recurrent non Hodgkin's lymphoma Seattle trials have demonstrated objective responses in 90% of patients, complete responses in 85% of patients, a progression free survival of 62%, and an overall survival of 93% with a median follow-up of 2 years. In recurrent acute myelogenous leukemia, or myelodysplasia treated with radiolabeled antibodies, total body irradiation, and high dose chemotherapy 67% of patients remain disease free with a median follow-up of 33 months.

Red cell and platelet kinetics in chronic cytopenias following transplantation

Thirty seven patients with unexplained anemia and/or thrombocytopenia after bone marrow, kidney, liver or heart transplantation were referred to the Department of Nuclear Medicine for erythrocyte or platelet kinetic studies in order to determine the mechanism of the cytopenia: accelerated destruction, or production defect. We observed only one definite case of thrombocytopenia due to accelerated autologous platelet destruction, while the life span was normal in the other 16 cases. Anemia was due to accelerated hemolysis in 7 cases, while the red blood cell life-span was normal in 12 other cases. Kinetic studies can therefore be useful, by demonstrating the mechanism of cytopenia observed after transplantation, and by facilitating the choice of appropriate treatment.

The site of destruction of autologous 111In-labelled platelets and the efficiency of splenectomy in children and adults with idiopathic thrombocytopenic purpura: a study of 578 patients with 268 splenectomies

The indication for splenectomy in chronic idiopathic thrombocytopenic purpura (ITP) remains a controversial subject. The mortality rate of persistent thrombocytopenia is very low, except in severe cases. Conversely, the risks of splenectomy are significant (in the present series, morbidity: 4.1% mortality: 1.4%), with a success rate of only 60-75%. It is therefore useful to define a parameter able to predict the efficacy or failure of splenectomy. An analysis of 578 cases of chronic ITP, where the site of platelet destruction has been determined, is presented. 268 of these cases had been splenectomized. When platelet destruction was splenic, 96% of subjects aged 5-30 years and 91% of cases over the age of 30 years obtained a remission. Conversely, when platelet destruction was hepatic or diffuse, failure or incomplete results were observed in 92% of cases. The site of platelet destruction therefore constitutes a parameter which can help the clinician to make the decision to perform splenectomy.

Early localization and reoperation for persistent primary hyperparathyroidism

BACKGROUND

Reoperation for persistent primary hyperparathyroidism is often performed after a delay of 4-6 months. Success can be expected in over 90 per cent of cases but exploration is technically difficult and there is the possibility of creating permanent hypoparathyroidism and vocal cord paralysis. This is a study of early localization and reoperation.

METHODS

In a consecutive series of 273 patients who had surgery for primary hyperparathyroidism, three remained hypercalcaemic and in three the abnormal parathyroid was not found at initial exploration. They underwent early (6-48 h) single-tracer 99mTc Sestamibi scintigraphy with factor analysis of dynamic structures (FADS) and single photon emission computed tomography (SPECT) followed by reoperation within 24-72 h.

RESULTS

Scintigraphy with FADS and SPECT was helpful in all six patients, who were cured by reoperation with no morbidity or symptomatic hypocalcaemia.

CONCLUSION

Reoperation for persistent primary hyperparathyroidism is possible and may be easier within days of an initially unsuccessful procedure. With the intact 1-84 parathyroid hormone measurement, the diagnosis is accurate. Single-tracer 99mTc Sestamibi scintigraphy with FADS and SPECT is non-invasive, easily and rapidly performed, and was accurate in these six patients.

Advantages of SPECT in technetium-99m-sestamibi parathyroid scintigraphy

We demonstrate several advantages of SPECT in parathyroid scintigraphy.

METHODS

Forty-four parathyroid 99mTc-MIBI scintigrams were obtained before surgery in 43 patients suffering from hyperparathyroidism. For each patient, we obtained dynamic views and planar and SPECT images of the neck and thorax. For 15 patients, we also acquired a delayed static view of the neck 2 hr after tracer injection. Abnormal thyroid-area glands were detected with factor analysis of dynamic structure (FADS) of the initial dynamic acquisition. In the 15 patients with delayed views of the neck, we compared FADS and the double-phase study results to detect glands in the thyroid uptake area. Glands outside the thyroid area were demonstrated on planar views. The location of enlarged glands was more precisely defined on the tomographic slices. The anatomic and histologic findings and the evolution of hypercalcemia after surgery were taken as reference.

RESULTS

Sixty-four abnormal glands were found during surgery, including 39 observed in patients who underwent reoperation for persistent or recurrent hyperparathyroidism. Twenty-two of these glands were in an abnormal location, including 10 in the mediastinum. SPECT allowed the detection of three glands not demonstrated on planar views or FADS. Fifty-eight glands were correctly localized scintigraphically, including 34 in patients who underwent reoperation. Therefore, SPECT raised the sensitivity from 86% to 90.5% and from 79.5% to 87% in the reoperated patients. Tracer uptake in the low mediastinal area was better analyzed on tomographic slices than on planar views. Only seven false-positive results were depicted by planar views or FADS; none were depicted on SPECT.

CONCLUSION

A combination of FADS and SPECT permits detection of small glands, even in a posterior location, inside or outside the thyroid area. This scintigraphic method enables the surgeon to define more precisely details about the location of the enlarged gland and contributes to improved parathyroid surgery.

Bone marrow scintigraphy as a useful method for estimating the physiological status of bone marrow and spleen in polycythaemia vera

Bone marrow scintigraphy is a simple and noninvasive examination useful to define the status of the bone marrow and spleen in polycythaemia vera (P.V.). Despite the absence of specificity of Indium 111 labelled transferrin (In-Tf) for myelopoietic tissue, there is a close correlation between bone marrow In-Tf uptake and bone marrow cellularity and between splenic In-Tf uptake and splenic metaplasia. The results of scintigraphy are compared to clinical data, radioactive iron kinetics, bone marrow and spleen histology and the course of the disease. The diagnostic and prognostic value of bone marrow scintigraphy is discussed, particularly at the stage of transformation of P.V. into postpolycythaemia myeloid metaplasia (Post-P.V.M.M.).

Identifying abnormal parathyroid glands in the thyroid uptake area using technetium-99m-sestamibi and factor analysis of dynamic structures

A rapid (25 min) single tracer scintigraphic method to localize parathyroid gland abnormalities was evaluated in 24 patients with hyperparathyroidism.

METHODS

Scintigraphy was performed with 99mTc-sestamibi prior to surgery. A 25-min dynamic series centered on the neck was acquired immediately after injection of 99mTc-MIBI. Two planar static views were obtained after 1 and 2 hr. To identify abnormal parathyroid tissue in the thyroid uptake area, a factor analysis of dynamic structure (FADS) was applied to the dynamic acquisition. The results were compared to the analysis of the two planar static views.

RESULTS

FADS demonstrated abnormal uptake of the tracer in the thyroid area for 26 of the 31 parathyroid glands found to be abnormal at surgery (5/6 adenomas, 21/25 hyperplastic glands). In three cases, FADS demonstrated parathyroid uptake despite the absence of parathyroid tissue at surgery. FADS revealed as specific and more sensitive than the visual analysis of the two static views, since only 13/30 glands were still visible after 1 hr, and 5/26 after 2 hr. Furthermore, a study with two static views was found to be less sensitive for the detection of hyperplastic glands.

CONCLUSION

FADS99mTc-MIBI is performed in less time than existing scintigraphic protocols. It is a promising method to detect abnormal parathyroid glands in the cervical area with a single tracer.