Oxidant and Antioxidant Effects of Gentisic Acid in a 177Lu-Labelled Methionine-Containing Minigastrin Analogue.

BACKGROUND: The radiolabelling of receptor-binding peptides for therapy is a challenge since the peptide itself is exposed (during labelling, storage and transport) to radiation-induced damage, directly or indirectly, in aqueous solution. Hence, the use of radiostabilizers seems to be mandatory, especially in peptide molecules that contain radiation-sensitive amino acids. OBJECTIVE: The aim of this study was to investigate the effect of two stabilizers, gentisic acid and methionine, to delve into how each of them affects the radiolabelling and stability of the minigastrin analogue [177Lu]Lu-DOTA-His-His-Glu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2 through the analysis of the 22 species distinguished over time by an optimized HPLC system. METHODS: The stabilizers, in different combinations, were present from the beginning of the labelling process carried out at 96 °C for 15 min. The stability was studied for up to 7 days. RESULTS: The unexpected selective oxidation of the methionine residue of the radiolabelled peptide, promoted by gentisic acid, led to studying the effect of pH, from 3.5 to 6.0, in the presence of only this stabilizer. A pH-dependent antioxidant behaviour was revealed, showing a decrease in peptide impurities but an increase in the selective oxidation as the pH was increased. CONCLUSION: The selective oxidation of the methionine residue could be induced by oxidizing species probably produced in the reaction between gentisic acid and free radicals of water, during the protection of the radiolabelled peptide from the attack of these harmful species. Therefore, the addition of methionine becomes necessary to effectively decrease this selective oxidation in the methioninecontaining peptide.

68Ga-PSMA and 11C-Choline comparison using a tri-modality PET/CT-MRI (3.0 T) system with a dedicated shuttle.

BACKGROUND: The aim of this study was to prospectively compare the detection rate of 68Ga-PSMA versus 11C-Choline in men with prostate cancer with biochemical recurrence and to demonstrate the added value of a tri-modality PET/CT-MRI system. METHODS: We analysed 36 patients who underwent both 11C-Choline PET/CT and 68Ga-PSMA PET/CT scanning within a time window of 1-2 weeks. Additionally, for the 68Ga-PSMA scan, we used a PET/CT-MRI (3.0 T) system with a dedicated shuttle, acquiring MRI images of the pelvis. RESULTS: Both scans were positive in 18 patients (50%) and negative in 8 patients (22%). Nine patients were positive with 68Ga-PSMA alone (25%) and one with 11C-Choline only (3%). The median detected lesion per patient was 2 for 68Ga-PSMA (range 0-93) and 1 for 11C-Choline (range 0-57). Tumour to background ratios in all concordant lesions (n = 96) were higher for 68Ga-PSMA than for 11C-Choline (110.3 ± 107.8 and 27.5 ± 17.1, mean ± S.D., for each tracer, respectively P = 0.0001). The number of detected lesions per patient was higher for 11C-Choline in those with PSA ≥ 3.3 ng/mL, while the number of detected lesions was independent of PSA levels for 68Ga-PSMA using the same PSA cut-off value. Metastatic pelvic lesions were found in 25 patients (69%) with 68Ga-PSMA PET/CT, in 18 (50%) with 11C-Choline PET/CT and in 21 (58%) with MRI (3.0 T). MRI was very useful in detecting recurrence in cases classified as indeterminate by means of PET/CT alone at prostate bed. CONCLUSIONS: In patients with prostate cancer with biochemical recurrence 68Ga-PSMA detected more lesions per patient than 11C-Choline, regardless of PSA levels. PET/CT-MRI (3.0 T) system is a feasible imaging modality that potentially adds useful relevant information with increased accuracy of diagnosis.

An optimized clarithromycin-free 14-day triple therapy for Helicobacter pylori eradication achieves high cure rates in Uruguay / El tratamiento triple, optimizado y sin claritromicina durante 14 días consigue altas tasas de curación de Helicobacter pylori en Uruguay

Background: Strong acid inhibition increases cure rates with triple therapy and 14-day are more effective than 7-day treatments. The combination of amoxicillin plus metronidazole at full doses has been shown to overcome metronidazole resistance and to achieve good eradication rates even in patients harboring resistant strains. No previous studies have been reported in Latin-America with this optimized triple-therapy scheme. Aims: The aim of the present study was to assess the eradication rate and tolerance of a new first-line treatment regimen associating strong acid inhibition, amoxicillin and metronidazole. Methods: Patients from the Clínica de Gastroenterología of the Hospital de Clínicas (Montevideo, Uruguay) were included. Hp status was mainly assessed by at least one of the following: histologyor urea breath test (UBT). A 14-day treatment was prescribed comprising esomeprazole 40mg twice a day plus amoxicillin 1g and metronidazole 500mg, both three times a day. H. pylori cure was assessed by UBT. Results: Forty-one patients were enrolled. Mean age was 53.3±13 years and 17.1% of patients were male. Main indications for treatment were: functional dyspepsia (27.5%), gastritis (45%), gastric or duodenal erosions (20%), gastric ulcer (5%) and intestinal metaplasia (2.5%). H. pylori eradication was achieved in 33 of the 37 patients who returned for follow-up. Eradication rates were 80.5% (95% CI: 68.4-92.6) by intention-to-treat (ITT) analysis and 89.2% (95% CI; 79.2-99.2) per protocol (PP). No major side effects were reported; 26 patients (65.8%) complained of mild side effects (nausea, diarrhea and headache). Conclusions: Cure rates of this triple therapy including esomeprazole, amoxicillin and metronidazole were 81% per ITT and the treatment was well tolerated. These optimal results with a simple clarithromycin-free triple therapy are better than described for standard triple therapy but there is still room for improvement to reach the desired target of 90% per ITT (AU)

Antecedentes: La inhibición ácida potente aumenta las tasas de curación de la triple terapia, y 14 días de tratamiento son más efectivos que 7 días. La combinación de amoxicilina y metronidazol a dosis completas ha demostrado que supera la resistencia al metronidazol y que consigue buenas tasas de erradicación, incluso en pacientes que poseen cepas resistentes. No se han reportado estudios con este tratamiento triple optimizado en Latinoamérica. Objetivos: El objetivo del presente estudio es valorar las tasas de erradicación y la tolerancia de un nuevo tratamiento de primera línea que asocia inhibición ácida potente, amoxicilina y metronidazol. Métodos: Pacientes provenientes de la Clínica de Gastroenterología del Hospital de Clínicas (Montevideo, Uruguay) se incluyeron en el estudio. La infección por Helicobacter pylori fue demostrada por, al menos, una de las siguientes: histología o test del aliento. Se prescribió un tratamiento de 14 días con esomeprazol 40mg 2 veces al día junto a amoxicilina 1g y metronidazol 500mg ambos 3 veces al día. La curación de Helicobacter pylori fue confirmada por el test del aliento. Resultados: Se incluyeron 41 pacientes. La edad media fue de 53,3±13 años y el 17,1% de los pacientes eran hombres. La principal indicación para el tratamiento fue: dispepsia funcional (27,5%); gastritis (45%), erosiones gástricas o duodenales (20%), úlcera gástrica (5%) y metaplasia intestinal (2,5%). La erradicación de Helicobacter pylori se consiguió en 33 de los 37 pacientes que regresaron para el test de control. Las tasas de erradicación fueron del 80,5% (IC 95%: 68,4-92,6) por intención de tratar y del 89,2% (IC 95%: 79,2-99,2) por protocolo. No se reportaron efectos secundarios graves. Veintiséis pacientes (65,8%) presentaron efectos secundarios leves (náuseas, diarrea y cefalea). Conclusiones: Las tasas de erradicación de esta triple terapia que incluye esomeprazol, amoxicilina y metronidazol fueron del 81% por intención de tratar y el tratamiento fue bien tolerado. Estos resultados óptimos con un tratamiento triple sencillo, sin claritromicina, son mejores que los descritos para el tratamiento triple estándar, pero todavía existe espacio de mejora para alcanzar el objetivo deseado del 90% por intención de tratar (AU)

An optimized clarithromycin-free 14-day triple therapy for Helicobacter pylori eradication achieves high cure rates in Uruguay.

BACKGROUND: Strong acid inhibition increases cure rates with triple therapy and 14-day are more effective than 7-day treatments. The combination of amoxicillin plus metronidazole at full doses has been shown to overcome metronidazole resistance and to achieve good eradication rates even in patients harboring resistant strains. No previous studies have been reported in Latin-America with this optimized triple-therapy scheme. AIMS: The aim of the present study was to assess the eradication rate and tolerance of a new first-line treatment regimen associating strong acid inhibition, amoxicillin and metronidazole. METHODS: Patients from the Clínica de Gastroenterología of the Hospital de Clínicas (Montevideo, Uruguay) were included. Hp status was mainly assessed by at least one of the following: histologyor urea breath test (UBT). A 14-day treatment was prescribed comprising esomeprazole 40mg twice a day plus amoxicillin 1g and metronidazole 500mg, both three times a day. H. pylori cure was assessed by UBT. RESULTS: Forty-one patients were enrolled. Mean age was 53.3±13 years and 17.1% of patients were male. Main indications for treatment were: functional dyspepsia (27.5%), gastritis (45%), gastric or duodenal erosions (20%), gastric ulcer (5%) and intestinal metaplasia (2.5%). H. pylori eradication was achieved in 33 of the 37 patients who returned for follow-up. Eradication rates were 80.5% (95% CI: 68.4-92.6) by intention-to-treat (ITT) analysis and 89.2% (95% CI; 79.2-99.2) per protocol (PP). No major side effects were reported; 26 patients (65.8%) complained of mild side effects (nausea, diarrhea and headache). CONCLUSIONS: Cure rates of this triple therapy including esomeprazole, amoxicillin and metronidazole were 81% per ITT and the treatment was well tolerated. These optimal results with a simple clarithromycin-free triple therapy are better than described for standard triple therapy but there is still room for improvement to reach the desired target of 90% per ITT.

68Ga-NOTA-UBI-29-41 as a PET Tracer for Detection of Bacterial Infection.

UNLABELLED: The cationic peptide (68)Ga-NOTA-UBI-29-41 was synthesized and characterized. Biodistribution and PET/CT examinations were performed for evaluation of its biologic behavior. Differentiation of infection from sterile inflammation was investigated using microbiology methods at the sites of bacterial infections. METHODS: Labeling of UBI-29-41 conjugated with NOTA with (68)Ga was optimized at 20°C-100°C and pH 3.5-5.5. Radiochemical purity, stability up to 260 min, and binding to serum proteins were determined. In vitro binding to Staphylococcus aureus was evaluated from 9.14 × 10(7) to 1.17 × 10(10) cfu/mL. Of 3 groups of Mus musculus Swiss male mice, the first was inoculated intramuscularly with 1.2 × 10(8) cfu of S. aureus to provoke infection, and the second, with 1.2 × 10(8) cfu of heat shock-treated S. aureus to generate sterile inflammation. The third mouse was not treated and served as a control. After 24 h, (68)Ga-NOTA-UBI-29-41 was administrated intravenously, and biodistribution was performed at 30, 60, and 120 min. PET/CT dynamic studies (120 min) were acquired. Sinograms were reconstructed using 3D maximum-likelihood expectation maximization and analyzed with software. Infected or inflamed muscles were dissected, homogenized, and cultured in tryptic soy agar medium. Recovered S. aureus was calculated as cfu/g. RESULTS: (68)Ga-NOTA-UBI-29-41 showed high renal excretion (83.2% ± 7.3%) of injected dose and rapid blood clearance. More than 95% was bound in vitro to 5 × 10(9) cfu/mL. A significantly higher (P< 0.05) accumulation of (68)Ga-NOTA-UBI-29-41 was observed at sites of S. aureus inoculation in infected mice (ratio of target to nontarget, 5.0 at 60 min and 4.1 at 120 min) compared with animals with inflammation (ratio of target to nontarget, 1.6 at 60 min and 1.2 at 120 min). CONCLUSION: The difference in uptake of (68)Ga-NOTA-UBI-29-41 in the infected muscles compared with the inflamed muscles was clearly observed in the PET/CT images and positively correlated with the degree of infection.

¹77Lu-Labeled Agents for Neuroendocrine Tumor Therapy and Bone Pain Palliation in Uruguay.

Lutetium-177 is an emerging radionuclide due its convenient chemical and nuclear properties. In this paper we describe the development and evaluation in Uruguay of the targeted 177Lu labelled radiopharmaceuticals EDTMP (for bone pain palliation) and DOTA-TATE (neuroendocrine tumors). We optimized the preparation of these 177Lu radiopharmaceuticals including radiolabelling, quality control methods, in vitro and in vivo stability and their therapeutic application in patients. Radiation dosimetry aspects of 177Lu are also included. Nine male patients with prostate cancer and four female patients with breast carcinoma with multiple bone metastatic lesions were treated with 177Lu-EDTMP. Four patients with gastroentheropancreatic neuroendocrine tumors (GEP-NET) and one patient with bronchial NET were treated with 1- 3 cycles with a cumulative dose of 4.44-22.2 GBq of 177Lu-DOTA-TATE. Scintigraphic images of the patients treated with 177Lu-EDTMP evidenced high and rapid uptake in bone metastasis, remaining after 7 days post administration. Images allow skeletal visualization with high definition and demonstrate increased uptake in bone metastases. For 177Lu-DOTA-TATE, partial remissions were obtained in 4 patients and the remaining patient did not show significant progression 3 months after the second cycle. No serious adverse effects were registered, even in two patients with confirmed renal disease and high risk for renal disease Dosimetry assessments confirm the predictive value of the personalized therapy with radiolabelled peptides. We found it is possible to accumulate high therapeutic doses in tumours in sequential administrations of 177Lu-DOTA-TATE, increasing the probability of biological response without significant impairment of the renal function in patients with risk factors. These results demonstrate the attractive therapeutic properties of these two 177Lu labelled agents and the feasibility of this metabolic therapy in regions far away from 177Lu producing countries.

[Evolution of the response to the first-line therapy for Helicobacter pylori infection in Uruguay]. / Evolución de la respuesta al tratamiento de primera línea de la infección por Helicobacter pylori en Uruguay.

INTRODUCTION: The eradication rate of the Helicobacter pylori (H pylori) infection using standard triple therapy has dropped globally in recent years, primarily due to the occurrence of antibiotic resistance. METHODS: Several therapy regimens were assessed in 823 patients treated the first time for H pylori infection in Uruguay, during the 1997 to 2011 period, divided into five-year groups. All patients underwent 13C isotope-urea breath testing, between the 8th and 24th weeks after therapy. The standard triple plan (amoxicillin, clarithromycin and proton pump inhibitors) was the most commonly used (86.8%). RESULTS: The overall eradication rate was 66.6% (548 patients). With the standard triple plan, the reported eradication rates were 75% for the first 5-year term and 70.1% for the second 5-year term. The difference between these two periods was not statistically significant (P = 0.201). However, in the last term the eradication rate further declined to 62.4%, with a statistically significant difference (P = 0.014). No significant correlations were found between the response to therapy in this population and either the use of alcohol and/or yerba mate or the smoking habits. CONCLUSIONS: In Uruguay, the eradication rate of H pylori infection has dropped in the last five years and is below the internationally accepted levels. This feature demands searching for more effective alternative therapies, adapting the management to the national reality based on local antibiotic resistance patterns and drug availability.

Evolución de la respuesta al tratamiento de primera línea de la infección por Helicobacter pylori en Uruguay / [Evolution of the response to the first-line therapy for Helicobacter pylori infection in Uruguay].

INTRODUCTION: The eradication rate of the Helicobacter pylori (H pylori) infection using standard triple therapy has dropped globally in recent years, primarily due to the occurrence of antibiotic resistance. METHODS: Several therapy regimens were assessed in 823 patients treated the first time for H pylori infection in Uruguay, during the 1997 to 2011 period, divided into five-year groups. All patients underwent 13C isotope-urea breath testing, between the 8th and 24th weeks after therapy. The standard triple plan (amoxicillin, clarithromycin and proton pump inhibitors) was the most commonly used (86.8

(548 patients). With the standard triple plan, the reported eradication rates were 75

for the first 5-year term and 70.1

for the second 5-year term. The difference between these two periods was not statistically significant (P = 0.201). However, in the last term the eradication rate further declined to 62.4

, with a statistically significant difference (P = 0.014). No significant correlations were found between the response to therapy in this population and either the use of alcohol and/or yerba mate or the smoking habits. CONCLUSIONS: In Uruguay, the eradication rate of H pylori infection has dropped in the last five years and is below the internationally accepted levels. This feature demands searching for more effective alternative therapies, adapting the management to the national reality based on local antibiotic resistance patterns and drug availability.

Evolución de la respuesta al tratamiento de primera línea de la infección por Helicobacter pylori en Uruguay. / [Evolution of the response to the first-line therapy for Helicobacter pylori infection in Uruguay].

INTRODUCTION: The eradication rate of the Helicobacter pylori (H pylori) infection using standard triple therapy has dropped globally in recent years, primarily due to the occurrence of antibiotic resistance. METHODS: Several therapy regimens were assessed in 823 patients treated the first time for H pylori infection in Uruguay, during the 1997 to 2011 period, divided into five-year groups. All patients underwent 13C isotope-urea breath testing, between the 8th and 24th weeks after therapy. The standard triple plan (amoxicillin, clarithromycin and proton pump inhibitors) was the most commonly used (86.8

). RESULTS: The overall eradication rate was 66.6

(548 patients). With the standard triple plan, the reported eradication rates were 75

for the first 5-year term and 70.1

for the second 5-year term. The difference between these two periods was not statistically significant (P = 0.201). However, in the last term the eradication rate further declined to 62.4

, with a statistically significant difference (P = 0.014). No significant correlations were found between the response to therapy in this population and either the use of alcohol and/or yerba mate or the smoking habits. CONCLUSIONS: In Uruguay, the eradication rate of H pylori infection has dropped in the last five years and is below the internationally accepted levels. This feature demands searching for more effective alternative therapies, adapting the management to the national reality based on local antibiotic resistance patterns and drug availability.

A potencial theranostic agent for EGF-R expression tumors: (177)Lu-DOTA-nimotuzumab.

In this work Nimotuzumab (monoclonal antibody, recognizes the EGF-R) was radiolabeled with (177)Lu as a potential cancer therapy radiopharmaceutical. In-vitro cell binding studies and in-vivo biodistribution and imaging studies were performed to determine the radiochemical stability, targeting specificity and pharmacokinetics of the (177)Lu-labeled antibody. Nimotuzumab was derivatized with DOTA-NHS at room temperature for 2 hours. DOTA-Nimotuzumab was radiolabeled with (177)LuCl3 (15 MBq/mg) at 37°C for 1 h. The radiochemical purity was assessed by ITLC, silica gel and by RP-HPLC. Binding specificity studies were performed with EGF-R positive A431 human epithelial carcinoma and EGF-R negative MDA-MB-435 breast carcinoma cells. Biodistribution studies were performed in healthy female CD-1 mice at 1 h, 4 h, 24 h, and A431 xenografted nude mice at 10 min, 1 h, 4 h, 24 h, 48 h, and 96 h. SPECT-CT imaging studies were performed in A431 xenografted mice at 24 h post injection. DOTA-Nimotuzumab was efficiently labeled with (177) LuCl(3) at 37°C. The in vitro stability of labeled product was optimal over 24 h in buffered saline and mouse serum. Specific recognition of EGF-R by (177)Lu-DOTA-Nimotuzumab was observed in A431 cell binding studies. Biodistribution studies demonstrated increasing tumor uptake of (177)Lu-DOTA-Nimotuzumab over time, with tumor to muscle ratios of 6.26, 10.68, and 18.82 at 4 h, 24 h, and 96 h post injection. Imaging of A431 xenografted mice showed high uptake in the tumor. (177)Lu-DOTA-Nimotuzumab has the potential to be a promising therapy agent, which may be useful in the treatment of patients with EGF-R positive cancer.

[177Lu]DOTA-anti-CD20: labeling and pre-clinical studies.

Anti-CD20 (Rituximab®), a specific chimeric monoclonal antibody used in CD20-positive Non-Hodgkin's Lymphoma, was conjugated to a bifunctional quelate (DOTA) and radiolabeled with (177)Lu through a simple method. [(177)Lu]-DOTA-anti-CD20 was obtained with a radiochemical purity higher than 97%, and showed good chemical and biological stability, maintaining its biospecificity to CD20 antigens. Monte Carlo simulation showed high doses deposited on a spheroid tumor mass model. This method seems to be an appropriate alternative for the production of [(177)Lu]-DOTA-anti-CD20 as therapeutic radiopharmaceutical.

M cells prefer archaeosomes: an in vitro/in vivo snapshot upon oral gavage in rats.

The archaeolipids (lipids extracted from archaebacterias) are non saponificable molecules that form self sealed mono or bilayers (archaeosomes-ARC). Different to liposomes with bilayers made of conventional glycerophospholipids, the bilayer of ARC posses a higher structural resistance to physico chemical and enzymatic degradation and surface hydrophobicity. In this work we have compared the binding capacity of ARC exclusively made of archaeols containing a minor fraction of sulphoglycophospholipids, with that of liposomes in gel phase on M-like cells in vitro. The biodistribution of the radiopharmaceutical (99m)Tc-DTPA loaded in ARC vs that of liposomes upon oral administration to Wistar rats was also determined. The fluorescence of M-like cells upon 1 and 2h incubation with ARC loaded with the hydrophobic dye Rhodamine-PE (Rh-PE) and the hydrophilic dye pyranine (HPTS) dissolved in the aqueous space, was 4 folds higher than upon incubation with equally labeled liposomes. Besides, 15% of Rh-PE and 13 % of HPTS from ARC and not from liposomes, were found in the bottom wells, a place that is equivalent to the basolateral pocket from M cells. This fact suggested the occurrence of transcytosis of ARC. Finally, 4 h upon oral administration, ARC were responsible for the 22.3 % (3.5 folds higher than liposomes) shuttling of (99m)Tc-DTPA to the blood circulation. This important amount of radioactive marker in blood could be a consequence of an extensive uptake of ARC by M cells in vivo, probably favored by their surface hydrophobicity. Taken together, these results suggested that ARC, proven their adjuvant capacity when administered by parenteral route and high biocompatibility, could be a suitable new type of nanoparticulate material that could be used as adjuvants by the oral route.

In-site interaction evaluation of Tn density by inhibition/competition assays.

The tumor-associated structure N-acetyl-galactosamine-O-Ser/Thr (Tn antigen), which is overexpressed in various tumor cell types, notably of the breast, ovary and colon, is an interesting determinant that is useful for cancer diagnosis and follow-up. The aim of this research was to study different assay strategies in order to determine the most sensitive system for further application in epitope characterization and binding assessment. The tetrameric isolectin obtained from Vicia villosa seeds (VVLB(4)) shows high affinity for the tumor-associated structure. A monoclonal antibody against VVLB(4), MabVV(34), was generated, and the interaction between MabVV(34) and VVLB(4) was studied by means of binding and inhibition assays. Several synthetic peptides (10 amino acid sequences) designed from the amino acid sequence of VVLB(4) and obtained from trypsin digestion were tested to determine which amino acids were involved in the interaction between MabVV(34) and VVLB(4). The further unraveling of this epitope was investigated by inhibition using designed synthetic peptides as well as mixtures mimicking variable density effect. Under the experimental circumstances, MabVV(34) was able to inhibit the binding of VVLB(4) to Tn. Two of the four peptide sequences assayed showed better inhibition properties. Finally, mixtures containing these selected sequences allowed the evaluation of binding and inhibition as a function of Tn density. We conclude that the present study facilitates the further development of a specific Tn marker and may contribute to the development of Tn-like radiolabelled peptides or Tn-specific radiolabelled fragments providing a highly selective tool for cancer diagnosis and treatment. This strategy may contribute to characterize the new generation of radiopharmaceuticals for diagnosis and therapy based on biomolecules like antibodies, fragments or peptides, whose application is directly guided by their specific molecular recognition.

Radiolabelled DOTA-TATE: its evaluation for targeted radiotherapy

La marcación de péptido análogo de somatostatina DOTA-TATE (DOTA-D-phe-cys-tyr-D-trp-lys-thr-cys-thr) con 125I y sus propiedades biológicas fueron investigadas. 125I-DOTA-TATE se marco por el método de cloramina-T y se purificó por RP-HPLC a fin de aumentar su actividad especifica. La estabilidad fue evaluada por HPLC, cromatografía y electroforesis. La interacción del péptido marcado con receptores de somatostatina fue investigada usando membranas obtenidas de tejidos o de células AR42J, y por unión e internalización en cultivos celulares. El rendimiento de marcado fue mayor de 90 por ciento, el perfil de HPLC reveló dos especies radioquímicas con tiempos de retención diferentes respecto del péptido no marcado, permitiendo la obtención de una mayor actividad especifica. La máxima capacidad de unión fue de 23 por ciento y la concentración inhibitoria 50 ppor ciento fue 9 µg/mL. Se internalizó el 73 por ciento de la actividad unida en 3-4 horas. El radioconjugado presenta la capacidad de unirse específicamente a los receptores de somatostatina expresados en células tumorales viables así como en preparaciones de membranas obtenidas de tejidos animales.

Monoclonal antibodies against the Tn-specific isolectin B4 from Vicia villosa seeds: characterization of the epitope of the blocking antibody VV34.

Vicia villosa isolectin B4 (VVLB4) recognizes the Tn antigen (GalNAc-O-Ser/Thr) exposed in certain human carcinomas. We have produced anti-VVLB4 monoclonal antibodies (MAbs), and their lectin recognition selectivity was assessed by ELISA and Western blot against the purified Gal/GalNAc-specific lectins from Vicia villosa, Salvia sclarea, Helix pomatia, Arachis hypogaea, Glycine max, and Dolichos biflorus. The antibodies were also tested for their ability to block the binding of VVLB4 to the Tn antigen expressed on immobilized asialo ovine submaxillary mucin. Two MAbs, VV34 and VV2, specifically recognized VVLB4 and impaired the binding of the lectin to the Tn antigen by 98% and 21%, respectively. On the other hand, MAbs VV1 and VV22 cross-reacted with other purified lectins. The four antibodies recognized native and periodate-oxidized nonreduced as well as reduced VVLB4 after SDS-PAGE and Western blot, suggesting that they were recognizing continuous polypeptide epitopes. The VV34 antibody recognized two tryptic peptides (7-29 and 96-106) from VVLB4, which are contiguous in the three-dimensional structure of the lectin. The minimum structural determinant of the epitope was mapped to the polypeptide stretch (18)LILQED(23) using a set of overlapping synthetic peptides. This region of the molecule encompasses the C-terminal part of the loop joining strands beta1 and beta2 and the N-terminal part of beta2, and is located about 20-25 A away from the center of the Tn-combining site.

Radiochemical and biological characteristics of 99mTc-UBI 29-41 for imaging of bacterial infections.

A technetium-99m-labeled peptide derived from ubiquicidine, further referred to as 99mTc-UBI 29-41, targets bacterial and fungal infections, but not sterile inflammatory processes, in experimental animals. This paper reports on the radiochemical and biological features of this radioactive agent and the importance of the amino acid sequence of UBI 29-41 for imaging of infections. Radiochemical analyses of 99mTc-UBI 29-41 and a radiolabeled scrambled version of this peptide, i.e. 99mTc-Sc-UBI 29-41, revealed that both peptides were labeled rapidly (within 10 min) and effectively with little colloid formation (less than 5% of the total radioactivity) and very little free pertechnetate (or radioactive intermediates) in the preparations containing radiolabeled peptide. Furthermore, association of the peptides with bacteria could be competed with excess unlabeled peptide and this association proved to be temperature-dependent. Based on this in vitro data we concluded that labeling of peptides with 99mTc by this direct method is rapid, efficient, and safe. Scintigraphy demonstrated that radioactivity is rapidly removed from the circulation (half-lifes of UBI 29-41 and Sc-UBI 29-41 were 16 and 21 min, respectively) mainly by renal clearance. Analysis of murine blood revealed that only a small proportion of the intravenously injected 99mTc-peptides is associated with blood cells. Although both radiolabeled peptides accumulated rapidly at sites of infection, the values for 99mTc-UBI 29-41 were higher (P < 0.05) than for 99mTc-Sc-UBI 29-41. Moreover, injection of excess unlabeled UBI 29-41, but not Sc-UBI 29-41, into Staphylococcus aureus-infected mice prior to injection of 99mTc-UBI 29-41 significantly (P < 0.05) reduced the accumulation of this radiopharmaceutical at the site of infection. In addition, we observed significantly (P < 0.01) higher amounts of 99mTc-UBI 29-41 at the site of infection in mice using a carrier-free radiolabeled UBI 29-41 as compared with unpurified preparations containing radiolabeled UBI 29-41. This in vivo data indicates that the amino acid sequence of 99mTc-UBI 29-41 contributes to its accumulation at the site of infection.

Labeling and quality control of 188Re-lanreotide.

Lanreotide was labelled with 188Re obtained from 188W/188Re generator, using stannous ion as reducing agent, ascorbic acid as stabilizers and hydroxy ethylidene bisphosphonate (HEDP) as intermediary ligand at different molar ratios, pH and incubation times. Best yields (>95%) were obtained using molar ratios SnF2/lanreotide, ascorbic/lanreotide and HEDP/lanreotide of 40, 12 and 260, respectively, pH 1-2 with an incubation at 100 degrees C for 30 min. Quality control evaluation and stability of the radiolabel compound was done by the following selected methods: chromatography in Whatman 3 MM with MEK and NaCl 0.15 M as solvents, ITLC-SG with ethanol-HCl 0.01N (90:10); reverse phase extraction cartridge (Sep-pak C18, Waters Associated) and RP-HPLC with radiometric and UV detection (220 nm) using MCH-5 n-capp column with linear gradient from 90% H2O (TFA 0.1%): 10% ACN (TFA 0.1%) up to 10% H2O (TFA 0.1%):90% ACN (TFA 0.1%) in 30 min, at flow 1 ml/min. Biodistribution in normal mice showed that 188Re-lanreotide is excreted mainly through the hepatobiliary system: more than 70% I.D. is present in gallbladder and intestines at 2 hr post injection. The stability of the 188Re-peptide bond by cysteine challenge test at 37 degrees C, during 2 and 24 hr of incubation time, reveals that approximately 300 and 100 molar ratio cys/peptide is required to displace 50% of the 188Re from the complex. In vitro stability of 188Re-lanreotide at room temperature (Rt) was demonstrated during 24 hr Future works must be done in order to investigate its binding capacity to somatostatin receptors.

Re-HEDP : pharmacokinetic characterization, clinical and dosimetric evaluation in osseous metastatic patients with two levels of radiopharmaceutical dose.

BACKGROUND: A study for pain relief therapy with 188Re-HEDP was done in patients with bone metastases secondary to breast and prostate cancer. MATERIALS AND METHODS: Patients received 1.3 or 2.2 GBq, in single or multiple doses. Platelets, white and red cells were evaluated during 11 weeks. Pharmacokinetic characterization was done from blood and urine samples for 5 patients along 24 hours. Urinary excretion was evaluated in other 16 patients during 6 hours. Bone uptake was estimated as remaining activity in whole body. Scintigraphic images were acquired at 2 and 24 hs post-administration. Absorbed dose in bone marrow was estimated with Mirdose3. Analgesics intake and pain score were daily recorded. Tumour markers (PSA, and Tn-structure) were monitored in 9 patients during 4 to 6 months. Single doses of low activity (1.3 GBq) were given to twelve patients. Nine patients received multiple doses. RESULTS: All except one patient had normal levels of platelets, white and red cells. Remaining dose in blood at 2 hours was 9%. Urinary elimination was 58%. Bone uptake at 24 hours was 43% (mean value; n = 5). No changes of the haematological parameters were detected along follow-up period. Pain relief was evidenced by decrease or supression of opioid analgesic and by subjective index. PSA showed a decrease in prostate cancer patients (n = 4). Tn-structure showed a significant increase after 4 to 8 months. CONCLUSION: Single or multiple dose scheme could be safely used, with administered activity of 188Re-HEDP up to 60 mCi, with low bone marrow absorbed doses.

Estudio comparativo de tres planes terapéuticos en la infección por Helicobacter pylori / Comparative study of three therapeutic plans for infection caused by helicobacter pylori

Objetivos: Comparar el test rápido de ureasa y la histología en el diagnóstico de la infección por H.P. y conocer la tasa de erradicación de la misma con diferentes planes terapéuticos en el Uruguay. Material y métodos: Se realizó un trabajo prospectivo, doble ciego aleatorizado, en el que se incluyeron 64 pacientes, a los que se les realizó endoscopía digestiva alta debido a síntomas referidos a dicha esfera, diagnosticándose infección por H.P. por test rápido de la ureasa y/o histología. Los pacientes fueron incluidos en tres grupos (L,A,C por diez días; L, C, o L, A por 14 días). Se realizó control clínico de los efectos colaterales de la medicación. La erradicación se controló mediante test de aire espirado con C13. Resultados: La histología diagnosticó el 100 por ciento de los pacientes, mientras que el test rápido de la ureasa lo hizo en el 77 por ciento de los casos. El plan con L, A, C, erradicó 85 por ciento (IT) y 95 por ciento (PP), el plan L, C, lo hizo en el 76 por ciento (IT y PP) y el plan L, A, 45 por ciento y 47 por ciento respectivamente. Los tres planes fueron bien tolerados con solamente tres pacientes que tuvieron que abandonar el tratamiento (dos del grupo L, A, C, y una del grupo L,A). Conclusiones: La histología fue superior al test rápido de la ureasa en el diagnóstico de la infección por H.P. El triple plan con L, A, C, por diez días fue superior a los dobles planes por dos semanas. Los tres planes fueron bien tolerados. El test del aire espirado con C13 es una herramienta útil en el control de la erradicación de la infección por H.P