RESUMO
COVID-19 patients are prone to coinfections during their hospitalization. These coinfections are challenging as they involve longer hospital stays, high costs, and higher risk of mortality. Here, we present a case of a patient with multi-infection by resistant parasites, fungi, and bacteria during his hospitalization in a hospital in Lima, Peru.
RESUMO
Resumen Objetivo: Determinar los factores de riesgo en adultos con COVID-19 en población rural andina durante 2020. Métodos: En este estudio de cohorte retrospectivo multicéntrico, incluimos a 184 pacientes adultos (≥18 años) con pruebas serológicas y moleculares para CO VID-19 de tres hospitales de la sierra peruana (Ancash y Apurímac) incluidos con sospecha clínica entre abril y junio. Se utilizó análisis descriptivos y regresión logística univariable para explorar los factores de riesgo asociados a los pacientes con COVID-19. Resultados: Del total de pacientes, 14 (7.6%) tuvieron SARS-CoV-2. En los pacientes infectados 12 (85.7%) fueron varones con promedio de edad de 47.3±21 años. Las comorbilidades estuvieron presentes en cerca de la tercera parte de pacientes, siendo la hipertensión y diabetes las más frecuentes (ambas 14.3%), y la sinto matología más frecuentes fueron fiebre y cefalea (57.2%). La regresión univariable mostró mayores probabilidades de infección con SARS-CoV-2 en la población rural andina asociada con la edad avanzada (OR: 1.1 IC95% 0.7-1.8; p=0,019), comorbilidades previas (OR: 1.7, IC95% 0.32-9.39; p=0,006), y sintomatología previa (OR: 49.8, IC95% 5.6-436.9; p=0,0011). Conclusiones: Los posibles factores de riesgo como la edad avanzada, las comorbilidades y sintomatología previas están relacionados con el desarrollo de CO VID-19 en población rural andina de Perú.
Abstract Objective: To determine the risk factors in adults with COVID-19 in the rural Andean population during 2020. Methods: This multicenter retrospective cohort study included 184 adult patients (≥18 years) with COVID-19's serological and molecular tests from three Hospitals in the Peruvian mountains (Ancash and Apurímac) included with clinical suspicion between April and June. Descriptive analysis and univariate logistic regression were used to explore the risk factors associated with patients with COVID-19. Results: Of total of patients, 14 (7.6%) had a SARS-CoV-2. In infected patients 12 (85.7%) were men with an average age of 47.3±21 years. Comorbidities were present in about a third of patients, with hypertension and diabetes being the most frequent (both 14.3%), and the most frequent symptoms were fever and hea dache (57.2%). Univariate regression showed higher probabilities of infection with SARS-CoV-2 in the rural Andean population associated with advanced age (OR: 1.1 95% CI 0.7 - 1.8; p = 0.019), previous comorbidities (OR: 1.7, 95%CI 0.32 - 9.39; p = 0.006), and previous symptoms (OR: 49.8, 95%CI 5.6 - 436.9; p = 0.0011). Conclusions: Possible risk factors such as advanced age, comorbidities and previous symptoms are related to the development of COVID-19 in the rural Andean population of Peru.
Assuntos
Humanos , Masculino , Feminino , Criança , Adolescente , Adulto , Pessoa de Meia-Idade , Idoso , COVID-19 , Peru , População Rural , Fatores de Risco , Estudos de Coortes , SARS-CoV-2 , Cefaleia , Hospitais , Hipertensão , InfecçõesRESUMO
Lophomonas infection is an emerging parasitic disease causing respiratory infections. After China, Peru is the second country with the highest number of cases. In the bright-field microscopy evaluation of fresh samples, most of them are incorrectly estimated. Therefore, correct identification using cytological stains is to be supplemented. We report a case of a 29-year-old male with typical clinical symptoms of pneumonia, marked eosinophilia, and noninfiltrative pattern in chest X-ray, who had bronchopulmonary lophomoniasis.
RESUMO
Background: Cytological samples are cleared with xylene in two or three baths during a Pap test, however, this solvent has a high degree of toxicity, and being a controlled reagent infers high costs for its purchase and implications for environmental pollution. We estimated the impact of xylene during the Pap test in terms of the number of liters and cost of two baths of xylene, and also estimated the impact with three baths Methods: This cross-sectional study was carried out in four hospitals of EsSalud in Peru in two stages. First, the analysis of the impact due to the use of two baths of xylene was conducted during the period 2015-2019, and second, the estimates were calculated based on the assumption of three baths of xylene for the years 2020-2025. The assumption was based on the recommendations of the 2018 EsSalud cytology guideline. The monthly amount of xylene was ~10 liters per bath/month and the cost per liter was estimated at 8.13 USD (27 soles). Results: For the staining of 594,898 cytology tests, 7,848 liters of xylene were necessary, resulting in a cost of 60,861 USD (202,068 soles) during the period 2015-2019. The estimates showed a maximum assumption of 9,483 liters and 77,110 USD (256,040 soles) for the use of three baths of xylene in the four EsSalud hospitals (p = 0.0025) during the period 2020-2025. Conclusions: We determined that there was a high economic impact of using xylene with two baths from 2015 to 2019 and a dramatic increase in costs with the possible use of three baths of xylene in the Pap test for the following five years.
Assuntos
Neoplasias do Colo do Útero , Xilenos , Estudos Transversais , Poluição Ambiental , Feminino , Hospitais , Humanos , Peru , Neoplasias do Colo do Útero/diagnósticoRESUMO
The aim of this study was to characterize carbapenem-resistant Klebsiella pneumoniae (CR-Kp) isolates recovered from adults and children with severe bacteremia in a Peruvian Hospital in June 2018. Antimicrobial susceptibility was determined by disc/gradient diffusion and broth microdilution when necessary. Antibiotic resistance mechanisms were evaluated by PCR and DNA sequencing. Clonal relatedness was assessed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Plasmid typing was performed with a PCR-based method. Thirty CR-Kp isolates were recovered in June 2018. All isolates were non-susceptible to all ß-lactams, ciprofloxacin, gentamicin and trimethoprim-sulfamethoxazole, while mostly remaining susceptible to colistin, tigecycline, levofloxacin and amikacin. All isolates carried the blaNDM-1 gene and were extended spectrum ß-lactamase (ESBL) producers. PFGE showed four different pulsotypes although all isolates but two belonged to the ST348 sequence type, previously reported in Portugal. blaNDM-1 was located in an IncFIB-M conjugative plasmid. To our knowledge, this is the first report of an New Delhi metallo-ß-lactamase (NDM)-producing K. pneumoniae recovered from both children and adults in Lima, Peru, as well as the first time that the outbreak strain ST348 is reported in Peru and is associated with NDM. Studies providing epidemiological and molecular data on CR-Kp in Peru are essential to monitor their dissemination and prevent further spread.
RESUMO
OBJECTIVE: The aim of the study was to describe our experience using a modified nasal cannula to deliver nasal continuous positive airway pressure and/or nasal intermittent positive pressure ventilation during primary neonatal resuscitation of preterm and term newborns. STUDY DESIGN: Data were collected retrospectively for all neonates resuscitated with nasal cannula in the delivery room. The primary outcome was the number of newborns intubated in the delivery room. Secondary outcomes included need for chest compressions, intubations in the first 24 hours, air-leaks, and surfactant administration. RESULTS: A total of 102 infants were resuscitated using nasal cannula. Eight (7.8%) were intubated in the delivery room, five (4.9%) required chest compressions, and five (4.9%) had pneumothorax noted on chest X-ray. No deaths occurred in the delivery room. Twenty-eight patients (27.5%) received early rescue surfactant after admission to the neonatal intensive care unit. CONCLUSION: Neonatal resuscitation can be effectively performed in preterm and term newborns using a modified nasal cannula in the delivery room.
Assuntos
Reanimação Cardiopulmonar/instrumentação , Pressão Positiva Contínua nas Vias Aéreas/instrumentação , Ventilação com Pressão Positiva Intermitente/instrumentação , Oxigenoterapia/instrumentação , Salas de Parto , Feminino , Massagem Cardíaca , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Terapia Intensiva Neonatal , Intubação Intratraqueal , Masculino , Nariz , Nascimento Prematuro/terapia , Surfactantes Pulmonares/uso terapêutico , Estudos Retrospectivos , Nascimento a TermoRESUMO
PKN3 is an AGC-family protein kinase implicated in growth of metastatic prostate cancer cells with phosphoinositide 3-kinase pathway deregulation. The molecular mechanism, however, by which PKN3 contributes to malignant growth and tumorigenesis is not well understood. Using orthotopic mouse tumor models, we now show that inducible knockdown of PKN3 protein not only blocks metastasis, but also impairs primary prostate and breast tumor growth. Correspondingly, overexpression of exogenous PKN3 in breast cancer cells further increases their malignant behavior and invasiveness in-vitro. Mechanistically, we demonstrate that PKN3 physically interacts with Rho-family GTPases, and preferentially with RhoC, a known mediator of tumor invasion and metastasis in epithelial cancers. Likewise, RhoC predominantly associates with PKN3 compared to its closely related PKN family members. Unlike the majority of Rho GTPases and PKN molecules, which are ubiquitously expressed, both PKN3 and RhoC show limited expression in normal tissues and become upregulated in late-stage malignancies. Since PKN3 catalytic activity is increased in the presence of Rho GTPases, the co-expression and preferential interaction of PKN3 and RhoC in tumor cells are functionally relevant. Our findings provide novel insight into the regulation and function of PKN3 and suggest that the PKN3-RhoC complex represents an attractive therapeutic target in late-stage malignancies.
Assuntos
Neoplasias da Próstata/metabolismo , Proteína Quinase C/metabolismo , Proteínas ras/metabolismo , Animais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Doxiciclina/uso terapêutico , Imunofluorescência , Imunoprecipitação , Masculino , Camundongos , Metástase Neoplásica/genética , Neoplasias da Próstata/patologia , Ligação Proteica , Proteína Quinase C/antagonistas & inibidores , Proteína Quinase C/genética , RNA Interferente Pequeno , Proteínas ras/genética , Proteína de Ligação a GTP rhoCRESUMO
Visual analytics is a new interdisciplinary field of study that calls for a more structured scientific approach to understanding the effects of interaction with complex graphical displays on human cognitive processes. Its primary goal is to support the design and evaluation of graphical information systems that better support cognitive processes in areas as diverse as scientific research and emergency management. The methodologies that make up this new field are as yet ill defined. This paper proposes a pathway for development of visual analytics as a translational cognitive science that bridges fundamental research in human/computer cognitive systems and design and evaluation of information systems in situ. Achieving this goal will require the development of enhanced field methods for conceptual decomposition of human/computer cognitive systems that maps onto laboratory studies, and improved methods for conducting laboratory investigations that might better map onto real-world cognitive processes in technology-rich environments.
Assuntos
Ciência Cognitiva , Pesquisa Translacional Biomédica , Interface Usuário-Computador , Percepção Visual , Cognição , HumanosRESUMO
OBJECTIVE: To determine the efficacy and safety of automated adjustment of the fraction of inspired oxygen (Fio(2)) adjustment in maintaining arterial oxygen saturation (Spo(2)) within an intended range for mechanically ventilated preterm infants with frequent episodes of decreased Spo(2). METHODS: Thirty-two infants (gestational age [median and interquartile range]: 25 weeks [24-27 weeks]; age: 27 days [17-36 days]) were studied during 2 consecutive 24-hour periods, one with Fio(2) adjusted by clinical staff members (manual) and the other by an automated system (automated), in random sequence. RESULTS: Time with Spo(2) within the intended range (87%-93%) increased significantly during the automated period, compared with the manual period (40% ± 14% vs 32% ± 13% [mean ± SD]). Times with Spo(2) of >93% or >98% were significantly reduced during the automated period (21% ± 20% vs 37% ± 12% and 0.7% vs 5.6% [interquartile ranges: 0.1%-7.2% and 2.7%-11.2%], respectively). Time with Spo(2) of <87% increased significantly during the automated period (32% ± 12% vs 23% ± 9%), with more-frequent episodes with Spo(2) between 80% and 86%, whereas times with Spo(2) of <80% or <75% did not differ between periods. Hourly median Fio(2) values throughout the automated period were lower and there were substantially fewer manual Fio(2) changes (10 ± 9 vs 112 ± 59 changes per 24 hours; P < .001), compared with the manual period. CONCLUSIONS: In infants with fluctuations in Spo(2), automated Fio(2) adjustment improved maintenance of the intended Spo(2) range led to reduced time with high Spo(2) and more-frequent episodes with Spo(2) between 80% and 86%.
Assuntos
Recém-Nascido Prematuro , Oxigênio/administração & dosagem , Respiração Artificial/métodos , Estudos Cross-Over , Humanos , Lactente , Recém-NascidoRESUMO
PURPOSE: To compare TTI-237 (5-chloro-6-[2,6-difluoro-4-[3-(methylamino)propoxy]phenyl]-N-[(1S)-2,2,2-trifluoro-1-methylethyl]-[1, 2, 4]triazolo[1,5-a]pyrimidin-7-amine butanedioate) with paclitaxel and vincristine in order to better understand the properties of this new anti-microtubule agent. METHODS: Tubulin polymerization and depolymerization were followed by turbidimetric assays. Effects of compounds on the binding of [(3)H]guanosine triphosphate ([(3)H]GTP) to tubulin were studied by competition binding assays. Effects of compounds on the phosphorylation of a panel of intracellular proteins were determined by flow cytometry using phosphoprotein-specific antibodies. RESULTS: At low molar ratios of TTI-237:tubulin heterodimer (about 1:30), TTI-237 enhanced depolymerization kinetics in response to low temperature, but stabilized the aggregates at higher ratios (about 1:4). Similarly, the aggregates induced in microtubule protein by TTI-237 were depolymerized by excess Ca(++) at low TTI-237:tubulin-heterodimer molar ratios, but were stable at higher ratios. TTI-237 inhibited the exchange of [(3)H]GTP at the exchangeable nucleotide site of the tubulin heterodimer, and was similar to vincristine in its effects on the phosphorylation of eight intracellular proteins in HeLa cells. CONCLUSIONS: TTI-237 has properties that distinguish it from typical vinca-site and taxoid-site ligands, and therefore it may exemplify a new class of microtubule-active compounds.
Assuntos
Antineoplásicos/farmacologia , Hidrocarbonetos Halogenados/farmacologia , Microtúbulos/efeitos dos fármacos , Paclitaxel/farmacologia , Triazóis/farmacologia , Vincristina/farmacologia , Biopolímeros , Temperatura Baixa , Citometria de Fluxo , Guanosina Trifosfato/metabolismo , Células HeLa , Humanos , Ensaio Radioligante , Tubulina (Proteína)/efeitos dos fármacos , Tubulina (Proteína)/metabolismoRESUMO
The synthesis and SAR of a series of 6-chloro-4-fluoroalkylamino-2-heteroaryl-5-(substituted)phenylpyrimidines as anti-cancer agents are described. This series of 2-heteroarylpyrimidines was developed by modifying a series of anti-tumor [1,2,4]triazolo[1,5-a]pyrimidines and 2-cyanoaminopyrimidines we reported earlier. For the 2-heteroaryl group, the best activity is obtained when the heteroaryl group has a nitrogen atom at the ortho-position to the pyrimidyl core. The structure-activity relationship for the rest of the molecule in this 2-heteroarylpyrimidine series mimics that of the [1,2,4]triazolo[1,5-a]pyrimidine series. Like triazolopyrimidines and 2-cyanoaminopyrimidines, the 2-heteroarylpyrimidines retain the capability to overcome multidrug resistance due to Pgp. Mechanism of action studies showed that the lead compounds behaved in the same manner as triazolopyrimidines and 2-cyanoaminopyrimidines. The lead compounds in this series are more potent than the corresponding triazolopyrimidines in vitro and in vivo. Compound 21 (PTI-868) showed tumor growth inhibition in several nude mouse xenograft models, and was selected to advance to preclinical development.
Assuntos
Antineoplásicos/síntese química , Pirimidinas/síntese química , Animais , Antineoplásicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Humanos , Camundongos , Camundongos Nus , Neoplasias/tratamento farmacológico , Pirimidinas/farmacologia , Relação Estrutura-Atividade , Carga Tumoral/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
5-Chloro-6-[2,6-difluoro-4-[3-(methylamino)propoxy]phenyl]-N-[(1S)-2,2,2-trifluoro-1-methylethyl]-[1,2,4]triazolo[1,5-a]pyrimidin-7-amine butanedioate (TTI-237) is a microtubule-active compound of novel structure and function. Structurally, it is one of a class of compounds, triazolo[1,5a]pyrimidines, previously not known to bind to tubulin. Functionally, TTI-237 inhibited the binding of [(3)H]vinblastine to tubulin, but it caused a marked increase in turbidity development that more closely resembled the effect observed with docetaxel than that observed with vincristine. The morphologic character of the presumptive polymer is unknown at present. When applied to cultured human tumor cells at concentrations near its IC(50) value for cytotoxicity (34 nmol/L), TTI-237 induced multiple spindle poles and multinuclear cells, as did paclitaxel, but not vincristine or colchicine. Flow cytometry experiments revealed that, at low concentrations (20-40 nmol/L), TTI-237 produced sub-G(1) nuclei and, at concentrations above 50 nmol/L, it caused a strong G(2)-M block. The compound was a weak substrate of multidrug resistance 1 (multidrug resistance transporter or P-glycoprotein). In a cell line expressing a high level of P-glycoprotein, the IC(50) of TTI-237 increased 25-fold whereas those of paclitaxel and vincristine increased 806-fold and 925-fold, respectively. TTI-237 was not recognized by the MRP or MXR transporters. TTI-237 was active in vivo in several nude mouse xenograft models of human cancer, including LoVo human colon carcinoma and U87-MG human glioblastoma, when dosed i.v. or p.o. Thus, TTI-237 has a set of properties that distinguish it from other classes of microtubule-active compounds.
Assuntos
Antineoplásicos/farmacologia , Hidrocarbonetos Halogenados/farmacologia , Triazóis/farmacologia , Animais , Carcinoma de Células Escamosas/tratamento farmacológico , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Células HeLa , Humanos , Camundongos , Camundongos Nus , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Tubulina (Proteína)/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
A series of 4-chloro-2-cyanoamino-6-fluoroalkylamino-5-phenylpyrimidines was prepared as a result of our efforts to modify a series of [1,2,4]triazolo[1,5-a]pyrimidines that proved to be potent anticancer agents with a unique mechanism of tubulin inhibition. On the cyanoamino nitrogen, a methyl group is optimal for activity among alkyl groups introduced. The structure-activity relationship for the rest of the molecule resembles that of [1,2,4]triazolo[1,5-a]pyrimidines. A lead compound (5) retained in vitro potency compared with TTI-237. In the mechanism of action studies, it behaved in the same manner as TTI-237. In addition, it is also capable of overcoming multidrug resistance due to P-gp. These findings strongly suggest that this series of 2-cyanoaminopyrimidines binds at the same site and in the same binding mode as TTI-237. Further modifications of the 2-cyanoamino group are underway.
Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Pirimidinas/química , Pirimidinas/farmacologia , Triazóis/química , Triazóis/farmacologia , Tubulina (Proteína)/efeitos dos fármacos , Antineoplásicos/síntese química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Hidrocarbonetos Halogenados/química , Pirimidinas/síntese química , Relação Estrutura-Atividade , Triazóis/síntese química , Tubulina (Proteína)/metabolismoRESUMO
The synthesis and SAR of a series of triazolopyrimidines as anticancer agents are described. Treatment of 5-chloro-6-(trifluorophenyl)-N-fluoroalkyl [1,2,4]triazolo[1,5-a]pyrimidin-7-amine with an alcohol, a thiol, or an alkylamine provided the corresponding final compounds. A clear SAR requirement has been established for optimal activity. A (1S)-2,2,2-trifluoro-1-methylethylamino group or an achiral 2,2,2-trifluoroethylamino group is required at the 5-position to achieve high potency. On the phenyl ring, both fluoro atoms, at the positions ortho to the triazolopyrimidine core, are needed for optimal activity. At the position para to the triazolopyrimidine core, on the phenyl ring, the best activity is achieved with an oxygen linkage followed by a three-methylene unit, and an alkylamino or a hydroxy group. The mechanism of action for this series of triazolopyrimidines was shown to be unique in that they promoted tubulin polymerization in vitro, but did not bind competitively with paclitaxel.1 Instead, they inhibit the binding of vincas to tubulin. Selected compounds were studied further, and it was shown that these compounds were able to overcome resistance attributed to several multidrug resistance transporter proteins. Lead compounds were shown to inhibit tumor growth in several nude mouse xenograft models, with high potency and efficacy, when dosed either orally or intravenously.
Assuntos
Pirimidinas/síntese química , Triazóis/síntese química , Moduladores de Tubulina/síntese química , Administração Oral , Animais , Proliferação de Células/efeitos dos fármacos , Feminino , Humanos , Injeções Intravenosas , Camundongos , Camundongos Nus , Pirimidinas/química , Pirimidinas/farmacologia , Estereoisomerismo , Relação Estrutura-Atividade , Triazóis/química , Triazóis/farmacologia , Moduladores de Tubulina/química , Moduladores de Tubulina/farmacologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Analogs of hemiasterlin (1) and HTI-286 (2), which contain various aromatic rings in the A segment, were synthesized as potential inhibitors of tubulin polymerization. The structure-activity relationships related to stereo- and regio-chemical effects of substituents on the aromatic ring in the A segment were studied. Analogs, which carry a meta-substituted phenyl ring in the A segment show comparable activity for inhibition of tubulin polymerization to 2, as well as in the cell proliferation assay using KB cells containing P-glycoprotein, compared to those of 1 and 2.
Assuntos
Antineoplásicos/síntese química , Oligopeptídeos/síntese química , Moduladores de Tubulina , Tubulina (Proteína)/química , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Biopolímeros , Proliferação de Células/efeitos dos fármacos , Humanos , Células KB , Melanoma Experimental/tratamento farmacológico , Camundongos , Camundongos Nus , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Estereoisomerismo , Relação Estrutura-Atividade , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Hemiasterlin, a tripeptide isolated from marine sponges, induces microtubule depolymerization and mitotic arrest in cells. HTI-286, an analogue from an initial study of the hemiasterlins, is presently in clinical trials. In addition to its potent antitumor effects, 2 has the advantage of circumventing the P-glycoprotein-mediated resistance that hampers the efficacy of other antimicrotubule agents such as paclitaxel and vincristine in animal models. This paper describes an in-depth study of the structure--activity relationships of analogues of 2, their effects on microtubule polymerization, and their in vitro and in vivo anticancer activity. Regions of the molecule necessary for potent activity are identified. Groups tolerant of modification, leading to novel analogues, are reported. Potent analogues identified through in vivo studies in tumor xenograft models include one superior analogue, HTI-042.
Assuntos
Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Aminas/química , Animais , Morte Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Linhagem Celular , Ciclização , Ésteres/química , Humanos , Concentração Inibidora 50 , Metilaminas/síntese química , Metilaminas/química , Camundongos , Microtúbulos/química , Estrutura Molecular , Neoplasias/patologia , Oligopeptídeos/síntese química , Oxirredução , Peptídeos/síntese química , Peptídeos/química , Ácido Pirúvico/química , Relação Estrutura-Atividade , Tubulina (Proteína)/metabolismoRESUMO
Hemiasterlin is a natural product derived from marine sponges that, like other structurally diverse peptide-like molecules, binds to the Vinca-peptide site in tubulin, disrupts normal microtubule dynamics, and, at stoichiometric amounts, depolymerizes microtubules. Total synthesis of hemiasterlin and its analogues has been accomplished, and optimal pharmacological features of the series have been explored. The biological profile of one analogue, HTI-286, was studied here. HTI-286 inhibited the polymerization of purified tubulin, disrupted microtubule organization in cells, and induced mitotic arrest, as well as apoptosis. HTI-286 was a potent inhibitor of proliferation (mean IC(50) = 2.5 +/- 2.1 nM in 18 human tumor cell lines) and had substantially less interaction with multidrug resistance protein (P-glycoprotein) than currently used antimicrotubule agents, including paclitaxel, docetaxel, vinorelbine, or vinblastine. Resistance to HTI-286 was not detected in cells overexpressing the drug transporters MRP1 or MXR. In athymic mice implanted with human tumor xenografts, HTI-286 administered i.v. in saline inhibited the growth of numerous human tumors derived from carcinoma of the skin, breast, prostate, brain, and colon. Marked tumor regression was observed when used on established tumors that were >1 gram in size. Moreover, HTI-286 inhibited the growth of human tumor xenografts (e.g., HCT-15, DLD-1, MX-1W, and KB-8-5) where paclitaxel and vincristine were ineffective because of inherent or acquired resistance associated with P-glycoprotein. Efficacy was also achieved with p.o. administration of HTI-286. These data suggest that HTI-286 has excellent preclinical properties that may translate into superior clinical activity, as well as provide a useful synthetic reagent to probe the drug contact sites of peptide-like molecules that interact with tubulin.