Miositis por Bartonella henselae: caso clínico en una adolescente / Bartonella henselae myositis: case report in an adolescent

La miositis de origen vírico o bacteriano es frecuente en la edad pediátrica. Causa dolor muscular y debilidad, con fiebre y malestar general. Una causa es la infección por Bartonella henselae, bacteria implicada en la enfermedad por arañazo de gato que, a veces, causa afectación multisistémica. Se presenta el caso de una adolescente que acudió al servicio de urgencias por mialgia intensa, malestar, adelgazamiento y esplenomegalia. En el labortorio se observaron parámetros inflamatorios elevados. Refería contacto con un gato. Entre los estudios realizados, la resonancia magnética (RM) de miembros inferiores mostró una imagen compatible con miositis inflamatoria bilateral. En la RM abdominal, se observaron tres lesiones esplénicas no detectadas previamente y el fondo de ojo mostraba una lesión compatible con oclusión arterial retiniana o vasculitis. Se indicó tratamiento antibiótico por vía intravenosa durante 21 días con cefotaxima y cloxacilina, tras los cuales desaparecieron los signos y síntomas, aunque los reactantes inflamatorios persistieron elevados. Con base en el cuadro clínico (miositis + coriorretinitis + absceso esplénico) se pensó en una posible infección por B. henselae y se inició tratamiento oral con azitromicina y rifampicina durante 14 días. Luego del tratamiento, los valores de laboratorio fueron normales, así como la RM de control, y se constató una IgG positiva para la bacteria

Infectious myositis, whether viral or bacterial, is frequent in pediatric age. It causes muscle pain and weakness, associated with fever and general malaise. One cause is Bartonella henselae, responsible for cat scratch disease, which sometimes causes systemic symptoms. We report the case of an adolescent who came to the emergency room with intense myalgia, malaise, weight loss and splenomegaly. Blood tests showed high inflammatory markers. She had been in touch with a cat. Studies were carried out including: lower limbs MRI suggestive of bilateral inflammatory myositis, abdominal MRI with three previously undetected splenic lesions and dilated fundus examination that showed possible retinal arterial occlusion or vasculitis. After 21 days of intravenous antibiotic therapy (cefotaxime + cloxaciline), she became asymptomatic, but inflammatory markers remained high. Suspecting Bartonella henselaeinfection (myositis + chorioretinitis + splenic abscess), oral azithromycin and rifampicin were prescribed for 14 days. Blood tests and control MRI became normal, and IgG was positive.

[Bartonella henselae myositis: case report in an adolescent]. / Miositis por Bartonella henselae: caso clínico en una adolescente.

Infectious myositis, whether viral or bacterial, is frequent in pediatric age. It causes muscle pain and weakness, associated with fever and general malaise. One cause is Bartonella henselae, responsible for cat scratch disease, which sometimes causes systemic symptoms. We report the case of an adolescent who came to the emergency room with intense myalgia, malaise, weight loss and splenomegaly. Blood tests showed high inflammatory markers. She had been in touch with a cat. Studies were carried out including: lower limbs MRI suggestive of bilateral inflammatory myositis, abdominal MRI with three previously undetected splenic lesions and dilated fundus examination that showed possible retinal arterial occlusion or vasculitis. After 21 days of intravenous antibiotic therapy (cefotaxime + cloxaciline), she became asymptomatic, but inflammatory markers remained high. Suspecting Bartonella henselae infection (myositis + chorioretinitis + splenic abscess), oral azithromycin and rifampicin were prescribed for 14 days. Blood tests and control MRI became normal, and IgG was positive.

La miositis de origen vírico o bacteriano es frecuente en la edad pediátrica. Causa dolor muscular y debilidad, con fiebre y malestar general. Una causa es la infección por Bartonella henselae, bacteria implicada en la enfermedad por arañazo de gato que, a veces, causa afectación multisistémica. Se presenta el caso de una adolescente que acudió al servicio de urgencias por mialgia intensa, malestar, adelgazamiento y esplenomegalia. En el labortorio se observaron parámetros inflamatorios elevados. Refería contacto con un gato. Entre los estudios realizados, la resonancia magnética (RM) de miembros inferiores mostró una imagen compatible con miositis inflamatoria bilateral. En la RM abdominal, se observaron tres lesiones esplénicas no detectadas previamente y el fondo de ojo mostraba una lesión compatible con oclusión arterial retiniana o vasculitis. Se indicó tratamiento antibiótico por vía intravenosa durante 21 días con cefotaxima y cloxacilina, tras los cuales desaparecieron los signos y síntomas, aunque los reactantes inflamatorios persistieron elevados. Con base en el cuadro clínico (miositis + coriorretinitis + absceso esplénico) se pensó en una posible infección por B. henselae y se inició tratamiento oral con azitromicina y rifampicina durante 14 días. Luego del tratamiento, los valores de laboratorio fueron normales, así como la RM de control, y se constató una IgG positiva para la bacteria.

SEDAR-SEMICYUC consensus recommendations on the management of haemostasis disorders in severely ill patients with COVID-19 infection. / Recomendaciones de consenso SEDAR-SEMICYUC sobre el manejo de las alteraciones de la hemostasia en los pacientes graves con infección por COVID-19.

The infection by the coronavirus SARS-CoV-2, which causes the disease called COVID-19, mainly causes alterations in the respiratory system. In severely ill patients, the disease often evolves into an acute respiratory distress syndrome that can predispose patients to a state of hypercoagulability, with thrombosis at both venous and arterial levels. This predisposition presents a multifactorial physiopathology, related to hypoxia as well as to the severe inflammatory process linked to this pathology, including the additional thrombotic factors present in many of the patients. In view of the need to optimise the management of hypercoagulability, the working groups of the Scientific Societies of Anaesthesiology-Resuscitation and Pain Therapy (SEDAR) and of Intensive, Critical Care Medicine and Coronary Units (SEMICYUC) have developed a consensus to establish guidelines for actions to be taken against alterations in haemostasis observed in severely ill patients with COVID-19. These recommendations include prophylaxis of venous thromboembolic disease in these patients, and in the peripartum, management of patients on long-term antiplatelet or anticoagulant treatment, bleeding complications in the course of the disease, and the interpretation of general alterations in haemostasis.

Effects of corn silage and grass silage in ruminant rations on diurnal changes of microbial populations in the rumen of dairy cows.

Here, we examined diurnal changes in the ruminal microbial community and fermentation characteristics of dairy cows fed total mixed rations containing either corn silage (CS) or grass silage (GS) as forage. The rations, which consisted of 52% concentrate and 48% GS or CS, were offered for ad libitum intake over 20 days to three ruminal-fistulated lactating Jersey cows during three consecutive feeding periods. Feed intake, ruminal pH, concentrations of short chain fatty acids and ammonia in rumen liquid, as well as abundance change in the microbial populations in liquid and solid fractions, were monitored in 4-h intervals on days 18 and 20. The abundance of total bacteria and Fibrobacter succinogenes increased in solids in cows fed CS instead of GS, and that of protozoa increased in both solid and liquid fractions. Feeding GS favored numbers of F. succinogenes and Selenomonas ruminantium in the liquid fraction as well as the numbers of Ruminobacter amylophilus, Prevotella bryantii and ruminococci in both fractions. Minor effects of silage were detected on populations of methanogens. Despite quantitative changes in the composition of the microbial community, fermentation characteristics were less affected by forage source. These results suggest a functional adaptability of the ruminal microbiota to total mixed rations containing either GS or CS as the source of forage. Diurnal changes in microbial populations were primarily affected by feed intake and differed between species and fractions, with fewer temporal fluctuations evident in the solid than in the liquid fraction. Interactions between forage source and sampling time were of minor importance to most of the microbial species examined. Thus, diurnal changes of microbial populations and fermentative activity were less affected by the two silages.

[Therapeutic possibilities in refractory epilepsy in tuberous sclerosis complex]. / Posibilidades terapeuticas en la epilepsia refractaria en el complejo esclerosis tuberosa.

INTRODUCTION: Tuberous sclerosis complex (TSC) is frequently accompanied by difficult-to-treat epilepsy, which conditions these patients' quality of life and cognitive level. AIM. To describe the epidemiological and clinical characteristics, as well as the treatment of patients affected by TSC with epilepsy. PATIENTS AND METHODS: A retrospective review was carried out of the medical records of 30 patients aged under 18 registered in our database, who had been diagnosed with TSC and epilepsy. RESULTS: The age at onset of epilepsy in the patients with TSC in our series ranged from one month to four years. All of them began with partial crises. Two presented West's syndrome and four others had infantile spasms without hypsarrhythmia. In 19 of the patients, the epilepsy was medication resistant. As regards treatment with antiepileptic drugs, 11 are in monotherapy, 10 in bitherapy, seven in tritherapy and one with four drugs. Two were given ACTH, two carry an implanted vagal nerve stimulator, four receive treatment with everolimus and eight have undergone surgery. CONCLUSIONS: Epilepsy is a very common problem and begins in the early years of life in TSC. There are currently a large number of therapeutic options available, although 63.3% of patients have non-controlled epilepsy and most of them present crises on a daily basis. Poor control of their crises is correlated with mental retardation and autism spectrum disorder. The positive response obtained with other therapeutic possibilities, such as mTOR pathway inhibitors, surgery and vagal nerve stimulator, should be noted.

TITLE: Posibilidades terapeuticas en la epilepsia refractaria en el complejo esclerosis tuberosa.Introduccion. El complejo esclerosis tuberosa (CET) cursa frecuentemente con epilepsia de dificil control, lo que condiciona la calidad de vida y el nivel cognitivo de estos pacientes. Objetivo. Describir las caracteristicas epidemiologicas, clinicas y el tratamiento de los pacientes afectos de CET con epilepsia. Pacientes y metodos. Se han revisado retrospectivamente las historias clinicas de 30 pacientes menores de 18 años, diagnosticados de CET y epilepsia registrados en nuestra base de datos. Resultados. La edad de inicio de la epilepsia en los pacientes con CET en nuestra serie esta comprendida entre el primer mes de vida y los 4 años. Todos comenzaron con crisis parciales. Dos presentaron sindrome de West y cuatro, espasmos infantiles sin hipsarritmia. En 19 de los pacientes, la epilepsia se comporto como farmacorresistente. Respecto al tratamiento con farmacos antiepilepticos, 11 estan en monoterapia, 10 en biterapia, siete en triterapia y uno con cuatro farmacos. Dos recibieron ACTH, dos tienen implantado un estimulador del nervio vago, cuatro reciben tratamiento con everolimus y ocho han sido sometidos a cirugia. Conclusiones. La epilepsia es un problema muy frecuente y de inicio en los primeros años de vida en el CET. Las opciones terapeuticas actuales son muchas, sin embargo el 63,3% de los pacientes tiene una epilepsia no controlada y la mayoria de ellos presenta crisis diarias. El mal control de las crisis se correlaciona con retraso mental y trastorno del espectro autista. Señalar la respuesta positiva obtenida con otras posibilidades terapeuticas: inhibidores de la via mTOR, cirugia y el estimulador del nervio vago.

A design of experiments to optimize a new manufacturing process for high activity protein-containing submicron particles.

A novel method for the manufacture of protein/peptide-containing submicron particles was developed in an attempt to provide particles with increased activity while using high energy input technologies. The method consists of antisolvent co-precipitation from an aqueous solution containing both an amino acid core material (e.g. D,L-valine), and either bovine serum albumin (BSA) or lysozyme (Lys) as model proteins. The aqueous solution was added to the organic phase by means of a nebulizer to increase the total surface area of interaction for the precipitation process. Sonication proved to be an effective method to produce small particle sizes while maintaining high activity of Lys. The use of a polysorbate or sorbitan ester derivatives as stabilizers proved to be necessary to yield submicron particles. Particles with very high yields (approximately 100%) and very high activity after manufacture (approximately 100%) could be obtained. A particle size of 439.0 nm, with a yield of 48.8% and with final remaining activity of 98.7% was obtained. By studying various factors using a design of experiments strategy (DoE) we were able to establish the critical controlling factors for this new method of manufacture.

[Responses by neuropaediatricians to a palliative care questionnaire]. / Cuestionario sobre cuidados paliativos a neuropediatras.

INTRODUCTION: Up to 70% of children currently treated by Palliative Care Units in Europe are neurological patients. Our objective is to assess the knowledge, interest and involvement in Paediatric Palliative Care (PPC) among Spanish paediatric neurologists. MATERIAL AND METHODS: We contacted 297 Neuropaediatricians by and attached a 10-question multiple choice test. This questionnaire was related to the level of knowledge of PPC, identification of patients requiring this specific care, involvement of a paediatric neurologist, use of local palliative resources, and formal training in this subject. RESULTS: Participation rate was 32% (96/297). Around 90% knew the definition of PPC, could identify patients with a short-term survival prognosis, and had treated children who eventually died due to their illnesses. A "non resuscitation order" had been written by 61% of them at least once; 77% considered the patient́s home as the preferred location of death (if receiving appropriate care), 9% preferred the hospital, and 14% had no preference for any of these options. Just over half (52%) had contacted local PC resources, and 61% had referred or would refer patients to be seen periodically by both services (PC and Paediatric Neurology). More than half (55%) consider themselves not trained enough to deal with these children, and 80% would like to increase their knowledge about PPC. CONCLUSION: The paediatric neurologists surveyed frequently deal with children who suffer from incurable diseases. Their level of involvement with these patients is high. However, there is an overwhelming necessity and desire to receive more training to support these children and their families.

[Hypothalamic hamartoma in paediatric patients: clinical characteristics, outcomes and review of the literature]. / Hamartoma hipotalámico en la edad pediátrica: características clínicas, evolución y revisión de la literatura.

OBJECTIVE: To describe the epidemiological and clinical-electroencephalographic characteristics, and associated morbidity of patients with hypothalamic hamartoma, as well as the treatment followed and outcomes PATIENTS AND METHODS: We have retrospectively reviewed the medical histories of 10 patients diagnosed with hypothalamic hamartoma by magnetic resonance imaging over the last 20 years. RESULTS: The age of onset of epilepsy in patients with hypothalamic hamartoma in our series was between the first days of life and 2 years. Of the 10 total patients, 8 had epileptic seizures during its progress. All of them had gelastic seizures, in addition to other types of seizures, with the most common being partial simple seizures. The electroencephalographic findings recorded were highly variable. One of the patients developed epileptic encephalopathy. Five patients had some kind of conduct disorder. Five patients had cognitive problems. At least 2 different antiepileptic drugs were measured in 8 of the patients who had seizures, and in 6 of these some type of non-pharmacological treatment had been used with the objective of seizure control. Only in 3 of 8 patients has been achieved Acceptable control of epilepsy had only been achieved in 3 out the 8 patients. Five patients of the series developed precocious puberty. The average time of follow-up of the series was approximately 6 years. CONCLUSIONS: Epilepsy is the most frequent manifestation of hypothalamic hamartomas. Most cases were drug-resistant, which led to difficulties in the management of these patients, requiring surgery for their control on many occasions. Psychiatric comorbidity and cognitive impairment is common.

Neuroimaging findings in patient series with mucopolysaccharidosis.

INTRODUCTION: Mucopolysaccharidoses (MPS) are a group of inherited disorders due to lysosomal enzyme deficiencies. The aims of this study are to describe the neuroimaging findings in children evaluated in our hospital with this diagnosis, looking for a possible correlation of these alterations with the type of MPS and clinical severity, and finally to compare these findings with those previously reported. MATERIAL AND METHODS: We retrospectively analysed the medical records of 19 patients who had been diagnosed with MPS between 1992 and 2010: 7 had type I (5 with Hurler syndrome and 2 with Hurler-Scheie syndrome), 10 had type II or Hunter syndrome (4 with the severe form and 6 with the mild form), 1 had type III or Sanfilippo syndrome and 1 had type VI or Maroteaux-Lamy syndrome. We assessed the brain neuroimaging studies: computed axial tomography (CAT) in 5 patients, and magnetic resonance imaging (MRI) in 15. RESULTS: We observed a broad spectrum of neuroimaging anomalies. In CAT: mega cisterna magna (3/5, 60%). In brain MRI: dilated Virchow-Robin perivascular spaces (11/15, 73%), white matter abnormalities (11/15, 73%), and ventriculomegaly (5/15, 33%). CONCLUSIONS: Abnormal findings in neuroimaging studies are frequent in MPS (dilated Virchow-Robin perivascular spaces, white matter abnormalities and ventriculomegaly). Thus, given these abnormalities we should be aware of this possible diagnosis, particularly when typical signs and symptoms are present. However, we did not find a correlation between these findings and either any specific type of MPS or clinical severity.

[Benign childhood epilepsies: academic difficulties and behavioural disorders]. / Epilepsias benignas de la infancia: dificultades académicas y alteraciones comportamentales.

INTRODUCTION: Some papers published in the literature have shown that patients can present behavioural disorders and learning difficulties in benign childhood epilepsies (BCE). AIMS: To review the patients diagnosed with BCE in our hospital and to determine whether they present such disorders. PATIENTS AND METHODS: The study consisted in a retrospective review of the medical records of patients diagnosed with BCE. An electroencephalogram (EEG) or video-EEG-polygraph recordings were performed on all patients during sleep. The Wechsler Intelligence Scale for Children was used to evaluate intelligence. RESULTS: Data were collected for 102 patients diagnosed with BCE. Dispersed attention was observed in 51.6% of the patients with rolandic epilepsy and 16.2% displayed an impulsive temperament. In the group of patients with Panayiotopoulos syndrome, 30.3% displayed dispersed attention and 27.3% presented an impulsive temperament. A psychometric evaluation was carried out in 43 patients. The overall mean intelligence quotient was 95 (range: 55-126). In the three groups, academic achievement was good in approximately half the sample, regular in about 30% and poor in around 15%. In the group with rolandic epilepsy, the EEG showed a relation between frontal (p = 0.039) and occipital paroxysms (p = 0.004) and poorer academic achievement. In this group, the children with behaviours classed as dispersed, impulsive or hyperactive showed left-side paroxysms more frequently (p = 0.030). CONCLUSIONS: BCE are conditions with a good prognosis, but seem to be associated to learning and behavioural disorders. Neuropsychological studies should be conducted on these patients to detect these disorders.

[Polymicrogyria: epidemiology, neurological and anatomical factors and clinical outcome in a series of 34 cases]. / Polimicrogiria: epidemiología, factores neurológicos y anatómicos y evolución clínica de una serie de 34 casos.

INTRODUCTION: The aim of our study is to describe the epidemiology, clinical evolution, and the anatomical and neurological factors involved in polymicrogyria in 34 patients with this disorder. SUBJECTS AND METHODS: We have compiled 34 patients diagnosed and/or in follow-up at the Department of Paediatric Neurology of the Hospital Infantil Niño Jesús between 1995 and 2010. All the patients had a magnetic resonance imaging suggestive of polymicrogyria, and most of the patients still have periodic checks, thus their outcome is known. RESULTS: The large majority were male (76.5%). The median age at presentation was 10 months; the reason for the study was psychomotor or mental delay (44%) followed by seizures (38.2%). During the condition patients presented with epilepsy (61.7%), infantile cerebral palsy (47%), psychomotor/mental retardation (94.1%), pervasive developmental disorder (26.4%), behavioural disturbances (38.2%), neurosensory deficit (35.2%) and microcephaly 67.6%. In 82.3% of patients there was bilateral involvement (42.8% perisylvian). Other abnormalities were observed in the MRI of 58.8% of patients. The electroencephalogram at diagnosis showed changes in 41.1%, and this rose to 67.6% during follow-up. 61.7% received antiepileptic treatment was received by 61.7% of patients, with 52.3% requiring ≥2 drugs. Epilepsy surgery was performed on two patients. Some type of sequelae was observed in 91.1% of patients. The aetiology was unknown in 61.7%; a congenital infection was suspected in 10 patients and syndromic or polymalformative disorder in three patients. CONCLUSIONS: This study shows the range of clinical and radiological expression in polymicrogyria, in addition to the possibilities for the future in terms of determining the aetiology of this pathology.

[What is the prognosis of chronic immune thrombocytopenia?]. / ¿Cuál es el pronóstico de la trombopenia inmunitaria crónica?

OBJECTIVES: To analyse the characteristics of children with chronic ITP (chronic immune thrombocytopenia) in the Hospital Infantil Universitario Niño Jesús (HIUNJ) between 2003 and 2008. To also evaluate whether clinical variables as age, gender, initial platelet count, and treatment have any prognostic significance on the outcome of ITP. PATIENTS AND METHODS: Data were retrospectively collected from 288 patients diagnosed with "Purpura and other haemorrhagic illnesses". Forty-two out of these 288 satisfied the criteria for "chronic ITP". RESULTS: Ten patients out of 42 (23.8%) achieved remission with splenectomy, and 25 (almost 60%) achieved it without splenectomy (14 were complete remissions and 11 were partial remissions). Eight patients (almost 20% of patients with chronic ITP) had spontaneous remissions between 6 and 12 months from initial diagnosis. None of the clinical variables analysed were related to the outcome of the disease and the prognosis of the disease. CONCLUSIONS: Almost 60% of children with chronic ITP achieve remission without treatment regardless of age, gender, initial treatment or platelet count. Splenectomy is one of the treatments with best results; however the high spontaneous recovery rate in children with cITP, the low percentage of bleeding, and the generally benign outcome should encourage delaying this as long as possible. As it is possible to have a remission between 6 and 12 months from the initial diagnosis, the term "chronic" should be reserved for patients with ITP lasting more than 1 year.

Development and characterization of paromomycin-resistant Leishmania donovani promastigotes.

Paromomycin is an antileishmanial chemotherapeutic agent. Leishmania donovani promastigotes resistant to 800 microM of paromomycin were selected by increasing drug pressure and cloned. These promastigotes did not acquire multidrug resistance. Paromomycin resistance was stable in the absence of the drug in the culture. It remained stable also in amastigotes isolated after a passage in mice. Furthermore the resistant parasites were still infective to macrophages in vitro and for mice in vivo. A sensitive method to detect and to quantify intracellular paromomycin by HPLC was developed and allowed to show that the main mechanism of resistance seems to be due to decreased drug uptake probably as a consequence of altered membrane composition.

Uptake into leishmania donovani promastigotes and antileishmanial action of an organometallic complex derived from pentamidine.

Iridium (Ir)-(COD)-pentamidine tetraphenylborate (CAS 225-75-4) was selected from a primary screening to be evaluated in vitro on three Leishmania (L.) strains comparatively to pentamidine used as reference compound. The IC50 values obtained from in vitro evaluation on promastigotes of L. major CRE 26, L. donovani DD8 and L. donovani LV9 were 3.9, 23.5, and 3.3 mumol/l for Ir-(COD)-pentamidine tetraphenylborate and 1.6, 7.7, and 3.9 mumol/l for pentamidine isethionate, respectively. Cytotoxicity on mouse peritoneal macrophages led to determine a chemotherapeutic index of 1.7 for Ir-(COD)-pentamidine tetraphenylborate and 4 for pentamidine. Considering L. donovani DD8, the uptake of iridium complex by the promastigotes was shown to be saturable with a Km value of 17.4 mumol/l and Vmax of 1.3 nmol/mg protein/2 h. After 2 and 4 h incubation of treated promastigotes in drug free medium the absence of Ir-complex efflux is in favour of intracellular drug binding. As a matter of fact iridium complex was shown to bind ribosomal subunits in vitro, with no effect on macromolecular biosynthesis.

Modification of kinetoplast DNA minicircle composition in pentamidine-resistant Leishmania.

Pentamidine, an antiprotozoal drug, was shown to have various cellular and molecular targets depending on the organism. In Leishmania, ultrastructural modifications of kinetoplast and mitochondria have been observed but no data is available on cellular and molecular events involved in development of pentamidine-resistance. The absence of modification of minicircle DNA in pentamidine treated L. donovani and L. amazonensis promastigotes suggested that topoisomerase II activity is not a target. This result was confirmed by quantitation of the enzyme by immunodetection. Southern blot experiments indicated that the kDNA network was altered in resistant clones. Molecular cloning and sequence analysis of kDNA minicircles showed transkinetoplastidy hitherto reported only for arsenite- and tunicamycin-resistant Leishmania. Comparison of wild-type and resistant sequences showed only 32-51% homology. The AT-rich regions, known as binding sites, of the drug occurred less frequently in the resistant clones and their locations were different. These minicircle sequence modifications leading to decreased binding sites for the drug might contribute to pentamidine-resistance in Leishmania.

Proton-ATPase activities involved in the uptake of an S-adenosylmethionine analogue.

Characteristics of the transport of sinefungin (SF) were studied in Leishmania donovani promastigotes grown in vitro in a semi-defined medium. The uptake is time and pH dependent, temperature sensitive, saturable and independent of the growth phase. Metabolic inhibitors decrease the influx, indicating that sinefungin uptake is an energy requiring process. The presence of Na+ is unnecessary for activity. The uptake is sensitive to valinomycin and nigericin and to the H+-ATPases inhibitors such as N'N'-dicyclohexylcarbodiimide, bafilomycin A and oligomycin. Sulfhydryl group(s) are involved in carrier activity. Use of SF analogues shows, stereospecificity of the transporter, recognition of the 6'-amino group and to a lesser degree of the 9'-amino group of the lateral chain, whereas the 9'-carboxyl group of the lateral chain is not implicated in the recognition. Adenosine and ornithine do not interfere with the uptake. No significant amount of SF is tightly bound to macromolecules. In a SF-resistant clone, though the uptake of SF is reduced (the apparent Vmax is 276 pmoles mg protein(-1) 30 min(-1) compared with 2061 pmoles mg protein(-1) 30 min(-1) for the wild-type clone), the apparent affinity for SF is similar to that of wild-type cells (Km 0.7 and 0.6 microM respectively). This lower uptake activity is not the reflection of an increased efflux of the drug. In these resistant cells, the susceptibility of SF uptake to variation of the external pH, as well as to azide, NaF, and valinomycin are decreased, that to nigericin is lost.

Mechanism of amphotericin B resistance in Leishmania donovani promastigotes.

Amphotericin B (AmB)-resistant Leishmania donovani promastigotes were selected by increasing drug pressure, and their biological features were compared with those of the wild-type parent strain. The 50% inhibitory concentration for resistant cells was 20 times higher than that for the wild-type. Resistance was stable after more than 40 passages in drug-free medium, and resistant promastigotes were infective to macrophages in vitro but lost their virulence in vivo. They had 2.5 times longer generation time, decreased AmB uptake, and increased AmB efflux in comparison to the wild type. Fluorescence measurement with a specific plasma membrane probe, 1-[4-(trimethylammonio)-1,6-diphenylhexa]-1,3,5-triene, showed increased membrane fluidity in drug-resistant promastigotes. Analysis of lipid composition showed that in resistant cells saturated fatty acids were prevalent, with stearic acid as the major fatty acid, and the major sterol was an ergosterol precursor, the cholesta-5, 7, 24-trien-3beta-ol and not ergosterol as in the AmB-sensitive strain.