Last twenty-years activity of cardiovascular tissue banking in Barcelona

The Barcelona Tissue Bank was established from the merge of two previous multi-tissue banks. Potential donors are screened by Donor Center staff and multi-tissue retrieval is performed by specialized own teams. Tissue processing and preservation is performed in clean room facilities by specialised personnel. After quality control of both donor and all tissues results, the heart valves and vascular segments are stored until medical request. The aim of this report is to present the cardiovascular tissue activity and retrospectively evaluate the outcomes of the changes performed in last 20 years. Cardiovascular tissue from 4088 donors was received, specifically 3115 hearts and 2095 vascular segments were processed and evaluated. A total of 48% of the aortic valves, 68% of the pulmonary valves and 75% of the vascular segments were suitable for transplant. The main reason for discarding tissue was macroscopic morphology followed by microbiological results, for both valves and arteries. Altogether, 4360 tissues were distributed for transplantation: 2032 (47%) vascular segments, 1545 (35%) pulmonary valves and 781 (18%) aortic valves. The most common indication for aortic valve surgery was the treatment of endocarditis, while for pulmonary valves, it was congenital malformation reconstruction. Vascular segments were mainly used for reconstruction after ischemia. During this period, a number of changes were made with the goal of enhancing tissue quality, safety and efficacy. These improvements were achieved through the use of a new antibiotic cocktail, increasing of donor age criteria and changing the microbiological control strategy.

Development of a full-thickness acellular dermal graft from human skin: Case report of first patient rotator cuff patch augmentation repair

The processing and initial testing of a new human tissue preparation is described. Full-thickness Acellular Dermal Matrix (ftADM) is the extracellular matrix (ECM) obtained by decellularization of full-thickness human skin from cadaveric donors. The safety, stability and usability of the graft are discussed with respect to the results of the residual cellular content, maintenance of ECM components, and biomechanical properties. Quantitative and qualitative analysis of the ECM demonstrated the absence of cell debris, while the native structure of human dermis was maintained. Biomechanical testing showed stiffness values comparable to other commercial products used for tendon reinforcement, suggesting that our ftADM could be successfully used not only in soft tissue regeneration surgeries, but also in tendon reinforcement. First case of ftADM in rotator cuff augmentation is described. Technical management of the patch during surgery and clinical outcomes are discussed.

Fast protocol for the processing of split-thickness skin into decellularized human dermal matrix

BACKGROUND

Dermal scaffolds for tissue regeneration are nowadays an effective alternative in not only wound healing surgeries but also breast reconstruction, abdominal wall reconstruction and tendon reinforcement. The present study describes the development of a decellularization protocol applied to human split-thickness skin from cadaveric donors to obtain dermal matrix using an easy and quick procedure.

METHODS

Complete split-thickness donor was decellularized through the combination of hypertonic and enzymatic methods. To evaluate the absence of epidermis and dermal cells, and ensure the integrity of the extracellular matrix (ECM) structure, histological analysis was performed. Residual genetic content and ECM biomolecules (collagen, elastin, and glycosaminoglycan) were quantified and tensile strength was tested to measure the effect of the decellularization technique on the mechanical properties of the tissue.

RESULTS

Biomolecules quantification, residual genetic content (below 50 ng/mg dry tissue) and histological structure assessment showed the efficacy of the decellularization process and the preservation of the ECM. The biomechanical tests confirmed the preservation of native properties in the acellular tissue.

CONCLUSIONS

The acellular dermal matrix obtained from whole split-thickness skin donor with the newly developed decellualrization protocol, maintains the desired biomechanical and structural properties and represents a viable treatment option for patients.

Histological findings of early graft biopsies in old donor renal transplant patients receiving induction therapy

Since recipients of transplants from elderly donors are exposed to an increased risk of delayed graft function (DGF) and acute rejection episodes, administration of induction treatment represents an alternative to preserve renal mass and improve graft survival. We compared the evolution and histological findings of early graft biopsies among 38 recipients treated with Thymoglobulim (33.6%) versus 75 (66.4%) with basiliximab. No differences were observes in the rate of DGF (P = .39). Forty kidneys were biopsed during the first 2 weeks after transplantation: 9 in the Thymoglobulin group (23.68%) and 31 in the basiliximab group (41.3%). Histological evaluation showed: acute tabular necrosis in 7 (78%) Thymoglobulin patients versus 14 (45%) basiliximab patients, with calcineurin nephrotoxicity in 2 (22%) and 1 (3.2%), respectively. An acute rejection episode was not diagnosed in the Thymoglobulin group, but 13 patients (17.3%) in the basiliximab group experienced this complication (P = .006). Banff classification showed: 6 grade IA (19.4%), 1 grade IB (3.2%), 3 grade IIA (9.7%), 1 grade IIB (3.2%), and 2 grade III (6.5%). Six of these patients required rescue treatment with Thymoglobulin. Serum creatinine and proteinuria levels between the 2 groups were not different (P > .05). There were no differences in cytomegalovirus (CMV) disease (P = .152), admission due to infection (P = .120), or neoplasia (P = .29). Graft and patient survivals at 3 years did not show a difference. The histological findings revealed that low doses of Thymoglobulin were much more effective to prevent renal inflammation and acute rejection episodes than basiliximab among renal transplant recipients, albiet without differences in survival at a mean of 3 years follow-up.

[Communication based on the P300 component of event-related potentials: a proposal for a matrix with images]

INTRODUCTION

For more than two decades, several research groups have tried to build a device called "brain computer interface" (BCI) to make it available for people having several disabilities such as the locked in syndrome through the use of the recording of electroencephalography activity while the patients are being visually stimulated. AIM. To obtain a P300 component elicited by intensifications of images arranged in a matrix in an oddball paradigm in two selection modes: assigned and free.

SUBJECTS AND METHODS

A 5 x 5 matrix for communication purposes was used to visually stimulate 12 volunteers while their event related potentials were recorded in three leads (Fz, Cz and Pz). Off-line analyses were performed to obtain the P300 component which was elicited by targets images intensified randomly by rows or columns.

RESULTS

In both modalities assigned and free, all volunteers generated a reliable P300 component. Confirmation of the selected images was made through a comparison of the P300 when each target, row and column matched. In the free selection mode, higher amplitude and a broader activation including frontal leads was observed. No significant differences in the P300 latency were found.

CONCLUSION

In all volunteers the elicited P300 allows the identification of the selected images in the 5 x 5 matrix. In the present study the use of drawings representing ideas instead of letters might increase the communication rate in a P300-based BCI.

Identification of a proximal promoter region critical for the expression of the β-F1-ATPase gene during Drosophila melanogaster development

We have studied the spatio-temporal pattern of expression of the gene encoding the H(+) adenosine triphosphate (ATP) synthase beta subunit (beta-F1-ATPase) during Drosophila melanogaster development. The beta-F1-ATPase mRNA is stored in the egg; as development proceeds it is distributed in most embryonic cellular territories, including the mesoderm, and in late embryos it is highly abundant in the ventral cord and midgut. Using a combination of transfection assays in Schneider cells and P-element transformation in flies, we have identified a proximal 5' upstream region of 258 bp essential for the transcriptional activity of the gene during D. melanogaster embryogenesis that is virtually inactive in adult tissues. Electrophoretic mobility shift assays using specific DNA fragments from the 258-bp region detect in embryonic nuclear extracts a complex set of DNA binding proteins that are largely absent in adults. The transcription factor CF2-II has been identified as a potential candidate in the regulation of the beta-F1-ATPase gene.

Electrical stimulation of the prelemniscal radiation in the treatment of Parkinson's disease: an old target revised with new techniques

OBJECTIVE

In the treatment of tremor and rigidity in patients with Parkinson's disease (PD), the prelemniscal radiation (RAPRL), a subthalamic bundle of fibers, is an exquisite target that can be visualized easily on ventriculograms. We sought to evaluate the effect of electrical stimulation of the RAPRL on symptoms and signs of PD in a long-term trial and to determine the localization of the stimulated area by means of stereotactic magnetic resonance imaging studies.

METHODS

Ten patients with PD predominantly on one side had tetrapolar electrodes stereotactically oriented through a frontal parasagittal approach to the RAPRL contralateral to the most prominent symptoms. Preoperative and postoperative evaluations at 3, 6, 9, and 12 months after surgery were performed using conventional PD scales and quantitative evaluations of tremor amplitude and reaction time. Stereotactic high-resolution magnetic resonance imaging studies with the electrodes in place were used for anatomic localization.

RESULTS

In all patients, temporary suppression of tremor occurred when the electrodes reached the target. The most effective stimulation was obtained when the pair of contacts was placed in the RAPRL. Long-term stimulation at 130 Hz, 0.09 to 0.450 milliseconds, and 1.5 to 3.0 V produced significant improvement in tremor and rigidity and mild improvement in bradykinesia.

CONCLUSION

The RAPRL is an effective target for the alleviation of tremor and rigidity in patients with PD by either lesioning or neuromodulation; however, neuromodulation has the advantage of not inducing an increase in bradykinesia. The stimulated area seems to be independent of the subthalamic nucleus.

Clinical, epidemiologic, and virologic features of dengue in the 1998 epidemic in Nicaragua

From July to December 1998, a hospital- and health center-based surveillance system for dengue was established at selected sites in Nicaragua to better define the epidemiology of this disease. Demographic and clinical information as well as clinical laboratory results were obtained, and virus isolation, reverse transcriptase-polymerase chain reaction, and serologic assays were performed. World Health Organization criteria were used to classify disease severity; however, a number of patients presented with signs of shock in the absence of thrombocytopenia or hemoconcentration. Therefore, a new category was designated as "dengue with signs associated with shock" (DSAS). Of 1,027 patients enrolled in the study, 614 (60%) were laboratory-confirmed as positive cases; of these, 268 (44%) were classified as dengue fever (DF); 267 (43%) as DF with hemorrhagic manifestations (DFHem); 40 (7%) as dengue hemorrhagic fever (DHF); 20 (3%) as dengue shock syndrome (DSS); and 17 (3%) as DSAS. Interestingly, secondary infection was not significantly correlated with DHF/DSS, in contrast to previous studies in Southeast Asia. DEN-3 was responsible for the majority of cases, with a minority due to DEN-2; both serotypes contributed to severe disease. As evidenced by the analysis of this epidemic, the epidemiology of dengue can differ according to geographic region and viral serotype.

[Confidentiality in medical oaths: (When the white crow becomes gray...)]

Confidentiality, together with the ethical principles of beneficence and non-maleficence, is the most important rule in Medical Oaths at the present time. However, the scientific-technical advances in medicine have made this rule one of the most controversial ones because of its exceptions. In consequence, the aim of the present paper is to comparatively analyze the rule of confidentiality in Medical Oaths of different places, times, origins and in different versions of the Hippocratic Oath in order to determine what should be kept a secret and with what degree of commitment (absolute or "prima facie"). Of the thirty six analyzed Oaths, twenty-seven manifest this rule and nine do not. No relation was found between the manifestation of this rule and the place, time, origin and different versions of the Hippocratic Oath. Most pledges suggest not to reveal what has been seen or heard during the medical act, the same as in the Hippocratic Oath. Seven texts point out that confidentiality should be absolute and four give exceptions in connection with beneficence and justice principles and the moral duty of causing no damage to third parties. Two pledges specify protection of privacy. In conclusion, today confidentiality is considered to be a moral duty for the benefit of the patient and out of consideration for his autonomy; however, at the present time in medicine the duty of keeping absolute secrecy is being reconsidered.

Subthalamic prelemniscal radiation stimulation for the treatment of Parkinson's disease: electrophysiological characterization of the area

Previous reports have provided evidence of a reticulo-thalamic system, extending from the mesencephalic reticular formation (MRF) to the ventrolateral thalamus (VL), involved in the production of tremor. In humans, a funnel of fibers in the posterior subthalamus named the prelemniscal radiations (Raprl) has been described as an exquisite target to treat tremor in cases of Parkinson's disease. In the present study, a group of 14 patients suffering from Parkinson's disease, with prominent unilateral tremor and rigidity, were implanted with tetrapolar depth brain stimulation (DBS) electrodes in Raprl to perform chronic electrical stimulation (ES) for the treatment of patient symptoms. Electrodes were left externalized to corroborate their placement throughout MRI studies and also to perform the following electrophysiological battery: (a) recording of somatosensory-evoked responses (SEP) through different electrode contacts and scalp by means of a paradigm to study the attention process; (b) evoking scalp EEG responses by stimulation with low (3 cps, 6 cps) and high (60-120 cps) frequencies with stimuli delivered through different electrode contacts, and (c) studying recovery cycle (RC) potentials in the Raprl while the upper MRF was being stimulated and, conversely, the RC in MRF while Raprl was being stimulated, before and after subacute Raprl stimulation. Thereafter, the electrodes were internalized and connected to a pulse generator (IPG) to carry on chronic ES, while the effects of stimulation were determined through a quantitative evaluation that measured phasic and tonic muscular activity with EMG recordings during different motor tasks. Results indicate the following: (a) that late, but not early, SEP components were recorded in Raprl and modulated in different attentive conditions; (b) that bilateral recruiting responses and spike and wave complexes were elicited by Raprl through low-frequency stimulation, while bilateral positive DC shifts induced by high-frequency stimulation were recorded, similar to those obtained in animals from MRF, and (c) that Raprl-ES induced RC inhibition at Raprl, but Raprl ES did not change MRF-RC. Long-term Raprl-ES induced a significant decrease in tremor and rigidity. It was concluded that Raprl represents a subthalamic circuit electrophysiologically related to MRF in the genesis of tremor and rigidity and in the process of selective attention. Raprl-ES induced a significant improvement in tremor and rigidity by causing inhibition of the stimulated area.

Optimization of the separation of phenolic compounds by micellar electrokinetic capillary chromatography

A group of phenolic compounds including phenolic aldehydes, acids and flavonoids are separated by micellar electrokinetic chromatography (MECC). The influence of buffer (concentration and pH), concentration of sodium dodecylsulphate (SDS) and applied voltage were studied. To increase the selectivity of the separation and the resolution of the solutes organic solvents are added to the separation buffer, the best results were obtained when methanol was used at lower percentages. An optimized buffer (150 mM boric acid (pH 8.5)-50 mM SDS-5% methanol) provides the optimum separation with regard to resolution and migration time. This method was applied to the determination of these compounds in wine samples with good results.

[Analysis of the ethical principles of beneficence and no harm in medical oaths in relation with the Hippocratic one]

The principles of beneficence and no-maleficence, already set forth in the Hippocratic Oath, have been the foundation of medical ethics for the last twenty-five centuries. The principle of beneficence is currently maintained in most wordings of the pledges of medical schools of the United States, Canada and Argentina; it is not the same with the principle of non-maleficence. The aim of this paper is to determine whether these principles are described in medical oaths at different times. These principles did not remain in an oaths. Of twenty-nine analyzed texts, nine describe both principles simultaneously, eleven only mention beneficence; three only express non-maleficence, and six indicate neither of them. Most wordings that describe these principles are modifications of the Hippocratic Oath. Two contemporary wordings describe the achievement of the greatest benefit with minimum harm. Two current wording also subordinate the principle of beneficence to the principle of respect for the patient's autonomy, and eight wordings indicate not only patients' benefit in particular but that of society in general. It is not possible to ignore that it is no enough to fulfill only these two principles. Physicians should encourage the development of patients' responsibility in managing their own health and respect their autonomy.

Use of different dietary protein sources for lactating goats: milk production and composition as functions of protein degradability and amino acid composition

To establish the effect of the nature of four different protein sources [fababeans, 27.8% crude protein (CP); sunflower meal, 41.7% CP; corn gluten feed, 18.8% CP; and cottonseed, 18.3% CP] on milk protein production by goats, the ruminal degradation of these feeds was studied as was the amino acid (AA) composition of the original material and that of the undegradable fractions of the protein sources. Four diets were designed; 20% of their protein was supplied by each of the different sources. Four groups of 5 Granadina goats were used to study the utilization of these diets for milk production. No significant differences were observed in dry matter intake or milk production. The milk produced by goats fed the diet containing sunflower meal had the lowest protein concentration; the highest milk protein concentration was observed for goats fed the diet containing corn gluten feed. From a multivariate analysis, it was deduced that the quickly degradable protein fraction in the rumen and the ruminally undegradable protein fraction were the components of the protein sources most directly related to the milk protein produced. Given the similar AA profiles of the undegradable fractions of the different protein sources, the possible supplementation achieved from these ruminally undegradable fractions must be established by the amount of protein supplied regardless of AA composition.

Artemia mitochondrial genome: molecular biology and evolutive considerations

During the last two decades an increasing amount of information has been accumulated regarding the gene structure and organization of the mitochondrial genome from various organisms. Many studies carried out mainly in mammals, have contributed to the knowledge of the basic elements involved in the replication and transcription of mitochondrial DNA. However, very little is known about these processes in invertebrates. In this review we discuss our current knowledge of the animal mitochondrial genetic system and briefly summarize the structure of the Artemia mitochondrial genome, the characteristics of its transcriptional machinery and how its expression is controlled during early development, in relation with what is known in other organisms. Artemia is the only crustacean where the mtDNA has been studied at this level of detail up to date.

Magnetic resonance imaging of apical hypertrophic cardiomyopathy

To assess the capability of magnetic resonance imaging (MRI) to define the presence, degree, and distribution of apical hypertrophic cardiomyopathy in patients of European descent, MRI examination was prospectively performed in patients diagnosed with hypertrophic cardiomyopathy on two-dimensional echocardiography. Twenty-five patients with hypertrophy located exclusively at the cardiac apex were the object of this study. Spin echo and gradient echo sequences were performed to evaluate the morphology, motility, and myocardial thickness of the left ventricle in diastole. In a short-axis gradient echo sequences from base to apex, septal, lateral, anterior, and posterior segments at the basal and apical levels were measured. A four-chamber view and horizontal long-axis images of the left ventricle were performed to measure the true apex. A concentric, symmetric distribution of hypertrophic myocardium was considered when the thickness was 1.5 cm or greater, with the four segments being affected to a similar degree. Asymmetric hypertrophy was considered when the wall thickness ratio was more than 1.3. Myocardial thicknesses at the apical level were 2.03 +/- 0.60 cm (mean +/- standard deviation) at the true apex; the septal thickness was 1.19 +/- 0.46 cm; lateral, 1.62 +/- 0.71 cm; anterior, 1.36 +/- 0.57 cm; and posterior, 1.28 +/- 0.53 cm. Based on the MRI findings, the distribution of apical hypertrophy was classified as symmetric (n = 2), asymmetric (n = 18), and true apex (n = 5). A spadelike configuration of the left ventricle was observed in only five cases. MRI demonstrates that in Western patients the morphologic spectrum of apical hypertrophy cardiomyopathy is quite wide and includes myocardial hypertrophy exclusively localized at the true apex.

The association of tooth lead content with dental health factors

The purpose of this study was to determine the relationships of lead content in the human tooth with the prevalence of caries, dental plaque, pH of saliva, levels of Salivalis lactobacilli (SL) and Mutans streptococci (MS), degree of dental abrasion, tooth colour and toothbrushing frequency. A total of 220 teeth (one per person) were analysed using a microwave oven digestion procedure and lead content was measured by atomic absorption spectrometry. Tooth lead content followed a logarithmic-normal distribution and it increased with the prevalence of caries. Tooth lead concentrations were positively correlated with all the considered dental health factors except the pH of saliva, for which there was a significant negative correlation. Coloured teeth and teeth subject to abrasion showed the highest lead content. The highest number of colonies of SL and MS in saliva paralleled the highest lead tooth levels. Teeth obtained from irregular brushers presented higher tooth lead contents than subjects with a regular toothbrushing frequency. Multiple logistic regression analysis showed a significant association between tooth lead levels and dental plaque surface, Salivalis lactobacilli number, dental abrasion and dental colour. We conclude that accumulation of lead in teeth is associated with those dental health factors.

[Detection of the PML/RAR alpha rearrangement in acute promyelocytic leukemia using a reverse PCR method]

AIMS

This study describes a molecular method of reverse transcription polymerase chain reaction (RT-PCR) to detect the rearrangement PML/RAR alpha in acute promyelocytic leukaemia (APL) in order to assess its specificity and sensibility, and to evaluate its utility in the characterization of APL patients.

PATIENTS AND METHODS

Between January and June of 1995, 64 samples of bone marrow and peripheral blood stem cells (PBSC) cytapheresis were studied. There were 58 APL samples (23 patients: 10 samples obtained with disease activity, 43 samples in complete remission (CR) and 5 PBSC samples) and 6 control samples, of non-APL hematological neoplasms (3 other AML, 1 CML, 1 ALL, and 1 MDS). On the RNA obtained from the isolated mononuclear cells of each sample a conserved region of the PML/RAR alpha fusion gene was amplified by using a RT-PCR with specific primers.

RESULTS

The sensitivity assays were performed by diluting PML/RAR alpha positive RNA samples into RNA of controls. The RT-PCR assay was capable to detect the PML/RAR alpha until an 1/1000 dilution in negative control RNA. Nine out of 58 APL samples failed in the amplification of the control gene, and were considered non-evaluable. None of the 6 control samples showed PML/RAR alpha rearrangement. Nine out of 10 APL samples with disease activity were positive for the presence of PML/RAR alpha (the non-positive sample was a non-evaluable one). Six out of 43 APL samples in CR showed the rearrangement, 3 of them corresponding to 2 patients who posteriory relapsed 12 and 19 months after 1st CR. The other 3 positive samples came from other 3 APL patients (24 months in 3rd CR, 14 months in 1st CR and early CR), who remained in CR at the end of the study. No relapse could be noted in patients with negative PCR samples. PML/RAR alpha was not found in any of the 5 APL PBSC samples studied.

CONCLUSIONS

The RT-PCR method described here seems to be highly specific as it only detects this rearrangement in LPA patients. Furthermore, the presence of PML/RAR alpha in CR patients could be related to relapse. For all these reasons, this molecular method shows great usefulness and can be advocated, not only for assessing diagnosis, but for as monitoring minimal residual disease in the post remission follow up.

Effect of ethylene on naringin, narirutin and nootkatone accumulation in grapefruit

This paper studies the effect of different concentrations of ethephon on the levels of the sesquiterpene, nootkatone, and of the flavanones, naringin and narirutin, in grapefruit fruits. The results show that nootkatone synthesis and/or accumulation was stimulated by all the concentrations of ethephon assayed, while the levels of naringin and narirutin in the rind diminished. These results open up new perspectives concerning the possible regulation of the secondary metabolism of the plants.

Dental lead levels in the Galician population, Spain

The aim of this study was to investigate tooth lead concentrations in a Spanish population living in Coruña, Spain. A total of 220 teeth were analysed using a microwave oven digestion procedure and lead content was measured by atomic absorption spectrometry. Samples were classified according to age, sex, type of tooth, cause of extraction and place of residence. Tooth lead levels followed a logarithmic-normal distribution. The general geometric mean was 10.36 micrograms/g of tooth. There was a significant increase in teeth lead levels with advancing age. Permanent teeth showed higher values (13.09 +/- 1.07 micrograms/g, mean +/- S.E.M.) than deciduous teeth (3.96 +/- 1.07 micrograms/g). However, no differences were found between sexes. High lead concentrations were detected in pathological teeth, particularly in those with periodontal pathology, suggesting a relation between lead levels and dental disease. Nevertheless, teeth with caries did not show any significant lead increase. People living in urban areas of the coast had the highest lead teeth contamination. This is the first study in Spain which describes the tooth lead levels as a marker of lead exposure.

Microwave oven digestion procedure for atomic absorption spectrometry analysis of bone and teeth

The purpose of this study was to develop a new method for determination of the mineral element in teeth and bone using a microwave digestion procedure coupled to atomic absorption spectrometry. Samples were ashed at 450 degrees C for 4.5 h and subsequently digested in a microwave oven at maximum power (600 W) for 10 s using a Teflon closed Parr bomb. This method permits the rapid dissolution of the biological samples, avoiding operations such as slicing and cutting which often introduce alterations in sample homogeneity and may contribute to their contamination. The analysis of Na, K, Ca, Mg, Fe, Zn, Ba, Cd and Pb showed good reproducibility, precision and accuracy as compared with the certified values for the IAEA H-5 animal bone. Average concentration for those elements in permanent teeth obtained from children aged 11-18 years by orthodontics are given.

Leishmania tropica: characterization of a lipophosphoglycan-like antigen recognized by species-specific monoclonal antibodies

Species-specific monoclonal antibodies to Leishmania tropica, T11 and T13-15, recognize membranal and secreted antigens. The membrane form of the antigen migrates on sodium dodecyl sulfate-polyacrylamide gels with a diffuse molecular weight from 15 to 50 kDa and can be labeled with palmitic acid, myoinositol, galactose, glucosamine, and inorganic phosphate. Both phosphate and sugar-labeled material were isolated from metabolically labeled promastigotes by affinity chromatography on antibodies coupled to Sepharose 4B. No binding to Ricinus communis agglutinin was observed. This material behaves like lipophosphoglycans from other Leishmania but contains unique species-specific epitopes. It is susceptible to cleavage by phospholipase C and after digestion no longer partitions into the detergent phase following a Triton X-114 extraction. All four monoclonal antibodies appear to recognize a carbohydrate epitope on the lipophosphoglycan since periodate treatment of this material bound to nitrocellulose essentially eliminated antibody binding. In addition, T15 binding could be blocked by 5 mM mannose-6-PO4 and fructose-1- or 6-PO4, but not by mannose, glucose, fructose, or the additional PO4 derivatives examined. The antibodies recognize a similar but not identical epitope, as demonstrated by a competitive radioimmunoassay using 125I-labeled T11, T13, and T15. Expression of surface antigen is elevated during the promastigote stationary phase.

Regulation of glycolysis in sea bass liver: phosphofructokinase isozymes

Sea bass (Dicentrarchus labrax L.) liver phosphofructokinase (PFK) presents biphasic kinetics with respect to fructose-6-phosphate (F-6-P) in experiments carried out with crude extract. After the enzyme had been purified, two isozymes have been detected after chromatographic treatment. The two isozymes present different kinetic behaviour PFK-L1, the first eluted phosphofructokinase activity shows positive cooperativity with respect to fructose-6-phosphate and PFK-L2, the second activity fraction, has a Hill coefficient of 0.38 (negative cooperativity). The first isozyme shows less affinity for fructose-6-phosphate than that shown by PFK-L2. The joint kinetics of both isozymes produces a biphasic kinetics with respect to fructose-6-phosphate, similar to that observed in crude extracts.

Metabolic regulation of glycolysis in sea bass (Dicentrarchus labrax L.) muscle. I. Kinetic study and characteristic modulators of pyruvate kinase

White muscle pyruvate kinase from sea bass presents positive cooperativity with respect to PEP substrate. The enzyme is regulated by F-1.6-P2 and L-Phenylalanine. The activator effect of F-1.6-P2 in experiments carried out for the substrate PEP with crude extract seems to indicate that the enzyme is activated in vivo by this compound. The enzyme was not inhibited by either alanine or ATP but was inhibited by L-phenylalanine. Therefore this enzyme presents kinetic and regulatory properties similar to those of the mammalian isozyme M2.

Pyruvate kinase of sea bass liver: interrelationship in regulating properties

Pyruvate kinase of sea bass liver show a joint modulation of both pH and temperature for PEP substrate. The effect of F-1,6-P2, alanine and ATP is not fundamentally affected by a variation in pH. The kinetic constants in the presence of ATP are not affected, but the intensity of its inhibitor effect varies with temperature. A study of different buffers: Tris-HC1, Tris-maleic and phosphate, on this enzymatic activity with or without effectors has been made.

Influence of ATP and magnesium on phosphofructokinase from sea bass (Dicentrarchus labrax L.) liver

Glycolytic enzyme phosphofructokinase (PFK) from sea-bass liver shows inhibition for ATP4- and MG-ATP2-, and ATP4- is a competitive inhibitor with respect to MG-ATP2-. Free Mg2+ behaves as a mixed inhibitor on the kinetic with respect to the true enzyme substrate Mg-ATP2-, and eliminates the inhibition effect of this substrate. The kinetics with respect to Mg-ATP2- at non-inhibiting concentrations is not visibly affected by temperature of pH variation. The inhibiting effect of Mg-ATP2- is more marked at 22 and 10 degrees C (of three assayed temperatures 22, 15 and 10 degrees C and at physiological pH 6.8) as opposed to the maximum activity pH (8.0).

Spanish delta-beta-thalassemia: hematological studies and composition of the gamma-chains in ten homozygous patients

We report the hematological studies and the composition of the gamma-chains of 10 homozygous delta beta(0)-thalassemia patients belonging to 6 families. These patients showed a mild to moderate chronic hemolytic anemia, morphological changes typical of thalassemia and 100% fetal hemoglobin in their peripheral blood. The homozygous studied synthesized A gamma- and G gamma-chains in approximately equal amounts, and the fetal hemoglobin with a threonyl residue at position 75 is present and accounts for all the A gamma production.