Cuidados Paliativos en las enfermedades respiratorias crónicas en fase avanzada. Situación actual y propuesta de organización asistencial / Palliative Care in advanced chronic respiratory disease. State and assitential organization purpose

Actualmente no existen unos criterios objetivos válidos para predecirla mortalidad e incluir directamente a los pacientes con enfermedades respiratorias crónicas en fase avanzada (ERCA) en un programa de atención paliativa. Las ERCA tienen unas particularidades propias que hacen que los cuidados paliativos respiratorios tengan unas características diferentes a la atención paliativa convencional. Esta revisión constata que las ERCA no reciben una cobertura paliativa equiparable a la recibida por los pacientes neoplásicos a pesar de tener índices de mortalidad comparables al de la mayoría de cánceres comunes. La principal diferencia entre la atención apacientes en fases finales de ERCA respecto a pacientes neoplásicos, radica en la accesibilidad a un dispositivo sociosanitario. En esta revisión se propone un programa de atención continuada integrado en un dispositivo sociosanitario que incluya los cuidados paliativos respiratorios, cuando estos sean necesarios como una alternativa para el manejo de estos pacientes (AU)

Currently there are no valid and objective criteria to predict mortality and to directly include patients with advanced chronic respiratory disease(ACRD) in a palliative care programme. The particular aspects of ACRD make respiratory palliative care different from conventional palliative care. This review shows that patients with ACRD fail to receive the level of palliative care given to those affected by terminal cancer in spite of mortality rates in ACRD comparable to those of most common cancers. The main difference between the care given in the final stages of ACRD when compared with the equivalent one received by patients with terminal cancer is the different level of accessibility to a socio-sanitary network within the health system. This review proposes an on-going care programme integrated in the socio-sanitary network that includes respiratory palliative care whenever that option is deemed necessary as an alternative for these patients (AU)

Differences in microtubule binding and self-association abilities of bovine brain tau isoforms.

We have fractionated tau isoforms by elution at increasing pH values using iron-chelated affinity chromatography, which discriminates between isoforms phosphorylated to different extents. Microtubule-associated tau elutes from the column at a pH gradient narrower than that of total brain tau. Neither under-phosphorylated nor highly phosphorylated isoforms are found in the microtubule-associated tau protein preparation. This indicates that phosphorylation at certain sites is needed for tau binding to microtubules, whereas phosphorylation at some other sites may prevent the association. The self-association ability of the different tau isoforms has also been analyzed. Tau isoforms containing three tubulin binding motifs form covalently bound dimers more efficiently than tau isoforms containing four motifs. This dimer-forming ability is notably diminished in the presence of a reducing agent, as determined by SDS-polyacrylamide gel electrophoresis, thus suggesting the involvement of cysteine residues. Additionally, tau forms larger aggregates, as detected by gel permeation chromatography, which are solubilized by SDS and cannot, therefore, be observed by SDS-polyacrylamide gel electrophoresis. These tau aggregates are observed even in the presence of reducing agents. These results support the idea that other regions in the tau molecule, besides the Cys-containing tubulin binding region, also contribute to tau self-association. Tau dimerization and aggregation may be prior steps to the formation of paired helical filaments.

Low resolution structure of microtubules in solution. Synchrotron X-ray scattering and electron microscopy of taxol-induced microtubules assembled from purified tubulin in comparison with glycerol and MAP-induced microtubules.

The structure of microtubules has been characterized to 3 nm resolution employing time-resolved X-ray scattering. This has revealed detailed structural features of microtubules not observed before in solution. The polymerization of highly purified tubulin, induced by the antitumour drug taxol, has been employed as a microtubule model system. This assembly reaction requires Mg2+, is optimal at a 1:1 taxol to tubulin heterodimer molar ratio, proceeds with GTP or GDP and is intrinsically reversible. The X-ray scattering profiles are consistent with identical non-globular alpha and beta-tubulin monomers ordered within the known helical surface lattice of microtubules. Purified tubulin-taxol microtubules have a smaller mean diameter (approx. 22 nm) than those induced by microtubule associated proteins or glycerol (approx. 24 nm), but nearly identical wall substructure to the resolution of the measurements. This is because the majority of the former consist of only 12 protofilaments instead of the typical 13 protofilaments, as confirmed by electron microscopy of thin-sectioned, negatively stained and ice-embedded taxol microtubules. It may be concluded that taxol induces a slight reduction of the lateral contact curvature between tubulin monomers. The main fringe pattern observed in cryo-electron micrographs is consistent with a simple 12 protofilament 3-start skewed lattice model. Cylindrical closure of this lattice can be achieved by tilting the lattice 0.8 degrees with respect to the microtubule axis. The closure implies a discontinuity in the type of lateral contacts between the tubulin monomers (regardless of whether these are of the -alpha-beta- or the -alpha-alpha-/-beta-beta- type), which indicates that lateral contacts and the subunit specificity of taxol binding are, to a large degree, equivalent.

An economic evaluation of the costs of alpha-interferon treatment of chronic active hepatitis due to hepatitis B or C virus.

An economic evaluation to compare the costs of care and likely outcome for patients treated with alpha-interferon for chronic active hepatitis B and C was performed. As complete prospective data are not available, we have made comparisons between two cohorts of 100 hypothetical patients. Treatment of chronic hepatitis B would be with alpha-interferon at an average dose of 9 million units three times per week for 16 weeks. Chronic active hepatitis C treatment is based on a dose of 3 million units three times weekly for a total of 6 months. In untreated patients with chronic active hepatitis B or C, the risk of developing cirrhosis is considered to be 10-20% in a 10-year period. Patterns of good practice are costed using typical costs of patients in our institution. These costs are aggregated using the probabilities of morbidity and mortality, from therapeutic and epidemiological studies, for patients developing cirrhosis. A sensitivity analysis has been applied to the results. If we assume a latency period of 10 years, the costs of a successfully treated patient with both hepatitis B and C will be recouped. For hepatitis C, benefits are apparent when social costs are added, the price of alpha-interferon is reduced by 10% and the response rate raised by 20%. Nevertheless, if morbidity effects and costs to patients are included, the advantages of treatment are more apparent, with potential savings in both chronic hepatitis B and C. The model we have developed can be adapted as firmer evidence becomes available.

A synchrotron X-ray scattering characterization of purified tubulin and of its expansion induced by mild detergent binding.

This report presents a synchrotron radiation X-ray scattering characterization of calf brain tubulin purified by the modified Weisenberg procedure. The results show that under nonassembly conditions (i.e., in 10 mM sodium phosphate and 0.1 mM GTP, pH 7, buffer) these preparations consist of a uniform population of molecules with a radius of gyration of 3.1 +/- 0.1 nm, which can be interpreted as arising from the native alpha-beta heterodimer. The uniformity in the population persists even at unusually high concentrations of protein. Binding of colchicine or substitution of GTP by GDP does not induce, within the statistical accuracy and resolution range of our measurements, any significant structural modification in soluble tubulin. In assembly buffer [i.e., 10 mM sodium phosphate, 6 mM magnesium chloride, 1 mM [ethylenebis(oxyethylenenitrilo)]tetraacetic acid, 1 mM GTP, and 3.4 M glycerol, pH 6.5], these preparations readily assemble into microtubules upon increasing the temperature from 4 to 37 degrees C. Binding of nondenaturing amphiphiles to soluble tubulin provides a simplified model for tubulin-membrane interactions. The X-ray scattering data show that the radius of gyration of tubulin progressively increases upon binding of the mild detergent sodium deoxycholate, reaching a maximum value of 4.3 +/- 0.1 nm at detergent saturation. The relative increase in the radius of gyration coincides within experimental error with the previously determined relative increase in the frictional coefficient [Andreu, J.M., & Muñoz, J.A. (1986) Biochemistry 25, 5220-5230]. Analysis of these observations suggests that the effect of detergent binding is to induce an isotropic swelling of the protein structure.

Localization of site-specific probes on the Ca-ATPase of sarcoplasmic reticulum using fluorescence energy transfer.

Highly reactive sulfhydryls, previously labeled with an iodoacetamide spin label on the Ca-ATPase of sarcoplasmic reticulum, were labeled with the fluorescent probe, 5-(2-[iodoacetyl)amino)ethyl)aminonaphthalene-1-sulfonic acid (IAEDANS), without loss of enzymatic activity. We have selectively measured the apparent distance of the more reactive site, relative to other site-specific probes at both the nucleotide and the high affinity calcium binding sites. Fluorescence energy transfer efficiencies from the donor IAEDANS to two acceptors: fluorescein 5'-isothiocyanate or 2',3'-O-(2,4,3-trinitrophenyl)adenosine monophosphate, situated at or near the nucleotide site, were measured using fluorescence lifetimes and yields. Fluorescence on polyacrylamide gels shows that the IAEDANS and fluorescein 5'-isothiocyanate labels are both associated with the B tryptic fragment. The energy transfer measurements are consistent with distances of 56 and 68 A between IAEDANS and these respective binding sites. On the other hand, energy transfer measurements using the lanthanide, praseodymium (Pr3+), as an acceptor indicate that IAEDANS is located 16-18 A from the binding site(s) of this calcium analog. Pr3+ is shown to be a good analog for calcium binding to the high affinity sites on the enzyme since it competitively displaces calcium, as evidenced by the reversal of the specific calcium-dependent intrinsic fluorescent signal and inactivation of ATPase activity, over the same narrow range in Pr3+ concentration where energy transfer is observed. Our observations suggest that the portion of the B fragment spanning the cytoplasmic portion of the ATPase is folded onto the A fragment, bringing the IAEDANS label in close proximity to the high affinity calcium binding domain.

Fluorometric titration of the sarcoplasmic reticulum adenosinetriphosphatase calcium sites in the presence of vanadate.

Titration of the specific calcium binding sites of sarcoplasmic reticulum ATPase was carried out by measurements of intrinsic fluorescence in the absence and in the presence of vanadate. The previous finding that vanadate binding to the enzyme inhibits high-affinity calcium binding was confirmed. In addition, taking advantage of the slow kinetics of vanadate association and dissociation from the enzyme, we were able to titrate the fraction of sites remaining in the high affinity state in the presence of non-saturating vanadate. These sites were demonstrated to retain the characteristics displayed by the high-affinity sites in the absence of vanadate, and yielded information consistent with a competitive inhibition between vanadate and calcium. Reversal of the vanadate effect and reconversion of the binding sites to the high-affinity state was demonstrated by adding appropriate calcium concentrations to the enzyme-vanadate complex, and showing the appearance of the intrinsic fluorescence signal which is indicative of calcium occupancy of the sites in the high-affinity state. Partial or total reversal of the vanadate effect was obtained with very slow kinetics following addition of micromolar calcium or, at a somewhat faster rate, following addition of millimolar calcium. The latter experiments yielded titration of the binding sites in the low-affinity state, with a dissociation constant of approx. 2 mM at neutral pH and 10 mM Mg2+. The time course of the fluorescence rise following addition of calcium in the presence of vanadate was more rapid in 'leaky' than in native sarcoplasmic reticulum vesicles, suggesting an intravesicular orientation of the low-affinity calcium sites involved in the reversal of the vanadate effect. Our observations provide experimental support for the postulated mechanism of high- and low-affinity interconversion of the ATPase calcium binding sites, and its dependence on the occupancy of the phosphorylation site by vanadate.