Tumor localization in patients by radiolabeled monoclonal antibodies against colon carcinoma.

A radiolabeled monoclonal antibody (MAb) that has been shown to react specifically in vitro and ex vivo to human colorectal carcinoma and to inhibit growth of human carcinomas grafted in nude mice was administered to 52 colorectal carcinoma patients and 15 patients with other types of cancer. Of 63 colorectal carcinoma tumor sites studied, 34 showed significant accumulation of antibody by external photoscanning and tomoscintigraphy, whereas none of the 20 sites of other cancer types gave positive results. One-third of the patients received F(ab')2 fragments of the MAb, which gave a slightly higher percentage (61%) of positive results than did intact MAbs (51%). A few patients scheduled for tumor resection were given injections simultaneously of 131I-labeled MAb and 125I-labeled normal immunoglobulin G. Antibody concentration in resected tumors was 3.6 to 6.3 times higher than the average antibody concentration in adjacent normal tissues (1.5, 3.4, and 9.4 as compared with normal mucosa, serosa, and fat, respectively), and the specificity indices, calculated by differential radioactivity analysis, ranged from 2.1 to 5.1. The results show the potential value and limitations of this particular MAb for tumor detection by immunoscintigraphy.

Radiation induced apoptosis and initial DNA damage are inversely related in locally advanced breast cancer patients.

Background. DNA-damage assays, quantifying the initial number of DNA double-strand breaks induced by radiation, have been proposed as a predictive test for radiation-induced toxicity. Determination of radiation-induced apoptosis in peripheral blood lymphocytes by flow cytometry analysis has also been proposed as an approach for predicting normal tissue responses following radiotherapy. The aim of the present study was to explore the association between initial DNA damage, estimated by the number of double-strand breaks induced by a given radiation dose, and the radio-induced apoptosis rates observed. Methods. Peripheral blood lymphocytes were taken from 26 consecutive patients with locally advanced breast carcinoma. Radiosensitivity of lymphocytes was quantified as the initial number of DNA double-strand breaks induced per Gy and per DNA unit (200 Mbp). Radio-induced apoptosis at 1, 2 and 8 Gy was measured by flow cytometry using annexin V/propidium iodide. Results. Radiation-induced apoptosis increased in order to radiation dose and data fitted to a semi logarithmic mathematical model. A positive correlation was found among radio-induced apoptosis values at different radiation doses: 1, 2 and 8 Gy (p < 0.0001 in all cases). Mean DSB/Gy/DNA unit obtained was 1.70 ± 0.83 (range 0.63-4.08; median, 1.46). A statistically significant inverse correlation was found between initial damage to DNA and radio-induced apoptosis at 1 Gy (p = 0.034). A trend toward 2 Gy (p = 0.057) and 8 Gy (p = 0.067) was observed after 24 hours of incubation. Conclusions. An inverse association was observed for the first time between these variables, both considered as predictive factors to radiation toxicity.

Uptake of macromolecules by cercariae during skin penetration and transformation to schistosomula (Schistosoma mansoni)

Here, we observed the uptake of membrane-impermeant molecules by cercariae as they penetrate the skin and are transformed into schistosomula. We propose that membrane-impermeant molecules, Lucifer Yellow, Propidium iodide and Hoechst 33258 enter the parasite through both thenephridiopore and the surface membrane and then diffuse throughout the body of the parasite. We present a hypothesis that the internal cells of the body of the schistosomulum represent a new host-parasite interface, at which skin-derived growth factors may stimulate receptors on internal membranes during transformation of the cercariae into the schistosomulum.

Combined low initial DNA damage and high radiation-induced apoptosis confers clinical resistance to long-term toxicity in breast cancer patients treated with high-dose radiotherapy

BACKGROUND. Either higher levels of initial DNA damage or lower levels of radiation-induced apoptosis in peripheral blood lymphocytes have been associated to increased risk for develop late radiation-induced toxicity. It has been recently published that these two predictive tests are inversely related. The aim of the present study was to investigate the combined role of both tests in relation to clinical radiation-induced toxicity in a set of breast cancer patients treated with high dose hyperfractionated radical radiotherapy. METHODS. Peripheral blood lymphocytes were taken from 26 consecutive patients with locally advanced breast carcinoma treated with high-dose hyperfractioned radical radiotherapy. Acute and late cutaneous and subcutaneous toxicity was evaluated using the Radiation Therapy Oncology Group morbidity scoring schema. The mean follow-up of survivors (n = 13) was 197.23 months. Radiosensitivity of lymphocytes was quantified as the initial number of DNA double-strand breaks induced per Gy and per DNA unit (200 Mbp). Radiation-induced apoptosis (RIA) at 1, 2 and 8 Gy was measured by flow cytometry using annexin V/propidium iodide. RESULTS. Mean DSB/Gy/DNA unit obtained was 1.70 ± 0.83 (range 0.63-4.08; median, 1.46). Radiation-induced apoptosis increased with radiation dose (median 12.36, 17.79 and 24.83 for 1, 2, and 8 Gy respectively). We observed that those "expected resistant patients" (DSB values lower than 1.78 DSB/Gy per 200 Mbp and RIA values over 9.58, 14.40 or 24.83 for 1, 2 and 8 Gy respectively) were at low risk of suffer severe subcutaneous late toxicity (HR 0.223, 95%CI 0.073-0.678, P = 0.008; HR 0.206, 95%CI 0.063-0.677, P = 0.009; HR 0.239, 95%CI 0.062-0.929, P = 0.039, for RIA at 1, 2 and 8 Gy respectively) in multivariate analysis. CONCLUSIONS. A radiation-resistant profile is proposed, where those patients who presented lower levels of initial DNA damage and higher levels of radiation induced apoptosis were at low risk of suffer severe subcutaneous late toxicity after clinical treatment at high radiation doses in our series. However, due to the small sample size, other prospective studies with higher number of patients are needed to validate these results.

Studying nanotoxic effects of CdTe quantum dots in Trypanosoma cruzi

Semiconductor nanoparticles, such as quantum dots (QDs), were used to carry out experiments in vivo and ex vivo with Trypanosoma cruzi. However, questions have been raised regarding the nanotoxicity of QDs in living cells, microorganisms, tissues and whole animals. The objective of this paper was to conduct a QD nanotoxicity study on living T. cruzi protozoa using analytical methods. This was accomplished using in vitro experiments to test the interference of the QDs on parasite development, morphology and viability. Our results show that after 72 h, a 200 μM cadmium telluride (CdTe) QD solution induced important morphological alterations in T. cruzi, such as DNA damage, plasma membrane blebbing and mitochondrial swelling. Flow cytometry assays showed no damage to the plasma membrane when incubated with 200 μM CdTe QDs for up to 72 h (propidium iodide cells), giving no evidence of classical necrosis. Parasites incubated with 2 μM CdTe QDs still proliferated after seven days. In summary, a low concentration of CdTe QDs (2 μM) is optimal for bioimaging, whereas a high concentration (200 μM CdTe) could be toxic to cells. Taken together, our data indicate that 2 μM QD can be used for the successful long-term study of the parasite-vector interaction in real time.

Resistance to thyroid hormone and down syndrome: coincidental association or genetic linkage?

We report the first case of RTH and DS. Although this congruence could be coincidental, we cannot exclude a possible linkage between both syndromes.

Miltefosine induces programmed cell death in Leishmania amazonensis promastigotes

In the current study, we evaluated the mechanism of action of miltefosine, which is the first effective and safe oral treatment for visceral leishmaniasis, in Leishmania amazonensis promastigotes. Miltefosine induced a process of programmed cell death, which was determined by the externalization of phosphatidylserine, the incorporation of propidium iodide, cell-cycle arrest at the sub-G0/G1 phase and DNA fragmentation into oligonucleosome-sized fragments. Despite the intrinsic variation that is detected in Leishmania spp, our results indicate that miltefosine causes apoptosis-like death in L. amazonensis promastigote cells using a similar process that is observed in Leishmania donovani.

The activity of a metronidazole analogue and its β-cyclodextrin complex against Trypanosoma cruzi

In this study we prepared an inclusion complex between an iodide analogue of metronidazole (MTZ-I) and cyclodextrin (CD) to develop a safer and more effective method of treating Trypanosoma cruzi infections. According to our results, MTZ-I and MTZ-I:β-CD were 10 times more active than MTZ, demonstrating that the presence of an iodine atom on the side chain increased the trypanocidal activity while maintaining its cytotoxicity. The selective index shows that MTZ-I was 10 times more active against T. cruzi than it was against mammalian cells. The modification of MTZ side chains provides a promising avenue for the development of new drugs.

Iodine intakes of 100-300 μg/d do not modify thyroid function and have modest anti-inflammatory effects.

Little information is available as to whether doses of iodide similar to those recommended in clinical practice for the prevention of iodine deficiency in pregnant women affect thyroid function. The aim of the present study was to analyse whether doses of iodide can affect thyroid function in adults, and evaluate its effect on plasma markers of oxidative stress, inflammation and acute-phase proteins. A total of thirty healthy volunteers (ten men and twenty women) with normal thyroid function were randomly assigned to three groups (n 10). Each group received a daily dose of 100, 200 or 300 μg of iodide in the form of KI for 6 months. Free tetraiodothyronine (FT4) levels at day 60 of the study were higher in the groups treated with 200 and 300 μg (P = 0·01), and correlated with the increase in urinary iodine (r 0·50, P = 0·007). This correlation lost its significance after adjustment for the baseline FT4. The baseline urinary iodine and FT4 correlated positively with the baseline glutathione peroxidase. On day 60, urinary iodine correlated with C-reactive protein (r 0·461, P = 0·018), and free triiodothyronine correlated with IL-6 (r - 0·429, P = 0·025). On day 60, the changes produced in urinary iodine correlated significantly with the changes produced in α1-antitrypsin (r 0·475, P = 0·014) and ceruloplasmin (r 0·599, P = 0·001). The changes in thyroid-stimulating hormone correlated significantly with the changes in α1-antitrypsin (r - 0·521, P = 0·005) and ceruloplasmin (r - 0·459, P = 0·016). In conclusion, the administration of an iodide supplement between 100 and 300 μg/d did not modify thyroid function in a population with adequate iodine intake. The results also showed a slight anti-inflammatory and antioxidative action of iodide.

Effect of iodine prophylaxis during pregnancy on neurocognitive development of children during the first two years of life.

CONTEXT The association between thyroid function during pregnancy and the later mental and psychomotor development of the child is supported by numerous experimental, clinical, and epidemiological studies. OBJECTIVE The aim of the study was to evaluate the psychological development of infants aged 3 to 18 months whose mothers had received 300 microg of potassium iodide during the first trimester of their pregnancy and compare with infants whose mothers had received no iodine supplements. DESIGN AND STUDY SUBJECTS: The study included 133 women who had received 300 microg of potassium iodine and 61 women who had received no iodine supplements. MAIN OUTCOME MEASURES The neuropsychological status of the children was evaluated with the Bayley Scales of Infant Development, and measurements were made of TSH, free T(3), free T(4), and urinary iodine. RESULTS Those children whose mothers had received an iodine supplement of 300 microg had a more favorable psychometric assessment than those of the other group of mothers. They had higher scores on the Psychomotor Development Index (P = 0.02) and the Behavior Rating Scale. CONCLUSIONS Dietary iodine supplements not only have no harmful effect on the neurodevelopment of the children, they may even be beneficial. Given the possible presence of confounding variables not controlled for in this study, these findings should be considered as preliminary.

Amniotic fluid iodine concentrations do not vary in pregnant women with varying iodine intake.

Iodine deficiency is an important clinical and public health problem. Its prevention begins with an adequate intake of iodine during pregnancy. International agencies recommend at least 200 microg iodine per d for pregnant women. We assessed whether iodine concentrations in the amniotic fluid of healthy pregnant women are independent of iodine intake. This cross-sectional, non-interventional study included 365 consecutive women who underwent amniocentesis to determine the fetal karyotype. The amniocentesis was performed with abdominal antisepsis using chlorhexidine. The iodine concentration was measured in urine and amniotic fluid. The study variables were the intake of iodized salt and multivitamin supplements or the prescription of a KI supplement. The mean level of urinary iodine was 139.0 (SD 94.5) microg/l and of amniotic fluid 15.81 (SD 7.09) microg/l. The women who consumed iodized salt and those who took a KI supplement had significantly higher levels of urinary iodine than those who did not (P = 0.01 and P = 0.004, respectively). The urinary iodine levels were not significantly different in the women who took a multivitamin supplement compared with those who did not take this supplement, independently of iodine concentration or multivitamin supplement. The concentrations of iodine in the amniotic fluid were similar, independent of the dietary iodine intake. Urine and amniotic fluid iodine concentrations were weakly correlated, although the amniotic fluid values were no higher in those women taking a KI supplement. KI prescription at recommended doses increases the iodine levels in the mother without influencing the iodine levels in the amniotic fluid.

Electrochemically promoted carbon-halide bond cleavage in 4-nitrobenzyl halides

This manuscript reports the study of the carbon-halide bond cleavage in 4-nitrobenzyl halides, taking special attention to the iodide and fluoride derivatives. The electrochemical reduction mechanism has been disclosed for both compounds by terms of cyclic voltammetry and controlled potential electrolysis. In the case of 4-nitrobenzyl iodide, a first one electron irreversible wave leads to the corresponding 4-nitrobenzyl radical and iodide. However, in the case of 4-nitrobenzyl fluoride, a first one-electron reversible wave appears at –1.02 vs. SCE followed by one electron irreversible wave. In this second electron transfer process, the cleavage of the C-F bond is taking place, so the bond cleavage reaction occurs at the dianion level. To disclose and understand the electrochemical reduction mechanisms that allows to obtain important thermodynamic and kinetic data that would help in the understanding of C-X bond cleavage. This type of bond dissociation reactions are involved in the metabolism pathways of the human body.

Efecto de los contenidos de C, Mn y Si en el comportamiento a fluencia en caliente de aceros de construcción al carbono y microaleados: aplicación a la obtención de grano ultrafino en productos largos laminados

Després d’aplicar alguns tractaments d’elaboració i conservació als aliments, queden bacteris lesionats. Aquests bacteris perden la capacitat de créixer en els medis de cultiu selectiu convencionals, de manera que se’n subestima el recompte. Malgrat això, poden recuperar-se als aliments i suposar un risc per la salut, ja que alguns encara poden mantenir activitat metabòlica i integritat estructural. En aquest projecte, es van optimitzar protocols de preparació de mostres per citometria de flux (CF) per avaluar l’estat fisiològic de patògens alimentaris (Escherichia coli O157:H7, Salmonella Enteritidis i Listeria monocytogenes) sotmesos a estrès. Es van estudiar principalment dos paràmetres fisiològics: la integritat de membrana, mitjançant iodur de propidi i fluorocroms de la família SYTO; i l’activitat respiratòria, per la reducció intracel•lular d’una sal de tetrazole, el CTC. En primer lloc, es van avaluar variables de protocol, com la concentració de colorant, la ràtio entre colorants, la solució de tinció i el temps d’incubació, en mostres control (cèl•lules sanes i mortes). A continuació, els protocols optimitzats es van aplicar a suspensions bacterianes en medi de cultiu que prèviament havien estat sotmeses a estressos físics i fisicoquímics. Durant l’etapa final del projecte, els coneixements adquirits sobre la preparació de mostres per CF es van aplicar a l’anàlisi de mostres de matriu complexa: amanides comercials inoculades amb E. coli O157:H7. Als assajos amb indicadors d’integritat de membrana en suspensions bacterianes sotmeses a estrès, es van poder quantificar cèl•lules amb la membrana parcialment danyada (presumptes cèl•lules lesionades). El recompte de cèl•lules que mantingueren l’activitat respiratòria després de ser sotmeses a estrès va ser superior al que es va obtenir mitjançant recompte en placa convencional, cosa que va evidenciar la presència de cèl•lules actives però no cultivables. La introducció d’estratègies per reduir les interferències provocades per les partícules alimentàries i l’ús d’un anticòs amb marcatge fluorescent va permetre detectar selectivament les cèl•lules d’E. coli O157:H7 i avaluar-ne la integritat de membrana simultàniament. L’anàlisi de cèl•lules bacterianes per CF requereix de la exhaustiva optimització dels protocols, que són específics per cada soca i matriu. Malgrat això, i a diferència del mètode convencional per recompte en placa, ofereix la possibilitat d’obtenir una gran quantitat d’informació sobre el sovint complex estat fisiològic d’una mostra.

Evaluation of Giardia duodenalis viability after metronidazole treatment by flow cytometry

Giardia duodenalis (syn. lamblia; syn. intestinalis) susceptibility testing is not routinely performed because the classical culture methods are very time-consuming and laborious. We developed a novel flow cytometry (FC) assay to evaluate the susceptibility of G. duodenalis trophozoites to metronidazole (MTZ). Different concentrations of MTZ were added to cultures of trophozoites (10 5 /mL) and the cultures were incubated for different periods. The 50% inhibitory concentration was calculated and propidium iodide (PI) was used to quantify the number of dead cells. After treatment, PI-positive trophozoites increased with increasing drug concentration and exposure time. An excellent correlation was found between FC and the classical method. A novel, accurate and reliable method is now available to evaluate G. duodenalis viability.

Imaging of human leukemic T-cell xenografts in nude mice by radiolabeled monoclonal antibodies and F(ab')2 fragments.

Monoclonal antibodies (MoAb) that react with the T-lymphocyte markers called cluster of differentiation CD5 and CD2 were labeled with iodine 131 (131I) and were injected intravenously in nude mice bearing solid subcutaneous xenografts derived from the human T-cell leukemia line Ichikawa. Both MoAb anti-CD5 and anti-CD2 yielded favorable mean tumor to whole-body ratios of 3.8 and 5.1, respectively. These ratios were further increased up to 10.0 for MoAb anti-CD5 and 15.5 for MoAb anti-CD2 by using their F(ab')2 fragments. The tumors could be imaged clearly by external scanning after injection of F(ab')2 fragments from both MoAb. F(ab')2 fragments from MoAb anti-CD2 and of a third MoAb recognizing the clonotypic determinant (Ti) of the antigen receptor expressed by the human T-cell line Jurkat were injected in mice bearing intrasplenic Jurkat xenografts. A selective localization of both fragments in tumor tissue was demonstrated with mean tumor to whole-body ratios of 7.5 and 4.1 for MoAb anti-CD2 and anti-Ti, respectively. These in vivo experimental results may provide useful information for the potential use of radiolabeled MoAb and fragments in the diagnosis and treatment of patients with T-cell lymphoma and different other forms of T-cell malignancies.