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Biomedical subjects

E Fernandez

Publications and source records attributed to E Fernandez.

At least 19 recordsLinked to original sources
PubMed2000

Catalytic asymmetric hydroboration/amination and alkylamination with rhodium complexes of 1,1'-(2-diarylphosphino-1-naphthyl)isoquinoline

Catecholboronate esters formed by asymmetric hydroboration of arylalkenes are not directly converted to amines by reaction with hydroxylamine-O-sulfonic acid. Prior conversion to a trialkylborane by reaction with ZnEt2 or MeMgCl permits a subsequent amination reaction to occur with essentially complete retention of configuration, leading to a range of primary alpha-arylalkylamines in up to 97% enantiomeric excess (ee). Secondary, but not tertiary amines may be formed by a related pathway when in situ generated alkylchloramines are employed as the aminating agent. The catalytic asymmetric hydroboration, beta-alkylation and amination steps may be combined in a single stage. Overall, this provides a practical procedure for the synthesis of enantiomerically enriched arylamines, exemplified inter alia by the synthesis of (S)-1,2,3,4-tetrahydro-1-naphthylamine in 95-97% ee and of (R)-N-(cyclohexyl)-1'-(4-methoxyphenyl)ethylamine in 93% ee.

Journal Article↗
PubMed2000

A technique to prevent dural adhesions to chronically implanted microelectrode arrays.

Minimizing relative movements between neural tissues and arrays of microelectrodes chronically implanted into them is expected to greatly enhance the capacity of the microelectrodes to record from single cortical neurons on a long-term basis. We describe a new surgical technique to minimize the formation of adhesions between the dura and an implanted electrode array using a 12 microm (0.5 mil) thick sheet of Teflon film positioned between the array and the dura. A total of 15 cats were implanted using this technique. Gross examination of 12 implant sites at the time of sacrifice failed to find evidence of adhesions between the arrays and the dura when the Teflon(R) film remained in its initial position. In six implants from which recordings were made, an average of nine of the 11 (81%) connected electrodes in each array recorded evoked neural activity after 180 days post implantation. Further, on average, two separable units were identified on each of the implanted electrodes in these arrays. No significant change was found in the density of cell bodies around implanted electrodes of four of the implanted electrode arrays. However, histological evaluation of the implant sites revealed evidence of meningeal proliferation beneath the arrays. The technique described is shown to be effective at preventing adhesions between implanted electrode arrays and improve the characteristics of chronic recordings obtained with these structures.

Animals↗
PubMed2000

Selection of the most common chromosome abnormalities in oocytes prior to ICSI.

So far, all preimplantation genetic diagnosis (PGD) protocols in use produce results after the eggs have been fertilized. However, these approaches are not acceptable for patients with moral objections to the generation and discard of supernumerary zygotes or embryos. In these circumstances, only those oocytes to be replaced may be inseminated. The purpose of this study was to develop a PGD protocol to diagnose first polar bodies (PBs) prior to Intracytoplasmatic Sperm Injection (ICSI) in order to inseminate only those oocytes found to be chromosomally normal. PB biopsy was performed 1 hour after ovum pick up, and after fixation, the PBs were analysed by FISH and the eggs inseminated by ICSI no later than 7 hours after retrieval. One third (33.3%) of the PBs were aneuploid. Fifty-four normal and 12 non-resolved oocytes were injected by ICSI, of which 65% became 2-PN zygotes. Embryo transfer on day 2 was possible in all 10 patients (average maternal age 35.2+/-3.2, range 29-39 years), of which 6 became pregnant with 8 fetuses (28.6% or 8/28 transferred embryos). The results indicate that PB analysis of some common chromosome abnormalities is feasible within time limits imposed by ICSI insemination (6 hours or less).

Adult↗
PubMed2000

Diet diversity and colorectal cancer.

BACKGROUND: Food diversity has been recommended to achieve a healthy diet and prevent cancer. The relation between diet diversity and the risk of colorectal cancer was investigated using data from a multicenter case-control study carried out between 1992 and 1996 in Italy. METHODS: The study included 1225 subjects with cancer of the colon (688 men and 537 women), 728 with cancer of the rectum (437 men and 291 women), and 4154 controls (2073 men and 2081 women) residing in the same geographical areas. Odds ratios (ORs) of colon and rectal cancer and the corresponding 95% confidence intervals (CI) according to food diversity were derived from unconditional multiple logistic regression equations. RESULTS: For colon cancer, an inverse association for total diversity was found in males (adjusted OR of 0.65 for the highest vs the lowest quintile of total diversity; 95% CI: 0.46-0.93) and in females (OR = 0.85; 95% CI: 0.57-1.26). With respect to specific food groups, there was an inverse association only with diversity within vegetables (OR = 0.66; 95% CI: 0.54-0.81 in colon cancer and OR = 0.71; 95% CI: 0.55-0.91 in rectal cancer). CONCLUSIONS: This study suggests that total diversity is moderately related to a decreased risk of colorectal cancer risk. A better understanding of the potential influence of dietary patterns on colorectal cancer is needed.

Adult↗
PubMed2000

Transabdominal surgical approach in the management of renal tumors involving the retrohepatic inferior vena cava.

Multiple reports over the last decade have documented the clear superiority of surgery over other alternative treatments in the management of renal cell carcinoma with extension into the inferior vena cava (IVC). Controversy persists, however, regarding the management of tumor thrombus that extends retrohepatically, but not entering the right atrium. In this report, we retrospectively review our experience with the use of a feasible transabdominal technique without any form of bypass or anticoagulation for safe removal of renal tumor involving the retrohepatic IVC. From 1988 to 1998, 132 patients with renal cell carcinoma underwent radical nephrectomies at the urology service of our hospital. Five patients (3.8%) had retrohepatic venous extension through the renal vein into the IVC. Our transabdominal approach was accomplished by complete mobilization of the liver, control of the hepatocaval connection, total vascular exclusion of the IVC without heparin administration, removal of the tumor thrombus, and primary closure of the longitudinal vena cavotomy. From our results, we found the transabdominal approach with total vascular exclusion of the IVC to be satisfactory, with no early deaths, acceptable morbidity, and a remarkable limitation of blood loss and transfusion requirements.

Adult↗
PubMed2000

Sex differences in colorectal cancer mortality in Europe, 1955-1996.

Colorectal cancer is the leading cancer in non-smokers in Western countries, and over the last decades its trends have been generally more favourable for women than for men. Possible explanations of the sex differentials in colorectal cancer relate to different exposure to exogenous hormones and to other risk factors including diet, physical activity and alcohol drinking. The objective of this investigation was to systematically analyse the trends in colorectal cancer mortality sex ratios in major European countries over the last four decades. Trends in death certification rates from colorectal cancer over the period 1955-1996 were analysed for 20 European countries (excluding the former Soviet Union and a few of the smaller countries). In all countries, the mortality sex ratios (M/F) were around or slightly above unity in the 1950s, and systematically increased to approach 1.5 in the 1990s. The extent of the rises varied across countries, ranging between + 0.8% in Germany, + 9.7% in Sweden, and + 12.1% in Denmark (the lowest increases) to + 65.3% in Spain, + 56.2% in Portugal, and + 50.4% in Hungary (the highest ones). Mortality sex ratios in Europe show more favourable trends for females, which may be attributable, in part, to the introduction of exogenous hormones in the late 1950s and 1960s, and, in part, to differential sex exposure to major environmental risk factors.

Adult↗
PubMed2000

The quality of care and influence of double health care coverage in Catalonia (Spain).

AIMS: To analyse inequalities by social class in children's access to and utilisation of health services in Catalonia (Spain), private health insurance coverage, and certain aspects of the quality of care received. DESIGN: Cross sectional study using data from the 1994 Catalan Health Interview Survey. SETTING: Child population of Catalonia. PARTICIPANTS: A representative sample of non-institutionalised children younger than 15 years (n = 2433). MAIN OUTCOME MEASURES: Health services utilisation, perceived health, type of health insurance (only National Health System (NHS) or both NHS and private health insurance), and social class. RESULTS: No inequalities by social class were found for the utilisation of health care services provided by the NHS among children in most need. Double health care coverage does not influence the social pattern of visits. Nevertheless, social inequalities still remain in the use of those health services provided only partially by the NHS (dentist) and when characteristics of the last consultation are taken into account. That is, subjects who paid for a private service waited an average of 14.8 minutes less than those whose visit was paid for by the NHS only. CONCLUSION: Equitable access and use of medical care services in relation to need, regardless of the type of insurance and social class of their children and families, has been achieved in this region of Spain; differences by social class remain for those services incompletely covered by national health insurance and aspects of the quality of care provided.

Adolescent↗
PubMed2000

Pattern of smoking initiation in Catalonia, Spain, from 1948 to 1992.

OBJECTIVES: This study analyzed the pattern of smoking initiation by sex and educational level in Catalonia, Spain. METHODS: Data from the 1994 Catalan Health Interview Survey were used (n = 12,245). The age and smoking status of each subject were reconstructed for each calendar period. Age-specific smoking initiation rates were calculated. RESULTS: Smoking initiation among females was rare until the 1960s, but from the period 1968-1972 onward a converging pattern was observed between the genders. Women with higher levels of education started smoking before other women, but the gradient of educational level has changed in recent years, with higher initiation rates among less-educated women. CONCLUSIONS: These results are consistent with diffusion-of-innovations theory and could be related to social and economic changes from the 1960s onward in Spain.

Adolescent↗
PubMed2000

Aortic valve replacement with bioprostheses in liver transplant recipients.

Three cases of aortic valve replacement with porcine bioprostheses are reported in liver transplant recipients at two to six years after transplantation. Indications for aortic valve replacement (AVR) were aortic stenosis (n = 2) and aortic regurgitation (n = 1). The use of bioprostheses was recommended because of patient age, the need for multiple liver biopsies, and contraindication to the use of anticoagulation therapy. The patient who underwent AVR because of aortic regurgitation developed structural valve deterioration (SVD) during the next five years after surgery, and thus replacement of the bioprosthetic valve was required. Recipients of liver transplant who undergo valve replacement with tissue valves should be carefully followed up because of the risk of early SVD. AVR may be performed safely after liver transplantation.

Adult↗
PubMed1999

Precipitation of carbonated apatite in the cement system alpha-Ca(3)(PO(4))(2)-Ca(H(2)PO(4))(2)-CaCO(3).

Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to assess their potential for the precipitation of a carbonated apatite suitable for cement applications from a supersaturated solution. Of particular interest was the requirement of carbon dioxide release during the setting reaction to obtain Ca(9-x)(HPO(4))(1-1.5x) (PO(4))(5-2.5x)(CO(3))(3.5x)(OH)(1 + 1.5x) with a fixed carbonate content. Results indicated that a compromise is necessary with respect to the maximum permissible level of CaCO(3) addition to the powder mixture as against appropriate setting and hardening properties. Cementlike materials with good setting and hardening properties were obtained when alpha-Ca(3)(PO(4))(2) was the main reactant using Ca(H(2)PO(4))(2) and CaCO(3) as additives in relative proportions of <10 wt % corresponding, approximately, to the stability field area (x,lambda) contained within the lines lambda = -1.5x, x = 0.3, and lambda = -1. Desirable workability and setting properties were lost as the parameters x and -lambda increased. Finally, it was also found to be virtually impossible to obtain a predetermined chemical composition for the setting apatite precipitate, since to increase the amount of carbon dioxide released from the initial powder mixture during setting, the solution pH would need to be decreased, and in doing so the nature of the precipitate could be altered to fulfil the thermodynamic conditions of the solubility diagrams of calcium phosphates.

Apatites↗
PubMed1999

Corrigendum

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Journal Article↗
PubMed1999

Carbohydrate binding, quaternary structure and a novel hydrophobic binding site in two legume lectin oligomers from Dolichos biflorus.

The seed lectin (DBL) from the leguminous plant Dolichos biflorus has a unique specificity among the members of the legume lectin family because of its high preference for GalNAc over Gal. In addition, precipitation of blood group A+H substance by DBL is slightly better inhibited by a blood group A trisaccharide (GalNAc(alpha1-3)[Fuc(alpha1-2)]Gal) containing pentasaccharide, and about 40 times better by the Forssman disaccharide (GalNAc(alpha1-3)GalNAc) than by GalNAc. We report the crystal structures of the DBL-blood group A trisaccharide complex and the DBL-Forssman disaccharide complex.A comparison with the binding sites of Gal-binding legume lectins indicates that the low affinity of DBL for Gal is due to the substitution of a conserved aromatic residue by an aliphatic residue (Leu127). Binding studies with a Leu127Phe mutant corroborate these conclusions. DBL has a higher affinity for GalNAc because the N-acetyl group compensates for the loss of aromatic stacking in DBL by making a hydrogen bond with the backbone amide group of Gly103 and a hydrophobic contact with the side-chains of Trp132 and Tyr104. Some legume lectins possess a hydrophobic binding site that binds adenine and adenine-derived plant hormones, i.e. cytokinins. The exact function of this binding site is unknown, but adenine/cytokinin-binding legume lectins might be involved in storage of plant hormones or plant growth regulation. The structures of DBL in complex with adenine and of the dimeric stem and leaf lectin (DB58) from the same plant provide the first structural data on these binding sites. Both oligomers possess an unusual architecture, featuring an alpha-helix sandwiched between two monomers. In both oligomers, this alpha-helix is directly involved in the formation of the hydrophobic binding site. DB58 adopts a novel quaternary structure, related to the quaternary structure of the DBL heterotetramer, and brings the number of know legume lectin dimer types to four.

ABO Blood-Group System↗