Recording and erasure of photorefractive holograms in undoped BTO crystal at moderate to high intensities of 639.7 nm laser under action of 532 nm laser pre-illumination

We investigate recording and erasure of photorefractive holographic gratings in an undoped Bi₁₂TiO₂₀ crystal in a moderate to high intensity regime of the recording beams at 639.7 nm without and with the action of laser pre-illumination at 532 nm. The detected hologram without pre-illumination indicates the participation of two photorefractive electronic gratings in its recording process, and the diffracted signal by itself exhibits a fivefold enhancement when the total intensity increases from 38.4 to 214.5  mW/cm². The dependence of the measured total diffraction efficiency on intensity was investigated and showed linear behavior. At least three gratings are present in the regime of pre-illumination and participate in the writing and erasure of holographic mechanisms. Two of them are electronic, and one is hole-based, with a phase difference of Δϕ between them. The theoretical approach used to analyze the total diffraction efficiency based upon the photorefractivity standard model, and considering the presence of the three gratings, showed good agreement with the holographic erasure experimental data and permitted us to compute Δϕ, which exhibited strong and unusual dependence on the total intensity.

Susceptibility of Biomphalaria glabrata submitted to concomitant infection with Angiostrongylus costaricensis and Schistosoma mansoni

The easy adaptation of Angiostrongylus costaricensis, nematode responsible for abdominal angiostrongyliasis to several species of terrestrial and freshwater molluscs and the differences observed in the interactions of trematodes with their intermediate hosts have induced us to study the concomitant infection of Biomphalaria glabrata with Schistosoma mansoni and A. costaricensis. Prior exposure of B. glabrata to A. costaricensis (with an interval of 48 hours), favored the development of S. mansoni, observing higher infection rate, increased release of cercariae and increased survival of molluscs, when compared to molluscs exposed only to S. mansoni. Prior exposure of B. glabrata to A. costaricensis and then to S. mansoni also enabled the development of A. costaricensis since in the ninth week of infection, higher amount of A. costaricensis L3 larvae was recovered (12 larvae / mollusc) while for molluscs exposed only to A. costaricensis, the number of larvae recovered was lower (8 larvae / mollusc). However, pre-exposure of B. glabrata to S. mansoni (with an interval of 24 hours), and subsequently exposure to A. costaricensis proved to be very harmful to B. glabrata, causing extensive mortality of molluscs, reduced pre-patent period to release cercariae and greater recovery of L3 A. costaricensis larvae.

Autoimmune primary ovarian insufficiency

Primary ovarian insufficiency (POI) is defined as sustained amenorrhea, increased follicle-stimulating hormone and low estrogen levels, whereas diminished ovarian reserve (DOR) is characterized as regular menses and alterations of ovarian reserve tests. POI of autoimmune origin may be associated with adrenal autoimmunity, non-adrenal autoimmunity or isolated. This autoimmune disease is characterized by serum ovarian, adrenocortical or steroidogenic cell autoantibodies. POI of adrenal autoimmune origin is the most frequent type observed in 60-80% of patients. Clinically, amenorrhea is the hallmark of POI, however before menstruation stops completely, irregular cycles occur. Infertility, hot flushes, vaginal atrophy, and dyspareunia are also common. Autoimmune oophoritis is characterized by mononuclear inflammatory cell infiltrate in the theca cells of growing follicles, with early stage follicles without lymphocytic infiltration. This infiltrate includes plasma, B and T-cells. A novel classification criterion for autoimmune POI/DOR is proposed subdividing in three distinct categories (possible, probable and confirmed) according to autoantibodies, autoimmune disease and ovarian histology. Unfortunately, up to date guidelines for the treatment of autoimmune oophoritis are not available. Strategies to POI treatment include hormone replacement and infertility therapy. Assisted conception with donated oocytes has been proven to achieve pregnancy by intra cytoplasmic sperm injection in POI women.

Influence of GSTM1 and GSTT1 polymorphisms on the survival rate of patients with malignant glioma under perillyl alcohol-based therapy

GSTM1 (glutathione S-transferase mu 1) and GSTT1 (glutathione S-transferase theta 1) are critical enzymes for detoxification of endogenous and environmental carcinogens. Constitutive GST gene polymorphisms may be associated with increased risk for cancer development. We made an explorative study of a Brazilian population with malignant glioma to determine whether GSTM1 and GSTT1 genetic polymorphisms influence the response to intranasal administration of perillyl alcohol and the survival rate. Patients were stratified into groups according to clinical presentation, tumor classification, and tumor location. Circulating DNA was extracted from blood plasma or serum, and genotypes were detected by multiplex PCR. The cohort included 95 patients with recurrent malignant glioma included in a Phase I/II clinical trial with perillyl alcohol and 100 matched healthy control subjects. GSTM1 frequency was similar in patients with glioma (44%) and healthy controls (54%), but GSTT1 deletion was found in 11.5% patients, contrasting with 36% in controls. A longer survival rate was associated with a lack of GSTM1 deletion (31 weeks) and a deletion for GSTT1 (28 weeks). A poor survival rate was associated with GSTM1 deletion (23 weeks) and with a lack of a GSTT1 deletion (19 weeks). A significantly lower frequency of GSTT1 deletion in glioma patients compared to healthy controls indicates that GSTT1 deletion may exert a protective role against gliomagenesis, influence therapeutic response to intranasal perillyl alcohol treatment, and increase overall survival, especially considering tumor topography.

Shoenfeld's syndrome after pandemic influenza A/H1N1 vaccination

Recently, reports have suggested grouping different autoimmune conditions that are triggered by external stimuli as a single syndrome called autoimmune/inflammatory syndrome induced by adjuvants (ASIA). This syndrome is characterized by the appearance of myalgia, myositis, muscle weakness, arthralgia, arthritis, chronic fatigue, sleep disturbances, cognitive impairment and memory loss, and the possible emergence of a demyelinating autoimmune disease caused by systemic exposure after vaccines and adjuvants. In the current study, the authors reported the first Brazilian case of a woman who developed ASIA, which was characterized by arthralgia, changes in inflammatory markers, and chronic fatigue, after the pandemic anti-influenza A/H1N1 vaccine without causing any other rheumatic disease, and it had a positive outcome.

Digital vasculitis in systemic lupus erythematosus: a minor manifestation of disease activity?

The objective of this study is to determine if digital vasculitis (DV), a clinical manifestation with a high systemic lupus erythematosus disease activity index (SLEDAI) score, is associated with lupus severity. DV and other clinical manifestations defined according to the SLEDAI were evaluated in 168 consecutive patients with systemic lupus erythematosus (SLE). Two groups were defined according to presence (DV+, n = 27) or absence of DV (DV-, n = 141) at the time of evaluation. The exclusion criterion was the presence of antiphospholipid syndrome (Sapporo's criteria). The two groups were comparable with regard to age (P = 0.09), gender (P = 1.00), white race (P = 0.81), and disease duration (P = 0.78). Compared to the DV- group, the DV+ group had a significantly higher frequency of mucocutaneous manifestations (66.7 vs. 39.0%, P = 0.01), haematological abnormalities (22.2 vs. 6.4%, P = 0.02) and constitutional symptoms (11.1 vs. 0.7%, P = 0.01). Renal and neurological involvements were similar in both groups (P = 0.57 and P = 1.00, respectively). The evaluation of each SLEDAI parameter confirmed that the DV+ group had higher frequencies of mild manifestations, such as new rash (P = 0.02), alopecia (P = 0.02), oral ulcers (P = 0.045), fever (P = 0.01) and leucopenia (P = 0.005). In contrast, both groups had similarly increased anti-dsDNA (P = 0.78) and decreased complement levels (P = 0.29). In conclusion, DV in patients with SLE identifies a subgroup of a mild disease. The high 'weighted' index attributed to this alteration in the SLEDAI score should therefore be revised.

Vaccination, atherosclerosis and systemic lupus erythematosus

Atherosclerosis is an inflammatory disease, leading to the formation of pro-inflammatory and pro-oxidative lipids that generate an immune response. Several antigens have been shown to activate the immune response and affect the development of atherogenesis. Systemic lupus erythematosus is an autoimmune and inflammatory disease strongly associated with premature development of atherosclerotic plaques. Modulation of the immune system could represent a useful approach to prevent and/or treat atherosclerosis. A vaccination-based approach might be a useful, effective tool in the modern arsenal of cardiovascular therapies and could be used on a large scale at a low cost. In non-systemic lupus erythematosus populations, vaccines against oxidized low-density lipoprotein, beta-2-glycoprotein I, heat shock proteins, lipoproteins, cholesterol, molecules involved in cholesterol metabolism, and other molecules (CD99, vascular endothelial growth factor-receptor, and interleukin-2) have been tested, with promising results. However, there are no studies of vaccination against atherosclerosis in systemic lupus erythematosus.

[Traditional risk factors for cardiovascular disease in primary antiphospholipid syndrome (APS) when compared with secondary APS: a study with 96 patients]

OBJECTIVE

To evaluate the prevalence of traditional risk factors in patients with primary antiphospholipid syndrome (APS) in comparison to those with systemic lupus erythematosus-secondary APS.

METHODS

Transversal study of 96 APS patients (Sapporo's criteria). Demographic and clinical data, cardiovascular risk factors and drug use were investigated.

RESULTS

Thirty-nine Primary APS and 57 secondary APS were included. The groups did not differ regarding age (38.5 +/- 9.9 vs. 39.4 +/- 10.5 years, p=0.84) and female gender (84.6 vs. 96.5%, p=0.06), respectively. Arterial events were more observed in primary than secondary APS (59 vs. 36.8%, p=0.04) patients. No difference was seen concerning venous and obstetric events. In regard to traditional risk factors for cardiovascular disease, both groups were comparable related to current or previous smoking, sedentarism, family history for coronary disease, systemic hypertension, diabetes mellitus, overweight and obesity. The frequencies of altered lipid profiles were alike in the two groups, except for a higher prevalence of low HDL-c levels in primary APS group (84.6 vs. 45.5%, p=0.0001). Concerning drug use, no significant differences were observed related to chloroquine and statin use, however the secondary APS patients had a higher rate of prednisone use (10.2 vs. 57.9%, p<0.001) as well as mean dose of corticosteroid (1.5 +/- 5.7 vs. 9.2 +/- 12.5mg/ /day, p=0.0001).

CONCLUSION

Traditional risk factors for cardiovascular disease are present and comparable between patients with primary and secondary APS, except for a high frequency of low HDL-c in primary APS patients.

A Brazilian registry of juvenile dermatomyositis: onset features and classification of 189 cases

OBJECTIVE

To describe onset features, classification and treatment of juvenile dermatomyositis (JDM) and juvenile polymyositis (JPM) from a multicentre registry.

METHODS

Inclusion criteria were onset age lower than 18 years and a diagnosis of any idiopathic inflammatory myopathy (IIM) by attending physician. Bohan & Peter (1975) criteria categorisation was established by a scoring algorithm to define JDM and JPM based on clinical protocol data.

RESULTS

Of the 189 cases included, 178 were classified as JDM, 9 as JPM (19.8: 1) and 2 did not fit the criteria; 6.9% had features of chronic arthritis and connective tissue disease overlap. Diagnosis classification agreement occurred in 66.1%. Median onset age was 7 years, median follow-up duration was 3.6 years. Malignancy was described in 2 (1.1%) cases. Muscle weakness occurred in 95.8%; heliotrope rash 83.5%; Gottron plaques 83.1%; 92% had at least one abnormal muscle enzyme result. Muscle biopsy performed in 74.6% was abnormal in 91.5% and electromyogram performed in 39.2% resulted abnormal in 93.2%. Logistic regression analysis was done in 66 cases with all parameters assessed and only aldolase resulted significant, as independent variable for definite JDM (OR=5.4, 95%CI 1.2-24.4, p=0.03). Regarding treatment, 97.9% received steroids; 72% had in addition at least one: methotrexate (75.7%), hydroxychloroquine (64.7%), cyclosporine A (20.6%), IV immunoglobulin (20.6%), azathioprine (10.3%) or cyclophosphamide (9.6%). In this series 24.3% developed calcinosis and mortality rate was 4.2%.

CONCLUSION

Evaluation of predefined criteria set for a valid diagnosis indicated aldolase as the most important parameter associated with definite JDM category. In practice, prednisone-methotrexate combination was the most indicated treatment.

Pathogenic role of anti-endothelial cell antibodies in autoimmune rheumatic diseases

Anti-endothelial cells antibodies have been detected in numerous autoimmune and inflammatory diseases, including systemic lupus erythematous, rheumatoid arthritis, vasculitis and sarcoidosis. Anti-endothelial cells antibodies bind to endothelial cell antigens and induce endothelial damage. Their effects on the endothelial cell have been considered responsible, at least in part, by the vascular injury which occurs in these pathological conditions.

Primary antiphospholipid syndrome with thrombotic thrombocytopenic purpura: a very unusual association

This report considers the rare situation in which primary antiphospholipid syndrome (PAPS) is linked with thrombotic thrombocytopenic purpura (TTP). It describes the case of a young lady with PAPS, characterized by recurring cerebro-vascular abnormalities and marked livedo reticularis, combined with circulating anticardiolipin and lupus anticoagulant antibodies. On follow-up, while on oral anticoagulation, she developed severe thrombocytopenia associated with hematuria, microangiophatic anaemia and neurological manifestations consistent with a diagnosis of TTP. The patient was treated with pulses of methylprednisolone and plasmapheresis with plasma exchange. The result was a favourable outcome. To our knowledge, this is the seventh report on this rare association in the English-language literature of this field.

The frequency of anti-β2-glycoprotein I antibodies is low and these antibodies are associated with pulmonary hypertension in mixed connective tissue disease

The objective of this study is to evaluate the prevalence of antiphospholipid antibodies, mainly anti-β2-glycoprotein I (anti-β2-GPI), and their possible clinical and laboratory relevance in mixed connective tissue disease (MCTD). This study included 39 consecutive patients with MCTD (Kasukawa’s criteria) from January, 2005, to March, 2007, and compared them with 21 age- and sex-matched healthy controls. IgG and IgM anticardiolipin (aCL) and anti-β2-GPI were measured by ELISA. Lupus anticoagulant (LA) was detected by functional coagulation tests. Medium to high titres of aCL and anti-β2-GPI antibodies were found in sera from four (10.2%) MCTD patients. One of these patients was found to be positive for IgM aCL, IgM anti-β2-GPI and LA antibodies simultaneously. Additionally, this patient had a previous history of foetal loss in the second trimester and new-onset pulmonary arterial hypertension (PAH). The other three patients had none of the manifestations of antiphospholipid syndrome (APS) or PAH. The mean value of IgG anti-β2-GPI was higher among those MCTD patients with PAH than in the group without PAH (34.2 ± 46.8 vs 12.3 ± 9.1, P = 0.018). None of the controls were positive for antiphospholipid antibodies. High to moderate titres of anti-β2-GPI as well as APS were rare in MCTD, and these antibodies may be correlated with the development of PAH in these patients.

Behaviour of albino and melanic variants of Biomphalaria glabrata Say, 1818 (Mollusca: Planorbidae) following infection by Schistosoma mansoni Sambon, 1907

The behaviour of the albino and melanic variants of Biomphalaria glabrata of Belo Horizonte (MG. Brazil) was studied comparatively, in terms of their respective susceptibilities to infection by Schistosoma mansoni of the same origin, through observation of the elimination of cercariae for a three-month period and the calculation of mortality and infection rates, in control and in infected snails. The number of amoebocytes, granulocytes and hyalinocytes in the circulating hemolymph during different periods of infection was analyzed. The evolution of the infection in the tissues was observed by means of histological cross-sections. The melanic variant showed greater susceptibility to infection and a higher mortality rate. The albino variant showed a higher number of circulating amoebocytes, both granulocytes and hyalinocytes. A higher number of degenerated sporocysts were seen in the histological cross-sections of the albino variant. The results suggest that the melanic variant of B. glabrata was more susceptible to infection by S. mansoni than was the albino variant.

Influence of saccharose on the development of cercariae from Schistosoma mansoni strains BH and SJ

The development of cercariae from Schistosoma mansoni strains BH and SJ in Biomphalaria glabrata and Biomphalaria tenagophila treated with saccharose was studied. The molluscs were maintained in dechlorinated tap water containing 0.01% saccharose. After one week of treatment with saccharose, B. glabrata and B. tenagophila were exposed to ten S. mansoni miracidia, from BH and SJ strains respectively. Control snails of both species were maintained in dechlorinated tap water without saccharose and exposed to the same number of miracidia. There was no significant difference between the infection rates of snails treated or not with saccharose. However, the two groups of B. glabrata had significantly greater infection rates than the corresponding B. tenagophila groups. Molluscs treated with saccharose had a lower survival rate, with the greatest mortality occurring immediately before and at the beginning of cercariae release. Treatment with saccharose did not result in the release of more cercariae, but larvae from molluscs so treated showed a greater capacity to penetrate mouse skin, which was attributed to the greater energy supply during larval development in the mollusc.

Single crystal EPR study of electronic structure and exchange interactions for copper(II)(L-arginine)2(SO4).(H2O)6: a model system to study exchange interactions between unpaired spins in proteins

We report EPR measurements at 9.77 and 34.1 GHz in powder and single crystal samples of the ternary copper amino acid complex Cu(L-arginine)(2)(SO(4)).(H(2)O)(6). The single crystal Electron Paramagnetic Resonance spectra display a single resonance for all magnetic field orientations in the ca and cb crystal planes. In the ab plane they display two resonances for most orientations of the magnetic field, and only one resonance for orientations close to the crystal axes. This behavior is a result of the selective collapse of the resonances corresponding to the four copper sites in the unit cell produced by the exchange interactions between copper ions. From the characteristics of the collapse and the angular dependences of the position and width of the resonances we evaluate the g-tensors of the copper molecules and estimate exchange interactions |J(1)/k(B)|=0.9 K and |J(2)/k(B)|=0.009 K between copper neighbors at 5.908 A and at 15.684 A, respectively. J(1) is assigned to a syn-anti equatorial-apical carboxylate bridge with a total bond length of 7.133 A. J(2) is assigned to a long bridge of 12 atoms with a total bond length of 19.789 A, that includes two hydrogen bonds. The results are discussed in terms of the crystal and electronic structure of Cu(L-arginine)(2)(SO(4)).(H(2)O)(6). We show that J(2) is in excellent agreement with the observed magnetic interaction between the reduced quinone acceptors in the photosynthetic reaction center protein of the bacterium Rb. sphaeroides, which is transmitted along a similar chemical path containing two hydrogen bonds. Our findings indicate that it is valid to estimate values for the exchange interactions between redox centers in proteins transmitted along long chemical paths containing sigma and H-bonds, from data obtained in model systems, and emphasize the importance of measuring exchange interactions in biologically relevant model systems.

RANK, RANKL and osteoprotegerin in arthritic bone loss

Rheumatoid arthritis is characterized by the presence of inflammatory synovitis and destruction of joint cartilage and bone. Tissue proteinases released by synovia, chondrocytes and pannus can cause cartilage destruction and cytokine-activated osteoclasts have been implicated in bone erosions. Rheumatoid arthritis synovial tissues produce a variety of cytokines and growth factors that induce monocyte differentiation to osteoclasts and their proliferation, activation and longer survival in tissues. More recently, a major role in bone erosion has been attributed to the receptor activator of nuclear factor kappa B ligand (RANKL) released by activated lymphocytes and osteoblasts. In fact, osteoclasts are markedly activated after RANKL binding to the cognate RANK expressed on the surface of these cells. RANKL expression can be upregulated by bone-resorbing factors such as glucocorticoids, vitamin D3, interleukin 1 (IL-1), IL-6, IL-11, IL-17, tumor necrosis factor-alpha, prostaglandin E2, or parathyroid hormone-related peptide. Supporting this idea, inhibition of RANKL by osteoprotegerin, a natural soluble RANKL receptor, prevents bone loss in experimental models. Tumor growth factor-beta released from bone during active bone resorption has been suggested as one feedback mechanism for upregulating osteoprotegerin and estrogen can increase its production on osteoblasts. Modulation of these systems provides the opportunity to inhibit bone loss and deformity in chronic arthritis.

Interictal hyposexuality in male patients with epilepsy

The purpose of this study was to compare the serum levels of androgens between hyposexual and non-hyposexual patients with epilepsy. Adult male patients with epilepsy were investigated. Serum levels of testosterone (T) and free-T, estradiol, and sex hormone binding globulin (SHBG) were measured and the free androgen index (FAI) was calculated. While there were no differences between hyposexual and non-hyposexual patients in the serum levels of T, free-T, and estradiol, or to the FAI, the serum levels of SHBG were significantly higher in hyposexual patients than in non-hyposexual patients. Thus, the effects of increased SHBG upon serum levels of testosterone biologically active in patients with epilepsy and hyposexuality were not detected by the methods used in this study. Four (44%) of nine hyposexual patients who were re-evaluated after two years follow-up improved sexual performance. Thus, clinical treatment that results in good seizure control may improve sexual performance in some patients with epilepsy.

Chagasic patients lack CD28 expression on many of their circulating T lymphocytes

A balanced host-parasite interaction during Trypanosoma cruzi infection allows for the establishment of a chronic infection that can last for many years. T cells are a major element responsible for parasite specific and non-specific immunity during the complex immune response of the host. However, the subpopulations of T cells involved in the response, as well as the exact mechanisms through which those cells are activated or rendered unresponsive, are not well defined. It is known that co-stimulatory signals, some of which are mediated via CD28, are of critical importance in the triggering of appropriate T cell responses. In this study the authors performed double-labelling studies to determine the frequency of expression of CD28 by CD4+ and CD8+ T lymphocytes in the peripheral blood of patients with Chagas' disease. The results show that chagasic patients throughout the spectrum of chronic clinical forms of the infection have significantly higher mean frequencies of CD4+CD28- and CD8+CD28-T cells, as compared with non-chagasic individuals. Considering the importance of CD28 for T-cell activation, the observed down-regulation or loss of CD28 during infection may indicate a possible basis for observed immunoregulatory events or distinct stages of T-cell activation in this infection. Recent evidence from patients with HIV/AIDS indicates that CD28- cell populations are more likely to undergo apoptosis, and increased apoptosis has been observed in experimental Chagas disease.

Flow cytometry, a new approach to detect anti-live trypomastigote antibodies and monitor the efficacy of specific treatment in human Chagas' disease

Sera from patients chronically infected with Trypanosoma cruzi display antibodies that bind to epitopes of living trypomastigotes, known as lytic antibodies (LA), and are detected by a complement-mediated lysis test. Conventional serology antibodies (CSA) are also present in sera from patients with chronic infections but, in contrast to LA, are unable to recognize viable trypomastigotes. The presence of LA has been used as an important element in the criterion of cure in human Chagas' disease. Using flow cytometry technology, we introduced a new and sensitive immunomethod for the detection of anti-live trypomastigote membrane-bound antibodies. On the basis of serological tests (LA and CSA detection) and parasitological assays such as hemoculture (HE), patients were classified into the following groups: chronically infected untreated patients (NT) and treated not-cured patients (TNC), with positive HE and both LA and CSA in their sera; "dissociated" HE-negative patients (DIS), in whom LA was not detected whereas CSA were present; a group of cured HE-negative patients (CUR), who were both LA and CSA negative; and, as control, a group of non-chagasic individuals (NC). Sera from these patients were assayed by incubation with live bloodstream trypomastigotes, which were subsequently exposed to fluorescein isothiocyanate-conjugated anti-human immunoglobulin G. The parasites were then fixed, run in the cytometer, and identified on basis of their size and granularity gain adjustments. On the basis of experience with the complement-mediated lysis test, a level of 20% of parasites being fluorescein isothiocyanate fluorescence positive was used as a cutoff between effective and ineffective treatments. With this criterion, our results indicated that sera from NT and TNC patients were antibody positive whereas all sera from DIS, CUR, and NC patients did not contain membrane-bound antibodies. This new approach is a tool to easily identify anti-live T. cruzi membrane-bound antibodies that can be used to monitor the efficacy of Chagas' disease treatment.

The synthesis and evaluation of macrocyclic gadolinium-DTPA-bis(amide) complexes as magnetic resonance imaging contrast agents

The authors found that DTPA bis(amide) macrocycles can be prepared in reasonable yields using simple methods and readily available starting materials. Gadolinium complexation is facile and gives rise to monomeric and dimeric species. The "pocket size" influences the solid state structure of the final complex, with Gd-DTPA-EAM existing as a dimer wherein the macrocycle bridges between two metal centers. Increasing the size of the bridging diamide moiety yields a macrocycle with a sufficiently large pocket to allow for the formation of nine-coordinant monomeric complexes. The solution behavior of all the complexes studied is consistent with the complex being present as monomers. All complexes display kinetic lability comparable to Gd-DTPA-BMA. The measured KTherm and KSel values of the complexes vary with the size of the pocket. Values similar to those observed for Gd-DTPA-BMA have been obtained with Gd-DTPA-OAM. There appears to be a good correlation between log K(Gd/Zn) and the acute toxicity for the complexes studied, with Gd-DTPA-OAM showing a toxicity value similar to that of Gd-DTPA-BMA. Although many of these complexes are chemically interesting, they do not offer any unique advantages as new magnetic resonance imaging contrast agents compared with the DOTA- and DTPA-based products currently used clinically.

Transcriptional and post-transcriptional control of tubulin gene expression in Trypanosoma cruzi

We have shown that tubulin mRNA accumulation is regulated at the transcriptional level during metacyclogenesis of Trypanosoma cruzi, although the contribution of post-transcriptional mechanisms is also indicated. mRNA heterogeneity is not restricted to beta-tubulin, and differential regulation of alpha-tubulin mRNAs is observed during this stage of the parasite's life cycle. Treatment of epimastigotes with the microtubule-depolymerizing agent vinblastine resulted in growth inhibition and morphological alterations. Vinblastine also induced a rise in the pool of free tubulin subunits, concomitant with diminished tubulin synthesis and reduced mRNA levels. Tubulin gene transcription remained unaltered during vinblastine treatment, suggesting post-transcriptional control. These observations are in agreement with the autoregulatory model of tubulin gene expression described for a variety of cell types. We conclude that T. cruzi utilizes transcriptional and post-transcriptional control mechanisms for tubulin gene expression.

HSP 70 gene expression in Trypanosoma cruzi is regulated at different levels

The level of HSP 70 mRNA is altered in Trypanosoma cruzi cells incubated at supra-optimal temperatures: the total amount of this RNA per cell is increased at 37 degrees C, and slightly decreased at 40 degrees C relative to its level at 29 degrees C. However, its amount is greater in the polysomes at either temperature. The relative increase of this RNA is larger in the polysomes fraction than it is in the total RNA. In addition the level of HSP 70 protein in heat-shocked cells is greater than would be expected from the recruitment of HSP 70 mRNA in the polysomal fraction. Taken together the data are interpreted as indicating that at 37 degrees C and 40 degrees C the HSP 70 gene regulation in T. cruzi involves both the selective accumulation of the HSP 70 mRNA in the polysomes and its preferential translation. At 37 degrees C, in addition, an increase in the total amount of this template is observed in the cells.

Alpha- and beta-tubulin mRNAs of Trypanosoma cruzi originate from a single multicistronic transcript

The cluster of alternated alpha- and beta-tubulin genes in the genome of Trypanosoma cruzi was shown to be transcribed into a single RNA molecule which upon processing gives rise to the mature alpha- and beta-tubulin mRNAs. This conclusion was based on: (i) nuclear RNA species with the same molecular mass hybridize to both alpha- and beta-tubulin cDNA probes; (ii) S1 nuclease assay of the clustered tubulin genes has shown protected DNA fragments of the same size and of greater molecular mass than that corresponding to the mRNAs, hybridizable to both alpha- and beta-tubulin cDNA probes; (iii) beta-tubulin hybrid selected RNA is still able to hybridize to alpha-tubulin probe.

The epidemiology and control of schistosomiasis mansoni where Biomphalaria tenagophila is the snail host

The epidemiology and control of schistosomiasis mansoni in the Municipality of Pedro de Toledo (State of S. Paulo, Brazil) since 1980, has been studied. In 1980 the prevalence evaluated by stool exams (Kato-Katz method) was 22.8% and no statistical difference at 5.0% level was observed between rural and urban zones. The intensity of infection was low (58.5 eggs/g of faeces); the highest prevalence and intensity of infection rates were observed within the group of from 5 to 29 years of age, respectively. The transmission of schistosomiasis usually occurred during leisure time. The majority of the carriers of the parasite were asymptomatic. Of the B. tenagophila examined only 0.4% were found to be infected. The control programme has been intensified from 1981 on resulting in a sharp decrease in the prevalence from 22.8% in 1980 to 6% at the present time. This result shows that, in spite of the control programme there is a residual human prevalence. A beginning has been made on the investigation into the possible causes of this residual prevalence (6.0% was maintained through out 1987).

Trypanosoma cruzi: an in vitro cycle of cell differentiation in axenic culture

The operation of an in vitro cycle of cell differentiation of Trypanosoma cruzi in axenic culture was obtained. When epimastigote forms, grown in LIT medium, were transferred to a modified LIT medium (E. Chiari, 1981, "Diferenciação do Trypanosoma cruzi em cultura." Ph.D. dissertation, Universidade Federal de Minas Gerais, Brazil), metacyclic trypomastigotes were generated. The latter, upon treatment with fresh human serum, and subsequent incubation in LIT medium gave origin to clusters of spheromastigote cells. The spheromastigotes were resistent to lysis mediated by the complement system and possess a morphology shown by optical and electron microscopy to be very similar to spheromastigotes derived from tissues of infected vertebrates. Blood-like trypomastigotes, or epimastigotes, could be obtained from spheromastigotes depending on the incubation conditions: at high serum concentration (55%) at 37 C, blood-like trypomastigotes were generated; by aging or heating (37 C), at low serum concentration (10%), epimastigotes were formed, closing the whole sequence of cell differentiation of T. cruzi. The molecular characterization of the different cell forms by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of metabolic pulse labeled proteins showed that the in vitro differentiated cells were distinct, not only by morphological criteria, but by differential gene expression as well. All the forms described could be obtained in large amounts (6 x 10(7) to 1 x 10(8)/ml), making it possible to perform preparative biochemical, molecular biological, and immunological experiments.

Protein biosynthesis changes in Trypanosoma cruzi induced by supra-optimal temperature

Early during vertebrate infection, T. cruzi is exposed to the host blood at an elevated temperature. Bearing this in mind, the pattern of protein synthesis of two parasite forms was examined. SDS-PAGE of heated organisms showed an increase in at least four proteins (103, 92, 75 and 61 kD). The temperature effect is also manifested in cells whose RNA synthesis is reduced by actinomycin D treatment. The synthesis of the '29 degrees proteins' is inhibited at 40 degrees C in organisms growing in culture medium; when the organisms were maintained in serum, the inhibition was not observed. The inhibitory effect observed at 40 degrees C was reversed when the temperature was shifted to 29 degrees C. These proteins were synthesized for 180 min at 37 degrees C or 360 min at 40 degrees C. The increased protein synthesis manifested at 37 degrees C had decreased 45 min after the temperature was lowered to 29 degrees C. When the cells were pre-incubated at 40 degrees C and shifted to 29 degrees C, the synthesis of the heat-induced proteins proceeded for at least 180 min. This pattern of heat induction in epimastigotes and trypomastigotes is the same irrespective of whether the incubation medium is LIT (for epimastigotes), M-16 (for trypomastigotes), or when serum was used for both cell types.

Control of tubulin gene expression during metacyclogenesis of Trypanosoma cruzi

During differentiation of the dividing epimastigote to the non-dividing metacyclic trypomastigote form of the parasitic protozoan Trypanosoma cruzi there is a marked reduction in the rate of synthesis of the major proteins alpha- and beta-tubulin. Our results indicate that the control of synthesis of these proteins during the differentiation event is exerted at the level of alpha- and beta-tubulin mRNA accumulation.

Biological characterization of various forms of elongation factor 1 from rabbit reticulocytes

Two forms of elongation factor 1 (EF-1) have been tested for a variety of biological functions. One form, EF-1H, is a high-molecular-weight aggregate (Mr greater than 500,000) containing four distinct polypeptides (alpha, beta, gamma, delta). The other form, EF-1 alpha, consists of a single polypeptide which is the same as the alpha subunit of EF-1H. Both EF-1 alpha and EF-1H function catalytically in binding Phe-tRNA to ribosomes, and in poly(U)-directed polyphenylalanine synthesis. The activity of EF-1 alpha is enhanced in polyphenylalanine synthesis by a complementary component, EF-1 beta delta. It is also shown that EF-1 beta delta can facilitate an exchange of EF-1 alpha-bound GDP for GTP. The EF-1 alpha dissociation constants for GDP and GTP were 0.47 and 0.55 microM respectively, while the EF-1H dissociation constants for GDP and GTP were 2.0 and 1.6 microM, respectively. Thus, while EF-1 alpha and EF-1H had approximately the same affinities for GDP and GTP, the EF-1 alpha dissociation constants were about fourfold lower than the EF-1H dissociation constants. Attempts to isolate complexes of EF-1 alpha or EF-1H with GTP and Phe-tRNA or with GTP, Phe-tRNA, and ribosomes were unsuccessful using either Millipore filters, gel filtration, or sucrose density gradients. The results presented in this report, along with studies from other laboratories, strengthen the hypothesis that the general mechanism of the elongation cycle is similar in eucaryotes and procaryotes.

Purification of various forms of elongation factor 1 from rabbit reticulocytes

Previous studies have indicated that the high-molecular-weight form of elongation factor 1 (EF-1H) contained four subunits (alpha, beta, gamma, and delta). Using the conventional methods of gel-filtration and ion-exchange chromatography, various forms of elongation factor 1 (EF-1 alpha, EF-1 beta delta, EF-1 beta gamma delta) have been purified from rabbit reticulocyte lysate. The procedure described allows one to purify these factors from a single batch of lysate in sufficient amounts for physical and biochemical studies. EF-1 alpha is a single polypeptide of Mr 52,000, and has an isoelectric point of 9.1. EF-1 beta delta and EF-1 beta gamma delta are composed of two and three nonidentical polypeptides, respectively, as judged by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Both proteins can form stable aggregates in native conditions that can reach more than 2,000,000 Da. The isoelectric point for each polypeptide was determined; 5.8 for EF-1 beta, 5.5 for EF-1 gamma, and 4.8 for EF-1 delta. The activity of both proteins was compared on a molecular basis by their ability to stimulate EF-1 alpha in the poly(U)-directed synthesis of polyphenylalanine. On the basis of this assay EF-1 beta gamma delta is slightly more active than EF-1 beta delta. The similarity of the amino acid composition of EF-1 gamma and EF-1 delta and the molar ratio of alpha: beta: gamma: delta in EF-1H of approximately 1:1:0.5:0.5 have led to the conclusion that EF-1 delta is probably a breakdown product of EF-1 gamma, and that the native form of EF-1H probably contains only the alpha, beta, and gamma subunits.

Nalidixic acid and macromolecular metabolism in Tetrahymena pyriformis: effects on protein synthesis

A study on the effect of nalidixic acid on macromolecular metabolism, particularly of protein, in Tetrahymena pyriformis was performed. It was shown that the compound is a potent inhibitor of deoxyribonucleic acid, ribonucleic acid, and protein synthesis for this organism. A conspicuous breakdown of polysomes, accompanied by the accumulation of 80S ribosomes, occurred in cells incubated for 10 min with the drug; polysome formation was prevented. The accumulating 80S particles were shown to be run-off ribosomal units. The incorporation of amino acids by a cell-free system is not affected by nalidixic acid. In nonproliferating cells the incorporation was also not prevented, unless the cells were previously incubated with the drug. These results are discussed in terms of the possible mechanism of action of nalidixic acid in T. pyriformis.