Search PubMed⌕ Search

Biomedical subjects

R Santos

Publications and source records attributed to R Santos.

At least 37 records · Page 2Linked to original sources
PubMed2000

Glucose-6-phosphate dehydrogenase aveiro: a de novo mutation associated with chronic nonspherocytic hemolytic anemia.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common X-linked enzyme abnormality. The clinical phenotype is variable but often predictable from the molecular lesion. Class I variants (the most severe forms of the disease) cluster within exon 10, in a region that, at the protein level, is believed to be involved in dimerization. Here we describe a de novo mutation (C269Y) of a new class I variant (G6PD Aveiro) that maps to exon 8. Mutant and normal alleles were found in both hematopoietic and buccal cells, indicating the presence of mosaicism. The available model of the protein predicts that this lesion lies in proximity to the dimer interface of the molecule. A possible mechanism to explain the severity of the defect is proposed. (Blood. 2000;95:1499-1501)

Amino Acid Substitution↗
PubMed2000

Clinical improvement in patients with orthostatic intolerance after treatment with bisoprolol and fludrocortisone.

Orthostatic intolerance is the development of disabling symptoms upon assuming an upright posture that are relieved partially by resuming the supine position. Postural tachycardia syndrome (POTS) is an orthostatic intolerance syndrome characterized by palpitations because of excessive orthostatic sinus tachycardia, lightheadedness, tremor, and near-syncope. Patients usually undergo extensive medical, cardiac, endocrine, neurologic, and psychiatric evaluation, which usually fails to identify a specific abnormality. The authors investigated the autonomic and hemodynamic profile of patients with POTS and the effectiveness of bisoprolol and fludrocortisone. The authors evaluated 11 female patients with POTS before and after medical treatment with a cardioselective bisoprolol beta-blocker or fludrocortisone, or both, and 11 age-matched control patients. Variability of heart rate and systolic blood pressure was assessed by fast Fourier transform, and spontaneous baroreceptor gain was assessed by use of the temporal sequences slope and alpha index. Modelflow was used to quantify hemodynamics. Symptoms in all patients improved greatly after medication. The autonomic and hemodynamic impairment observed in patients with POTS, particularly after orthostatic stress, is treated effectively with bisoprolol or fludrocortisone or both. These results need further confirmation in a controlled double-blind study. Proper medical treatment improves dramatically the clinical and autonomic-hemodynamic disturbances observed in patients with POTS. The data support the hypothesis that POTS is the result of a hyperadrenergic activation or hypovolemia during orthostasis.

Adolescent↗
PubMed2000

Pregnancy outcomes after antepartum diagnosis of oligohydramnios at or beyond 34 weeks' gestation.

OBJECTIVE: Our purpose was to assess whether antepartum oligohydramnios is associated with adverse perinatal outcomes. STUDY DESIGN: Women delivered between July 1, 1991, and September 30, 1996, who underwent ultrasonography at >/=34 weeks' gestation were analyzed. Oligohydramnios was defined as an amniotic fluid index </=50 mm. Perinatal outcomes in pregnancies with oligohydramnios were compared with those with an amniotic fluid index of >50 mm. RESULTS: In our analysis of 6423 pregnancies, 147 (2.3%) were complicated by oligohydramnios. This complication was associated with increased labor induction (42% vs 18%; P <.001), stillbirth (1. 4% vs 0.3%; P <.03), nonreassuring fetal heart rate (48% vs 39%; P <. 03), admission to the neonatal intensive care nursery (7% vs 2%; P <. 001), meconium aspiration syndrome (1% vs 0.1%; P <.001), and neonatal death (5% vs 0.3%; P <.001). CONCLUSION: Antepartum oligohydramnios is associated with increased perinatal morbidity and mortality.

Adult↗
PubMed2000

Evaluating environmental contamination in Ria Formosa (Portugal) using stress indexes of Spartina maritima.

Species of Spartina are potentially useful for biomonitoring coastal systems because they are abundant in the intertidal and have a wide geographic distribution in temperate zones. In this study, three indexes of physiological stress, thiolic protein concentration, adenylic energy charge (AEC) index [AEC = ATP + 0.5ADP/(ATP + ADP + AMP)] and photosynthetic efficiency (Fv/Fm), are measured in Spartina maritima plants collected at four sites and compared with metal concentrations in the sediments and Spartina tissues. Two sites were close to urban centers and two were located further away, in less contaminated areas. Concentrations of copper, cadmium, lead and zinc were determined by atomic absorption spectrophotometry, thiolic proteins were determined by polarography and adenilic nucleotides were determined by high performance liquid chromatography. Photosynthetic efficiencies were measured with a fluorometer. The sediments of sites closer to urban centers had higher concentrations of metals than the sites located further away. Metal concentration within plants did not follow this spatial pattern, probably due to spatial differences in metal bioavailability, uptake rates, internal transport and excretion processes. Concentrations of all metals studied were higher in underground plant structures than aerial, except cadmium whose levels were not significantly different. On the other hand, the stress indexes followed the spatial pattern of metals in the sediment. Thiolic protein concentrations were higher in plants from polluted sites, and were three to four times higher in aerial than in underground plant structures. Leaf AEC ratios and photosynthetic efficiencies were lower in plants from polluted sites indicating that they were growing under stressful conditions. We conclude that the use of these indexes in S. maritima represent a useful tool to monitor contamination in Ria Formosa lagoon as they provide an integrated measure of the toxicological burden of contamination.

Environmental Monitoring↗
PubMed2000

Bacillary angiomatosis by Bartonella quintana in an HIV-infected patient.

Bacillary angiomatosis and bacillary peliosis are opportunistic infections caused by Bartonella henselae and Bartonella quintana, which occur in patients with late-stage infection. We report a case of bacillary angiomatosis in an HIV-infected patient with skin, bone, and probably liver involvement, The identification of the agent (B quintana ) was done by polymerase chain reaction in the skin specimen. The patient had complete regression of all lesions after a 6-month regimen of oral erythromycin.

AIDS-Related Opportunistic Infections↗
PubMed2000

Critical protective role of bacterial superoxide dismutase in rhizobium-legume symbiosis.

In nitrogen-poor soils, rhizobia elicit nodule formation on legume roots, within which they differentiate into bacteroids that fix atmospheric nitrogen. Protection against reactive oxygen species (ROS) was anticipated to play an important role in Rhizobium-legume symbiosis because nitrogenase is extremely oxygen sensitive. We deleted the sodA gene encoding the sole cytoplasmic superoxide dismutase (SOD) of Sinorhizobium meliloti. The resulting mutant, deficient in superoxide dismutase, grew almost normally and was only moderately sensitive to oxidative stress when free living. In contrast, its symbiotic properties in alfalfa were drastically affected. Nitrogen-fixing ability was severely impaired. More strikingly, most SOD-deficient bacteria did not reach the differentiation stage of nitrogen-fixing bacteroids. The SOD-deficient mutant nodulated poorly and displayed abnormal infection. After release into plant cells, a large number of bacteria failed to differentiate into bacteroids and rapidly underwent senescence. Thus, bacterial SOD plays a key protective role in the symbiotic process.

Bacterial Proteins↗
PubMed2000

Reversible sympathetic vasomotor dysfunction in POTS patients.

BACKGROUND: Orthostatic intolerance refers to the development upon assuming an upright posture of disabling symptoms, which are partly relieved by resuming the supine position. Postural tachycardia syndrome (POTS) is an orthostatic intolerance syndrome characterized by palpitations due to excessive orthostatic sinus tachycardia, lightheadedness, tremor, and near-syncope. Patients usually undergo extensive medical, cardiac, endocrine, neurological and psychiatric evaluation, which usually fails to identify a specific abnormality. We investigated the autonomic and hemodynamic profile of POTS patients and the efficacy of bisoprolol and or fludrocortisone. METHODS AND RESULTS: We evaluated eleven female patients with POTS before and after medical treatment with a cardio-selective beta blocker (bisoprolol) and/or fludrocortisone, and eleven age-matched controls. Variability of heart rate and systolic blood pressure was assessed by Fast Fourier Transform, and spontaneous baroreceptor gain by temporal sequences slope and alpha index. Modelflow was used to quantify hemodynamics. All patients improved greatly after medication. The autonomic and hemodynamic impairment observed in patients with POTS, particularly after orthostatic stress, is treated effectively with bisoprolol and/or fludrocortisone. These results need further confirmation in a controlled double-blind study. CONCLUSIONS: Proper medical treatment dramatically improves the clinical and autonomic/hemodynamic disturbances observed in patients with POTS. The data support the hypothesis that POTS is due to a hyperadrenergic activation and/or hypovolemia during orthostasis.

Adolescent↗
PubMed1999

Functional analysis of the hemK gene product involvement in protoporphyrinogen oxidase activity in yeast.

The Escherichia coli hemK gene has been described as being involved in protoporphyrinogen oxidase activity; however, there is no biochemical evidence for this. In the context of characterizing the mechanisms of protoporphyrinogen oxidation in the yeast Saccharomyces cerevisiae, we investigated the yeast homolog of HemK, which is encoded by the ORF YNL063w, to find out whether it has any protoporphyrinogen oxidase activity and/or whether it modulates protoporphyrinogen oxidase activity. Phenotype analysis and enzyme activity measurements indicated that the yeast HemK homolog is not involved in protoporphyrinogen oxidase activity. Complementation assays in which the yeast HemK homolog is overproduced do not restore wild-type phenotypes in a yeast strain with deficient protoporphyrinogen oxidase activity. Protein sequence analysis of HemK-related proteins revealed consensus motif for S-adenosyl-methionine-dependent methyltransferase.

Amino Acid Sequence↗
PubMed1999

Characterization of an atypical superoxide dismutase from Sinorhizobium meliloti.

Sinorhizobium meliloti Rm5000 is an aerobic bacterium that can live free in the soil or in symbiosis with the roots of leguminous plants. A single detectable superoxide dismutase (SOD) was found in free-living growth conditions. The corresponding gene was isolated from a genomic library by using a sod fragment amplified by PCR from degenerate primers as a probe. The sodA gene was located in the chromosome. It is transcribed monocistronically and encodes a 200-amino-acid protein with a theoretical M(r) of 22,430 and pI of 5. 8. S. meliloti SOD complemented a deficient E. coli mutant, restoring aerobic growth of a sodA sodB recA strain, when the gene was expressed from the synthetic tac promoter but not from its own promoter. Amino acid sequence alignment showed great similarity with Fe-containing SODs (FeSODs), but the enzyme was not inactivated by H(2)O(2). The native enzyme was purified and found to be a dimeric protein, with a specific activity of 4,000 U/mg. Despite its Fe-type sequence, atomic absorption spectroscopy showed manganese to be the cofactor (0.75 mol of manganese and 0.24 mol of iron per mol of monomer). The apoenzyme was prepared from crude extracts of S. meliloti. Activity was restored by dialysis against either MnCl(2) or Fe(NH(4))(2)(SO(4))(2), demonstrating the cambialistic nature of the S. meliloti SOD. The recovered activity with manganese was sevenfold higher than with iron. Both reconstituted enzymes were resistant to H(2)O(2). Sequence comparison with 70 FeSODs and MnSODs indicates that S. meliloti SOD contains several atypical residues at specific sites that might account for the activation by manganese and resistance to H(2)O(2) of this unusual Fe-type SOD.

Amino Acid Sequence↗
PubMed1999

Economic outcomes of a targeted intervention program: the costs of treating allergic rhinitis patients.

OBJECTIVES: To determine the annual costs of treating allergic rhinitis patients in a managed care environment and to assess the effect of a treatment intervention program on direct and indirect costs. DESIGN: Two arms of an economics study were designed to calculate annual costs of treating allergic rhinitis in Lovelace Health Systems. Direct and indirect costs were also reviewed for patients participating in an intervention program designed to improve patient outcomes during the 1996 fall allergy season. PATIENTS AND METHODS: Annual medical costs of treating allergic rhinitis within the Lovelace system were reviewed using a patient database. A total of 7936 patients with allergic rhinitis symptoms were identified in the database using a case-finding algorithm. An equal number of patients without allergy conditions were selected for the comparison group. In addition to calculating annual costs of treating allergic rhinitis, direct and indirect costs were reviewed for patients participating in a rhinitis intervention program to determine differences in cost between the treatment and control groups. An intervention group of 247 patients was selected to receive care at clinics randomized to use practice guidelines to improve treatment, while 255 patients were treated in the control group clinics, which did not alter treatment practices. RESULTS: Annual expenditures were nearly $2 million more for the allergic rhinitis group than for the control group. In the intervention study, treatment and control groups expended the same in direct costs, but the intervention group showed a trend toward decreased indirect costs. CONCLUSION: Costs of allergic rhinitis are not trivial to a managed care organization; a specifically designed intervention program shows potential for minimizing the costs associated with the ailment.

Anti-Allergic Agents↗
PubMed1999

BSE in Portugal: anticipating the decline of an epidemic.

BACKGROUND: Attention throughout Europe continues to focus on bovine spongiform encephalopathy (BSE), with increasing evidence linking it to the new variant of Creutzfeldt-Jakob disease in humans. In particular, recent attention has been directed at Portugal, where the incidence of confirmed BSE cases continues to rise. METHODS: We modelled the age-specific incidence of BSE in Portuguese-born cattle by birth cohort as a function of: the survival distribution; the cohort-specific incidence of BSE infection; the age-specific probability, conditional on survival, that an infected animal will experience clinical onset; and the under-reporting rate of BSE cases prior to 1998. RESULTS: We obtained good fits to the age-specific incidence of BSE by birth cohort in Portugal. Under a range of assumptions, the estimated incidence of BSE infection was relatively low initially, except possibly in the 1989 cohort, and then rose gradually between the 1992 and 1994 cohorts. The estimated decrease in infection incidence between the 1994 and 1995 cohorts probably reflects the effectiveness of the ban on the use of mammalian meat and bone-meal introduced in Portugal in mid-1994. Assuming no infections in animals born after June 1995, the models predict that the incidence of BSE cases in Portugal will peak in 1999 with BSE case-incidence declining thereafter. DISCUSSION: Our results illustrate the power of epidemiological analysis to detect decreasing trends in infection incidence prior to the resulting decrease in case incidence. The findings should inform the deliberations of the European Commission, which recently reported concerns about the sharp increase in case incidence from 1997 to 1998.

Adolescent↗
PubMed1998

Modification of Saccharomyces cerevisiae thermotolerance following rapid exposure to acid stress.

Thermotolerance was induced in cells of Saccharomyces cerevisiae YPH499 pre-exposed, during 10 min and in the presence of glucose, to a mild acid-stress with HCl at pH 3.5. Thermotolerance was not induced in cells exposed to a severe acid stress by 50 mM acetic acid at pH 3.5, or HCl at pH 2.5 or pH 2.0. Yeast cells pre-incubated under glucose starvation were found to be more tolerant to a lethal heat stress than cells pre-incubated in glucose-supplemented media, despite the pH value of the media (range 2.0-6.5) and the type of acidulant used (HCl or acetic acid). Moreover, the high thermotolerance exhibited by cells pre-incubated at pH 6.5 for 10 min under glucose starvation was not significantly modified by the acidification of the pre-incubation medium. Results are discussed based on the effect that glucose and a mild or severe acid stress have on plasma membrane H+-ATPase activity and on cytosolic pH values, estimated in a previous work.

Acetic Acid↗
PubMed1998

Principles for Sustainable Governance of the Oceans

Pressures being exerted on the ocean ecosystems through overfishing, pollution, and environmental and climate change are increasing. Six core principles are proposed to guide governance and use of ocean resources and to promote sustainability. Examples of governance structures that embody these principles are given.

Journal Article↗
PubMed1998

Genome diversity in temperate bacteriophages of Oenococcus oeni.

The genome structure of six bacteriophages of Oenococcus oeni was compared. Two distinct groups with no apparent restriction site conservation were defined. In members of the alpha group (fOgML34, fOg4029, fOg30 and fOg218) a 7.5 kb region containing the origin of DNA packaging (cos) was highly conserved. Stretches of DNA heterogeneity could also be assigned to particular regions and were mostly evident in the right area of the genomes. fOg44 and fOgPSU1 (beta group) were indistinguishable in the left half of their genomes, including cos, but were markedly dissimilar in other regions. Strong labelling signals detected in cross-hybridizations involving members of different groups were confined to fragments centrally located in their physical maps. The attachment site (attP) of fOg44 was assigned to this conserved region. It is suggested that recombination events at this location may have been important in generating the observed diversity of oenophage genomes.

Bacteriophages↗
PubMed1998

[Current concepts in maxillo-facial surgery].

The authors make a brief and concise overview of the evolution of maxillofacial surgery over the last decades namely the concepts and methods used. Some case reports are presented which illustrate the application of the current methodology with the purpose of covering various fields of application (traumatologic, othognatic and tumoural). The need for an interdisciplinary assessment of these patients is discussed.

Adolescent↗
PubMed1997

Severe latex allergy after a vaginal examination during labor: a case report.

There has been an alarming increase in latex allergy, which can be a potential cause of occupational atopic disease. Physicians should be aware of this entity in high-risk groups and in patients with other allergies. A 32-year-old pregnant woman, with an allergy to orange juice, was first seen with a 39-week pregnancy in the labor room, where she had on two occasions a severe atopic reaction when examined with a latex glove. A latex allergy was suspected, and management with hydrocortisone resulted in remission of symptoms. Two hours later a vaginal delivery was performed with nonlatex, nonvinyl gloves. A week later immunoglobulin E antilatex antibodies determined by radioallergosorbent test were still positive at 585 IU. It is concluded that symptoms of latex allergy may develop in high-risk groups or in those with other known allergies. Because of the increasing frequency of this entity, physicians should take greater care and give more attention to the clinical history, as well as be aware of this possibility in these groups of patients.

Adult↗