Development of Plasmodium falciparum protease inhibitors in the past decade (2002-2012)

New drug targets for the development of antimalarial drugs have emerged after the unveiling of the Plasmodium falciparum genome in 2002. Potential antimalarial drug targets can be broadly classified into three categories according to their function in the parasite's life cycle: (i) biosynthesis, (ii) membrane transport and signaling, and (iii) hemoglobin catabolism. The latter plays a key role, as inhibition of hemoglobin degradation impairs maturation of bloodstage malaria parasites, ultimately leading to remission or even cure of the most severe stage of the infection. Intraerythrocytic Plasmodia parasites have limited capacity to biosynthesize amino acids which are vital for their growth. Therefore, the parasites obtain those essential amino acids via degradation of host cell hemoglobin, making this a crucial process for parasite survival. Several plasmodial proteases are involved in hemoglobin catabolism, among which plasmepsins and falcipains are well-known examples. Hence, development of P. falciparum protease inhibitors is a promising approach to antimalarial chemotherapy, as highlighted by the present review which is focused on the Medicinal Chemistry research effort recorded in the past decade in this particular field.

Lesões melanocíticas em suínos abatidos para consumo

O presente estudo teve como principais objetivos conhecer a taxa de ocorrência de lesões melanocíticas (melanose, melanocitomas e melanomas) em suínos abatidos para consumo e identificar possíveis padrões de distinção e de classificação macroscópica dessas lesões. Para tal, procedeu-se à recolha de lesões melanocíticas em matadouro, durante oito meses, e à sua avaliação macroscópica e microscópica. Os resultados deste estudo demonstraram que as melanoses foram as lesões melanocíticas mais frequentemente encontradas (74,04%) e que, relativamente às lesões tumorais, os melanomas (malignos) foram os mais frequentes (21,15%) comparativamente com os melanocitomas (benignos) (4,81%). Pela análise comparativa das características macroscópicas e microscópicas, verificou-se que, nem sempre, por uma avaliação macroscópica, é possível a distinção entre essas lesões (melanoses, melanocitomas e melanomas). No entanto, identificaram-se, neste estudo, algumas características sugestivas da malignidade, como: o tamanho superior a 2,5cm, a presença de ulceração, a libertação de pigmento negro e a presença de coloração negra do gânglio linfático regional. É, portanto, de extrema importância a observação criteriosa e sistemática dessas lesões, para a avaliação das suas características, uma vez que a decisão sanitária é diferente consoante se trate de uma melanose, de um tumor maligno ou de um tumor benigno.

Are there real advantages of induction therapy with basiliximab in renal transplantation?

BACKGROUND

Randomized clinical trials have supported the use of interleukin-2 receptor (IL-2R) antagonists as induction therapy in renal transplantation. This strategy has reduced the incidence of acute rejection episodes (ARE) but not improved graft survival. Our objective was to investigate the impact of induction therapy using the IL-2R antagonist basiliximab, as compared with no induction therapy, on relevant clinical outcomes-initial length of stay, incidence of ARE, long-term graft function, and graft survival.

METHODS

We retrospectively reviewed the medical records of patients transplanted in a tertiary care center between 1996 and 2011. We selected patients who received cyclosporine, mycophenolate mofetil, and prednisolone (n = 334) to classify as: no induction therapy (n = 131; group 1); induction therapy with basiliximab (n = 203; group 2). Estimated glomerular filtration rate (eGFR) was assessed with the 4-variable Modification of Diet in Renal Disease (MDRD) equation.

RESULTS

Mean follow-up was 72.7 ± 35.4 months. Patients who received basiliximab had a shorter mean hospital stay (19.2 versus 22.5 days; P = .02), lower incidence of ARE (10.8% versus 23.7%; P = .02) and better graft function post transplantation at 12 months (mean eGFR 59.4 ± 18.4 versus 54.8 ± 18.7 mL/min/1.73 m(2); P = .015) and 5 years (mean eGFR 64.1 ± 21.5 versus 55.4 ± 19.6 mL/min/1.73 m(2); P = .009). On multivariate analysis, induction therapy with basiliximab was independently associated with a lower incidence of ARE and better graft function at 1 and 5 years after transplantation. There was no difference in 5-year graft survival between the two groups (log-rank: P = .54).

CONCLUSIONS

Induction therapy with basiliximab was associated with a reduced incidence of ARE and better long-term graft function but no difference in 5-year graft survival.

Guidelines for maintenance of adult patients with brain death and potential for multiple organ donations: the Task Force of the Brazilian Association of Intensive Medicine the Brazilian Association of Organs Transplantation, and the Transplantation Center of Santa Catarina

INTRODUCTION

The organ shortage for transplantation, the principal factor that increases waiting lists, has become a serious public health problem. In this scenario, the intensivist occupies a prominent position as one of the professionals that first has a chance to identify brain death and to be responsible for the maintenance of the potential deceased donor.

OBJECTIVE

This report attempts to establish guidelines for care and maintenance of adult deceased donor organs guiding and standardizing care provided to patients with brain death.

METHOD

These guidelines were composed by intensivists, transplant coordinators, professionals from various transplant teams, and used transplant center. The formulated questions were forwarded to all members and recommendations were constructed after an extensive literature review selecting articles with the highest degree of evidence.

RESULTS

Guidelines were developed in the form of questions reflecting frequent experiences in clinical intensive care practices. The main questions were: Is there an optimal interval for keeping organs of deceased donors viable? What actions are considered essential for maintaining deceased donors in this period? What are the limits of body temperature? How should the patient be warmed? Which laboratory tests should be performed? What is the collection interval? What are the limits in the laboratory and the capture scenario? What are the limits of blood pressure? When and how should one use catecholamines?

CONCLUSIONS

This pioneer project involved a multidisciplinary team working in organ transplantation seeking to provide treatment guidance to increase the number of viable organs from deceased adult donors.

Experimental models in vaccine research: malaria and leishmaniasis

Animal models have a long history of being useful tools, not only to test and select vaccines, but also to help understand the elaborate details of the immune response that follows infection. Different models have been extensively used to investigate putative immunological correlates of protection against parasitic diseases that are important to reach a successful vaccine. The greatest challenge has been the improvement and adaptation of these models to reflect the reality of human disease and the screening of vaccine candidates capable of overcoming the challenge of natural transmission. This review will discuss the advantages and challenges of using experimental animal models for vaccine development and how the knowledge achieved can be extrapolated to human disease by looking into two important parasitic diseases: malaria and leishmaniasis.

One year of Lamivudine therapy for portuguese patients with chronic hepatitis B

OBJECTIVE

To assess the efficacy of lamivudine treatment on hepatitis B e antigen (HBeAg) and/or hepatitis B surface antigen (HBsAg) seroconversion, on other virological and serological markers of response including hepatitis B virus (HBV) DNA and serum aminotransferases, and the safety of lamivudine treatment in hepatitis B patients.

PATIENTS

This phase III open-label study evaluated the virological and biochemical response to lamivudine in 70 Portuguese patients with HBeAg positive chronic hepatitis B. Patients were treated with lamivudine 100mg once daily for 12 months.

METHODS

Antiviral activity was assessed by measuring alanine aminotransferase (ALT)/aspartate aminotransferase (AST) levels at all protocol visits, and hepatitis B serology and HBV DNA were performed at baseline and at month 12 visits. Evaluation of safety and tolerance was based on clinical adverse events and laboratory analyses.

RESULTS

The primary endpoint was virological response at month 12, defined as loss of detectable HBeAg from serum with a reduction of HBV DNA to undetectable levels, and this was observed in 19/69 (27.5%) of patients. Almost half of the patients were HBV DNA negative by this time. Mean ALT values decreased steadily during treatment and by 12 months 61% of patients had values within the normal range. HBeAg seroconversion (HBeAg negative, HBeAb positive) was achieved in 27.9% of patients by 12 months, although all patients remained HBsAg positive.

CONCLUSION

Lamivudine was well tolerated and the incidence of adverse events was similar to those reported in previous studies. Lamivudine treatment resulted in virological and biochemical improvements in HBeAg positive chronic hepatitis B patients, with HBeAg seroconversion in one-third of patients.

Noradrenaline Use is Not Associated with Extubation Failure in Septic Patients

Standard clinical practice recommends minimal doses of vasoactive drugs during weaning of patients from mechanical ventilation. However, there are currently no clinical data to inform clinicians about whether the use of noradrenaline during weaning predisposes to weaning failure. The objective of this study was to evaluate whether the necessity of the vasopressor noradrenaline in mechanically ventilated patients recovering from septic shock changed the extubation outcome.

A total of 656 patients recovering from septic shock on mechanical ventilation were selected from intensive care units in two university hospitals. Patients receiving noradrenaline at the time of weaning and case-controls not taking noradrenaline were matched for age, gender, haemodynamic and ventilatory parameters, aetiology of respiratory failure and APACHE II score. One hundred and forty-five patients who successfully tolerated a spontaneous breathing trial were extubated while on noradrenaline therapy and the reintubation rate was measured.

In the noradrenaline group, the mean dose of noradrenaline during initial shock treatment was 0.52±0.29 μg/kg/min and 0.12±0.10 μg/kg/min during weaning. The reintubation rate was 12/63 (19%) in the noradrenaline group and 15/82 (18.3%) in the control group (P=1.00). Intensive care unit mortality was also similar in both groups (10/63, 15.9%) for noradrenaline patients and (11/82, 13.4%) for control patients (P=0.81). Arterial blood gases and ventilatory and haemodynamic parameters were similar in all patients regardless of weaning success.

We did not find that the use of noradrenaline at the time of weaning was associated with extubation failure. Low doses of noradrenaline may not preclude weaning from mechanical ventilation.

Identification of XLRS1 gene mutation (608C > T) in a Portuguese family with juvenile retinoschisis

PURPOSE

To characterize electroretinogram (ERG) and molecular genetic findings in a family with XLRS1 mutation. The authors present two cases of a Portuguese family with juvenile retinoschisis with a mutation in exon 6.

METHODS

Two brothers and their parents, grandmother, and uncle underwent a full ophthalmic examination. The two brothers with ophthalmic disease were evaluated with color fundus photography, fluorescein angiography, optical coherence tomography (OCT), molecular genetic study (Group VI of Retinoschisis Consortium), pattern visual evoked potential (PVEP), and full field ERG.

RESULTS

Both patients presented funduscopic manifestations of vitre o retinal degeneration. They presented peripheral schisis and retinal detachment. However, foveal schisis had never been observed at funduscopy. A negative ERG was recorded in both. Six months after that, the younger brother showed a typical foveal schisis at fundus examination. A retinoschisis gene (XLRS1) mutation with transition of cytosine by thymine at position 608 (608C > T) had been identified in both.

CONCLUSIONS

Negative ERG is the most secure clinical marker to establish the diagnosis of juvenile retinoschisis. XLRS1 gene 608C > T mutation was described for the first time in a Portuguese family.

Identification of XLRS1 gene mutation (608C>T) in a Portuguese family with juvenile retinoschisis

PURPOSE

To characterize electroretinogram (ERG) and molecular genetic findings in a family with XLRS1 mutation. The authors present two cases of a Portuguese family with juvenile retinoschisis with a mutation in exon 6.

METHODS

Two brothers and their parents, grandmother, and uncle underwent a full ophthalmic examination. The two brothers with ophthalmic disease were evaluated with color fundus photography, fluorescein angiography, optical coherence tomography (OCT), molecular genetic study (Group VI of Retinoschisis Consortium), pattern visual evoked potential (PVEP), and full field ERG.

RESULTS

Both patients presented funduscopic manifestations of vitre o retinal degeneration. They presented peripheral schisis and retinal detachment. However, foveal schisis had never been observed at funduscopy. A negative ERG was recorded in both. Six months after that, the younger brother showed a typical foveal schisis at fundus examination. A retinoschisis gene (XLRS1) mutation with transition of cytosine by thymine at position 608 (608C>T) had been identified in both.

CONCLUSIONS

Negative ERG is the most secure clinical marker to establish the diagnosis of juvenile retinoschisis. XLRS1 gene 608C>T mutation was described for the first time in a Portuguese family. (Eur J Ophthalmol 2005; 15: 638-40 ).

Congenital dacryocystocele with intranasal extension

PURPOSE

Congenital dacryocystocele is a rare anomaly in the newborn child. The swelling of lachrymal sac is observed by birth and it is associated with obstruction of lachrymal system either above or below lachrymal sac.

METHODS

Diagnosis was made by clinical observation. Some ancillary examinations, such as ultrasonography, tomography, and rhinoscopy, were useful.

RESULTS

The authors describe the clinical case of a newborn with a unilateral congenital dacryocystocele. This anomaly was successfully treated with probing and marsupialization of the nasal cyst.

CONCLUSIONS

Treatment of this congenital anomaly is by light compressive massage, probing with silicone intubation of lachrymal system to assure prolonged permeability of the system, or with marsupialization of the nasal cyst. In some cases with intranasal extension of dacryocystocele, collaboration with an otolaryngologist may be necessary. (Eur J Ophthalmol 2004; 15: 126-8).

RasGRP links T-cell receptor signaling to Ras

Stimulation of the T-cell receptor (TCR) alters a number of intracellular signaling pathways including one that involves protein tyrosine kinases, phospholipase C-gamma1 (PLC-gamma1), diacylglycerol (DAG), and calcium messengers. By a divergent pathway, TCR-stimulated protein tyrosine kinase activity is thought to result independently in recruitment of the Ras activator Sos to the plasma membrane, leading to Ras activation. Here we show that RasGRP, a Ras activator that contains calcium-binding EF hands and a DAG-binding domain, is expressed in T cells. A PLC-gamma1 inhibitor diminished activation of Ras following TCR stimulation. Membranes from TCR-stimulated Jurkat T cells exhibited increased RasGRP and increased Ras-guanyl nucleotide association activity that was inhibited by antibodies directed against RasGRP. Overexpression of RasGRP in T cells enhanced TCR-Ras-Erk signaling and augmented interleukin-2 secretion in response to calcium ionophore plus DAG analogues phorbol ester myristate or bryostatin-1. Thus, RasGRP links TCR and PLC-gamma1 to Ras-Erk signaling, a pathway amenable to pharmacologic manipulation.

Contribution of B(2) receptors for bradykinin in arthus reaction-induced plasma extravasation in wild-type or B(2) transgenic knockout mice

The aim of the present study was to investigate the contribution of bradykinin (BK) B(1) and B(2) receptors in a model of type III hypersensitivity, the reverse passive Arthus reaction (RPA), in wild-type mice and transgenic B(2) knockout littermates. BK (10 microg mouse(-1)) or bovine serum albumin (0.5 mg mouse(-1)) induced a sustained Evans blue extravasation for more than 80 min in naive or rabbit anti-bovine serum albumin-treated mice (RPA model), respectively. The response to the two stimuli was prevented by the B(2) receptor antagonist, HOE-140, but not by [Leu(8)]desArg(9)-BK (B(1) receptor antagonist). In contrast to the wild-type littermates, RPA and bradykinin were unable to trigger an increase in plasma extravasation in B(2) knockout mice. Furthermore, endothelin-1 (5 microg mouse(-1)) and a selective NK-1 receptor agonist [Sar(9),Met (O(2))(11)]-SP (20 microg mouse(-1)), triggered a significant increase in peritoneal plasma extravasation in both wild-type and B(2) knockout animals. A pretreatment with indomethacin (200 microg mouse(-1)) significantly reduced the RPA-induced but not the BK-induced increase in Evans blue extravasation. Furthermore, RPA, but not BK, triggered a significant indomethacin-sensitive increase in peritoneal prostaglandin E(2) content. Our results suggest a pivotal role for B(2) receptors in the mechanism of plasma extravasation which occurs during the reverse passive Arthus reaction in the mouse. Moreover, our results suggest an important contribution of prostanoids in the plasma leakage mechanisms triggered by RPA but not by bradykinin.

CDK2 is a target for retinoic acid-mediated growth inhibition in MCF-7 human breast cancer cells

Retinoic acid (RA) inhibition of breast cancer cell growth is associated with an accumulation of cells in G1 phase of the cell cycle. We have investigated the effects of RA on the expression and activity of cell cycle-regulatory proteins in MCF-7 human breast cancer cells. Flow cytometry analysis of MCF-7 cells treated with RA revealed a decrease in the percentage of cells in S phase by 48 h, which was maximal by 72 h. Phosphorylation of the retinoblastoma protein (pRb) was partially reduced in RA-treated cells accompanied by a decrease in the level of retinoblastoma protein. Expression of the cyclin D1 transcript was reduced by 48 h and cyclin-dependent kinase 2 (cdk2) mRNA levels declined within 8 h posttreatment followed by a decrease in cyclin D1 and cdk2 protein levels. Message and protein levels of cdk4 and cdc2 were not affected by RA. While cdk4 activity was similar in control and RA-treated cells, cdk2 activity began to decrease within 48 h of exposure to RA and was profoundly reduced after 72 h. This reduced activity was associated with decreased phosphorylation of cdk2. The decrease in cdk2 activity occurred in the absence of RA-mediated increases in the levels of the cdk inhibitors p21 and p27. However, assays of cdk2 from pooled lysates from RA-treated and control cells showed that RA-treated cells contain a cdk2-inhibitory activity. Our results show that RA inhibits cell cycle progression of MCF-7 cells by inhibiting cdk2 mRNA and protein production and by decreasing cdk2 activity.

The AF-2 region of the retinoic acid receptor alpha mediates retinoic acid inhibition of estrogen receptor function in breast cancer cells

The growth of estrogen receptor (ER)-positive breast cancer cells is inhibited by all-trans-retinoic acid (RA). In the present study, estrogen (E2) induction of pS2 mRNA levels was significantly reduced within 6 h following cotreatment with RA. In transient transfection experiments, RA repressed transactivation from a vitellogenin E2-responsive element by approximately 50% and wild-type RA receptor alpha (RARalpha) or RARbeta enhanced this inhibition. Transfection of truncated RARalpha mutants terminating before or at amino acid 412 markedly decreased RA inhibition of E2-induced reporter gene activity. Expression of RARs with deletions of amino acids 413 and 414 in the transactivation-2 (AF-2) domain also reduced RA inhibition, while deletions and point mutations beyond amino acid 414 behaved like the wild-type RARalpha. RA-treated MCF-7 cells transfected with an RARalpha AF-2 region mutant were twice as sensitive to growth inhibition as untransfected and vector-transfected control cells. Thus, the AF-2 domain in the C terminus of the RARalpha mediates RA inhibition of ER-induced transcription in breast cancer cells. In addition, transcriptional interference between RARs and ERs may contribute to RA inhibition of ER-positive breast cancer cell growth.

Estrogen promotes chemotherapeutic drug resistance by a mechanism involving Bcl-2 proto-oncogene expression in human breast cancer cells

Recent studies have shown that the Bcl-2 protein suppresses programmed cell death or apoptosis induced by a variety of stimuli including chemotherapeutic drugs. Because estrogen promotes the survival of estrogen-dependent breast cancer cells in vivo, we investigated whether estrogen might regulate levels of Bcl-2 gene expression in an estrogen-responsive human breast cancer cell line. Estrogen receptor-positive MCF-7 human breast cancer cells cultured in the presence of estrogen express the 8.5-kb Bcl-2 mRNA transcript. Depletion of estrogen from the medium results in loss of expression of the mRNA, whereas reexposure to estrogen markedly induces the Bcl-2 transcript. The changes in Bcl-2 mRNA are paralleled by changes in Bcl-2 protein levels. Estrogen-induced increases in Bcl-2 are significantly inhibited by inclusion of the pure antiestrogen ICI 164,384 in the medium. The Bax protein that heterodimerizes with Bcl-2 and promotes cell death is expressed in MCF-7 cells grown in the presence of estrogen and is unaffected by culture in estrogen-free medium. Estrogen depletion doubles the sensitivity of MCF-7 cells to the cytotoxic effects of Adriamycin compared with cells cultured in medium supplemented with estrogen, consistent with a decrease in the Bcl-2 levels. MCF-7 cells treated simultaneously with estrogen and ICI 164,384 exhibit markedly lower resistance to Adriamycin compared with cells treated with estrogen alone. In the absence of estrogen, MCF-7 cells transfected with Bcl-2 expression plasmids display a marked increase in resistance to Adriamycin. In the presence of estrogen, MCF-7 cells expressing Bcl-2 antisense transcripts are rendered twice as sensitive to acute Adriamycin cytotoxicity as a control clone. We conclude that estrogen can promote resistance of estrogen receptor bearing human breast cancer cells to chemotherapeutic drugs through a mechanism that involves regulation of the Bcl-2 proto-oncogene.

BF phenotype distribution in five populations of Spain: anthropological considerations

The genetic polymorphism of the human Properdin Factor B (BF) in five populations of the Iberian Peninsula (Galicia, Castilla-Leon, Castilla-La Mancha, Extremadura and Western Andalusia) was analysed by means of Isoelectric Focusing in polyacrylamide gels followed by Immunofixation-Silver Staining. Statistical analysis of heterogeneity showed significant differences in the distribution of BF allele frequencies among the Iberian populations so far examined. The high allele frequencies obtained for BF*F and BF*F1 give support to the allelocline distribution hypothesis in the European continent (regression analysis between allele frequency and latitude: r = -0.6237 and r+ -0.8058, for BF*F1 and BF*F respectively).

Distribution of alpha-2-HS-glycoprotein (AHSG) phenotypes in Cabo Verde (west Africa): description of a new allele, AHSG*32

The genetic polymorphism of alpha-2-HS-glycoprotein (AHSG) was studied in the population of Cabo Verde (West Africa), using isoelectric focusing in polyacrylamide gels followed by immunofixation-silver stain. AHSG frequencies are reported for the first time in a subsaharan African population. In addition to the common variants, AHSG 1 and AHSG 2, five AHSG variants were observed, including a new variant, tentatively designated AHSG 32. The allele frequencies were, AHSG*1: 0.7289, AHSG*2: 0.2111, AHSG*10: 0.0276, AHSG*3: 0.0162, AHSG*11: 0.0081, AHSG*22: 0.0065, AHSG*32:0.0016.