Identification of a potent and selective LAPTc inhibitor by RapidFire-Mass Spectrometry, with antichagasic activity

BACKGROUND

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and leads to ~10,000 deaths each year. Nifurtimox and benznidazole are the only two drugs available but have significant adverse effects and limited efficacy. New chemotherapeutic agents are urgently required. Here we identified inhibitors of the acidic M17 leucyl-aminopeptidase from T. cruzi (LAPTc) that show promise as novel starting points for Chagas disease drug discovery.

METHODOLOGY/PRINCIPAL FINDINGS

A RapidFire-MS screen with a protease-focused compound library identified novel LAPTc inhibitors. Twenty-eight hits were progressed to the dose-response studies, from which 12 molecules inhibited LAPTc with IC50 < 34 μM. Of these, compound 4 was the most potent hit and mode of inhibition studies indicate that compound 4 is a competitive LAPTc inhibitor, with Ki 0.27 μM. Compound 4 is selective with respect to human LAP3, showing a selectivity index of >500. Compound 4 exhibited sub-micromolar activity against intracellular T. cruzi amastigotes, and while the selectivity-window against the host cells was narrow, no toxicity was observed for un-infected HepG2 cells. In silico modelling of the LAPTc-compound 4 interaction is consistent with the competitive mode of inhibition. Molecular dynamics simulations reproduce the experimental binding strength (-8.95 kcal/mol), and indicate a binding mode based mainly on hydrophobic interactions with active site residues without metal cation coordination.

CONCLUSIONS/SIGNIFICANCE

Our data indicates that these new LAPTc inhibitors should be considered for further development as antiparasitic agents for the treatment of Chagas disease.

[Congenital syphilis: incidence among newborns]

OBJECTIVE: To determine the incidence of congenital syphilis among newborns at the maternity of a public hospital. METHODS: The study was conducted at the maternity of Fundação Santa Casa de Misericórdia do Pará, from May to September 1996; 361 mothers were interviewed, and physical examination was performed in their newborns. Serum samples from both, mothers and neonates, were tested using three methods: VDRL, FTA - Abs, ELISA IgM. The diagnosis of congenital syphilis was established according to the criteria defined by Ministério da Saúde in 1993. RESULTS: The rate of congenital syphilis was of 9.1% (33); in 14 cases, there were one or more signs of the disease: prematurity, hepatomegaly, stillbirth, splenomegaly, perinatal death, abdominal distention, nasal stuffiness, jaundice, newborn small for gestational age. The majority of the infected mothers belonged to the age group of 20-35 years (81.8%); 60.6% were married; 63.6% received prenatal care; 48.5% reported previous spontaneous abortion, and 12.1% previous stillbirth. The rate of bisexuality among fathers was of 9.1%. CONCLUSION: The syphilis control measures and the prenatal care, have not been sufficient to prevent the high rate of the disease.

O contexto político-administrativo da implantação de Distritos Sanitários no Estado da Bahia, Brasil

O presente trabalho foi realizado com o objetivo de caracterizar o contexto político-administrativo da implantação dos Distritos Sanitários na Bahia. Procedeu-se a uma revisão documental abrangendo acordos, convênios e leis, nos âmbitos estadual e federal, no período compreendido entre 1987 e 1989, correspondente à primeira fase da gestão estadual após as eleições de 1986. As informações foram completadas através de entrevistas com informantes-chave e ex-dirigentes do nível central da Secretaria Estadual de Saúde. Descreve-se o processo de formulação da política de regionalização territorial e populacional e faz-se uma revisão do processo de planificação, a níveis nacional e estadual, com a identificação dos eventos que conduziram à decisão de se criar os Distritos Sanitários. São listados os instrumentos de política que materializaram esta decisão e analisada a posição dos distintos atores do sistema de saúde em relação a esta opção estratégica de reorientação da organização dos serviços. Conclui-se com breves comentários sobre as dificuldades que esta proposta encontra para institucionalizar-se no período em estudo.

[Coronary angioplasty in octogenarians]

PURPOSE

To evaluate the indications, results and follow-up of patients with 80 years old and over, who had undergone percutaneous transluminal coronary angioplasty (PTCA).

METHODS

From July 1987 through July 1990, 36 patients, 80 years of age and over, had PTCA as an alternative method to treat coronary artery disease. Their age ranged from 80 to 85 (mean = 83) years. Twenty five were male. Significative obstruction was considered when 70% or more of the internal diameter was stenosed. Satisfactory results were achieved when reduction of 50% or more of the coronary artery obstruction was obtained.

RESULTS

In 34 of 36 patients (94.4%), PTCA was successfully performed. Forty four of 46 coronary arteries were successfully dilated. One patient had acute coronary occlusion with acute myocardial infarction treated clinically. There were no emergency surgeries or early deaths. Clinical follow-up was obtained in 15 of the 34 patients. Four had repeated coronary arteriography (at 1, 3, 6 and 12 months after primary PTCA) due to angina. Two of them had restenosis and were successfully redilated (the patients restudied at 3 and 6 months, respectively). Within a mean clinical follow-up period of 9.6 (ranging from 1 from 21) months the following features were observed: two of 15 patients (13.3%) had acute myocardial infarction and were clinically followed; late death occurred in 3 patients (20%) with only one related to cardiac events. Survival has been observed in 12 of these 15 patients (80%).

CONCLUSION

PTCA represents an alternative, safe and effective invasive procedure to treat octogenarians with coronary artery disease.

[Directional coronary atherectomy. The initial experience]

Four male patients, 38 to 59 years old (mean 49 +/- 2.5), with angina and the angiographic features has been the classical indications for the method, underwent directional coronary atherectomy. Vessels treated were, respectively, left anterior descending artery (LAD), right coronary artery (RCA), saphenous vein graft (SVG) to LAD and SVG to left marginal branch. Reductions to 50% or less of the internal diameter was considered a satisfactory result. Early success was obtained in all four patients. Obstructions of 75 to 95% (mean of 83 +/- 7.5%) were reduced to 0-25% (mean 12 +/- 5%) after atherectomy. Only one patient died suddenly five days after de procedure. So, directional coronary atherectomy may represent a reliable and safe method for special situations.

[Angioplasty in native coronary circulation in patients treated with myocardial revascularization]

PURPOSE

To evaluate the clinical results after angioplasty in the native coronary vessels in patients who had undergone previous coronary artery surgery.

METHODS

From June 1987 to July 1990, 69 patients with previous coronary artery surgery underwent coronary angioplasty in the native arteries. Age ranged from 31 to 82 (mean = 57.5) years, fifty eight were males. Angina was present in all patients. The patients were classified in three groups according to the following criteria: group I--incomplete revascularization following bypass surgery (28 patients); group II--progression of the disease in ungrafted vessels (24 patients) and group III--progression of the disease in grafted vessels (17 patients).

RESULTS

Primary success was achieved in 94% (65/69). Ninety-five percent in group I, 92% in group II and 94% in group III. Complications occurred in 4%; emergency surgery or deaths were not observed in this study. Forty patients (61%) repeated coronary arteriography an average follow-up of 4 months and restenosis was detected in 10 (25%); 8 of them were redilated. Survival rates was 95% and 75% of them were free of coronary events after an average follow-up of 13 months.

CONCLUSION

Coronary angioplasty in these patients is a safe and effective interventional procedure in the treatment of coronary artery disease in native coronary vessels.

[Directional atherectomy and coronary angioplasty: a therapy complementary to myocardial revascularization surgery]

A white male patient, 59 years old, with two prior surgical myocardial revascularization and unstable angina, was submitted to coronary arteriography that showed: all the saphenous vein grafts patent and obstruction of 75% in the saphenous vein graft to the second marginal branch of left circumflex artery. Left internal mammary artery (LIMA) was angiographically normal and 80% stenosis was detected in the distal segment of the left anterior descending coronary artery (LAD). The patient was submitted to directional coronary atherectomy for saphenous vein graft and coronary angioplasty for distal-LAD. Both procedures were successfully performed.

[Anatomical limitations for the performance of angioplasty in coronary multivessel disease]

PURPOSE

To study anatomical limitation of coronary angioplasty, as alternative therapy in patients with multivessel disease and submitted to bypass surgery.

METHODS

In 380 patients with multivessel disease and submitted to previous coronary bypass surgery, age ranged from 41 to 72 (average = 51) years, being 68% males. The following parameters were analyzed in the coronary arteriographies: anatomic aspects of the coronary arteries and distribution of the atherosclerotic stenosis. The patients were arranged in accordance to the criteria: complete revascularization, incomplete and no indication for coronary angioplasty.

RESULTS

The patients were arranged in 3 different groups: I-80 (21%) patients included those in whom complete revascularization would be possible; II--55 (14.5%) patients in whom only incomplete revascularization but satisfactory would be possible and III--245 (65.5%) those patients in whom coronary angioplasty would no have indication. The data referind the patients of groups I and II were analyzed together--135 (35.5%) and arranged according to the number of arteries involved. It was observed: two vessel disease--71.8%, three vessel--18.6% and 4 or more vessel--9.6%. In group III it was observed 51.0% of the patients with 3 or more vessel disease. The major factors to contra indicate coronary angioplasty in group III included: chronic coronary obstruction 99 (40.4%); diffuse disease 11 (4.5%); technical difficulties 10 (4.1%); left main coronary artery obstruction 5 (2%) or when two or more causes were combined 120 (49%).

CONCLUSIONS

Patients with multivessel disease and classic indication for coronary bypass surgery, have a basic limitation for angioplasty due to several anatomic factors. However, coronary angioplasty could be beneficial for a selected group of patients (35.5%) whenever a complete or incomplete revascularization could be obtained.

[Coronary angioplasty in young patients]

PURPOSE

To evaluate the results of coronary angioplasty in patients at the age of 40 years old or under.

METHODS

From July 1987 to July 1990, 878 coronary angioplasty procedures were performed. Sixty six patients (7.5%) were 40 years old or under. The coronary obstruction was considered significant when 70% or more of the arterial diameter was involved and the post angioplasty results were considered satisfactory when residual obstruction was less than the 50%.

RESULTS

Fifty four patients (81.8%) were male with an average age of 37 years (ranging from 29 to 40). Forty four patients (67%) had stable angina, 18 (27%) unstable angina, 3 (4%) acute myocardial infarction (AMI) and one (1.5%) AMI after streptokinase treatment. Eight of these patients had previous report of AMI and 3 (4.5%) had undergone coronary bypass grafting surgery. Fifty five patients (83%) had single vessel disease and 11 (17%) had multivessel disease. Eighty coronary arteries had balloon dilatation. In 32 patients (58%) with single vessel artery, 12 (22%) in the RCA, 10 (18%) in the left circumflex and one (2%) into a saphenous vein bypass grafting. In 12 patients (48%) with multivessel disease it was performed in the LAD coronary artery, 8 (32%) in the RCA and 5 (20%) in the left circumflex. Angioplasty was successfully performed in 53 (96%) patients with single vessel disease and in 10 (01%) with multivessel disease. One of the patients died immediately after the procedure. A follow up of 11.6 months (ranged from 1 to 27 months) was possible in 63 patients. Re-stenosis was depicted in 10 (19%) of the 55 patients with single vessel disease and in 3 of the 11 patients (30%) with multivessel disease. Nine patients had a successful redilatation in the first group and 2 in the second one. The two remaining patients had undergone coronary bypass surgery. The clinical evaluation among patients who had been dilated as the first procedure and those who had redilatation (61 patients) showed: 92% were asymptomatic and 8% had mild angina.

CONCLUSION

Coronary angioplasty performed in young patients is an effective procedure with very low rate of early complications and favorable clinical follow-up.

[Occlusion of secondary branches after angioplasty of the left descending coronary artery]

PURPOSE

To evaluate the incidence and clinical presentation of the occlusion of such secondary branches in patients with single vessel coronary artery disease in the left anterior descending artery, who underwent a first elective and successful PTCA.

MATERIAL AND METHODS

Two hundred and thirteen side branches of 121 patients considered to be at risk. They were divided into group I (GI-85 side branches, 39.9%), if they originated from the atherosclerotic site; and group II (GII-120 side branches, 61.5%), if their origin would be involved during the balloon inflation. In the GI there were 54 septal branches and 31 diagonal branches, and 36& had angiographic evidence of ostium disease. GII was constituted by 77 septal and 51 diagonal branches, and 7.8% of them had evidence of ostium disease.

RESULTS

Seven side branches (3.3%) at risk occluded, 4 from GI (4.7%) and 3 (2.3%) from GII. As for the clinical presentation, 57% of them had angina, where as 28.6% showed minor abnormalities in the ECG. No patient elevated its serum CK-MB, and silent occlusion occurred in 43% of them.

CONCLUSION

Occlusion of side branches is a low incidence phenomenon, which happens more often in septal branches with ostium disease that originates from the atherosclerotic site; that about half of the patient had silent occlusion (43%) or mild ischemic manifestations.