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Biomedical subjects

E Gomez

Publications and source records attributed to E Gomez.

At least 55 records · Page 3Linked to original sources
PubMed1998

High-potential states of blue and purple copper proteins.

Electrochemical measurements show that there are high-potential states of two copper proteins, Pseudomonas aeruginosa azurin and Thermus thermophilus CuA domain; these perturbed states are formed in guanidine hydrochloride (GuHCl) solution in which the proteins are still blue (azurin) and purple (CuA). In each case, the high-potential state forms reversibly. Absorption (azurin, CuA), visible circular dichroism (azurin, CuA), resonance-Raman (CuA), and EPR (CuA) spectra indicate that the structure of the oxidized copper site of each high-potential form is very similar to that of the native protein. It is proposed that GuHCl perturbs one or more H-bonds in the blue or purple copper active site, thereby allowing Cu(I) to adopt a more favorable coordination structure than that in the rigid cavity of the native protein.

Azurin↗
PubMed1998

Budd-Chiari syndrome, portal vein and mesenteric vein thrombosis in a patient homozygous for factor V Leiden mutation treated by TIPS and thrombolysis.

We present the first case of Budd-Chiari syndrome in association with portal and mesenteric vein thrombosis in a patient homozygous for the factor V Leiden mutation. She was treated by transjugular intrahepatic portosystemic stent (TIPS) placement followed by local thrombolytic therapy. Venous outflow from the liver was established and the thrombi in the portal and mesenteric veins were lysed completely. This therapeutic approach may be used for such patients with this severe thrombotic event, who generally have a poor prognosis.

Adult↗
PubMed1998

Evaluation of a spectrophotometric assay for the measurement of malondialdehyde and 4-hydroxyalkenals in human spermatozoa: relationships with semen quality and sperm function.

A spectrophotometric assay for the measurement of malondialdehyde and 4 hydroxyalkenals (MA + 4HA) has been evaluated for the detection of sperm pathologies involving oxidative stress. In order to make sensitive measurements of MA + 4HA on human spermatozoa, the stimulation of a lipid peroxidation cascade with a ferrous ion promoter was found to be necessary. The optimal configuration for the promoter was defined (0.64 mM FeSO4 + 20 mM ascorbate for 2 h in Ca2+ and Mg2 free Hanks' balanced salt solution) and the assay used in a series of studies to elucidate the functional significance of MA + 4HA determinations. Such measurements were found to give highly significant correlations (p < 0.001) with the loss of motility induced by oxidative stress created either with a xanthine oxidase, free radical generating system or by prolonged incubation under aerobic conditions. Experiments involving the stimulation and suppression of lipid peroxide release from human sperm suspensions, in concert with a bioassay for cytotoxicity, confirmed the strength and causative nature of these associations. Measurements of lipid peroxidation potential in highly purified, leucocyte-free sperm suspensions revealed the presence of inverse correlations with the motility of the spermatozoa, their viability, their competence for sperm-oocyte fusion and, most significantly, the quality of sperm movement in the original semen samples. Similar negative correlations were observed between sperm function and phorbol ester-stimulated reactive oxygen species generation but, unlike the MA + 4HA determinations, these relationships were obfuscated by the presence of leucocytes. We conclude that the measurement of MA + 4HA in human spermatozoa provides important information on the underlying quality of spermatogenesis and should be of value in the clinical diagnosis of infertility involving oxidative stress and the selection of patients for antioxidant therapy.

Acrosome↗
PubMed1998

Analysis of the impact of intracellular reactive oxygen species generation on the structural and functional integrity of human spermatozoa: lipid peroxidation, DNA fragmentation and effectiveness of antioxidants.

Exposure of human spermatozoa to nicotinamide adenine dinucleotide phosphate (NADPH) resulted in the dose dependent generation of reactive oxygen species (ROS) which, at a critical level of intensity, induced lipid peroxidation, DNA damage and a dramatic decline of sperm motility. This system was then used as a model for screening the ability of different antioxidants to combat oxidative stress created through the excessive intracellular generation of toxic oxygen products of metabolism. A variety of antioxidants that has previously been shown to be protective against extracellularly derived oxidants (e.g. superoxide dismutase, catalase, vitamin E, hypotaurine) were ineffective in this system. Albumin, however, could provide complete protection against NADPH induced oxidative stress via mechanisms that did not involve the suppression of the lipid peroxidation cascade but rather the inactivation of lipid peroxides generated during this process. Albumin did not protect against DNA damage induced by NADPH but was extremely effective at preventing DNA fragmentation arising from the suppression of glutathione peroxidase activity with mercaptosuccinate. These studies emphasize that the design of clinically effective antioxidant treatments will depend, critically, upon the source of the oxidative stress. For cases involving excessive intracellular ROS generation, albumin appears to be an important means of neutralizing lipid peroxide-mediated damage to the sperm plasma membrane and DNA.

Antioxidants↗
PubMed1998

The environment for telemedicine in the Canary Islands.

We studied the environment for telemedicine in the Canary Islands. The population's attitude to telemedicine was surveyed in 503 questionnaire interviews with doctors, nurses, paramedical staff and patients on the seven islands. Almost half the respondents (46-50% across groups) had a positive opinion of telemedicine. We also collected data about telephone medicine. A total of 479 medical-support telephone calls were made to four doctors, in psychiatry, ophthalmology and paediatrics. The telephone calls resolved the problem in 73% of cases and 86% would have come to the doctor if not made. Therapy was prescribed in 11% and 10% were just for information. The number of telephone calls per day was highest in psychiatry. Finally, we carried out a detailed analysis of the number of transfers between the islands (14,942 people in 1995 and 22,418 in 1996). According to the number of transfers and location of the referral hospital, oncology, psychiatry, dermatology and traumatology were the specialties that would be most likely to benefit from telemedicine.

Child↗