Partial characterization of the epitope on excretory-secretory products of Fasciola hepatica recognized by monoclonal antibody ES78

This report contains a partial characterization of the epitope recognized by monoclonal antibody (MAb) ES78 produced against excretory-secretory (ES) antigens of Fasciola hepatica. ES78 is currently used for the detection of ES antigens in serum and stool samples of cattle and humans with fasciolosis, using a highly sensitive and specific sandwich enzyme-linked immunosorbent assay (ELISA). The epitope was characterized by periodate oxidation, alkaline borohydride reduction, trichloroacetic acid precipitation, beta-mercaptoethanol treatment, and enzymatic proteolysis. These results, together with those of the 2-site ELISA, lectin immunoassays, and beta-galactosidase digestion, showed that MAb ES78 reacts with a partly protein/partly carbohydrate antigenic determinant that is found on several ES molecules of adult specimens of F. hepatica and contains at least 1 disulfide bond and beta-galactose probably as galactose-beta(1-3)-N-acetylgalactosamine disaccharide.

Reverse-phase high pressure liquid chromatographic analysis of harpagoside, scorodioside and verbascoside from Scrophularia scorodonia: quantitative determination of harpagoside

A reversed-phase high performance liquid chromatographic method has been developed for the determination of the main compounds (harpagoside, scorodioside, and verbascoside) from different samples of Scrophularia scorodonia. The chromatographic method has been validated and applied for quantitative determination of harpagoside. The results show the highest levels of harpagoside in the leaf extract. The purity and identity of peaks were controlled by diode-array detection and comparison with standards.

[Prevention of infections in patients with lymphoproliferative syndromes and myeloma by nebulization of an IgA concentrate]

Infection of the upper respiratory tract is a major cause of morbidity and mortality in patients with lymphoproliferative syndromes and multiple myeloma. Nebulizations with IgA tested in a randomized double blind trial to evaluate its efficacy to prevent respiratory infections in patients with lymphoproliferative syndromes and multiple myeloma. Forty nine patients were evaluated (chronic lymphocytic leukaemia, 22; multiple myeloma, 11; lymphoma, 8; HCL, 6; Waldenström and lymphoepiteliod tymoma, 1 patient each) were randomized to receive nebulizations every 12 hours during 3 months of IgA or placebo. Seven infectious episodes (4 respiratory tract infections) in 25 IgA treated patients and 25 episodes (16 respiratory tract infections) in 24 control patients were recorded (p <0.0002). Eighteen patients belonging to the treated group remained free of infections against only 5 from the control group (p < 0.001). No difference related to the grade of infections was observed between groups. The arithmetic media for the first infection observed in each group was 45.6 +/- 22.0 days for the IgA treated and 28.6 +/- 17.5 days for the placebo (p < 0.025). According to this study, IgA nebulization therapy was useful to prevent respiratory tract infections and also delay the onset of infection in patients with lymphoproliferative syndromes and myeloma.

A comparative study of alpha2- and beta-adrenoceptor distribution in pigeon and chick brain

The pharmacological properties and anatomical distribution of alpha2-, beta1- and beta2-adrenoceptors in pigeon and chick brains were studied by both homogenate binding and tissue section autoradiography. [3H]Bromoxidine (alpha2-adrenoceptor-), [3H]CGP 12177 (beta-adrenoceptor) and [125I]cyanopindolol (beta-adrenoceptor) were used as radioligands. In both species, [3H]bromoxidine binding to avian brain tissue showed a pharmacological profile similar to that previously reported for alpha2-adrenoceptors in mammals. Regarding the anatomical distribution, the areas with the highest densities of alpha2-adrenoceptors in the pigeon brain included the hyperstriatum, nuclei septalis, tectum opticum and some brainstem nuclei. Most beta-adrenoceptors found in tissue membranes and sections from chick and pigeon brain were of the beta2 subtype, in contrast to what has been reported in the mammalian brain, where the beta1 subtype is predominant. A striking difference was found between the two species regarding the densities of these receptors: while pigeon brain was extremely rich in [125I]cyanopindolol binding throughout the brain (mainly cerebellum) in the pigeon, the levels of labelling in the chick brain were much lower; the exception was the cerebellum, which displayed a higher density than other parts of the brain in both species. Overall, our results support the proposed anatomical equivalences between a number of structures in the avian and mammalian encephalon.

[Severe-grade tetanus in a multipurpose ICU: review of 13 cases]

BACKGROUND

The mortality of severe tetanus (grades II-III) remains high today, being greater than 20% with a large number of complications, due to the lengthy stay of these patients in the ICU.

METHODS

A review of 13 cases of severe tetanus over the last 5 years was performed analyzing age, entrance, previous immunization, ICU stay, grade of severity, complications and mortality.

RESULTS

The ages ranged between 35 to 79 years (mean 54 years). No patient had been previously immunized. Entrance was determined in 11 patients (84.6%). The mean ICU stay was 27.3 days. Complications were presented in 76.8% of the patients, with the most frequent being vegetative alterations (38%). The global mortality was 30.7% (4 patient), 3 secondary to sepsis of pulmonary origin and one from a cardiac arrest of vegetative etiology.

CONCLUSIONS

The authors believe that prophylaxis is fundamental in prevention of the disease but an important sector of the population remains unvaccinated. On appearance of severe tetanus, admission to the ICU is essential since many complications may appear requiring specialized techniques and personnel.

Complement evasion by Echinococcus granulosus: sequestration of host factor H in the hydatid cyst wall

Hydatid disease, which affects humans and various livestock species, is caused by the larval stages of the cestode parasite Echinococcus granulosus. The disease involves the growth of a fluid-filled cyst in the host's internal organs. The hydatid cyst wall is generally thought to preclude the access of host immune cells to the cyst, while allowing passage of macromolecules. Thus, evasion of humoral effector mechanisms, in particular the complement system, may be crucial to parasite survival. Evasion of complement might involve inhibition of the C3b deposition step, which can in principle be achieved through parasite-derived or host-derived and parasite-bound regulatory molecules. In this work, extracts from bovine hydatid cysts were analyzed for the presence of factor H-like function, namely the cofactor activity for the breakdown of amidated bovine C3 by bovine factor I. Both this activity and antigenically detectable bovine factor H were found in most extracts. The cofactor activity was retained by an anti-bovine factor H Ab column; as no factor H-cross-reactive parasite molecules were detected in the active extracts, the activity was indeed due to host factor H. The pattern of extraction of host factor H from the parasite tissue indicated that at least part of it was selectively bound to the cyst wall, and that a strong charge component was involved in the binding. Our results indicate that the selective concentration of host factor H from plasma/interstitial fluid may contribute to complement evasion by E. granulosus.

Complement evasion by Echinococcus granulosus: sequestration of host factor H in the hydatid cyst wall

Hydatid disease, which affects humans and various livestock species, is caused by the larval stages of the cestode parasite Echinococcus granulosus. The disease involves the growth of a fluid-filled cyst in the host's internal organs. The hydatid cyst wall is generally thought to preclude the access of host immune cells to the cyst, while allowing passage of macromolecules. Thus, evasion of humoral effector mechanisms, in particular the complement system, may be crucial to parasite survival. Evasion of complement might involve inhibition of the C3b deposition step, which can in principle be achieved through parasite-derived or host-derived and parasite-bound regulatory molecules. In this work, extracts from bovine hydatid cysts were analyzed for the presence of factor H-like function, namely the cofactor activity for the breakdown of amidated bovine C3 by bovine factor I. Both this activity and antigenically detectable bovine factor H were found in most extracts. The cofactor activity was retained by an anti-bovine factor H Ab column; as no factor H-cross-reactive parasite molecules were detected in the active extracts, the activity was indeed due to host factor H. The pattern of extraction of host factor H from the parasite tissue indicated that at least part of it was selectively bound to the cyst wall, and that a strong charge component was involved in the binding. Our results indicate that the selective concentration of host factor H from plasma/interstitial fluid may contribute to complement evasion by E. granulosus.

Reduction of bone mass in women after bone marrow transplantation

Osteoporosis is a common disease among patients undergoing transplantation. Its prevalence and complications have been well described in solid organ recipients, especially kidney, liver, and heart. However, studies in bone marrow transplantation (BMT) are scarce. Among the mechanisms invoked in the pathogenesis of BMT osteoporosis are the baseline disease, the use of immunosuppressive drugs and, more remarkably, secondary hypogonadism. We present a study of 27 women who underwent BMT, all of them suffering ovarian failure. We studied different biochemical markers of bone formation/resorption and also evaluated the presence of osteopenia/osteoporosis by dual energy X-ray absorptiometry (DXA) of the lumbar spine. Osteopenia was observed in nine patients (33%) and osteoporosis in another five (18%), according to the World Health Organization criteria. We also detected a subgroup showing elevation of several bone turnover biochemical markers, indicating high osseous remodeling. A remarkable increase in urine hydroxyproline/creatinine was detected in 95% of cases, although an explanation is lacking. We outline a reasonable therapeutic approach for osteoporosis in BMT emphasizing the need to monitor these patients after transplantation.

The genus Rhodosporidium: a potential source of beta-carotene

Four wild-type species of the genus Rhodosporidium have been studied as as possible sources for the industrial production of beta-carotene. HPLC-based studies showed that their carotenoid composition consisted of almost pure beta-carotene at concentrations ranging from 226 to 685 micrograms/g of dried yeast biomass. These results are consistent with those obtained by spectrophotometry at 480 nm.

A randomized double-blind clinical trial of two antivenoms in patients bitten by Bothrops atrox in Colombia. The Regional Group on Antivenom Therapy Research (REGATHER)

A randomized double-blind clinical trial in 39 patients envenomed by Bothrops atrox in Antioquia and Chocó, Colombia, was performed to compare the efficacy and safety of 2 equine-derived antivenoms prepared at Instituto Clodomiro Picado, University of Costa Rica. Twenty patients received a monovalent anti-B. atrox antivenom (group A) and 19 patients were treated with a polyvalent (Crotalinae) antivenom (group B). Both antivenoms were equally efficient in the neutralization of the most relevant signs of envenoming (haemorrhage and blood clotting time alteration). Fourteen patients (36%) presented early adverse reactions to antivenoms and no significant difference between the 2 groups was observed. Urticaria (18%) was the most frequent early adverse reaction and there was no life-threatening anaphylactic reaction. Based on clinical criteria and serum venom levels, estimated by an enzyme immunoassay, 15 patients were classified into 2 groups: mild and moderate/severe envenoming. With the antivenom doses used in this study (3, 6 and 9 vials for mild, moderate and severe envenoming, respectively), both antivenoms were equally efficient in clearing serum venom levels within the first hour of treatment, and the levels remained below the lower limit of venom detection for 24 h. Antivenom concentration in serum remained high for up to 24 h after antivenom infusion, suggesting that an excess of antibody in relation to circulating antigen had been administered.

[Effect of adenosine on glycolysis of cultured cardiac myocytes of newborn rats]

Adenosine is a hormonal modulator of metabolic processes. In some tissues the effect of adenosine on glycolysis is well established. Nevertheless, there are controversial data in heart. We believe that these discrepancies in the literature are due to haemodynamic factors which are not unified in those reports. We studied the direct effect of adenosine in cardiac myocytes in culture, isolated from neonatal rat heart, which are not influenced by haemodynamics forces as whole heart. Myocytes were isolated using conventional methods. Glycolysis was measured following the formation of tritium water from D-[3-3H]glucose. The results obtained showed that the nonmetabolizable adenosine analogue, N6-(L-2-phenylisopropyl)adenosine, (10 microM) stimulates basal glycolysis (49.86%). This effect was observed in the absence or presence of (5 mM) glucose. In separated group of experiments we examined different concentrations of N6-(L-2-phenylisopropyl)adenosine, (1, 10 and 100 microM, glucose 5 mM). Concentrations of 1 y 10 microM of the adenosine analogue stimulated glycolysis in a concentration-dependent fashion, however 100 microM of N6-(L-2-phenylisopropyl)adenosine inhibited glycolysis by 83% possibly through a toxic effect on the myocardial cells. The natural agonist adenosine, (100 microM) also stimulated glycolysis but with less potency. Stimulation of glycolysis by insulin (1 microM) or isoproterenol (1 microM) was potentiated by N6-(L-2-phenylisopropyl)adenosine. We concluded that adenosine stimulates basal or stimulated glycolysis in the myocardial isolated cells. It could be of benefit for the energetic economy in situations were the nucleoside is released.

[Outbreak of Shigella boydii dysentery in the county of El Bierzo]

BACKGROUND

Investigation of an outbreak of bacillar dysentery of possible transmission by water produced by Shigella boydii.

METHODS

The strains were isolated in the stools and studies of identification, serotyping, susceptibility to antibiotics and plasmid profile were carried out according to standard methods. The epidemiological investigation was carried out retrospectively.

RESULTS

51 strains were isolated from 48 patients. All were identified as S. boydii serotype 4. The pattern of susceptibility was variable, all of them showed resistance to ampicillin, tetracycline and chloramphenicol. The plasmid profile was homogeneous. Of the 41 patients who completed the questionnaire all were living in the same town or nearby localities.

CONCLUSIONS

The serotype 4 of S. boydii, infrequent in Spain, the homogeneous plasmid profile and the relationship between time and place of the cases, suggest that we find ourselves faced with an outbreak epidemiologically relationed. The localisation of the cases and the network of the drinking water supply represented on the plan of the town, support the hypothesis of the origin of hte outbreak as being in the lack of chlorination of one of the tanks of the network of supply.

A comparative thermodynamic analysis by laser-flash absorption spectroscopy of photosystem I reduction by plastocyanin and cytochrome c6 in Anabaena PCC 7119, Synechocystis PCC 6803 and Spinach

A comparative thermodynamic analysis of photosystem I (PSI) reduction by plastocyanin (Pc) and cytochrome c6 (Cyt) has been carried out by laser-flash absorption spectroscopy in the cyanobacteria Anabaena PCC 7119 and Synechocystis PCC 6803 as well as in spinach. These three organisms have been reported to exhibit different reaction mechanisms [Hervas, M., Navarro, J. A.. Díaz, A., Bottin, H., & De la Rosa, M. A. (1995) Biochemistry, 34, 11321-11326]. Whereas the activation free energy for the overall reaction is mainly enthalpic in nature, long-range electrostatic interactions appear to be attractive in Anabaena, but repulsive in Synechocystis and spinach. The net interaction between PSI and its two donor proteins in Anabaena is similarly affected by ionic strength (the rate constant decreases with increasing salt concentration), but the activation parameters delta H+/+ delta S+/+ show different dependencies on ionic strength. A compensation effect between entropy and enthalpy at varying ionic strength is found in all these Pc/PSI and Cyt/PSI systems, except with Cyt and PSI from Anabaena. Such a compensation effect is proposed to be mainly due to stabilization of the intermediate electrostatic complex by hydrophobic forces. The electron transfer step seems to be well optimized in the Anabaena Cyt/PSI couple, which exhibits a temperature-independent fast kinetic phase and, therefore, a low activation energy barrier. Short-distance forces appear to have gained relevancy in the reaction mechanism of PSI reduction by Cyt and Pc throughout evolution, whereas long-range interactions are prevalent in less evolved organisms.

Acrosome content release in streptolysin O permeabilized mouse spermatozoa

Sperm cell plasma membrane and the outer acrosomal membrane fuse profusely during the acrosome reaction. The process is triggered by extracellular signals that elicit several intracellular events leading ultimately to membrane fusion. We have developed a streptolysin O permeabilizing protocol that selectively affects the spermatozoon plasma membrane without causing a significant loss of the acrosomal content. Most of the acrosomal acid phosphatase remained sperm-associated even after a 20 min incubation at 37 degrees C. However, the presence of 100 microM Ca2+ in the incubation buffer stimulates the release of the enzyme. The reaction was followed biochemically, measuring the acid phosphatase activity released to the medium and morphologically by the binding of fluorescein isothiocynate-conjugated peanut agglutinin and by electron microscopy. The results show that the streptolysin O permeabilized spermatozoon is a promising model for studying the complex set of events mediating and regulating the acrosome reaction.

Ontogenetic development of 5-HT1D receptors in human brain: an autoradiographic study

The pattern of pre- and postnatal appearance of 5-HT1D receptors throughout the different areas of the human brain was studied by quantitative in vitro autoradiography, using [125I]GTI (serotonin O-carboxymethyl-glycyl-[125I]tyrosinamide) as a ligand. The anatomical distribution of 5-HT1D receptors in neonatal, infant and children's brain was in good agreement with that observed in the adult, the basal ganglia and substantia nigra being the most intensely labelled areas. The development of these receptors throughout the human brain was mainly postnatal: low densities of [125I]GTI binding sites were observed at the fetal/neonatal stage in most regions analyzed, in contrast with the high levels of labelling found in infant and children's brains. Indeed, in a number of regions, including the globus pallidus, substantia nigra and visual cortex, a peak of overexpression of 5-HT1D receptors was observed in the first decade of life. Such overexpression could support a regulatory role for 5-HT1D receptors in advanced periods of the CNS developmental process. Our results also indicate that the administration of drugs acting on 5-HT1D receptors during the early postnatal period of life could result in modifications of their properties, as these receptors are already functional in this period.

Laser-flash kinetic analysis of the fast electron transfer from plastocyanin and cytochrome c6 to photosystem I. Experimental evidence on the evolution of the reaction mechanism

The reaction mechanism of electron transfer from the interchangeable metalloproteins plastocyanin (Pc) and cytochrome c6 (Cyt) to photooxidized P700 in photosystem I (PSI) has been studied by laser-flash absorption spectroscopy using a number of evolutionarily differentiated organisms such as cyanobacteria (Anabaena sp. PCC 7119 and Synechocystis sp. PCC 6803), green algae (Monoraphidium braunii), and higher plants (spinach). PSI reduction by Pc or Cyt shows different kinetics depending on the organism from which the photosystem and metalloproteins are isolated. According to the experimental data herein reported, three different kinetic models are proposed by assuming either an oriented collisional reaction mechanism (type I), a minimal two-step mechanism involving complex formation followed by intracomplex electron transfer (type II), or rearrangement of the reaction partners within the complex before electron transfer takes place (type III). Our findings suggest that PSI was able to first optimize its interaction with positively charged Cyt and that the evolutionary replacement of the ancestral Cyt by Pc, as well as the appearance of the fast kinetic phase in the Pc/PSI system of higher plants, would involve structural modifications in both the donor protein and PSI.

Regulation of dihydropyridine-sensitive Ca++ channels during opioid tolerance and supersensitivity in rats

The changes in cerebral dihydropyridine (DHP)-sensitive Ca++ channels (L-type) associated with tolerance and supersensitivity to the antinociceptive effect of the mu-opioid receptor agonist sufentanil were analyzed in rats. The tail-flick test was used to assess the nociceptive threshold. DHP binding and autoradiographic assays were performed with [3H]nimodipine and [3H]PN 200-110 [isopropyl 4-(2,1,3-benzoxadizol-4-yl)- 1,4-dihydro-2,6-dimethyl-5-methoxycarbonylpyridine-3-carboxylate], respectively. Chronic s.c. infusion of sufentanil (2 micrograms/hr) for 7 days induced tolerance (tolerance index, 5.6) in association with up-regulation of DHP binding sites in cerebral cortex membranes (+36%), as well as in brain sections. Animals were rendered hypersensitive to the antinociceptive effect of sufentanil by chronic and simultaneous infusion of sufentanil (2 micrograms/hr) and nimodipine (1 microgram/hr) for 7 days (potentiation index, 40 vs. tolerant). Under these conditions, a greater increase in the number of DHP binding sites was observed in cortex membranes (+71%), and more evidently in brain sections. In these animals, withdrawal of nimodipine for 48 hr returned the dose-response curve of sufentanil to the tolerant values, whereas Ca++ channels remained increased. The role of an increased influx through L-type channels in opioid tolerance is reinforced. Our results also suggest that, although changes in neuronal Ca++ fluxes are not the only underlying mechanism, the increase and the sustained blockade of Ca++ channels with nimodipine is essential for the expression of opioid supersensitivity.

Reagents that activate GTP-binding proteins trigger the acrosome reaction in human spermatozoa

The acrosome reaction is a specialized exocytotic process. In the mouse there is compelling evidence that receptor-mediated activation of GTP-binding proteins by factors in the zona pellucida of oocytes is a central event in the acrosome reaction. Several reagents are able to affect GTP-binding proteins directly, bypassing the receptor-ligand step for activation. We have assessed the effect of several of these compounds on human spermatozoa, monitoring cell vitality and the acrosome reaction simultaneously using the triple-stain technique. GTP gamma S and aluminium fluoride complexes promote sperm activation very efficiently; amphiphilic peptides capable of activating G(o) and Gi, also elicit the acrosome reaction. The results indicate that activation of heterotrimeric GTP-binding proteins is sufficient to trigger acrosome exocytosis in human spermatozoa.

Echinococcus granulosus: interactions with host complement in secondary infection in mice

Complement has been shown to lyse protoscoleces of Echinococcus granulosus, but products from this parasite are able to consume complement, and this has been proposed as an evasion mechanism. The murine secondary hydatidosis model, with intraperitoneal inoculation, is used in this work to assess the occurrence in vivo of complement consumption by the parasite as well as the role of complement during the establishment of infection. Although the measurement of systemic levels of C3 activation, total C3, and hemolytic complement in challenged mice yielded no evidence of complement consumption, the relevance of local consumption at the site of infection cannot be ruled out. The role of complement during establishment of infection was assessed by comparing parasite burdens in normal and complement-depleted mice. Complement depletion by treatment with cobra venom factor caused a 79% reduction in cyst numbers (P < 0.05). Possible explanations of this unexpected result are discussed. The results presented suggest that lysis or opsonization by host complement are not effective against the establishing parasite in this model. They also indicate the significance of complement activation by the parasite needs to be studied at a local level.

Multiple roles for DNA polymerase I in establishment and replication of the promiscuous plasmid pLS1

The polymerase activity of DNA polymerase I is important for the establishment of the pLS1 replicon by reconstitutive assembly in Streptococcus pneumoniae after uptake of exogenous pLS1 plasmid DNA. In polA mutants lacking the polymerase domain, such establishment was reduced at least 10-fold in frequency. Chromosomally facilitated establishment of pLS1-based plasmids carrying DNA homologous to the host chromosome was not so affected. However, both types of plasmid transfer gave mostly small colonies on initial selection, which was indicative of a defect in replication and filling of the plasmid pool. Once established, the pLS1-based plasmids replicated in polA mutants, but they showed segregational instability. This defect was not observed in strains with the wild-type enzyme or in an S. pneumoniae strain that encodes the polymerase and exonuclease domains of the enzyme on separate fragments. The role of DNA polymerase I in stably maintaining the plasmids depends on its polymerizing function in three separate steps of rolling-circle replication, as indicated by the accumulation of different replication intermediate forms in polA mutants. Furthermore, examination of the segregational stability of the pLS1 replicon in an Escherichia coli mutant system indicated that both the polymerase and the 5'-to-3' exonuclease activities of DNA polymerase I function in plasmid replication.

Cloning and correct expression in E. coli of the petJ gene encoding cytochrome c6 from Synechocystis 6803

Cytochrome c6 from the cyanobacterium Synechocystis 6803 has been isolated and purified to electrophoretic homogeneity. The gene coding for such a heme protein (petJ) has been cloned and properly expressed in E. coli. This procedure yields a protein preparation completely identical to that obtained from the cyanobacterial cells. The N-terminal amino acid sequences of cytochrome c6 synthesized in both organisms are the same, thus allowing us to conclude that the petJ gene product is correctly processed in E. coli. To the best of our knowledge, this is the first time that any cytochrome c6 is produced in the enterobacterium. The identical physicochemical and kinetic properties of the proteins isolated from both sources confirm that expression of the petJ gene in E. coli is an adequate tool to address the study of Synechocystis cytochrome c6 by site-directed mutagenesis in a parallel way to that carried out with plastocyanin from the same organism.

A thermodynamic study by laser-flash photolysis of plastocyanin and cytochrome c6 oxidation by photosystem I from the green alga Monoraphidium braunii

Plastocyanin and cytochrome c6 from the green alga Monoraphidium braunii reduce the photo-oxidized algal photosystem I (PSI) reaction center chlorophyll (P700) with similar kinetics, as expected from their functional equivalence. The observed P700+ reduction rate constants show a non-linear dependence on metalloprotein concentration, which indicates a (minimal) two-step kinetic mechanism involving complex formation prior to electron transfer. The dependence of the observed rate constants on NaCl concentration suggests that the electrostatic interaction forces between the negatively charged donor proteins and PSI are repulsive at neutral pH and relatively low ionic strength (I), although attractive dipole-dipole interactions may play a role at higher ionic strengths. Activation parameters for P700+ reduction by cytochrome c6 and plastocyanin have been determined by studying the temperature dependence of the respective rate constants at varying ionic strength and pH. Changes in NaCl concentration and pH induce significant changes in the activation free energy of the overall reaction, even though the corresponding values for activation enthalpy and entropy undergo changes in opposite directions. Such a compensation effect between enthalpy and entropy is observed with both cytochrome c6 and plastocyanin. Protein concentration dependencies of the observed rate constants at different temperatures has allowed an estimate of the free energy change during complex association, as well as the activation parameters for electron transfer, according to a two-step kinetic model.

Transient localization of 5-HT1A receptors in human cerebellum during development

The appearance and distribution of 5-HT1A receptors in the human cerebellum during the ontogenetic development was studied in samples from a group of fetal, neonatal and adult cases, by means of quantitative autoradiography and membrane binding. [3H]8-OH-DPAT was used as a ligand. High densities of 5-HT1A receptors were found during the fetal and neonatal stages over the whole cerebellar cortex, with a slight predominance in the external part, in a band which included the molecular layer. In contrast, the adult cerebellum was nearly devoid of such sites. This finding supports a role for 5-HT1A receptors in the regulation of development in the human cerebellum.

Superinduction of mitogen-stimulated interferon-gamma production and other lymphokines by Sendai virus

We observed that Sendai virus preinduction of peripheral blood mononuclear cells and subsequent mitogenic stimulation resulted in: (i) Superproduction of interferon-gamma, (IFN-gamma) (ii) an increase in interleukin-2 (IL-2) synthesis that correlates with DNA synthesis when stimulated with phytohemagglutinin (PHA) or pokeweed mitogen (PWM) after treatment with the Sendai virus, while stimulation with Protein A from Staphylococcus aureus was not affected, and (iii) enhanced tumor necrosis factor-alpha (TNF-alpha) production in response to bacterial lipopolysaccharide (LPS). Treatment of monocyte cultures with LPS and cycloheximide or actinomycin-D inhibited the superinduction phenomenon. When cycloheximide was added at the viral induction time, the inhibition of TNF-alpha superproduction and DNA synthesis was still observed. These results suggest that Sendai virus lymphocyte superinduction is specific for a particular stimulatory pathway, not dependent on mRNA accumulation, and probably mediated by induction of an activating protein.

[The prescription of physical exercise in the individual with aortic prostheses. The role of Doppler exercise study]

BACKGROUND AND OBJECTIVES

Exercise Doppler echocardiography allows measure valvular gradient during exercise, that could be useful in the prescription of physical activity in patients with a prosthetic aortic valve.

METHODS

Exercise Doppler echocardiography was performed in 50 patients (mean age 53 +/- 12 years) with normally-functioning aortic prosthesis. Maximal exercise was performed by supine bicycle ergometry in 35 and modified Bruce protocol in 15. Continuous wave Doppler examinations were obtained at rest, during and at maximal exercise with a nonimaging transducer.

RESULTS

The mean value of workload was 6.9 +/- 2 METS and there were no complications. Gradients at peak exercise were available in 43/50 patients. Exercise induced a statistic significant increase in the heart rate (76 +/- 14 to 136 +/- 26), systolic blood pressure (128 +/- 19 to 182 +/- 19 mmHg), peak gradient (29 +/- 9 to 61 +/- 17 mmHg) and mean gradient (16 +/- 5 to 32 +/- 9 mmHg). The gradient was greater than 59 mmHg in 18/43 patients, greater than 69 mmHg in 12/43 and greater than 79 mmHg in 5/43.

CONCLUSIONS

Prescription of exercise in patients with aortic prosthesis requires perform an exercise Doppler echocardiography to measure the increase of valvular gradient with the exercise in each patient, since the stress testing could be normal, it can advise a rate of physical activity that determine very high prosthetic gradients.

Immunological relationship among rat erythrocyte membrane sialoglycoproteins and with human glycophorins

1. Specific antibodies against a whole preparation of glycophorins from rat erythrocyte membrane and against its most prominent component (32 kDa) were prepared. 2. Both antisera and the respective affinity-purified antibodies recognize the 74, 32 and 25 kDa components of rat glycophorins; therefore, a close antigenic relationship between them can be inferred. 3. On the other hand, a cross-reaction with human glycophorin A (both MM- and NN-type) is observed for both antisera. 4. This suggests the existence of epitopes common to human and rat glycophorins.

A comparative laser-flash absorption spectroscopy study of Anabaena PCC 7119 plastocyanin and cytochrome c6 photooxidation by photosystem I particles

Laser-flash absorption spectroscopy has been used to investigate the kinetics of electron transfer from reduced cytochrome c6 and plastocyanin, isolated from Anabaena PCC 7119, to oxidized P700 in photosystem-I particles isolated from the same cyanobacterium and from spinach. For all metalloproteins and photosystems, the observed rate constant has a non-linear protein-concentration dependence, thus suggesting complex formation preceding electron transfer. Plastocyanin and cytochrome c6 have similar association constants for complex formation with spinach photosystem I, but the copper protein exhibits a higher intracomplex-electron-transfer rate constant (twofold). With Anabaena photosystem I, the two redox proteins are more effective with respect to both complex formation (5-10-fold) and electron transfer (1.5-4-fold) than with the spinach photosystem. In all cases, the observed rate constants for electron-transfer monotonically decrease with increasing NaCl or MgCl2 concentration. This is interpreted in terms of the involvement of attractive electrostatic interactions, which result in the initial collision complex having the most productive orientation for the electron transfer process, without a requirement for further reorientation. The magnitude of the response to MgCl2 suggests the occurrence of specific ion effects as well. In the absence of added salts, the reduction rate of oxidized P700 increases with pH from approximately 6 to 8, but decreases slightly at pH 8.5.

Synechocystis 6803 plastocyanin isolated from both the cyanobacterium and E. coli transformed cells are identical

Native plastocyanin from Synechocystis 6803 has been isolated and purified to electrophoretic homogeneity. The corresponding gene (petE) has been cloned and expressed in E. coli, thus leading to a protein completely identical to plastocyanin purified from the cyanobacterial cells. The petE gene product is correctly processed in E. coli as deduced from the N-terminal amino acid sequences. These results, along with the identical physicochemical and kinetic properties of the two protein preparations, confirm that expression of petE in E. coli is an adequate tool to address the study of Synechocystis plastocyanin by site-directed mutagenesis.

In vitro progesterone effects on 3H-dopamine release from rat corpus striatum slices obtained under different endocrine conditions

The release of dopamine (DA) from corpus striatum is affected by the endocrine state of the animal being progesterone suggested as a potential hormonal modulatory signal. Most of its actions have been described on endogenous DA release induced by amphetamine. However, the release of DA and the mechanism of the drug effect have been shown to be highly complexes. Considering that DA recently incorporated and/or synthetized is preferentially used we have characterized the effect of progesterone in vitro on the K(+)-induced release of 3H-dopamine (3H-DA) from rat corpus striatum slices. These were obtained during the estrous cycle or under conditions of high or low levels of endogenous progesterone (pregnant and ovariectomized rats). The release of 3H-DA was independent of the cycle. However, progesterone in vitro modified the induced release in a cycle-dependent way. Low concentrations of the hormone (100-200 mM) reduced the K+ (30 mM) effect while higher doses (300-500 mM) were facilitatories. After 7 days of ovariectomy, the induced release of 3H-DA was unchanged while in pregnant rats it was found decreased. In both cases the inhibitory effect of the hormone disappeared. Both progesterone (200 nM) and omission of Ca++ from the superfusion medium did not modified tyramine (20 microM) or K+ induced release, respectively. Data suggest that the pool of DA, related to exocytotic mechanism of release, could be specifically affected by progesterone, in a bimodal way, probably through independent genomic and non-genomic influences.

Erythropoietin treatment in allogeneic BMT accelerates erythroid reconstitution: results of a prospective controlled randomized trial

Twenty-eight allogeneic BMT patients (16 with acute leukemia, 12 with chronic myeloid leukemia) were included in a single center, prospective, randomized, controlled trial to assess the value of recombinant human erythropoietin (rh-Epo) in this setting. rh-Epo was administered through a central venous catheter as a single bolus injection (days 0-7: 100 U/kg/d; days 7-30: 150 U/kg/d). No secondary effects to rh-Epo treatment were detected. An earlier appearance of reticulocytes and a diminished need of red blood cells (RBCs) transfusions were observed in patients who were treated with rh-Epo (4 units vs 12 units; p < 0.05). The time to unsupported platelets above 25 x 10(9)/l was less in patients treated with rh-Epo than in control patients (19 days vs 31; p < 0.05), and they received significantly fewer platelet transfusions (36 units vs 138.5; p < 0.05). Our results show that rh-Epo treatment is capable of accelerating the erythroid reconstitution and decreasing the need for RBC transfusions. A beneficial effect on platelet reconstitution is also suggested, but further studies are necessary to confirm this point.

[Primary adenocarcinoma of the duodenum: a report of 2 cases and a review of the world literature]

We presented two cases of adenocarcinoma of the duodenum diagnosed at the Gastroenterology Unit of the General Hospital of Lidice Dr. Jesús Yerena and reviewed retrospectively the pathology cases from 1980-1990. We review the world literature and found that the most common clinical presentation was as obstructive type. In our cases perforation and jaundice were the presentation.

The 5' to 3' exonuclease activity of DNA polymerase I is essential for Streptococcus pneumoniae

Three different mutations were introduced in the polA gene of Streptococcus pneumoniae by chromosomal transformation. One mutant gene encodes a truncated protein that possesses 5' to 3' exonuclease but has lost polymerase activity. This mutation does not affect cell viability. Other mutated forms of polA that encode proteins with only polymerase activity or with no enzymatic activity could not substitute for the wild-type polA gene in the chromosome unless the 5' to 3' exonuclease domain was encoded elsewhere in the chromosome. Thus, it appears that the 5' to 3' exonuclease activity of the DNA polymerase I is essential for cell viability in S. pneumoniae. Absence of the polymerase domain of DNA polymerase I slightly diminished the ability of S. pneumoniae to repair DNA lesions after ultraviolet irradiation. However, the polymerase domain of the pneumococcal DNA polymerase I gave almost complete complementation of the polA5 mutation in Escherichia coli with respect to resistance to ultraviolet irradiation.

[The cardiology consultation in a health-service area hospital. The clinical aspects and the demand for diagnostic procedures]

Four consecutive years (1987-1990) outpatients attendance at a cardiology clinic was recorded in a district hospital with a catchment area of 200,000 inhabitants. The aim being to identify and evaluate the demand for cardiology consultations. A system for recording diagnoses was developed, based on the WONCA. The total number of consultations was 26,273, 27% being new patients, 78% of whom were referred by family doctors and health centers. Of the total, 57% were male. The most common age groups being from 60 to 69 (25%) and from 50 to 59 (23%); 22% were over 69. In 13.7% of the consultations, the find diagnosis was of "healthy hearts", in 16.7% valvular heart disease, in 31.5% ischaemic heart disease, in 15.1% arrhythmias, in 8.4% hypertension, and the remainder were other diseases. We carried out 4,406 echocardiograms, 1,408 exercise tests and 511 Holter monitoring traces. There were 322 direct hospital admissions, and 6,094 discharges in the four years period. We consider this type of records to be useful organizing cardiology outpatients clinics, analyzing the demand, and planning the use of health care resources, as well as estimating future needs and assessing quality of care.