Sterically hindered cisplatin derivatives with multiple carboxylate auxiliary arms: synthesis and reactions with guanosine-5'-monophosphate and plasmid DNA

Two novel sterically hindered cisplatin derivatives with the ligand L=NH(2)C(CH(2)CH(2)COOH)(3) were prepared: cis-PtCl(2)L(2) and cis-PtCl(2)L(NH(3)). The starting compound for the syntheses was NH(2)C(CH(2)CH(2)COOtBu)(3), also known as a building block for dendrimers. cis-PtCl(2)L(2) was prepared from K(2)PtCl(4) in an unusual two-phase reaction in water-chloroform, followed by deprotection of the tert-butyl protective groups with formic acid to yield a water-soluble complex. The mixed-ligand compound cis-PtCl(2)L(NH(3)) was prepared from [PPh(4)][PtCl(3)(NH(3))] in methanol, with subsequent deprotection in formic acid. DNA-binding properties of the two compounds were investigated using the model base guanosine-5'-monophosphate (5'-GMP) and pBR322 plasmid DNA. While cisplatin [cis-PtCl(2)(NH(3))(2)] induced an unwinding of 12 degrees in pBR322 plasmid DNA, cis-PtCl(2)L(NH(3)) induced only 3 degrees unwinding, which is indicative of a monofunctional binding mode. Remarkably, cis-PtCl(2)L(2) did not induce any distortion in plasmid DNA, which strongly suggests that the compound does not bind to DNA. Test reactions with 5'-GMP, monitored by 1H and 195Pt NMR, confirmed that cis-PtCl(2)L(2) is unable to bind to DNA, whereas cis-PtCl(2)L(NH(3)) binds only one nucleotide. Apparently, binding of platinum to nucleotides at the coordination site cis with respect to the ligand L is prevented by steric crowding. Thus, cis-PtCl(2)L(NH(3)) must bind DNA monofunctionally at the trans position. Besides, both compounds have a chloride replaced by one of the carboxylate arms, forming a a seven-membered chelate ring. In theory, cis-PtCl(2)L(2) could also form a second chelate ring, but this was not observed.

The R71G BRCA1 is a founder Spanish mutation and leads to aberrant splicing of the transcript

In a BRCA1 screening in familial breast cancer carried out in different centres in Spain, France, and United Kingdom, a missense mutation 330A>G which results in a Arg to Gly change at codon 71 (R71G) was independently identified in 6 families, all of them with Spanish ancestors. This residue coincides with the -2 position of the exon 5 donor splice site. We further investigated the effect of this base substitution on the splicing of BRCA1 mRNA. The sequence analysis of the cDNA indicated that 22 bp of exon 5 were deleted, creating with the first bases of exon 6 a termination codon at position 64, which results in a truncated protein. The BRCA1 haplotype of the R71G carrier patients and Spanish controls was analysed by use of six microsatellites located within or near BRCA1. Our results are consistent with the possibility that these families shared a common ancestry with BRCA1 R71G being a founder mutation of Spanish origin.

Conditions for single-strand conformation polymorphism (SSCP) analysis of BRCA1 gene using an automated electrophoresis unit

The single-strand conformation polymorphism procedure has been applied in routine testing for hereditary diseases and cancer. However, temperature, running time, gel composition, fragment length, etc. can influence its sensitivity. Mutation detection in the clinical setting depends on the development of automated technology, especially for large genes such as the breast cancer gene BRCA1. We analysed DNA samples with BRCA1 mutations in an automated system (GenePhor System; Amersham-Pharmacia Biotech, Uppsala, Sweden). The concentrations of DNA template and PCR primers, the effect of chilling after denaturation, and the temperature and time of the electrophoresis were investigated. All band-shifts were detected by electrophoresis at 5 degrees C for 2 h 15 min. Concentrations of DNA and samples used in the PCR did not affect the SSCP pattern, but chilling the PCR product in ice after denaturation was required. The type and position of mutation in the fragments did not influence the probability of a mobility shift, although SSCP analysis was more sensitive for fragments shorter than 350 bp. This automated SSCP method meets the requirements of fast turnaround and sensitivity and can be readily adapted to the screening of large genes such as BRCA1.

[Effect of supragingival plaque control on subgingival microflora and periodontal tissues]

The aim of this study was to investigate, clinically and microbiologically, forty-four sites in 11 patients presenting with generalized chronic periodontitis. Plaque Index (PI), Gingival Index (GI), Probing Bleeding (PB), Probing Depth (PD) and Insertion Level (IL) were registered. Samples of subgingival plaque were collected in the same sites for cultivation of anaerobic bacteria and determination of microbiological morphotypes using dark field microscopy. Clinical and microbiological data were recorded on the baseline and 4 weeks after the adoption of a program to control supragingival plaque and calculus. The microbiological analysis categorized the degree of development as follows: 0--not detected, 1--scarce, 2--moderate and 3--abundant. The clinical results at the baseline and on the 28th day were, respectively: PI--1.73 +/- 0.10 and 0.30 +/- 0.08; GI--1.73 +/- 0.08 and 1.41 +/- 0.08; PB--0.91 +/- 0.04 and 0.59 +/- 0.07; PD--6.43 +/- 0.20 and 5.77 +/- 0.25; and IL--6.86 +/- 0.32 and 6.52 +/- 0.34. There was significant decrease in PI, GI, PB and PD. However, the difference in IL was not significant. The relative proportions of the microbial morphotypes observed under dark field microscopy at the baseline and on the 28th day were, respectively: coccoid cells--21.16 +/- 3.77 and 36.00 +/- 4.66; mobile bacillus--44.86 +/- 2.65 and 39.50 +/- 2.64; and total treponemes--24.66 +/- 3.08 and 19.25 +/- 2.75. The cultures presented, at the baseline and on the 28th day, respectively: Prevotella intermedia/nigrescens (Pi/n)--1.36 +/- 0.18 and 0.43 +/- 0.11; Porphyromonas gingivalis--0.48 +/- 0.16 and 0.32 +/- 0.13; Actinobacillus actinomycetemcomitans--0.23 +/- 0.09 and 0.23 +/- 0.10; Fusobacterium nucleatum--0.32 +/- 0.14 and 0.41 +/- 0.13; and peptostreptococci--0.82 +/- 0.19 and 0.54 +/- 0.16. There was a significant increase in the number of coccoid cells and a decrease in the number of treponemes and Pi/n.

Is cisplatin-induced cell death always produced by apoptosis?

It is generally accepted that DNA damage and subsequent induction of apoptosis may be the primary cytotoxic mechanism of cisplatin and other DNA-binding antitumor drugs (Fisher,1994). Because the final step of apoptosis is characterized by morphological changes in the nucleus, the death signals of the execution phase must be transmitted from the cytoplasm to the nucleus. Thus, the recognition and processing of cisplatin-induced DNA damage through"classic" apoptosis, requires that a nuclear signal, generated at the initiation phase, be transmitted to the cytoplasm to be processed through the effector and execution phases. At the end of the execution phase, the apoptotic signal must come back to the nucleus to produce internucleosomal DNA degradation. Therefore, the induction of apoptosis from detection and subsequent processing of cisplatin-induced DNA damage seems to be a long and complex process of cell death. However, because cisplatin is a nonspecific drug and reacts not only with DNA but also with proteins,we cannot rule out the possibility that in some cases of cisplatin-induced apoptosis, an easier process of initiation, such as damage to cytoplasmic proteins, may take place (Pérez, 1998). Thus, damage to proteins is worth considering as a factor contributing to cisplatin-induced apoptosis. Moreover, it is possible that cisplatin damage to proteins could induce apoptosis at the execution phase level. In fact, initiation of apoptosis at the execution phase (activation of caspases) has been previously reported for the cell killing produced by cytotoxic T lymphocytes (Golstein et al., 1991). Although apoptosis and necrosis are conceptually distinct forms of cell death with very different morphological and biochemical characteristics, these two types of demise may occur simultaneously in tissues or cell cultures exposed to the same insult (Eguchi et al., 1997, Zhan et al., 1999). In fact, both types of cell death have been found in the same population of cisplatin-treated cells (Pestell et al., 2000). Moreover, it has been hypothesized that in a tissue or cell population,apoptosis and necrosis might be two extremes of a continuum of possible types of cell demise. Individual cell death would be decided by factors such as the availability of energy and the metabolic condition of the cell (Leist et al., 1997). Thus, some cells might die as a result of an unfinished apoptotic program. In fact, in L1210 leukemic cells, cisplatin-induced cell death seems to be the result of a defective apoptotic program that lacks some morphological and biochemical characteristics attributed to apoptosis (Segal-Bendirdjian and Jacquemin-Sablon, 1995). In addition, at high doses, cisplatin could damage molecules involved in cellular energy supply (i.e., ATP) and also proteins directly or indirectly involved in the apoptotic process (i.e., p53, Bax, Bcl-2, and caspases), leading to necrotic cell death. In fact, in cisplatin-resistant keratinocytes transformed by H-ras oncogene, a high dose of cisplatin (312 microM) induces characteristic features of necrotic cell death(Pérez et al., 1999). Thus, depending on the level of cellular damage induced by cisplatin, necrosis could take place either directly or as a consequence of an unfinished apoptotic program. In summary, a growing body of evidence suggests that cisplatin-induced cell death does not always come from "classic"apoptosis. Depending on both cisplatin dose and cellular status, cisplatin may also induced cell death by a defective apoptotic program or even by necrosis. Elucidation of the conditions under which the apoptotic program induced by cisplatin as well as other antitumor drugs is totally or partially executed may have important implications for the outcome of cancer chemotherapy.

[Dual chamber rate responsive pacing and chronotropic insufficiency. Comparison of double and respiratory sensors]

Late responsive DDD pacemakers are the most technically advanced devices presently available. These pacemakers are particularly useful in patients with chronotropic insufficiency when the sinus node is incapable of accelerating during exercise. The latest pacemakers have two sensors to reproduce optimal physiological sinus acceleration. The aim of this study was to analyse the performances of a new rate responsive pacemaker with a double activity and respiratory sensor, the interaction of which is automatically controlled by a sophisticated algorithm, in 12 patients (8 men and 4 women) with a mean age of 75 +/- 7 years. Analysis was based on the performance of the sensors used singly or in association: during three exercise stress tests with measurement of the VO2 max; during everyday activities using the data archived by the pacemaker and the answers to a simplified questionnaire on quality of life. The results showed that during exercise stress testing with measurement of VO2 max, the best performances were obtained with the double sensor or the respiratory sensor compared with the activity sensor alone, suggesting that these two sensors are more effective in intense exercise. This tendency was also observed in the analysis of the memory bank of the pacemaker which showed that the total duration of the faster heart rates was greater with the two sensors. On the other hand, the quality of life was not significantly different, whichever sensor was studied. Longer scale trials are necessary to appreciate the real value of these new double sensor pacing devices and to identify the best indications for their usage.

Analysis of the adjuvant effect of recombinant Leishmania infantum Hsp83 protein as a tool for vaccination

The properties of Leishmania infantum hsp83 (LiHsp83) to elicit an immune response against a fused reporter antigen, maltose binding protein (MBP), was studied. CF1 mice were immunized with different purified recombinant proteins: MBP, LiHsp83 and MBP fused to LiHsp83 (MBP-LiHsp83). Serum samples were obtained at days 0, 21, 28, 60, 90, 120 and 150 post-immunization. MBP-LiHsp83 fusion protein elicited a strong humoral response against MBP, higher than that one obtained in mice immunized with MBP alone or MBP mixed with LiHsp83, showing the secretion of both anti-MBP IgG2a and IgG1 isotypes (IgG2a/IgG1 ratio: 2:1). This response was specific for recombinant proteins and was maintained for at least 150 days, whereas the reactivity in mice immunized with MBP alone dissapeared at day 90. After in vitro stimulation with MBP, spleen cells from MBP-LiHsp83 immunized mice showed higher proliferation indices and produced higher secretion of IFN-gamma than spleen cells from either control or MBP-immunized mice. In all groups of mice IL-4 was undetectable. Thus we consider that LiHsp83 may be a promising candidate to be used as carrier of fused antigens for adjuvant-free vaccination.

Mapping of the antigenic determinants of the T. cruzi kinetoplastid membrane protein-11. Identification of a linear epitope specifically recognized by human Chagasic sera

The high variability among strains and isolates of Trypanosoma cruzi and the existence of shared antigenic determinants with other pathogens, particularly with members of the Leishmania genus make difficult the specific diagnosis of Chagas' disease. The data reported in this paper show that the T. cruzi KMP11 protein is an immunodominant antigen highly recognized by the sera from chagasic and leishmaniasis patients. By the use of amino- and carboxyl-terminal truncated KMP11 recombinant proteins and synthetic peptides, evidence is provided that while the sera from chagasic patients recognize linear peptides the sera from patients with visceral leishmaniasis must be predominantly directed against conformational epitopes. We found that a particular linear determinant, located in the carboxyl-terminal region of the protein, is recognized with high specificity and sensitivity only by sera from Chagas' disease patients, suggesting it could be a good candidate for differential serodiagnosis of Chagas' disease.

DNA interstrand cross-linking efficiency and cytotoxic activity of novel cadmium(II)-thiocarbodiazone complexes

We have prepared mono- and binuclear complexes of Zn(II) and Cd(II) with bis(2-pyridyl aldehyde) thiocarbodiazone (H(2)L(1)) and bis(methyl 3-pyridyl ketone) thiocarbodiazone (H(2)L(2)). Cytotoxicity data against the ovarian tumor cell line A2780cisR (acquired resistance to cisplatin) indicate that the mononuclear complex Cd/H(2)L(2) (1) and the binuclear complex Cd(2)/H(2)L(1) (4) are able to circumvent cisplatin resistance and that their cytotoxic activity does not substantially vary after depletion of intracellular levels of glutathione. Moreover, DNA binding studies show that complexes 1 and 4 have higher efficiency than cisplatin at forming DNA interstrand cross-links in both naked pBR322 plasmid and A2780cisR cellular DNA. Interestingly, the thiocarbodiazone ligands alone do not show the biological properties of complexes 1 and 4. Altogether these results suggest that DNA interstrand cross-link formation by compounds 1 and 4 might be related with their cytotoxic activity in cisplatin-resistant cells. We think that compounds 1 and 4 may represent a novel structural lead for the development of cadmium cytotoxic agents capable of improving antitumor activity in cisplatin-resistant tumors.

[Cardiac stimulation and heart insufficiency]

Dilated cardiomyopathies are frequently associated with atrioventricular and intra ventricular conduction disorders. Such conduction disorders modify the cardiac activation sequence and impair left ventricular systolic and diastolic function. The aim of pacing in dilated cardiomyopathy is to restore a cardiac activation sequence as normal as possible. Conventional dual-chamber pacing was first proposed to treat drug-refractory heart failure but was soon replaced by multisite biventricular pacing. The aim of biventricular pacing is to correct intraventricular asynchrony by pacing the two ventricles simultaneously. Acute studies have shown that biventricular pacing could improve hemodynamic parameters in patients with dilated cardiomyopathy and severe intraventricular conduction disorders. More recently, chronic studies demonstrated a significant improvement in exercise tolerance and quality of life with biventricular pacing in patients with drug-refractory heart failure and with intraventricular conduction disorders. To safely pace the left ventricle specific materials and tools had to be developed. With those developments, biventricular pacing is now a feasible and safe technique. Regarding the results of several clinical studies, biventricular pacing could now be proposed to treat patients with drug-refractory heart failure in the setting of chronic left ventricular systolic dysfunction and with major intraventricular conduction disorders.

Prognostic value of HER-2/neu and p53 expression in node-positive breast cancer. HER-2/neu effect on adjuvant tamoxifen treatment

HER-2/neu and p53 expression, conventional clinical and pathologic prognostic factors, were evaluated in a retrospective series of 283 node-positive breast cancer patients. Overexpression was determined by immunohistochemistry in formalin-fixed paraffin-embedded tissue blocks. Twenty one percent were HER-2/neu positive and 40% p53 positive. HER-2/neu expression was related to axillary lymph node metastasis (P=0.014), inflammatory infiltrates (P=0.004), and the absence of oestrogen (ER) (P=0.0026) and progesterone (P=0.01) receptors (PR). p53 expression was related to lymph node involvement (P=0.03), necrosis (P=0.036), absence of ER (P=0.028) and PR (P=0.065). p53 was not associated with outcome. HER-2/neu was an unfavourable prognostic factor for disease-free (DFS) (P=0.05) and overall survival (OS) (P=0.02) in univariate analysis. Multivariate analysis showed that the number of involved axillary nodes (P<0.00001), age (P=0.004), grade (P=0.04), and PR (P=0.04) were independent predictors for OS. ER-positive patients treated with adjuvant tamoxifen had shorter DFS and OS when they were HER-2/neu positive.

Biofilm structure and mass transfer in a gas phase trickle-bed biofilter

Mass transport phenomena occurring in the biofilms of gas phase trickle-bed biofilters are investigated in this study. The effect of biofilm structure on mass transfer mechanisms is examined using experimental observation from the operating of biofilters, microelectrode techniques and microscopic examination. Since the biofilms of biofilters used for waste gas treatment are not completely saturated with water, there is not a distinguishable liquid layer outside the biofilm. Results suggest that due to this characteristic, gas phase substrates (such as oxygen or volatile organic compounds) may not be limited by the aqueous phase because transport of the compound into the biofilm can occur directly through non-wetted areas. On the other hand, for substrates that are present only in the liquid phase, such as nitrate, the mass transfer limitation is more serious because of the limited liquid supply. Microscopic observations show that a layered structure with void spaces exists within the biofilm. Oxygen concentration distributions along the depth of the biofilms are examined using an oxygen microelectrode. Results indicate that there are some high dissolved oxygen zones inside the biofilm, which suggests the existence of passages for oxygen transfer into the deeper sections of the biofilm in a gas phase trickle-bed biofilter. Both the low gas-liquid mass transfer resistance and the resulting internal structure contribute to the high oxygen penetration within the biofilms in gas phase trickle-bed biofilters.

Teaching future professors how to teach

This paper describes a course designed to provide hands-on teaching experience to future professors and to incorporate techniques for more effective teaching. A team of Ph.D. candidates, under the direction of a senior faculty member, prepared a new course from beginning to end and then offered it to a class of graduate students. The course was developed using the unit map concept so that the presentations by the five student-instructors complemented and built upon one another. Immediately after each class, feedback was given to the student-instructors by the faculty advisor and the other student-instructors. Review of video tapes of the lecture reinforced this feedback. At the completion of the course, both students and student-instructors were surveyed as to the effectiveness of the course and the student-instructors. This teaching experience and the feedback obtained from the surveys will be invaluable to the student-instructors in their future development.

Calcium-induced conformational changes in Leishmania infantum kinetoplastid membrane protein-11

Total-reflection X-ray fluorescence has been used to study whether the Leishmania infantum kinetoplastid membrane protein-11 is a Ca2+-binding protein. The 108 amino acid helix-loop-helix protein has the loop region located between residues 45 and 57, having similarity to the EF-hand motifs. In particular, the sequence alignment of the putative motif revealed the existence of 67% similarity and 33% identity with the EF-hand of the plasmodia-specific 40-kDa protein from Physarum polycephalum. To address the type of conformational changes induced by Ca2+ binding, circular dichroism and fluorescence spectroscopy were used. The data showed that Ca2+ induces changes in both the secondary and tertiary structure of the protein in a temperature- and pH-dependent way. It also induces the precipitation of the protein at pH 7.5, in contrast with what occurs at pH 5.0, and the precipitation process can be reverted by addition of EGTA. At acidic pH values the complex EGTA-Ca2+ causes drastic structural changes, forcing the protein to adopt a structure close to that of a random coil. Because, at acidic pH values, protein:Ca2+:EGTA ternary complexes may be formed, the drastic change may be attributed to the presence of a high density of EGTA negative charges in the neighborhood of the alpha-helices.

Increased expression of NK cell markers on T lymphocytes in aging and chronic activation of the immune system reflects the accumulation of effector/senescent T cells

In humans, CD56, CD161, CD16, CD94 or CD57 represent prototypic markers of NK cells, although they are also found on a subset of CD8+ T cells. We propose here that the expression of NK receptors on CD8+ T cells can be considered a marker of cytotoxic effector T cells that are expanded in vivo after antigenic activation leading to extensive proliferation. The persistence of antigen will lead to loss of co-stimulatory molecules, telomere shortening and defective IL-2 production, changes that define the state replicative senescence in T lymphocytes. The majority of these "effector/senescent" T lymphocytes are CD8+, CD45RA+, CD11a(bright), CD28-, CD27-, CD62L- and CCR7-. They are cytotoxic T cells with strong expression of intracytoplasmic perforin and granzyme, but with low proliferative capacity and defective IL-2 production. Many of these characteristics are shared by the recently defined "effector/memory" T cells, being mainly distinguished by the absence of CD45RA expression on the memory cells. The expression of NK receptor in these effector cells will probably contribute to the regulation of their cytotoxic function. Expansion of cells with these characteristics can be found not only in the elderly but also in other clinical conditions involving chronic activation of the immune system such as viral infections, rheumatic and autoimmune diseases or tumors. Another subset of T cells that expresses the NK receptors is the alpha-galactosyl-ceramide specific T cell subset defined by the expression of canonical Valpha24JalphaQ TCR, recognition of CD1d and secretion of high amounts of IL-4 and IFN-gamma. However, the changes observed in the expression of NK-R on T cells associated to immunosenescence can not be attributed to expansion of this particular T cell subset, although alterations in the number and function of these cells have been demonstrated in some autoimmune diseases.

HSP70 from Trypanosoma cruzi is endowed with specific cell proliferation potential leading to apoptosis

The Trypanosoma cruzi HSP70 recombinant protein has the capacity to stimulate splenocytes or lymph node cells from naive mice in a non-haplotype-restricted way. The proliferative response is abolished by proteinase K digestion and by specific anti-HSP70 antibodies. The induced stimulation index was maximal after 24 h of incubation with the protein. This stimulation leads to cell death in a Fas-Fas ligand-independent way. The phenotype of the expanded cells was CD3(+) TCRalphass(+) CD4(+). HSP70-responsive cells express a broad range of cytokines including IFN-gamma, IL-2 and tumor necrosis factor-alpha. After 48 h of incubation with HSP70 there was a significant increase in relative intracellular levels of CD3 TCRalphass receptors. The expanded CD4(+) cell population expressed CD25; however, in contrast to concanavalin A-treated culture, delayed CD44 expression was observed.

A pilot experience with permanent biventricular pacing to treat advanced heart failure

BACKGROUND

The prognosis and quality of life of patients with advanced heart failure remain poor. The purpose of this study was to evaluate new nonpharmacologic approaches. Biventricular pacing was proposed in this indication, based on the encouraging results of acute hemodynamics studies.

METHODS

Fifty patients with drug-resistant heart failure (New York Heart Association [NYHA] class III/IV, 16 of 34) were consecutively implanted with biventricular pacemakers. All patients had severe dilated cardiomyopathy and intraventricular conduction delay. Survival, NYHA class, electrocardiogram, echocardiographic data, and exercise tolerance were assessed over a mean follow-up period of 15.4 +/- 10. 2 months.

RESULTS

At the end of follow-up, 55% of patients were alive without heart transplantation or left ventricular assistance device. The mortality rate was significantly lower in class III (12. 5%) than in class IV patients (52.5%). In survivors, biventricular pacing significantly improved symptoms (NYHA class 2.2 +/- 0.5 at follow-up vs 3.7 +/- 0.5 at baseline) and exercise tolerance ((. )VO(2) peak 15.5 +/- 3.4 mL/min per kilogram at follow-up vs 11.1 +/- 3 mL/min per kilogram at baseline).

CONCLUSIONS

Biventricular pacing appears to improve the functional status of patients with dilated cardiomyopathy with advanced heart failure. The technique appears to be attractive as an additive treatment, especially in class III patients. Controlled randomized studies are needed to validate this novel concept.

Cytokine-driven inflammatory response is associated with the hypermetabolism of AIDS patients with opportunistic infections

BACKGROUND

To assess a possible role of systemic inflammation in the resting metabolic response in AIDS patients with active secondary infections.

METHODS

Fifty-two patients with AIDS-defined criteria and concomitant active infections and 19 healthy subjects were studied. Measurements were as follows: body composition assessed by bioelectrical impedance; resting energy expenditure (REE) by 30-minute indirect calorimetry; cytokine concentrations (IL-6, IFNalpha, TNFalpha, sTNF-R1) by ELISA; C-reactive protein (CRP), erythrocyte sedimentation rate, fibrinogen, and nutritional parameters by standard techniques.

RESULTS

REE adjusted for fat-free mass (REEFFM) was significantly increased in AIDS patients despite 39% of them not being hypermetabolic. The patients were undernourished and were found to have increased levels of acute-phase proteins and increased concentrations of IL-6 and sTNF-R1 relative to controls. REE parameters were positively related to CRP, ESR, ferritin, IL-6, and sTNF-R1 and negatively related to albumin, prealbumin, and transferrin. CRP was an independent predictor of REEFFM in AIDS patients and explained 25% of its variability. Patients with severe inflammation (CRP > or = 37 mg/dL) were significantly hypermetabolic with respect to patients without inflammation (CRP < 6 mg/dL) and had higher levels of IL-6 and sTNF-R1 and lower levels of albumin and prealbumin. Although no significant differences were observed with respect to the infection type, patients with tuberculosis and Pneumocystis carinii infections had higher resting metabolic and inflammatory responses, whereas patients with recurrent bacterial pneumonia were normometabolic and had lower levels of inflammatory markers.

CONCLUSIONS

Resting hypermetabolism observed in AIDS patients with concurrent active infections is related to the presence and severity of systemic cytokine-driven inflammatory response, which could reflect the type of secondary infection.

The Leishmania infantum acidic ribosomal protein LiP2a induces a prominent humoral response in vivo and stimulates cell proliferation in vitro and interferon-gamma (IFN-gamma) production by murine splenocytes

The acidic ribosomal proteins of the protozoan parasite Leishmania infantum have been described as prominent antigens during both human and canine visceral leishmaniasis. In this study we present data showing that the intraperitoneal administration in BALB/c mice of the Leishmania LiP2a protein, in the absence of any added adjuvants, elicited a strong humoral response as an indication that the protein is a potent immunogen. Despite the evolutionary conservation of the acidic ribosomal proteins, the antibody response was found to be specific for the Leishmania protein. Another remarkable finding was the observation that the LiP2a protein stimulates the in vitro proliferation of splenocytes from either LiP2a-immunized or naive BALB/c mice. Since similar proliferative indices were observed in T cell-enriched cultures, it is likely that the LiP2a stimulating activity is due mainly to T lymphocyte expansion. Also, the stimulatory effect was demonstrated to be antigen-specific, since the proliferation was abrogated by the presence of anti-LiP2a antibodies. Interestingly, the LiP2a protein stimulated the production of substantial amounts of IFN-gamma in cultured splenocytes from LiP2a-immunized mice. Our data indicate therefore that the immunostimulatory properties shown by this antigen should be taken into account when developing therapeutic and prophylactic vaccines against leishmaniasis.

Immune and clinical parameters associated with Leishmania infantum infection in the golden hamster model

For experimental infections with viscerotropic strains of Leishmania, a suitable animal model is not yet defined. In the present work, we have reappraised the use of golden hamster (Mesocricetus auratus) as an experimental model for infection with Leishmania infantum. Groups of hamsters were challenged by the intracardial route with doses ranging from 10(3) to 10(5) infectious promastigotes and the animals were monitored for 1-year follow-up period. The outcome of the infection was assessed by clinical symptoms of leishmaniasis, parasite loads in both liver and spleen, humoral response to Leishmania antigens and antibody levels in kidneys. The humoral response was analysed using either crude antigens (by ELISA and Western blotting) or several recombinant Leishmania antigens (Hsp70, Hsp83, LiP2a, LiP2b, H2A, H3 and KMP-11). From the analysis of all these parameters, we established the existence of three groups of animals: symptomatic or susceptible, oligosymptomatic, and resistant. Given the parallelism existing between the outcomes of Leishmania-infection in hamsters, dogs and humans, we believe that our data illustrate that the hamster is an excellent experimental model to study visceral leishmaniasis and for the design of vaccine development.

Leishmania infantum: gene cloning of the GRP94 homologue, its expression as recombinant protein, and analysis of antigenicity

The complete nucleotide sequence for the Leishmania infantum homologue to the glucose-regulated protein 94 (GRP94) gene was determined from the isolation and characterization of a genomic clone. Like the mammalian and plant GRP94s, the L. infantum GRP94 sequence possesses both an N-terminal signal peptide and a putative endoplasmic reticulum retention signal, consisting of the C-terminal tetrapeptide EDDL. Thus, L. infantum is the first protozoan organism in which GRP94 has been identified. Southern blot analysis has indicated that this protein is encoded by a single-copy gene. The L. infantum GRP94 gene was expressed in Escherichia coli and the recombinant protein used to evaluate its antigenicity and immunogenicity. Eighty-four percent of sera from dogs with visceral leishmaniasis reacted with the protein, indicating that GRP94 is a potent immunogen during Leishmania infection. Given the immunogenic and antigenic properties shown by the L. infantum GRP94, we think that this protein constitutes a valuable molecule for diagnostic purposes and a potential candidate for studies of protective immunogenicity.