Isolation of bis-indole alkaloids with antileishmanial and antibacterial activities from Peschiera van heurkii (syn. Tabernaemontana van heurkii)

Extracts from leaves and stem bark of Peschiera van heurkii (Muell. Arg.) L. Allorge (syn. Tabernaemontana van heurkii Muell. Arg., Apocynaceae) have been assayed for antileishmanial and antibacterial activities. The activities were concentrated in the alkaloid fractions which yielded 20 indole and bisindole alkaloids. The strongest leishmanicidal and antibacterial activities were observed with the dimeric alkaloids conodurine (1), N-demethylconodurine (= gabunine) (2), and conoduramine (3). Weak toxicity towards macrophage host cells and strong activity against the intracellular amastigote form of Leishmania were observed for compounds 1 and 2. In vivo, 1 was less active than glucantime (= N-methylglucamine antimonate), the drug of reference, while 2 was devoid of activity at 100 mg/kg.

Helix stop and start signals in peptides and proteins. The capping box does not necessarily prevent helix elongation

Recently, several papers have addressed the existence of helix stop signals at the beginning of alpha-helices. It has been indicated that the existence of a reciprocal backbone-side-chain hydrogen-bond interaction, designated the capping box, could be one of these signals. The fingerprint sequence of this capping box is Ser/Thr-X-X-Glu/Gln. In the fifth alpha-helix of the chemotactic alpha/beta parallel protein CheY there is such a sequence in the middle of the helix. In a peptide corresponding to this alpha-helix the capping box is bypassed, as deduced from NMR analysis. However, making the peptide shorter so that the capping box fingerprint is closer to the beginning of the peptide results in the formation of the capping box. These results indicate that, although the capping box could play a role in stabilizing and nucleating helical peptides in solution, it is not necessarily a stop signal and can be bypassed when favourable interactions exist between the surrounding residues.

Inspiratory muscle training in chronic airflow limitation: comparison of two different training loads with a threshold device

The usefulness of inspiratory muscle training (IMT) in chronic airflow limitation (CAL) patients is a controversial issue, mainly due to differences in the training load. To further evaluate this aspect, we studied the effect of the magnitude of the load using a threshold pressure trainer. Ten CAL patients (5 males, 5 females) 67 +/- 2 yrs (mean +/- SEM) and forced expiratory volume in one second (FEV1) 36 +/- 2% pred, were trained for 30 min a day using a load of 30% of their maximal inspiratory mouth pressure (PImax) (Group 1). Another 10 CAL patients (5 males, 5 females), 73 +/- 2 yrs and FEV1 37 +/- 2% pred), were trained using only 12% of their PImax (Group 2). Training was assessed by PImax, inspiratory muscle power output (IMPO), sustainable inspiratory pressure (SIP), maximal inspiratory flow rate (VImax), pattern of breathing during loaded breathing, Mahler's dyspnoea score, and the 6 min walking distance (6MWD). After 5 weeks of training, Group 1 exhibited significant increments in: PImax (34 +/- 11%); IMPO (92 +/- 16%); SIP (36 +/- 9%); and VImax (34 +/- 13%). Dyspnoea was also reduced, and the 6MWD increased by 48 +/- 22 m. We observed no significant changes in Group 2. During loaded breathing, Group 1 showed a significant increment in tidal volume (VT) and mean inspiratory flow (VT/TI), and a reduction in inspiratory time (TI). In Group 2, VT and VT/TI also increased significantly, but the breathing frequency increased with a reduction of expiratory time.(ABSTRACT TRUNCATED AT 250 WORDS)

Elucidating the folding problem of helical peptides using empirical parameters

Using an empirical analysis of experimental data we have estimated a set of energy contributions which accounts for the stability of isolated alpha-helices. With this database and an algorithm based on statistical mechanics, we describe the average helical behaviour in solution of 323 peptides and the helicity per residue of those peptides analyzed by nuclear magnetic resonance. Moreover the algorithm successfully detects the alpha-helical tendency, in solution, of a peptide corresponding to a beta-strand of ubiquitin.

Kinetic characterization of the chemotactic protein from Escherichia coli, CheY. Kinetic analysis of the inverse hydrophobic effect

CheY, the 129 amino acid chemotactic protein from Escherichia coli, is a good model for studying the folding process of the parallel alpha/beta family of proteins. A study of the folding kinetics of CheY using fluorescence and far-UV circular dichroism (CD) stopped-flow measurements is reported. CheY has three prolines, two of them in the trans conformation and one, Pro110, with a cis Lys-Pro peptide bond. This protein presents a unimolecular, but complex, kinetic mechanism that is dominated by a slow phase compatible with a trans-cis isomerization. Mutation of Pro110 to Gly results in the disappearance of this slow phase, indicating that this cis prolyl bond is responsible for it. The slow phase is catalyzed in a very inefficient way by prolyl isomerase, indicating that the cis bond is poorly accessible to the enzyme during refolding. In agreement with this is the fact that the isomerization of the Lys109-Pro110 bond occurs in an intermediate which contains 96% of the native far-UV CD signal and 80% of the native fluorescence signal. Analysis of the unfolded protein with all its prolines in the native conformation shows the existence of a very stable intermediate in the folding reaction. Mutation of a hyperexposed hydrophobic residue, Phe14, to Asn results in an increase in the free energy of unfolding of the protein of approximately 3 kcal mol-1. Kinetic analysis of the unfolding and refolding reactions of this mutant indicates that the major stabilization effect comes from the relative destabilization of the unfolded state and the kinetic intermediate with respect to the transition state, providing kinetic evidence for the inverse hydrophobic effect. This could also indicate the existence of nonnative interactions in folding intermediates.

[Laparoscopic lumboaortic retroperitoneal lymphadenectomy in testicular neoplasm]

Lumboaortic lymphadenectomy is a therapeutic alternative for patients with nonseminomatous testis tumors and its principal untoward effect is the loss of ejaculation. The anatomic knowledge of lymph node metastasis allows lower limit definition of aortic dissection, maintaining the diagnostic sensitivity and ejaculation. We report three patients with nonseminomatous testis tumors subjected to a reduced video-laparoscopic lumboaortic lymphadenectomy. An adequate amount of tissue was obtained in all and lymph node metastasis found in two. No complications occurred and patients were discharged 48 hours later. It is concluded that this technique is an alternative staging technique with low morbidity that allows a rapid patient discharge.

Antileishmanial activity of a tetralone isolated from Ampelocera edentula, a Bolivian plant used as a treatment for cutaneous leishmaniasis

The stem bark of Ampelocera edentula Kuhlm. (Ulmaceae) is used by the Chimanes Indians from Bolivia for the treatment of cutaneous leishmaniasis caused by the protozoan Leishmania braziliensis. A chloroform extract of the stem barks was found to be active against extracellular forms of Leishmania ssp. and Trypanosoma cruzi at 50 micrograms/ml. Bioassay-guided fractionation of this extract allowed us to isolate one active compound. Its structure was elucidated by spectral and chemical studies as 4-hydroxy-1-tetralone. BALB/c mice infected with L. amazonensis (PH8) or L. venezuelensis were treated one day after the parasitic infection with 4-hydroxy-1-tetralone (25 mg/kg/day) or with reference drug, Glucantime (56 mg Sbv/kg/day) for 14 days. Lesion development was the criteria used to evaluate the disease severity. 4-Hydroxy-1-tetralone was slightly less effective than the reference drug against L. amazonensis or L. venezuelensis. Single treatment near the site of infection, 14 days after infection with L. amazonensis, with 4-hydroxy-1-tetralone (50 mg/kg) was more effective than Glucantime (112 mg/kg). This study is, to our knowledge, the first to show the activity of a tetralone for the experimental treatment of New World cutaneous leishmaniasis.

Leishmanicidal and trypanocidal activities of Bolivian medicinal plants

Cutaneous and mucocutaneous leishmaniasis are endemic diseases in South America, especially in the subandean areas of the humid lowlands of Bolivia. Fourteen plants used topically in folk medicine to treat cutaneous leishmaniasis were collected in the tropical regions of colonization and in the rain forest occupied by Chimane Indians. Three of four plants used by the Chimane Indians exhibited an in vitro activity against three species of Leishmania. Two of ten plants used by the colonists showed an in vitro activity. We have also included results obtained with extracts from 53 Bolivian medicinal plants used for other diseases and from 43 plants collected with basis of chemotaxonomic criteria from all parts of Bolivia. All extracts were also screened in vitro against three strains of Trypanosoma cruzi (Trypanosomatidae), the causative agent of Chagas' disease.

2-substituted quinoline alkaloids as potential antileishmanial drugs

Ten 2-substituted quinoline alkaloids isolated from a plant used for treatment of New World cutaneous leishmaniasis have antileishmanial in vitro activities against the extracellular forms of Leishmania spp. BALB/c mice infected with Leishmania amazonensis PH8 or H-142 or Leishmania venezuelensis were treated 1 day after the parasitic infection with a quinoline alkaloid (100 mg/kg of body weight per day) or with reference drug N-methylglucamine antimonate (Glucantime) (56 mg of pentavalent antimony [Sbv] per kg per day) for 14 days. Lesion development was the criterium used to assess disease severity. Two three-carbon chain quinolines [2-n-propylquinoline and 2-(1',2'-trans-epoxypropyl)quinoline (chimanine D)] were more potent than N-methylglucamine antimonate against L. amazonensis PH8, and five quinoline alkaloids [2-(3,4-methylenedioxyphenylethyl)quinoline, cusparine, 2-(3,4-dimethoxyphenylethyl)quinoline, 2-(E)-prop-1'-enylquinoline (chimanine B), and skimmianine] were as effective as the reference drug. Single treatment near the site of infection, 14 days after infection with L. amazonensis, with 2-n-propylquinoline or chimanine B reduced the severity of lesions but less notably than N-methylglucamine antimonate. 2-n-Propylquinoline exhibited significant activity against the virulent strain L. venezuelensis. The active products did not show any apparent toxicities during the experiment. This study is, to our knowledge, the first to show the activity of 2-substituted quinoline alkaloids for experimental treatment of New World cutaneous leishmaniasis. Further investigations of these compounds might yet prove helpful for the development of new antileishmanial drugs.

Effect of natural naphthoquinones in BALB/c mice infected with Leishmania amazonensis and L. venezuelensis

Plumbagin, 3,3'-biplumbagin and 8,8'-biplumbagin are naphthoquinones isolated by activity-directed fractionation from a Bolivian plant, Pera benensis, used in folk medicine as treatment of cutaneous leishmaniasis caused by Leishmania braziliensis. BALB/c mice were infected with L. mexicana or L. venezuelensis and treated 24 h after the parasitic infection with plumbagin (5 or 2.5 mg/kg/day), 3,3'-biplumbagin, 8,8'-biplumbagin (25 mg/kg/d) or Glucantime (200 mg/kg/d). Lesion development was the criteria employed to evaluate the inhibitory effect. The bis-naphthoquinones were less potent than Glucantime against L. amazonensis and L. venezuelensis. Plubagin and Glucantime delayed the development of L. amazonensis and L. venezuelensis. Assays of a single local treatment on foot-pad infection two weeks after the parasitic inoculation with L. amazonensis showed that 8,8'-biplumbagin (50 mg/kg/d) was as potent as Glucantime (400 mg/kg/d).

Inhibition by N-methyl-D-aspartic acid (NMDA) receptor antagonist of lordosis behavior induced by estrogen followed by progesterone or luteinizing hormone-releasing hormone (LHRH) in the rat

The effects of glutamate receptor antagonists on sexual receptivity induced by progesterone and LHRH were examined in ovariectomized, estradiol-primed rats (OVX-EB). Enhancement of lordosis/mounts quotient (L/M) by progesterone (0.5 mg) or LH-RH (150 ng; third ventricle, IVT) in OVX-EB rats was significantly decreased by IVT injection of (+) 2-amino-7-phosphonoheptanoic acid a competitive N-methyl-D-aspartic acid (NMDA) receptor antagonist. On the contrary, there were no changes in L/M quotient after IVT injection of 6,7-dinitroquinoxaline-2,3,dione at two dose levels, a Non-NMDA receptor antagonist. The NMDA antagonist did not modify lordosis behavior in OVX-EB rats. The results indicate that the NMDA type of glutamate receptors appears to mediate progesterone and LHRH facilitatory actions and suggest that glutamatergic synapses may be involved in lordosis-facilitating neural mechanisms.

[A method for permanent fixation of eggs of enteroparasitic helminths]

The results using the Hoyer method for examining eggs of helminths enteroparasites are presented. This method is particularly suited for teaching and on research purposes. Using this technique in fecal sample containing eggs of A. lumbricoides, T. trichiura, Uncinaria sp., Taenia sp., Diphyllobothrium sp., H. nana, H. diminuta and F. hepatica allowed the correct identification of then after 24 hours up to 180 days after the samples were obtained.

Photoreceptor Pigment for Blue Light in Neurospora crassa

Irradiating the mycelium of Neurospora crassa with moderate intensities of blue light causes a reversible photoreduction of a b-type cytochrome. The action spectrum for the photoreduction of cytochrome b is very similar to the absorption spectrum of flavin pigments. Prolonged irradiation of the mycelium with strong blue light irreversibly bleaches flavin-like pigments and as these pigments are bleached the photoresponse of cytochrome b is lost. We conclude from these and other data that a flavin is the photoreceptor pigment for the photoreduction of cytochrome b. The close similarity between the action spectrum for the photoreduction of cytochrome b and action spectra for a number of physiological photoresponses suggests that this photoreceptor pigment controls a wide variety of photobiological processes in a wide diversity of organisms.

A bimodal temperature response and effect of light intensity in the photocontrol of germination of seeds in Jussiaea suffruticosa

A bimodal temperature response is observed in the germination of seeds in Jussiaea suffruticosa, both under continuous and cyclic light treatments. Germination exhibits two maxima at around 25° C and at 40°, and a minimum in the region of 30-35°. The response depends on light intensity both under continuous and intermittent light treatments. This dependence is much more noticeable in the region of minimum germination (30°). Both preincubation in darkness at 35° and high light intensities (15 500 lux) tend to eliminate the bimodal temperature response.