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Biomedical subjects

A Ruiz

Publications and source records attributed to A Ruiz.

At least 19 recordsLinked to original sources
PubMed2003

Persistence of intracranial diastolic flow in transcranial Doppler sonography exploration of patients in brain death.

OBJECTIVE: The persistence of cerebral blood flow (CBF) in patients with whole brain death (BD) diagnosis is an unusual phenomenon. We describe patients with whole BD diagnosed despite persistence of intracranial blood flow on transcranial Doppler sonography (TDS). MATERIALS AND METHODS: From January 2001 to December 2002, we reviewed the records of 11 patients. Etiology of BD was craniocephalic trauma in 2 cases, schemic cerebrovascular accident (CVA) in 4 cases, Hemorrhagic CVA in 3 cases, subaracnoid hemorrhage in 1 case, and acute hydrocephalus in 1 case. Six patients had a cerebral decompressive mechanism. In all patients, TDS was used to confirm BD after clinical diagnosis. Additionally, all patients underwent an electroencephalogram (EEG). In 3 patients cerebral angiography (CA) and in 2 others radionuclide angiography (RA) with Tc99m HMPAO were done. RESULTS: All TDS studies showed persistent telediastolic positive flow in at least 1 artery. Because the TDS did not confirm the clinical diagnosis of BD, EEG tests were performed showing silence of bioelectrical activity. Those cases showed CA or RA results with a complete absence of CBF. CONCLUSION: The TDS technique directly evaluates the intracranial but not the intracerebral circulation. For this reason, during the BD diagnosis for patients with previous decompressive techniques, it was possible to find persistence of intracranial telediastolic flow using TDS. In those cases, it is advisable to use other tests to confirm the clinical diagnosis of BD.

Adult↗
PubMed2003

Evaluation of transplant procurement management courses: an educational project as a tool for the optimization of transplant coordination.

The process of obtaining organs and tissues includes a series of procedures and skills that are fundamental to obtain a large number and high quality of transplants. Health professionals involved in transplant coordination require robest and comprehensive training to integrate the donation-transplantation process within the clinical health care field. Based on a learning-through-experience model, Transplant Procurement Management (TPM) designed various courses adapted to local educational need to train transplant coordinators, to increase active donor detection, and to promote a positive attitude towards donation; namely, Advanced, Introductory and New Life Cycle courses respectively. Moreover, TPM has coordinated international programs (INTERCATT and INTERITALY). Since 1991, the model has included 29 Advanced courses (1215 participants), 22 Introductory courses (575 pupils), and 7 New Life Cycle courses (more than 400 attendees). The Advanced courses were attended by medical (intensive care unit, nephrology, and others) and nursing professionals. Assessment of the educational program showed achievement of teaching objectives. The evaluation averages above 3.5 (scale, 1-5) for content, presentation, and ability to answer questions. Likewise, the program's organization showed an average score of 4.4. The acquired knowledge was assessed by means of a self-evaluation test (correct answers >69%). Practical skills assessed through direct observation showed an average of 7 (scale, 1-10). The TPM educational program offers a range of necessary knowledge and skills to increase organ donation. Health professionals concerned about the organ shortage may find TPM training useful to increase their knowledge.

Curriculum↗
PubMed2003

The living kidney donation process: the donor perspective.

OBJECTIVE: To evaluate the living kidney donation (LKD) process using donors' opinions on the impact on social, emotional, and financial aspects affecting donor quality of life. MATERIALS AND METHODS: From May 2000 to December 2002, we studied 22 donors of living kidneys at the Hospital Clinic, Barcelona, Spain, who completed an anonymous survey 6 months after donation. RESULTS: Most donors (86%) had themselves informed the recipient about their wish to donate, the other 14% were asked by family members. Eighty-eight percent stated that the information provided to the donor about the evaluation process was well explained and understood whereas 12% disagreed with the statement. At the time of thin decision, 90.5% of donors understood the vital risk. For 95%, the explanations about the process corresponded with the actual experience. One hundred percent of donors stated after donation that they would again favor it. Mean hospital stay was 6 days (range, 3-9 days). Those donors with a labor contract have been out of work for an average of 57.8 days (range, 18 days to 6 months). Twenty-five percent of donors admitted financial effects as a result of donation. All but 1 felt completely recovered with the same quality of life after donation. DISCUSSION: LKD is a good therapeutic alternative. Some aspects should be developed, such as more information about living donation and the need to considering donors as healthy persons without loss of earnings. Recognition of the benefits of living donation requires more wide participation of all citizens nationally.

Attitude to Health↗
PubMed2003

Cold chain monitoring during cold transportation of human corneas for transplantation.

BACKGROUND: As recommended by international standards the cornea should be maintained in a specific temperature range (2 degrees -8 degrees C) to guarantee its viability. However, there is no standard packaging method to maintain these conditions during transport. Our packaging system is similar to those used by the main eye banks in Spain and elsewhere in Europe. The objective is to monitor the cold chain in the current packaging method to validate the maintenance of temperature within the adequate range for a minimum 24-hour period. METHODS: The effects of the following variables were studied: number and freezing temperature of the cold packs; air volume in the packaging system; position of the cornea in the packaging system; and the wall section of the container. Exterior temperature was maintained constant at 20 degrees to 24 degrees C. The cold chain was monitored using a device that measures temperature continuously and for which a histogram of temperature variation can be downloaded to a computer for further analysis. RESULTS: When the cold packs were frozen to -40 degrees C or the number of cold packs increased to four, the temperature decreased quickly to 0 degrees C and the transport period was not prolonged. The main objective was to improve isolation by reducing inner air volume, and maintaining the position of the cornea in the container. CONCLUSIONS: The currently used cold packaging systems (not frozen, 4 degrees C) do not maintain the temperature within the accepted range for the required distribution period. The improved system maintains the cornea at between 2 degrees C and 6 degrees C for a minimum of 24 hours.

Cornea↗
PubMed2003

The process of adult living liver donation.

OBJECTIVE: To evaluate both the opinion that living liver donors have of the process and the psychological, economic, and social consequences of donation. MATERIAL AND METHODS: Six months after the donation, an anonymous survey was sent to 22 donors of the right liver lobe between March 2000 and December 2002. RESULTS: 15 surveys were returned with all of the questions answered. Almost all the donors had no prior knowledge of living donation. When they were considered to be suitable donors, all of them felt happy, 21% were scared and 15% felt joy and insecurity. The information provided was well understood and accurately described the experiences of 93% of donors. All donors understood the vital risk, and 93% understood that transplantation is not always completely successful. All donors would repeat the experience. Mean hospital stay was 12.6 days. Mean convalescence was 50.6 days. Salaried donors were on sick leave for a mean of 96.4 days (21-150 days), causing financial problems in six cases (36%), due to no financial compensation and compulsory redundancy in one case. All donors had completely recovered at six months after donation. DISCUSSION: Adult living donation of the right liver lobe is an accepted therapeutic alternative. In order to regulate medical and economic protection to avoid additional disturbances after donation, the public, patients, and physicians require more complete information about living donation.

Adult↗
PubMed2002

Polygonal billiards and transport: diffusion and heat conduction.

A detail study of the diffusive and heat conduction properties of a family of nonchaotic billiards is presented. For dynamical systems with dynamical instability the relation between transport properties and characteristic quantities of the chaotic dynamics naturally emerge. On the contrary, in dynamical systems without chaos (in the sense of exponential separation of nearby trajectories) much less is known. From numerical simulations we compute several quantities related to diffusion, such as the mean square displacement, the behavior of the hydrodynamic modes for long wavelengths, through the properties of the incoherent intermediate scattering function and the velocity autocorrelation function, in connection with the Green-Kubo formula. The analysis of all these quantities indicates that some systems among the family studied have normal diffusion and others anomalous diffusion. The spectral measure associated with the velocity autocorrelation function is also studied. The same analysis reveals that for all the systems treated there is not a well defined super Burnett coefficient. The heat conduction is also explored and found that, naturally, it is valid for the systems that behave diffusively.

Journal Article↗
PubMed2002

Müllerian adenosarcoma of the cervix with heterologous elements: report of a case and review of the literature.

BACKGROUND: Müllerian adenosarcoma (MA) is a rare neoplasm composed of benign epithelial and malignant stromal components. Its location in the cervix and the presence of heterologous elements are extremely infrequent (to our knowledge, only 14 more cases have been reported in the English literature). We describe another case of MA of the uterine cervix with heterologous elements and review the clinical and pathological features of these tumors. CASE REPORT: A nulliparous 25-year-old woman was admitted to the hospital because of metrorrhagia and recurrent masses, dependent on the cervix, initially considered endocervical polyps. Microscopically, the last curettage performed revealed a tumor composed of two elements, epithelial and mesenchymal. The epithelial elements were benign endocervical type glands, and the mesenchymal were sarcomatous, containing minor foci of cartilage. A diagnosis of endocervical heterologous adenosarcoma was reached, and a total hysterectomy and bilateral salpingo-oophorectomy were performed. The patient is alive 2 years after the surgical procedure. Neither chemotherapy nor other adjuvant therapies have been administered, and she is clinically free of disease at the moment. CONCLUSION: Because MA with heterologous elements seems to appear at the earliest stages of the reproductive lifespan in women, commonly with a history of recurrent polyps, and because its malignant potential is uncertain, gynecologists and pathologists should be aware and think about the possibility of this tumor. Long-term follow-up is essential and so is the accumulation of individual cases to provide further experience with these unusual neoplasms.

Adenosarcoma↗
PubMed2002

Some non-linear aspects of the electronic stages in time-domain modelling of NDE pulse-echo ultrasonic systems.

Electronics interfacing with NDE probes frequently include non-linear switching devices and semiconductor networks, which influence the excitation pulses and detected echo signals. Classical approaches to modelling a pulse-echo process use ideal assumptions for the electronics and do not consider these influences on the echoes, which can be very relevant in HF cases. This paper proposes new ways to consider these non-linear effects in a time-domain simulation process, extending previous approaches by including new elements in the modelling. Specific electrical models covering the pulse-echo process are applied in the evaluation of echo-graphic signals. They include semiconductor devices and other non-ideal elements. From these models, and using SPICE as a simulation tool, strong non-linear effects on pulsed responses, computed for both E/R stages of typical NDE transceivers, are analysed.

Journal Article↗
PubMed2002

The role of surgery in stage IV neuroblastoma.

BACKGROUND/PURPOSE: The importance of primary tumor resection in stage IV neuroblastoma is controversial. The authors analyzed prospectively the role of surgery in a multicentric series of stage IV neuroblastoma patients. METHODS: Patients were studied according to the International Neuroblastoma Staging System (INSS) recommendations. Age, sex, location of the tumor, type of metastases, time of resection (initial or delayed), extension of resection, surgical complications, pathology, N-myc and Shimada classification results, relapses, and outcome were studied. After diagnosis, children received induction chemotherapy followed by delayed surgery and autologous stem cell transplantation or maintenance chemotherapy. Resection was classified as complete (C), greater than 90% (P1), greater than 50% (P2), less than 50% (P3), and biopsy (B). RESULTS: Ninety-eight stage IV children were admitted in the study from June 1992 to July 1999. Seventy-six were older than one year, and in 78 the primary tumor was abdominal. Bone was the most common metastatic site followed by bone marrow. Initial biopsy was performed in 74 patients, and resection in 6, with one complication in each group. N-myc was amplified in 20 of 80 tumors, and Shimada was unfavorable in 45 of 67. Delayed surgery was performed in 70 cases, achieving gross total resection in 55 (79%); there were minor complications in 10%. Mean survival rate time was 50 months. Event-free survival rate (EFS) at 5 years for the entire series is 0.32, but 0.0 for children having biopsy only, 0.25 for less than 50% resection, 0.31 for 50% to 90% resection, 0.44 for greater than 90% resection, and 0.33 for complete resection. Differences were statistically significant only when compared with the biopsied group. EFS rate for infants was 0.56, but, again, there was no difference in relation to the type of resection. There were 46 relapses, 12 of them local, 7 of 20 N-myc-amplified tumors, and 4 of 60 not amplified (P <.005). CONCLUSIONS: Biopsies of stage IV neuroblastoma allow safe assessment of N-myc and other biological factors on tumor tissue. Delayed surgery after chemotherapy is performed with a low rate of complications, achieving a good local control of disease. N-myc-amplified tumors have higher local relapse rates than nonamplified and therefore would need more intensive local treatment. The final outcome in these patients is determined more by metastatic relapses than by the degree of resection.

Abdominal Neoplasms↗
PubMed2002

[Peritoneal equilibrium test using icodextrin and glucose at different concentrations].

UNLABELLED: The aim of this study was to compare, under standard conditions (Peritoneal Equilibrium Test, "PET"), the peritoneal permeability to water and several solutes using icodextrin and glucose (3.86% and 1.36%) dialysates. The study includes 14 patients (3 women and 11 men), mean age 64 +/- 13 years, average time on peritoneal dialysis 23.5 +/- 17 months. PETs with icodextrin were performed in all of them (n = 14); PETs with 3.86% glucose were carried out in 7, and PETs with all the three solutions were performed in 5 patients. Samples were taken at 0, 30, 60, 120, 240 minutes, and after the rinsing procedure using 1.36% glucose in order to calculate the residual volume. RESULTS: Sodium concentration in the effluent and D/P sodium did not change significantly from minute 0 to 240 with icodextrin and 1.36% glucose; but with 3.86% glucose both sodium and D/P sodium decreased at thirty minutes, remained at the same levels till the 120 minutes and then had a tendency to increase. Glucose concentration and osmolarity in the effluent did not vary throughout the time with icodextrin, but progressively decreased during the 4-hour period with 3.86% and 1.36% glucose solutions. The drainage after the 4-hour period was higher for the 3.86% glucose (2,608 +/- 388 ml, p = 0.03) than for the 1.36% glucose (2,070 +/- 120 ml) or the icodextrin (2,212 +/- 213 ml). Low molecular weight permeability: D/P creatinine after the 4-hour dwell was significantly lower for the icodextrin (0.66 +/- 0.1, p = 0.05) than for the 3.86% glucose (0.71 +/- 0.1) or the 1.36% glucose (0.72 +/- 0.1). The creatinine clearance for 3.86% glucose (7.4 +/- 0.4 ml/min p = 0.007) was higher than for icodextrin (5.6 +/- 0.5 ml/min) or for 1.36% glucose (5.8 +/- 0.6 ml/min). The clearances for total protein, albumin and beta 2-microglobulin did not show significant differences between the solutions. CONCLUSIONS: Our study confirms that the icodextrin solution remains iso-osmolar with plasma during the 4-hour dwell. The sodium profile suggests that the ultrafiltration induced by icodextrin and 1.36% glucose depends on small pore-mediated sodium and water transport; on the other hand, 3.86% glucose also induces transport of water without solutes throughout the ultra-small aquaporin-mediated, pores, producing sodium dilution in the effluent. Ultrafiltration and solute clearances for icodextrin are lower than for 3.86 glucose during a 4-hour dwell.

Adult↗
PubMed2001

Modular furanoside phosphite ligands for asymmetric Pd-catalyzed allylic substitution.

A series of diphosphite, phosphine-phosphite, and thioether-phosphite ligands 1-5 with a furanoside backbone have been used in the enantioselective palladium-catalyzed allylic substitution of rac-1,3-diphenyl-2-propenyl acetate giving low to high enantioselectivies (from close to 0% to 97% ee). The modular nature of these ligands enables systematic investigations of the effect of the ligand structure on the enantioselectivity. The enantioselectivity is mainly determined by the configuration of the stereogenic center C-3 of the furanose backbone. From this we conclude that the attack of the nucleophile takes place trans toward the donating group at the stereogenic C-5 atom. Systematic variation of the donor group attached to the carbon atom C-5 indicated that the presence of a bulky phosphite functionality has a positive effect on enantioselectivity. Thus, the highest ee's are obtained using the bulky diphosphite ligand 1b containing a xylofuranoside backbone.

Journal Article↗
PubMed2001

Highly enantioselective Rh-catalyzed hydrogenation based on phosphine-phosphite ligands derived from carbohydrates.

A new class of efficient catalysts was developed for the asymmetric hydrogenation of alpha,beta-unsaturated carboxylic acid derivatives by synthesizing a series of novel phosphine-phosphite ligands (4a-d) derived from readily available D-(+)-xylose. Excellent enantioselectivities (> 99%) were achieved under very mild reaction conditions (1 bar H(2) and 20 degrees C). Varying the biphenyl substituents in the phosphite moiety greatly affected the enantioselectivity in the hydrogenation reactions. The results also indicate that the sense of enantioselectivity is mainly controlled by the configuration of the phosphite moiety. (31)P[(1)H] NMR and kinetic studies on intermediates of the catalytic cycle show that the [Rh(P(1)-P(2))(enamide)]BF(4) species is the resting state and that the rate dependence is first order in rhodium and hydrogen pressure and zero order in enamide concentration.

Carbohydrates↗
PubMed2001

Chiral diphosphites derived from D-glucose: new ligands for the asymmetric catalytic hydroformylation of vinyl arenes.

A series of novel diphosphite ligands derived from readily available D-(+)-glucose has been synthesized. These ligands have been applied to the Rh-catalyzed hydroformylation of vinyl arenes. Both excellent enantioselectivities (up to 91%) and regioselectivities (up to 98.8%) were achieved under mild conditions. The advantage of these ligands is that their modular natures allow facile, systematic variation in the configurations at the stereocenters [C(3), C(5)] at the ligand bridge and in the biphenyl substituents, enabling their effects on the stereoselectivity to be studied. Results show that the absolute configuration of the product is governed by the configuration at the stereogenic center C(3), while the level of the enantioselectivity is influenced by a cooperative effect between stereocenters C(3) and C(5). Replacement of the tert-butyl substituent by methoxy substituents at the para positions of the biphenyl moieties improved the enantioselectivities. We have characterized the rhodium complexes formed under CO/H2 by NMR techniques and in situ IR spectroscopy and have observed that there is a relationship between the structure of the [HRh(CO)2(PP)] species and their enantiodiscriminating performance in hydroformylation. Enantioselectivities were highest with ligands with a strong bis-equatorial coordination preference, while an equilibrium of species with bis-equatorial and equatorial-axial coordination modes considerably reduced the ee's.

Journal Article↗
PubMed2001

[Molecular analysis of the RPE65 gene in 72 Spanish families with autosomal recessive retinitis pigmentosa].

BACKGROUND: Autosomal recessive retinitis pigmentosa (arRP) is the most common form of retinitis pigmentosa (RP). It is characterized by a high degree of allelic and non-allelic genetic heterogeneity. Previously,it has been demonstrated that the RPE65 gene is responsible for 2% recessive or isolated RP cases and 16% Leber's congenite amaurosis cases. Although the concrete function of RPE65 is unknown as yet, it has been found to be involved in vitamin A metabolism and rhodopsin regeneration. PATIENTS AND METHOD: We studied the involvement of the RPE65 gene in 72 arRP Spanish families by means of indirect molecular and mutation analysis. RESULTS: The results obtained using the intragenic microsatellite marker D1S2803 allowed us to exclude RPE65 as the causative gene of the disease in 80.5% of the families studied. Three new variants of the RPE65 gene have been identified: IVS6-43delA, IVS6-42delT and IVS6-33CG. We found that IVS6-33C-->G was a common polymorphism. The other variants, namely IVS6-43delA and IVS6-42delT, were not identified in 150 control chromosomes studied. The segregation analysis of IVS6-42delT variant seemed to exclude it as being involved in the disease. CONCLUSIONS: Our results argue against the involvement of RPE65 gene in the families studied, indicating that the prevalence of RPE65 abnormalities in arRP Spanish families may be lower than that observed in other populations.

Carrier Proteins↗