Essential role of the conformational flexibility of helices 1 and 5 on the lipid binding activity of apolipophorin-III

It has been recently postulated that the conformational flexibility of helices 1 and 5 of Locusta migratoria apoLp-III could play an important role in early steps of binding of this apolipoprotein to a lipid surface (Soulages, J. L., and Arrese, E. L. (2000) J. Biol. Chem. 275, 17501-17509). To test this model, we have designed a double Cys mutant in which a disulfide bond linking helices 1 and 5 could be formed, resulting in an apolipoprotein with reduced conformational flexibility of its N- and C-terminal helices. Substitution of Thr(18) and Ala(147) by Cys residues provided a protein that under nonreducing conditions was fully oxidized. The far-UV CD spectra of this mutant in the reduced and oxidized states indicated that their secondary structures were identical to the structure of the wild type recombinant apoLp-III, which contains no Cys residues. Near-UV CD studies confirmed the formation of a disulfide bond and the absence of structural perturbations. The lipid binding activity of the reduced mutant, as determined by its ability to form discoidal lipoproteins, was nearly identical to that of the wild type protein. Contrarily, the disulfide form of the mutant was not able to form discoidal lipoproteins with liposomes of either dimirystoylphosphatidylcholine or dimyristoylphosphatidylglycerol. It is concluded that the separation of the helices 1 and 5 constitutes one of the key steps along the complex pathway for the formation of the final apolipoprotein lipid-bound state. It is inferred that the conformational flexibility of helices 1 and 5 is a key property of apoLp-III, allowing the exposure of hydrophobic protein regions and the interaction of the hydrophobic faces of the amphipathic alpha-helices with the lipoprotein lipid surface.

Isolation of mycobacteria from frozen fish destined for human consumption

Mycobacteria were isolated from defrost water and tissue of sole (Solea solea), hake (Merluccius merluccius), cod (Gadus morhua), ling (Genypterus blacodes), and monkfish (Lophius piscatorius) on Löwenstein-Jensen medium after incubation at different temperatures. Samples of frozen fish were obtained under sterile conditions inside a refrigeration chamber (-18 to -22 degrees C) in a wholesale market from which these products are distributed to shops for retail sale and human consumption.

Comparative in vitro antifungal activity of amphotericin B lipid complex, amphotericin B and fluconazole

Amphotericin B (AMB) is considered the gold standard in the treatment of serious systemic mycoses in spite of its nephrotoxicity and adverse effects. Association with lipids enables larger doses of AMB to be given with a longer t((1/2)) and C(max), without the toxic effects at lower concentrations. Liposome-encapsulated AMB shows a lower affinity for mammalian cells and improves V(d), thus decreasing toxicity. Amphotericin B lipid complex (ABLC) is an AMB formulation associated with a biodegradable phospholipid matrix (5% molar) from which the drug is released by cell phospholipases. ABLC is recommended for serious mycoses refractory to conventional antifungal therapy or when AMB is contraindicated. We compared the in vitro antifungal activity of ABLC, AMB and fluconazole (FLZ) against 328 strains of clinically significant opportunistic fungi using a microdilution method (NCCLS, M-27A). 64.9% of the yeasts were inhibited by MIC of ABLC </= AMB resulting in a similar or slightly superior efficacy compared to AMB when tested against Candida albicans, C. glabrata, C. guilliermondii, C. parapsilosis and C. tropicalis. Effectiveness against C. krusei was lower for ABLC (5.99 microg/ml for ABLC, 1.58 microg/ml for AMB). However, for Aspergillus fumigatus, the activities of AMB and ABLC were 1.62 and 2.46 microg/ml, respectively; A. niger 0.72 microg/ml, 0.76 microg/ml (ABLC and AMB, respectively); A. clavatus, A. candidus, A. tenuissima, A. corymbifera and Exophiala jeanselmei, Scedosporium spp. and Miceliophtora spp. showed a low susceptibility to both AMB formulations. ABLC is a useful alternative to AMB or FLZ for the treatment of severe fungal infections, due to the broad spectrum of antifungal actions observed in this study.

Major liver resection for carcinoma in jaundiced patients without preoperative biliary drainage

BACKGROUND

The role of preoperative biliary drainage (PBD) before liver resection in the presence of obstructive jaundice remains controversial. Our patients with proximal duct carcinoma undergo noninvasive assessment followed by rapid laparotomy without PBD if the lesion is deemed resectable.

HYPOTHESIS

Our aim was to report operative outcome of these patients and to analyze their specific features by comparison with patients without biliary obstruction who underwent major liver resection.

DESIGN

A case-comparison study.

SETTING

A tertiary care university hospital in a metropolitan area.

PATIENTS

Twenty consecutive jaundiced patients underwent major liver resection without PBD. The jaundiced patients were matched with 27 nonjaundiced patients with normal underlying liver selected from a computer bank of 261 patients undergoing liver resections and identical for age, tumor size, type of liver resection, and vascular occlusion.

MAIN OUTCOME MEASURE

Postoperative course including mortality, morbidity, transfusion rates, and results of liver function tests.

RESULTS

Seventeen jaundiced patients (85%) and 13 nonjaundiced patients (48%) received blood transfusions (P = .03). Morbidity was 50% in jaundiced and 15% in nonjaundiced patients (P = .006), mainly resulting from subphrenic collections and bile leaks occurring only in jaundiced patients. In contrast, there were no significant differences for mortality (5% vs 0%) and liver failure (5% vs 0%). Postoperative changes in liver function test results were comparable between groups.

CONCLUSIONS

Major liver resections without PBD are safe in most patients with obstructive jaundice. Recovery of hepatic synthetic function is identical to that of nonjaundiced patients. Transfusion requirements and incidence of postoperative complications, especially bile leaks and subphrenic collections, are higher in jaundiced patients. Whether PBD could improve these results remains to be determined.

Microwave ablation using a spiral antenna design in a porcine thigh muscle preparation: in vivo assessment of temperature profile and lesion geometry

INTRODUCTION

Theoretical studies have suggested that microwave energy can increase the depth of heating compared with radiofrequency energy. A spiral microwave antenna design may have advantages over previous designs using smaller designs because the resulting power deposition pattern is considerably larger than the catheter diameter. We tested the efficacy of a spiral antenna using microwave energy in a porcine thigh muscle preparation.

METHODS AND RESULTS

In five anesthetized pigs, the thigh muscle was exposed and bathed in heparinized bovine blood (36 degrees to 37 degrees C). A helical microwave catheter with a fiberoptic thermometer attached to the distal end was positioned perpendicular to the thigh muscle. The antenna-tissue interface and tissue temperatures at depths of 3.0 and 6.0 mm were measured. A 915-MHz microwave generator delivered energy at one of three power outputs (50, 100, or 150 W) for 60 seconds. Seventy lesions were created: 50 W (n = 23), 100 W (n = 24), and 150 W (n = 23). The mean depths at 50, 100, and 150 W were 4.3 +/- 1.8 mm, 7.2 +/- 1.7 mm, and 9.4 +/- 0.9 mm, respectively. Lesion depth (R = 0.96, P = 0.05), maximum surface dimension (R = 0.99, P = 0.06), and volume (R = 0.99, P = 0.04) were closely correlated to the power applied.

CONCLUSION

Power is an important determinant of lesion size using a spiral microwave antenna. A novel, spiral microwave antenna design can create lesions of significant depth that may be applicable for the ablative therapy of ventricular tachycardia.

Testing non-linearity and directedness of interactions between neural groups in the macaque inferotemporal cortex

Information processing in the visual cortex depends on complex and context sensitive patterns of interactions between neuronal groups in many different cortical areas. Methods used to date for disentangling this functional connectivity presuppose either linearity or instantaneous interactions, assumptions that are not necessarily valid. In this paper a general framework that encompasses both linear and non-linear modelling of neurophysiological time series data by means of Local Linear Non-linear Autoregressive models (LLNAR) is described. Within this framework a new test for non-linearity of time series and for non-linearity of directedness of neural interactions based on LLNAR is presented. These tests assess the relative goodness of fit of linear versus non-linear models via the bootstrap technique. Additionally, a generalised definition of Granger causality is presented based on LLNAR that is valid for both linear and non-linear systems. Finally, the use of LLNAR for measuring non-linearity and directional influences is illustrated using artificial data, reference data as well as local field potentials (LFPs) from macaque area TE. LFP data is well described by the linear variant of LLNAR. Models of this sort, including lagged values of the preceding 25 to 60 ms, revealed the existence of both uni- and bi-directional influences between recording sites.

Epidemiologic aspects of American visceral leishmaniasis in an endemic focus in Eastern Venezuela

An endemic focus of American visceral leishmaniasis (AVL) in eastern Venezuela has been evaluated in terms of patients (n = 48), immunologic reactivity to Leishmania in household contacts (n = 187) and neighborhood controls (n = 170), detection of Leishmania (L. donovani complex) in dogs and wild animals by the polymerase chain reaction (PCR) and characteristics of the sandfly population. The male:female ratio of patients was 1.18:1; 89.6% were < or =12 years old. Serologic reactivity was significantly higher in household contacts than in controls (P = 0.0008), as was the size of leishmanin reactions in contacts < or =10 years of age (P = 0.0141). Leishmania donovani complex-specific PCRs were positive in dogs, an opossum (Didelphis marsupialis), and a black rat (Rattus rattus). Lutzomyia longipalpis and Lu. evansi, both implicated in the transmission of AVL, were identified among the 386 sand flies examined. These observations provide the bases for an active control program as well as further studies of reservoirs and vector-host relationships in this area.

Use of scavenger beads to remove excess labeling reagents from capillary zone electrophoresis samples

In many cases, samples for capillary zone electrophoresis (CZE) are derivatized with a chromophore or fluorophore to enhance their detectability. To ensure efficient labeling, a large excess of labeling agent is often used, which leads to the presence of a large peak for unreacted reagent. Here we report that excess reagent can be reacted with "scavenger beads" carrying an appropriate functional group to remove it from the sample solution. We present examples of removal of aminonaphthalene mono-, di-, and trisulfonic acid from mixtures in which they were used to label mono- or oligosaccharides by reductive amination. Aldehyde-containing scavenger beads were made by oxidizing Sephadex G-50 beads with sodium periodate. These were added to the labeling reaction mixtures after the reductive amination of the sugars was complete. Almost complete elimination of the peak from the labeling agent could be achieved.

[Benign glial cysts of the pineal region]

A review of the pertinent literature regarding glial cysts of the pineal region is presented. Various pathogenic factors have been advocated such as the physiological involution of the pineal gland, a sequestration of the embryonic cavum pineale or the degenerative evolution of glial inclusions within the pineal gland. The pathological description is classical with three layers: an external fibrous capsule, an intermediate layer of pineal tissue and an internal glial wall. Imaging of these lesions is typical, namely the thin rim of peripheral contrast enhancement and the presence of calcifications. These cysts are more frequent in women in their third decade of life. They are almost always latent and their fortuitous disclosure at NMR examinations is common. Some of them will nevertheless cause intracranial hypertension due to hydrocephalus and hemorrhage. Those symptomatic cysts should be treated. Surgical excision has been the method of choice and the results are good. More recently a mere stereotactic needle aspiration has been performed with satisfactory long-term results.

European retirees on the Costa del Sol: a cross-national comparison

"This paper studies northern European retired immigrants, using data generated by a questionnaire survey of 300 respondents and in-depth interviews with 20 people in 13 municipalities. Reasons for moving to Spain, the advantages and disadvantages reported of living there, and the perceived impacts on the local region were analysed, paying particular attention to cross-national differences between British, German, Benelux and Nordic retirees. The results show that sociodemographic and economic features of the settlers tend to be quite similar, whilst reasons for moving, stated advantages and disadvantages, and consequences and impacts exhibit some cross-national differentiation."

Switching attention without shifting the spotlight object-based attentional modulation of brain potentials

Although psychophysical evidence for object-based attention has been reported, corresponding studies with event-related potentials (ERPs) are scarce. Here subjects were presented with perceptual fields containing two superimposed objects (transparent surfaces generated by two sets of dots in rigid rotation around fixation, each set of a different color and direction of motion) or only one object (the same dots but either at rest or all rotating in the same direction). Brief (150-msec) rectilinear displacements affected either of the sets at random ISIs of 350 to 550 msec. Attention was directed to one set of dots, guided by color, in order to discriminate the direction of their displacement. Motion-onset ERPs elicited by these displacements were compared for attended and unattended dots. When the perceptual field consisted of two objects, strong suppression of P1 and N1 was obtained in the ERPs associated with the unattended object. No suppression was found with the field containing a single object, although an enhanced selection negativity was found in ERPs associated with attended dots (selected by color). Since the two objects occupied the same region of visual space, the suppression of P1/N1 cannot be explained by the space-based mechanisms but is consistent with object-based attentional selection at early stages of vision. The results highlight the role of perceptual organizations in enabling alternative attentional mechanisms.

A follow-up study of multibacillary Hansen's disease patients treated with multidrug therapy (MDT) or MDT + immunotherapy (IMT)

Multibacillary (MB) leprosy patients treated with multidrug therapy (MDT) or MDT + immunotherapy (IMT) with BCG + heat-killed Mycobacterium leprae were tested annually for their ability to proliferate in vitro to the mycobacterial antigens BCG, M. leprae soluble extract, and intact M. leprae. IgM antibody responses to phenolic glycolipid I (PGL-I) were measured, as well as serum nitrite levels in patients' sera, before, during and after treatment. Patients who received only MDT did not present cellular reactivity to intact M. leprae antigens, in contrast to the results obtained with BCG, which elicited reactivity at time zero, that increased after treatment. Regarding PGL-I antibody variations in relation to the initial value, we observed a statistically significant marked decrease at the end of 2 years which continued to fall in successive evaluations. MB patients showed high initial serum nitrite concentrations which dropped drastically with treatment. This decay was apparently associated with the bacillary load present in these patients. The group submitted to IMT + MDT showed high and long-lasting T-cell responses to mycobacterial antigens in a significant number of initially unresponsive MB patients. There was a marked increase to M. leprae soluble extract and BCG, as well as a more variable response to whole bacilli. The antibody levels in this group of patients are sustained for a somewhat longer period and decreased more slowly during the 5-year follow up.

Differing antibody IgG isotypes in the polar forms of leprosy and cutaneous leishmaniasis characterized by antigen-specific T cell anergy

Leprosy and American cutaneous leishmaniasis are tropical diseases which present a spectrum of clinical and immunological manifestations. Lepromatous leprosy and diffuse cutaneous leishmaniasis are the severe, progressive polar forms of disease characterized by persistent T cell anergy. Relative concentrations of antibodies belonging to the four IgG isotypes have been determined in these forms of disease as well as active visceral leishmaniasis, which presents transitory T cell anergy. Leishmania-specific IgG4 antibodies predominated in 19/20 sera from patients with diffuse cutaneous leishmaniasis, and IgG1 antibodies predominated in 9/10 cases of untreated visceral leishmaniasis. The predominant IgG isotype of Mycobacterium leprae-specific antibodies in untreated lepromatous leprosy was remarkably variable (IgG1, IgG2, IgG3 and IgG4 in 8, 6, 2 and 1 sera, respectively). Differing IgG antibody isotypes have been associated with distinct CD4+ T cell helper subpopulations and their characteristic lymphokine profiles in several pathologies. These results suggest that T cell anergy in chronic intracellular infections may be associated with as yet undefined mechanisms which modulate reported T helper cell-lymphokine isotype relationships.

A longitudinal study of immunologic reactivity in leprosy patients treated with immunotherapy

More than 150 leprosy patients treated with multidrug therapy (MDT) plus immunotherapy (IMT) with a mixture of heat-killed Mycobacterium leprae plus live BCG were studied in relation to humoral and cell-mediated immune responses. Many previously had received prolonged sulfone monotherapy. Patients received 2 to 10 doses of IMT in a period of 1 to 3 years, depending upon their clinical form of leprosy. The patients were followed up for 5 to 10 years with repeated determinations of antibody levels to phenolic glycolipid-I; lymphoproliferative (LTT) responses to soluble extract of M. leprae, to whole bacilli and to BCG, skin-test responses and bacterial indexes (BIs). After MDT plus IMT there was a statistically significant decrease of antibody levels in the multibacillary (MB) group. The BI decreased proportionally to the ELISA results. LTT increased to M. leprae antigens, especially to soluble extract, in a high percentage of these patients (34% of LL patients positive). Lepromin positivity in MB patients increased from 5% initially positive to 75% at the cut-off during this follow up. These results show substantial early and persistent cell-mediated reactivity to M. leprae in many MB patients treated with MDT-IMT, confirming and expanding previously published data.

[Treatment of chronic lumbago and radicular pain by spinal cord stimulation. Long-term results]

Seventy-seven patients with chronic, refractory, low back and radicular pain underwent implantation of a spinal cord stimulator between 1984 and 1992. Most patients had failed back surgery syndrome. In every case, an epidural quadripolar "Resume" electrode was implanted surgically. Results were evaluated after three months then after six to 98 months (mean follow-up 42 months). Long-term efficacy was good in 63.6% of cases, fair in 22%, and poor in 6.5%; treatment failure occurred in 7.9% of cases. Adverse events included one case of meningitis, two cases of local infection, and one case each of cerebrospinal fluid fistula and necrosis of the skin overlying the stimulator. The main causes of treatment failure were complications, inappropriate patient selection, and the escape phenomenon. The results of this study demonstrate that spinal cord stimulation is effective for the treatment of chronic low back and radicular pain in carefully selected patients; scrupulous application of restrictive selection criteria is essential to the success of the method.

Microbiological quality of French yogurts commercialized in Spain

The microbiological quality has been evaluated in 6 batches of yogurt (plain, flavoured and fruit-added) produced commercially in France and purchased in Spain. The essential microflora: Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, and contaminants (coliform bacteria, yeasts and molds) were checked. The pH was also measured. The totality of the samples tested fulfilled French and Spanish regulation with respect to the presence of viable yogurt organisms. Likewise, in 100% of the yogurts, counts of contaminants were under 10 cfu/g. The pH ranged between 3.92 and 4.19.

Foreign minorities from developing countries in Madrid

"Spain, which has always been a land of emigrants, is currently a centre of attraction for immigrants, as are other countries in Mediterranean Europe. The proportion is not as high as in other countries with a longer tradition of immigration. In this survey we selected the six nationalities which provide the highest numbers of immigrants from the developing world, and which have the greatest racial or cultural contrast to the native population. We analyse their structural features, whether or not immigrants from the same country...collect in the Madrid Metropolitan Area, the recent mobility of the immigrant population, and the evolution of immigration since the Administration carried out a regularization process, as well as Spaniards' opinion of foreign immigrants."

Preparation of activated supports containing low pK amino groups. A new tool for protein immobilization via the carboxyl coupling method

A method for the preparation of new aminated agarose gels containing monoaminoethyl-N-aminoethyl structures, MANA-agarose gels, has been developed. These gels contain primary amino groups with a very low pK value (6.8). In addition to that, we have been able to prepare very highly activated gels (e.g., 10% agarose gels containing up to 200 mu Eq of primary amines per milliliter). These two properties make these activated supports suitable for performing novel and interesting methods for protein immobilizations via very mild carbodiimide activation of carboxy groups. For example, very effective coupling reactions can be performed at pH 5.0-6.0 in the presence of low concentrations of activating agent, e.g., 1 mM. By using a model industrial enzyme, beta-galactosidase from Aspergillus oryzae, we have been able to demonstrate the excellent prospects of these novel activated supports.