Nanoparticles as tools to study and control stem cells

The use of nanoparticles in stem cell research is relatively recent, although very significant in the last 5 years with the publication of about 400 papers. The recent advances in the preparation of some nanomaterials, growing awareness of material science and tissue engineering researchers regarding the potential of stem cells for regenerative medicine, and advances in stem cell biology have contributed towards the boost of this research field in the last few years. Most of the research has been focused in the development of new nanoparticles for stem cell imaging; however, these nanoparticles have several potential applications such as intracellular drug carriers to control stem cell differentiation and biosensors to monitor in real time the intracellular levels of relevant biomolecules/enzymes. This review examines recent advances in the use of nanoparticles for stem cell tracking, differentiation and biosensing. We further discuss their utility and the potential concerns regarding their cytotoxicity.

Synergic antitumoral effect of an IGF-IR inhibitor and trastuzumab on HER2-overexpressing breast cancer cells

BACKGROUND

Receptor tyrosine kinases play an important role in breast cancer. One of them, the type I insulin-like growth factor, has been linked to resistance to trastuzumab (Herceptin), an agent that targets human epidermal growth factor receptor 2. Here, we show that the insulin-like growth factor-I receptor (IGF-IR) antagonist NVP-AEW541 inhibits proliferation of breast cancer cells and synergizes with trastuzumab.

PATIENTS AND METHODS

Patient samples and breast cancer cell lines were evaluated for IGF-IR expression or activation by western blotting. 1-(4,5-Dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT) uptake assays and Annexin V staining were used for the analyses of cell proliferation/apoptosis. Biochemical and genomic studies were carried out to gain insights into the mechanism of action of NVP-AEW541.

RESULTS

The IGF-IR was expressed above normal levels in a number of breast cancer samples. Activation of this receptor was inhibited by NVP-AEW541 that also decreased cell proliferation and increased apoptosis. NVP-AEW541 decreased the amount of pAkt and increased the level of p27. Combination studies with several drugs used in the breast cancer clinic showed that NVP-AEW541 synergistically increased the action of trastuzumab.

CONCLUSIONS

Our results show the anti-breast cancer action of NVP-AEW541 and support the clinical development of anti-IGF-IR agents, especially in combination with trastuzumab.

Proteomic approaches for identifying new allergens and diagnosing allergic diseases

BACKGROUND

Allergic diseases are (IgE)-mediated hypersensitivity reactions affecting more than 25% of the world's population. Proteomic technologies have been increasingly used in the field of allergy and include the use of protein microarrays and two-dimensional gel electrophoresis coupled with immunoblotting.

METHODS

The literature relevant to proteomic approaches to allergic diseases was searched using MEDLINE database. We reviewed proteomics approaches and applications, focusing specifically on two-dimensional immunoblotting techniques and allergen microarrays.

RESULTS

The results obtained show that proteomic approaches using two-dimensional immunoblotting appear to be a powerful strategy for the identification of allergenic proteins. Likewise, the use of allergen microarrays allows a large number of IgE antibodies to be simultaneously identified.

CONCLUSIONS

Proteomic approaches are only beginning to be applied to the study of allergy. In the field of in vitro diagnosis, allergen microarrays provide a promising tool not routinely used in the allergy laboratory. In the near future this powerful technique will be used as a standard technique for in vitro diagnosis of allergy.

Insulin-like growth factor-I receptor kinase inhibitor NVP-AEW541 is active in breast cancer cells and enhances growth inhibition by herceptin through an increase in cell cycle arrest

21077

Background: Targeting ErbB2 with the monoclonal antibody trastuzumab (Herceptin) has shown to be active in breast cancer. However, a proportion of patients do not benefit from this treatment due to primary resistance. Mechanisms proposed for this resistance include activation of other receptors involved in proliferation as is the case of the insulin-like growth factor receptor (IGF-1R).Different strategies have been proposed for the inhibition of IGF-1R such as antibodies or small tyrosine-kinase inhibitors. In this study we analyzed the mechanism of action and the antiproliferative activity of an specific IGF-1R tyrosine-kinase inhibitor termed NVP-AEW541 alone and in combination with Herceptin. Methods: MCF7, SKBR3, BT474, and MDA-MB-231 breast cancer cells were used for this study. Proliferation and apoptosis were analyzed by MTT uptake assays or Annexin-V-FITC, respectively. The levels of different signalling proteins were analyzed by Western blotting. Microarray studies were performed using the HU-133A oligonucleotide arrays (Affymetrix, Santa Clara, CA). Real time quantitative PCR was used to confirm the differentially regulated genes. Results: The IGF-1R was expressed in all the cell lines studied. Exogenous addition of IGF-1 increased the tyrosine phosphorylation of IGF-1R, and this was prevented by preincubation with NVP- AEW541. The latter also decreased MTT uptake, and provoked a slight increase in apoptosis of BT474 cells. Combination of NVP-AEW541 and Herceptin had a synergistic effect on the inhibition of BT474 proliferation. Cell cycle analyses indicated that the combined addition of NVP- AEW541 and Herceptin increased the number of cells in the G0/G1 phases. These data were complemented with an increase in p27 levels upon treatment with both compounds. Microarray analyses identified several genes whose expression was modified by each agent alone and by the combination. Conclusions: Our results indicate that the combined targeting of two receptor tyrosine kinases known to play important roles in tumor cell proliferation may be more efficient than individual targeting of these receptors.

No significant financial relationships to disclose.

Newcastle disease virus may enter cells by caveolae-mediated endocytosis

The entry into cells of Newcastle disease virus (NDV), a prototype member of the paramyxoviruses, is believed to occur by direct fusion at the plasma membrane through a pH-independent mechanism. In addition, NDV may enter host cells by an endocytic pathway. Treatment of cells with drugs that block caveolae-dependent endocytosis reduced NDV fusion and infectivity, the degree of inhibition being dependent on virus concentration. The inhibitory effect was reduced greatly when drugs were added after virus adsorption. Cells treated with methyl beta-cyclodextrin, a drug that sequesters cholesterol from membranes, reduced the extent of fusion, infectivity and virus-cell binding; this indicates that cholesterol plays a role in NDV entry. Double-labelling immunofluorescence assays performed with anti-NDV monoclonal antibodies and antibodies against the early endosome marker EEA1 revealed the localization of the virus in these intracellular structures. Using fluorescence microscopy, it was found that cell-cell fusion was enhanced at low pH. It is concluded that NDV may infect cells through a caveolae-dependent endocytic pathway, suggesting that this pathway could be an alternative route for virus entry into cells.

[Epidemiological study of lung cancer in Portugal (2000/2002)]

Lung cancer is the most common form of cancer death in the world. Five-year survival is about 15%, without any change to this picture envisaged. It is the 3rd most prevalent type of cancer in Portugal and the primary cause of cancer death. 85% of lung cancer cases are attributable to smoking. One study performed in Portugal for 3 years (2000/2002) by the Lung Oncology Work Committee of the Portuguese Society of Pulmonology in 22 Hospitals showed that of a total of 4396 patients with lung cancer, 81.8% were male and 18.2% were female, with a mean age of 64.49 +/- 11.28 years. About 70% of patients were smokers or former smokers, with 50.3% of patients presenting with performance status (Zubrod) 1. Histologically, 37.5% were adenocarcinoma, followed by squamous carcinoma in 30.5% of cases, and small cell lung cancer in 12.5%; neuroendocrine carcinoma presented in 1.4% of cases; non small cell lung cancer in 10.5%; mixed carcinoma in 0.7%; large cell carcinoma in 2.3%; and others/not specified in 4.6% of cases. Staging (known in 4097 patients), showed 113 patients in stage IA (2.8%)and 250 patients in stage IB (6.1%); only 0.8% in stage IIA and 4.5% in stage IIB; 9.1% in stage IIIA and 29.9% in stage IIIB; 46.9% were already in stage IV by the time of diagnosis. The first therapeutic option was known in 3855 patients. Surgery was performed in 8.2% and 21.8% of cases were treated with combined therapies (surgery and chemotherapy or radiotherapy, or combination of chemotherapy and radiotherapy); chemotherapy alone was first choice in 43.7% of patients and in 20.3% only best support therapy was chosen.

Urinary proteomics

Protein measurement in urine has been used for many years for the diagnosis and monitoring of renal disease. The pattern of urinary protein excretion can be used to identify the cause of the disease and to classify proteinuria. In recent years, proteomics has proven to be a powerful tool in investigation and clinical medicine. Proteomics employs a protein separation method and the identification of proteins using mass spectrometry. One of the objectives of clinical proteomics is the identification of biological markers of disease. To accomplish this, it is necessary to have a normal proteome of the medium in question, which in our case is urine. Comparison of the normal urinary proteome with the urinary proteome from patients with a defined disease can detect proteins expressed differentially from one another. The aim of this review is to present the situation of urinary proteomics, putting special emphasis on its application in the diagnosis of glomerular diseases, renal allograft rejection, urological cancers and urolithiasis.

Structural analysis of dextran-based hydrogels obtained chemoenzymatically

This work reports the results of structural analysis in novel dextran-acrylate (dexT70-VA) hydrogels generated chemoenzymatically. Porous structure as well as hydrogel surface and interior morphologies were evaluated by mercury intrusion porosimetry (MIP), nitrogen adsorption (NA), and scanning electron microscopy (SEM) analyses, as a function of the degree of substitution (DS), and initial water content used in the preparation of the hydrogel. MIP analysis showed that the overall networks were clearly macroporous with pore sizes ranging from 0.065 to 10 microm. As expected, the average pore size decreased as DS increased and as initial water content decreased. Moreover, the porosity values ranged from 75 up 90%, which shows that these hydrogels present an interconnected pore structure. Nitrogen adsorption analyses showed that the specific surface area of dexT70-VA hydrogels increased either by increasing the DS or by decreasing the initial water content of the hydrogel. SEM results revealed that the surface of hydrogels with lower DS presented either a porous structure or a polymeric "skin" covering the pores, whereas hydrogels with higher DS were totally porous. Furthermore, the interior morphology varied according to the DS and the initial water content of the hydrogels. Finally, the average pore size was also determined from the swelling of hydrogel using a theoretical model developed by Flory-Rehner. The comparison of the SEM and MIP results with the ones obtained by the equilibrium swelling theory of Flory-Rehner shows that this approach highly underestimates the average pore size.

The effect of a remifentanil bolus on the bispectral index of the EEG (BIS) in anaesthetized patients independently from intubation and surgical stimuli

BACKGROUND AND OBJECTIVE

Remifentanil boluses are used in different clinical situations and the effects on bispectral index monitoring are unclear. We analysed the effect of a remifentanil bolus on the bispectral index of the electroencephalogram (bispectral index) under total intravenous anaesthesia with propofol and remifentanil.

METHODS

ASA I-III patients were included in this study. All patients received a 2 microg k g-1 remifentanil bolus in a period free from stimuli. Bispectral index and haemodynamic data were collected from an A-2000XP bispectral index monitor (every second) and an AS/3 Datex monitor (every 5 s). Bispectral index data were analysed using the area under the curve. Mean arterial pressure and heart rate were averaged at each 30-s period and analysed using analysis of variance.

RESULTS

A total of 240 bispectral index values were obtained per patient. The area under the curve between 90 and 120 s after the bolus was significantly lower than the basal area under the curve (average of all areas before the bolus, P < 0.05). Mean arterial pressure and heart rate were significantly reduced from 96.4 +/- 19.9 mmHg at the time of the bolus to 74.2 +/- 16.6 mmHg 120 s after, and from 70 +/- 16.4 bpm at the time of the bolus to 61 +/- 13.6 bpm after (P < 0.001), respectively.

CONCLUSIONS

There was a significant reduction in the areas under the curve between 90-120 s following the bolus. Heart rate and blood pressure also showed significant reductions. Thus, remifentanil bolus given under total intravenous anaesthesia with propofol and remifentanil decreases bispectral index, an effect independent of intubation and surgical stimuli.

N-terminal cleavage of proTGFalpha occurs at the cell surface by a TACE-independent activity

ProTGFalpha (transforming growth factor alpha precursor) maturation and conversion into soluble TGFalpha is a complex process that involves three proteolytic steps. One, that occurs co-translationally, eliminates the signal sequence. Another, occurring at the juxta-membrane domain, solubilizes TGFalpha. A third cleavage removes the N-terminal extension of proTGFalpha. This latter step has been poorly studied, mainly because of the rapid kinetics of this cleavage. In the present study, we have designed a strategy to analyse several aspects regarding this N-terminal cleavage. In vivo treatment with the hydroxamate-based metalloprotease inhibitors BB3103 or TAPI-2 (tumour necrosis factor-alpha protease inhibitor 2) reversibly induced accumulation of forms of proTGFalpha that included the N-terminal extension. N-terminal shedding was rapid, and occurred at the cell surface. However, the machinery responsible for the N-terminal cleavage was inactive in other cellular sites, such as the endoplasmic reticulum. Experiments of proTGFalpha expression and maturation in cells deficient in TACE (tumour-necrosis-factor-alpha-converting enzyme) activity indicated that this protease was dispensable for N-terminal processing of proTGFalpha in vivo, but was required for regulated cleavage at the C-terminus. These findings indicate that TACE is not involved in N-terminal processing of proTGFalpha, and suggest differences in the machineries that control the cleavage at both ends of TGFalpha within its precursor.

Mapping of the RNA promoter of Newcastle disease virus

The RNA promoters of the genome and antigenome of Newcastle disease virus (NDV) were studied by mutational analysis of their 3' terminal ends. Similarly to other paramyxoviruses, NDV RNA replication follows the rule of six, and the genomic and antigenomic promoters require two discontinuous regions: conserved region I (first 18 nucleotides) and conserved region II (nucleotides 73-90). Proper spacing between those regions and the phase of six in region II is critical for efficient RNA promoter activity. As expected, the gene start signal at the 3' end of the NDV genome was required for mRNA transcription, but not for RNA replication. Surprisingly, mutation of the polyadenylation signal in the 5' end did not affect gene expression transcription. Although the conserved region I of NDV (avulavirus) promoter appears to be more similar to that of Sendai virus (SeV) (respirovirus), conserved region II is analogous to that of rubulaviruses.

Tumour necrosis factor-alpha (TNF-alpha) levels and influence of -308 TNF-alpha promoter polymorphism on the responsiveness to infliximab in patients with rheumatoid arthritis

OBJECTIVE

To investigate the influence of -308 tumour necrosis factor-alpha (TNF-alpha) promoter polymorphism and circulating TNF-alpha levels in the clinical response to the infliximab treatment in patients with rheumatoid arthritis (RA).

METHODS

One hundred and thirty-two RA patients were genotyped for TNF-alpha promoter by polymerase-chain reaction restriction fragment-length polymorphism (PCR-RFLP) analysis. Ten patients with the -308 TNF-alpha gene promoter genotype G/A, and 10 with the G/G genotype were selected and received 3 mg/kg of infliximab at Weeks 0, 2, 6, and 14.

RESULTS

Both groups showed a significant improvement with treatment in all variables studied. Total mean TNF-alpha levels increased significantly with respect to basal levels in most of patients after treatment [probability (p)=0.04]. Only patients from G/A showed a statistically significant correlation between ACR 50 and the increase of TNF-alpha levels (p<0.03).

CONCLUSION

A relationship was detected between ACR criteria of improvement and increased circulating TNF-alpha levels in RA patients subjected to anti-TNF-alpha therapy.

Gangliosides and N-glycoproteins function as Newcastle disease virus receptors

The interaction of enveloped viruses with cell surface receptors is the first step in the viral cycle and an important determinant of viral host range. Although it is established that the paramyxovirus Newcastle Disease Virus binds to sialic acid-containing glycoconjugates the exact nature of the receptors has not yet been determined. Accordingly, here we attempted to characterize the cellular receptors for Newcastle disease virus. Treatment of cells with tunicamycin, an inhibitor of protein N-glycosylation, blocked fusion and infectivity, while the inhibitor of O-glycosylation benzyl-N-acetyl-alpha-D-galactosamide had no effect. Additionally, the inhibitor of glycolipid biosynthesis 1-phenyl-2-hexadecanoylamino-3-morpholino-1-propanol blocked viral fusion and infectivity. These results suggest that N-linked glycoproteins and glycolipids would be involved in viral entry but not O-linked glycoproteins. The ganglioside content of COS-7 cells was analyzed showing that GD1a was the major ganglioside component; the presence of GM1, GM2 and GM3 was also established. In a thin-layer chromatographic binding assay, we analyzed the binding of the virus to different gangliosides, detecting the interaction with monosialogangliosides such as GM3, GM2 and GM1; disialogangliosides such as GD1a and GD1b, and trisialogangliosides such as GT1b. Unlike with other viruses, our results seem to point to the absence of a specific pattern of gangliosides that interact with Newcastle disease virus. In conclusion, our results suggest that Newcastle disease virus requires different sialic acid-containing compounds, gangliosides and glycoproteins for entry into the target cell. We propose that gangliosides would act as primary receptors while N-linked glycoproteins would function as the second receptor critical for viral entry.

Sialidase, receptor-binding and fusion-promotion activities of Newcastle disease virus haemagglutinin–neuraminidase glycoprotein: a mutational and kinetic study

Mutations were generated in residues at the putative catalytic site of the haemagglutinin–neuraminidase (HN) protein of Newcastle disease virus Clone 30 strain (Arg498, Glu258, Tyr262, Tyr317 and Ser418) and their effects on its three associated activities were studied. Expression of the mutant proteins at the surface of HeLa cells was similar to that of the wild-type. Sialidase, receptor-binding and fusion-promotion activities were affected to different degrees for all mutants studied. Mutant Arg498Lys lost most of its sialidase activity, although it retained most of the receptor-binding activity, suggesting that, for the former activity, besides the presence of a basic residue, the proximity to the substrate molecule is also important, as Lys is shorter than Arg. Proximity also seems to be important in substrate recognition, since Tyr262Phe retained most of its sialidase activity while Tyr262Ser lost most of it. Also, Ser418Ala displayed most of the wild-type sialidase activity. However, a kinetic and thermodynamic study of the sialidase activity of the Tyr262Ser and Ser418Ala mutants was performed and revealed that the hydroxyl group of these residues also plays an important role in catalysis, since such activity was much less effective than that of the wild-type and these mutations modified their activation energy for sialidase catalysis. The discrepancy of the modifications in sialidase and receptor-binding activities in the mutants analysed does not account for the topological coincidence of the two sites. These results also suggest that the globular head of HN protein may play a role in fusion-promotion activity.

Conformational changes of Newcastle disease virus envelope glycoproteins triggered by gangliosides

We have investigated the conformational changes of Newcastle disease virus (NDV) glycoproteins in response to receptor binding, using 1,1-bis(4-anilino)naphthalene-5,5-disulfonic acid (bis-ANS) as a hydrophobicity-sensitive probe. Temperature- and pH-dependent conformational changes were detected in the presence of free bovine gangliosides. The fluorescence of bis-ANS was maximal at pH 5. The binding of bis-ANS to NDV was not affected by chemicals that denature the fusion glycoprotein, such as reducing agents, nor by the presence of neuraminidase inhibitors such as N-acetyl neuramicic acid. Gangliosides partially inhibited fusion and hemadsorption, but not neuraminidase hemagglutinin-neuraminidase glycoprotein (HN) activity. A conformational intermediate of HN, triggered by the presence of gangliosides acting as receptor mimics, was detected. Our results indicate that, upon binding to free gangliosides, HN undergoes a certain conformational change that does not affect the fusion glycoprotein.

Nitric oxide protects against pancreatic subcellular damage in acute pancreatitis

OBJECTIVES

Oxidative stress involvement in damage to the pancreas in acute pancreatitis (AP) is well documented. However, little is known about oxidative damage occurring in the different subcellular fractions of pancreatic cells. The aim of this study was to ascertain the main targets of oxidative damage inside cells after AP and the role of endogenous nitric oxide (NO) in it.

METHODS

A model of cerulein-induced AP in rats was used and N-nitro-l-arginine methyl ester (l-NAME) was administered as an NO production inhibitor. After pancreatitis induction, indicative parameters of lipid peroxidation and protein oxidation together with some enzymatic and nonenzymatic endogenous free radical scavengers were assessed in serum and pancreatic subcellular fractions.

CONCLUSIONS

In pancreatitic rats, malondialdehyde and protein carbonyl group concentrations were significantly increased (P < 0.05) in serum and some fractions. The increases were higher in l-NAME-treated rats (P < 0.05). Superoxide dismutase and catalase activities were also increased (P < 0.05) but were decreased (P < 0.05) with l-NAME. The alpha-tocopherol concentration diminished (P < 0.05) in serum and all the studied subcellular fractions and the decrease was stronger in l-NAME-treated rats. Our data suggest that microsomes followed by lysosomal + mitochondrial are the fractions most susceptible to oxidative damage in AP. Endogenous NO plays a protective role against oxidative damage to subcellular fractions.

The ability of Bipolaris sorokiniana to modify geraniol and (-)-alpha-bisabolol as exogenous substrates

The biocatalytic potential of Bipolaris sorokiniana was investigated in its ability to modify the monoterpene geraniol and the sesquiterpene alpha-bisabolol as exogenous substrates, using phosphate buffer as reaction medium. The cultures showed a promising oxidative profile, with conversion of geraniol to 6-methyl-5-hepten-2-one (74.9% yield) in a 5-day incubation and alpha-bisabolol to bisabolol oxide B (84.2% yield), in a 7-day incubation.

The role of adherence in tuberculosis HIV-positive patients treated in ambulatory regimen

Adherence to antituberculosis treatment, a major determinant of outcome, is of special concern in human immunodeficiency virus (HIV)-positive patients. However, tuberculosis death in HIV-positive patients remains higher than in HIV-negative patients, regardless of adherence. To assess determinants for an unfavourable tuberculosis outcome (defined as no cure or death), and determinants for nonadherence to antituberculosis treatment, 70 HIV-positive patients with tuberculosis referred to an outpatient centre were studied. Patient outcome was compared according to HIV risk factors, other opportunistic diseases, antiretroviral drugs use, current i.v. drugs use, a methadone programme participation, tuberculosis features, treatment characteristics and adherence. Adherent and non-adherent patient characteristics were also compared. An unfavourable outcome occurred in 22.9% of patients and 32.9% were nonadherent with therapy. Nonadherence was the only independent determinant for an unfavourable outcome. Adherence was independently associated with current i.v. drug use, treatment complications and use of methadone. This study confirms that human immunodeficiency virus-infected patients, treated as outpatients, have high rates of nonadherence and that adherence is the strongest determinant for tuberculosis outcome. Independently of the current use of drugs, a methadone programme improves adherence to treatment.

A mulher e o cancro do pulmão**Textos referentes à mesa-redonda com o mesmo título organizada pela Comissão de Trabalho de «Pneumologia Oncológica». Coimbra, 13 de Abril de 2002

The epidemiology of lung cancer has changed in the last years in several countries all over the world. In the 19th century, the lung cancer was rare but it incidence increase drastically during the 20th century, and the tendency is to continue in the 20th century. Actually the lung cancer's incidence and mortality are higher in the developed countries, especially in Europe and Unites States of America, with a increasing in the women incidence. These geographic differences and gender differences are related with smoking habits. Women begin to smoke earlier and have more difficulty to stop, because of problems related with obesity; they have more sensibility to the carcinogens and the risk of lung cancer is 1.5 times higher than the men with the same habits. Adenocarcinoma is the more frequent histological type in young people, in the total of the women and in non-smokers. Many factors since tobacco, home and professional pollution, nutritional, associated diseases even genetic and hormonal factors have been investigated to define its influence in development in women lung cancer. It specificity in women with lung cancer is the common problem for the medical people to treat this disease (pathology).The literature about this problem is not clear, and is necessary to advance with many studies in this area with the objective to clarify this important question.

The -308 polymorphism in the tumour necrosis factor (TNF) gene promoter region and ex vivo lipopolysaccharide-induced TNF expression and cytotoxic activity in Chilean patients with rheumatoid arthritis

OBJECTIVE

To investigate the association of the -308 polymorphism in the promoter region of the tumour necrosis factor (TNF) gene with susceptibility to the development of RA. We also explored the expression and cytotoxicity of TNF in relation to the -308 polymorphism.

METHODS

We recruited 92 RA patients and 42 healthy control subjects. Genotyping for the TNF promoter was performed by polymerase chain reaction-restriction fragment length polymorphism analysis. To study the overexpression of TNF we used a whole-blood culture system. TNF cytotoxicity was assessed in the L929 cell line.

RESULTS

The TNF2 allele was found in 23% of RA patients and 10% of controls. Although both groups showed high variability in serum TNF concentration, in the lipopolysaccharide-induced TNF level and in the cytotoxicity of the cytokine in the L929 cell line, these differences were not associated with the -308 TNF polymorphism.

CONCLUSION

No associations were found between the -308 TNF promoter polymorphism, serum and ex vivo TNF levels and the cytotoxic activity of TNF in RA patients.

Acute pancreatitis decreases pancreas phospholipid levels and increases susceptibility to lipid peroxidation in rat pancreas

The objective of this study was to analyze whether acute pancreatitis leads to changes in the lipid composition and susceptibility to lipid peroxidation of pancreatic membranes. Total lipids, cholesterol, phospholipids, FA, and lipid peroxidation were determined in the pancreatic tissue of rats treated with cerulein and of control rats. In pancreatitic rats, significant decreases in membrane total phospholipid contents (P < 0.05) and in choline and ethanolamine glycerophospholipid levels (P < 0.05 and P < 0.01, respectively), with concomitant significantly higher values of their lysoderivative forms, were found. The cholesterol/phospholipid molar ratio increased by 26%. The unsaturation index of the FA profile decreased significantly (P < 0.01) as a consequence of a decrease in the arachidonic acid content. Incubation of membranes with xanthine oxidase/hypoxanthine-Fe2+/ADP resulted in an increase in the production of TBARS in pancreatitic rats compared to controls. In summary, acute pancreatitis causes changes in the lipid composition of rat pancreatic crude membranes and a greater susceptibility of these membranes to lipid peroxidation.

Characterization of a candidate Trypanosoma brucei U1 small nuclear RNA gene

We have previously shown that the poly(A) polymerase (PAP) gene of Trypanosoma brucei is interrupted by an intervening sequence. It was postulated that removing this intron by cis-splicing requires a yet unidentified U1 small nuclear RNA (snRNA), which in other organisms engages in base-pair interactions across the 5' splice site during early spliceosome assembly. Here we present a characterization of a 75 nucleotide long candidate T. brucei U1 snRNA. Immunoprecipitation studies indicate that a trimethylguanosine cap structure is present at the 5' end and that the RNA is bound to core proteins common to spliceosomal ribonucleoprotein particles. The U1 snRNA has the potential for extensive intermolecular base pairing with the PAP 5' splice site. We used block replacement mutagenesis to identify sequences necessary for in vivo expression of U1 snRNA. We found that at least two cis-acting elements, tRNA-like A and B boxes, located in the 5'-flanking region are necessary for U1 snRNA synthesis; no internal sequences close to the transcription start site are essential, suggesting a promoter architecture distinct from other trypanosome U-snRNA genes.

Daily production of human tumor necrosis factor in lipopolysaccharide (LPS)-stimulated ex vivo blood culture assays

Tumor necrosis factor (TNF) is a pleiotropic cytokine with immunological and neuroendocrine activities. A useful tool for studying TNF is the measurement of its in vitro and/or ex vivo over-expression, induced by a variety of stimuli on isolated peripheral mononuclear cells or whole blood, respectively. The capacity to over-express TNF, in ex vivo LPS-stimulated whole blood from 18 normal individuals, showed inter-individual variations ranging from high (3 ng/ml) to low (0.7 ng/ml) producers. Although at a lower level, a similar situation was observed in the spontaneous production of the cytokine. In order to detect cyclic effects in these variations, blood samples were taken at 08:00, 12:00, 16:00 and 20:00 hours, from nine healthy volunteers, and cultured in the ex vivo system. TNF and cortisol were measured by immunometric assays. Both, LPS-stimulated whole blood and plasma showed important, individual variations in TNF levels. Although cortisol levels presented a normal circadian cycle, these individual patterns in TNF production were basically conserved during the day (p > 0.05), and no correlation was observed between the levels of the hormone and those of the cytokine. When total TNF levels were determined at 20:00 hours, a moderate, temporary variation pattern of the cytokine production was found. These results suggest that cortisol does not play a predominant role in determining the ex vivo capacity of blood to produce TNF. Presumably, the variable capacity to produce the cytokine may have a strong genetic component.

Tc45, a dimorphic Trypanosoma cruzi immunogen with variable chromosomal localization, is calreticulin

We demonstrate that Tc45, a polypeptide described as an immunogenetically restricted Trypanosoma cruzi antigen in mice, is calreticulin, a dimorphic molecule encoded by genes with variable chromosomal distribution. Previously we showed that IgG from A.SW (H2s) mice immunized with T. cruzi trypomastigotes or epimastigotes and sera from infected humans recognize Tc45, a 45 kD parasite polypeptide. Herein we describe the cloning, sequencing, and expression of the Tc45 gene. A 98% homology in the deduced amino acid sequence was found with a T. cruzi calreticulin-like molecule and 41% with Leishmania donovani and human calreticulin. In the T. cruzi CL Brener clone and in the Tulahuén strain, the gene is located in two and four chromosomes, respectively. Calreticulin was detected in several T. cruzi clones, in the Tulahuén strain, and in T. rangeli, displaying alternative 43 and 46 kD forms.

Development of an immunoenzymatic assay for the detection of human antibodies against Trypanosoma cruzi calreticulin, an immunodominant antigen

We have developed an indirect immunoenzymatic assay (ELISA) for the detection of human antibodies against calreticulin (formerly known as Tc45), a dimorphic Trypanosoma cruzi antigen, described in our laboratory. PVC microtitration plates were sensitized with the monoclonal anti-calreticulin antibody (MoAb) and reacted with calreticulin present in a partially purified preparation. The presence of anti-T. cruzi calreticulin IgG in sera from infected individuals was tested. The data generated with this assay were validated by correlation, in a regression analysis, with those obtained by an indirect immunoradiometric assay (IRMA). From the 12 seropositive sera (as defined by a commercial test), eight came out positive and four negative in both assays. The 12 human sera were also analyzed in direct immunometric assays (ELISA and IRMA), where the solid phase was sensitized with a whole parasite extract. The direct ELISA and IRMA correlated positively (P<0.01). Further validation of this ELISA was achieved with an indirect immunofluorescense assay. The high degree of significance obtained when the indirect IRMA and ELISA systems were compared, indicated that the relatively small sample number used (12) was statistically satisfactory for the purposes of this investigation. Thus, the IRMA can be replaced by the ELISA, with advantages mainly derived from the cumbersome manipulation of radioactive wastes. The MoAb used as an antigen capture agent in the ELISA proposed here, recognizes a homologous protein in Trypanosoma rangeli, suggesting that individuals infected with this parasite might have crossreactive antibodies. However, the system retains its diagnostic interest, given the facts that the MoAb does not recognize a homologous protein in Leishmania mexicana, Leishmania donovani, or Crithidia fasciculata.

Evaluation of poly(2-hydroxyethyl methacrylate) gels as drug delivery systems at different pH values

Studies of dynamic and equilibrium swelling, structural characterisation and solute transport in swollen poly(2-hydroxyethyl methacrylate) gels (pHEMA) cross-linked with tripropyleneglycol diacrylate (TPGDA) were done for a wide range of TPGDA concentrations. The influence of the pH on these pHEMA properties was evaluated. In swelling studies it was found that in changing the pH from 6.5 to 12.0, a large increase in swelling occurred, from approximately 48 to 55%, for the lowest concentration of TPGDA (1 mol%), and from 40 to 80% for the highest concentration (10 mol%). Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC) measurements were made after the equilibrium swelling of the gels at different pH values, to explain these results. The advantage of using these gels as controlled drug delivery systems is illustrated using salicylic acid (SA) as a model drug. The loading and the release of the SA were made at different pH values and the results obtained showed that it is possible to modulate the hydrogel performance by controlling an external factor, the pH at which the drug loading and release were performed.

[The metabolic-chronotropic relation in patients with heart failure--a correlation with functional capacity]

Previous studies on chronotropic incompetence (CI) in patients with congestive heart failure (CHF) have defined it as the inability to achieve > 80% of age predicted maximum heart rate (HR) (adequacy of HR response to submaximal exercise levels not being considered). The metabolic chronotropic relation (MCR) concept proposed by Wilkoff allows the assessment of the entire chronotropic function. The value of such an approach for the evaluation of CI in patients with CHF, and its relation to exercise capacity, is unclear at present.

METHODS

We imposed maximal symptom-limited treadmill exercise testing while measuring breath-by-breath oxygen consumption, using CAEP protocol, in 25 patients (19 men), 49 +/- 10 years, all in sinus rhythm, with CHF secondary to dilated cardiomyopathy (17) or ischemic heart disease (8), NYHA class II-III. Anaerobic threshold (AT) was attained by all. No exercise was terminated due to arrhythmia or ischemia. MCR was calculated as the slope of the relation between the percentages of HR and metabolic reserves achieved at the end of each exercise stage. Using 2.0 standard deviations below the mean level of MCR in healthy controls, we defined an MCR value < 0.84 as abnormal. The parameters analysed were: age, drug therapy, fractional shortening (FS-%), resting HR (RHR-bpm), exercise duration (DUR-min), peak HR (HRp), peak oxygen consumption (VO2p-ml/kg/min), percentages of predicted maximal HR (% PMHR) and VO2 (% PMVO2), peak ventilatory equivalent for CO2 (VE/VCO2-L/min), time to AT (T-AT), and VO2 at AT (VO2-AT).

RESULTS

MCR was normal (1.01 +/- 0.18-0.86 to 1.19) in 10 patients--Group I, and abnormal (0.66 +/- 0.13-0.42 to 0.81) in 15 (60%) patients--Group II. A similar proportion of patients in both groups were taking ACE inhibitors, digoxin and amiodarone. [table: see text] CI defined as an inability to achieve a % PMHR > 80% occurred only in 6 (24%) patients, all in Group 2 (p = 0.022 versus abnormal MCR).

CONCLUSIONS

In CHF patients, CI assessed as an abnormal MCR is frequent, and relates to an impaired exercise capacity.

[The nonpharmacological treatment of atrial fibrillation]

The authors describe the main forms of nonpharmacological treatment of atrial fibrillation considering catheter ablation and surgical therapy. A new methodology to modify atrioventricular conduction is discussed as well its long-term results. All studies are non-randomised with selected patients, which makes the development of a therapeutical algorithm difficult. However, the results have shown that it is possible to recover sinus rhythm through surgery or catheter ablation and to control the ventricular rate either by His ablation or modification of atrioventricular conduction.

[The influence of therapy (sympathomimetic amines versus vasodilators) in the indexes of ejection fraction derived from an analysis of Doppler aortic flow]

PURPOSE

To assess the influence of inotropic IV therapy--dobutamine and/or dopamine--versus vasodilator therapy--nitroprusside, captopril or hydralazine--in aortic flow ejection phase indexes obtained by pulsed Doppler echocardiography.

METHODS

In 17 patients admitted to the ICU (11 males, 62 +/- 14 years, 9 with ischemic cardiomyopathy and 8 with dilated cardiomyopathy, all in sinus rhythm), with congestive heart failure, and submitted to tailored therapy, 53 serial pulsed Doppler and hemodynamic evaluations were made as the therapy changed the hemodynamic and clinical status. Considering serial consecutive evaluations, a hemodynamic improvement was obtained only with inotropics in 13 (group A), and with vasodilators in only 15 (group B). The following ejection phase indexes were calculated from Doppler registers: average acceleration (AvAc) and ejection force (EFor), calculated according to the formula: Efor = 1.06 x Aortic Orifice Area x AvAc x Acceleration Velocity Time Integral.

RESULTS

Arterial blood pressure increased in gr A (76.2 +/- 14.1 to 81.4 +/- 14.8 mm Hg, p < 0.05) and decreased in gr B (85.1 +/- 12.6 to 76.2 +/- 9.7 mm Hg (p < 0.05). In both groups there was a significant (p < 0.05) increase in cardiac output (CO)-from 3.9 +/- 1.1 to 4.9 +/- 1.4 L/min in group A, and from 3.9 +/- 1.2 to 4.4 +/- 1.2 L/min in group B. CO increased 18.7% in group A and 13.8% in group B (NS). There was a decrease in pulmonary capillary wedge pressure (PCWP) from 19.5 +/- 6.0 to 15.1 +/- 5.8 mm Hg in group A (p < 0.05), and from (16.9 +/- 5.7 to 12.1 +/- 4.6 mm Hg in group B (p < 0.05). PCWP decreased 19.7% in group A and 27.8% in group B (NS). Systemic vascular resistance (SVR) changed from 18.2 +/- 7.0 to 16.2 +/- 7.1 Wood U in group A (p < 0.05), and from 22.3 +/- 9.3 to 17.7 +/- 5.7 Wood U in group B (p < 0.05). In group A, AvAc increased-from 1347 +/- 611 cm.s-2 (p < 0.05), as did Efor-from 15.4 +/- 10.7 to 20.2 +/- 11.0 g.cm,s-2 (p < 0.05), whereas in group B there was no significant change in either AvAc-from 1337 +/- 284 to 1277 +/- 256 cm.s-2, or Efor-from 22.7 +/- 17.0 to 23.8 +/- 15.0 g.cm.s-2.

CONCLUSIONS

Vasodilator therapy, although inducing hemodynamic changes similar to inotropics, does not alter the ejection phase indexes. Therefore, AvAc and Efor, in spite of being calculated from the aortic flow, are independent of the changes in PCWP and SVR and seem to reflect changes in inotropism in the clinical setting.