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Biomedical subjects

E Fernandez

Publications and source records attributed to E Fernandez.

At least 91 records · Page 5Linked to original sources
PubMed1999

Parathyroid function as a determinant of the response to calcitriol treatment in the hemodialysis patient.

BACKGROUND: Bolus calcitriol (CTR) is used for the treatment of secondary hyperparathyroidism in dialysis patients. Although CTR treatment reduces parathyroid hormone (PTH) levels in many dialysis patients, a significant number fail to respond. METHODS: To learn whether or not an analysis of parathyroid function could further illuminate the response to CTR, a PTH-calcium curve was performed before and after at least two months of CTR treatment in 50 hemodialysis patients with a predialysis intact PTH of greater than 300 pg/ml. RESULTS: For the entire group (N = 50), CTR treatment resulted in a 24% reduction in predialysis (basal) PTH from 773 +/- 54 to 583 +/- 71 pg/ml (P < 0.001), whereas ionized calcium increased from 1.10 +/- 0.02 to 1.22 +/- 0.02 mM (P < 0.001); however, maximal and minimal PTH did not change from pre-CTR values. Based on whether or not the basal PTH decreased by 40% or more during CTR treatment, patients were divided into responders (Rs, N = 25) and nonresponders (NRs, N = 25). Before CTR, the NR group was characterized by a greater basal (959 +/- 80 vs. 586 +/- 51 pg/ml, P < 0.001) and maximal (1899 +/- 170 vs. 1172 +/- 108 pg/ml, P < 0. 001) PTH and serum phosphorus (6.14 +/- 0.25 vs. 5.14 +/- 0.34 mg/dl, P < 0.01). Logistical regression analysis showed that the pre-CTR basal PTH was the most important predictor of the post-CTR basal PTH, and a pre-CTR basal PTH of 750 pg/ml represented a 50% probability of a response. Basal PTH correlated with the ionized calcium in the NR group (r = 0.59, P = 0.002) but not in the R group (r = 0.06, P = NS). In the R group, an inverse correlation was present between ionized calcium and the basal/maximal PTH ratio, an indicator of whether calcium is suppressing basal PTH secretion relative to the maximal secretory capacity (maximal PTH) r = -0.55, P = 0.004; in the NR group, this correlation approached significance but was positive (r = 0.34, P = 0.09). After CTR treatment, serum calcium increased in both groups, and despite marked differences in basal PTH (Rs, 197 +/- 25 vs. NRs, 969 +/- 85 pg/ml), an inverse correlation between ionized calcium and basal/maximal PTH was present in both groups (Rs, r = -0.61, P = 0.001, and NRs, r = -0.60, P = 0.001). CONCLUSIONS: (a) Dynamic testing of parathyroid function provided insights into the pathophysiology of PTH secretion in hemodialysis patients. (b) The magnitude of hyperparathyroidism was the most important predictor of the response to CTR. (c) Before CTR treatment, PTH was sensitive to calcium in Rs, and serum calcium was PTH driven in NRs, and (d) after the CTR-induced increase in serum calcium, calcium suppressed basal PTH relative to maximal PTH in both groups.

Calcitriol↗
PubMed1999

CD36 deficiency is frequent and can cause platelet immunization in Africans.

BACKGROUND: CD36 is expressed on several cell lineages. About 5 to 10 percent of Asians lack platelet membrane CD36 (pCD36), but the frequency of pCD36 deficiency in other ethnic groups is not known. Persons who are pCD36-negative are apparently healthy but can develop CD36 isoimmunization. STUDY DESIGN AND METHODS: The pCD36 phenotype was studied in 1885 subjects belonging either to a group of 1127 healthy French blood donors (almost all of whom were white Europeans) or to a group of 758 patients of known ethnic origin. RESULTS: No pCD36-negative persons were found among the blood donors. Only 1 of the 301 white European patients was pCD36-negative. In contrast, 16 of the 206 sub-Saharan Africans was pCD36-negative, a proportion higher than that among that black Caribbeans (1/148, p<0.01). The frequency of pCD36-negative patients was similar in blacks with and without sickle cell disease. Monocyte CD36 (mCD36) expression was studied in 15 of 22 pCD36-negative individuals: it was <10 percent in 7 subjects (type I deficiency) and between 12 and 100 percent in 8 others (type II deficiency). Thirteen pCD36-negative individuals had risk factors for immunization, and 4 had anti-CD36. Some had a history resembling posttransfusion purpura (n = 2), platelet transfusion refractoriness (n = 1), and recurrent miscarriage (n = 1). No correlation was found between immunization and the amount of mCD36. Anti-CD36 from an immunized type II-deficient woman reacted with monocytes from normal controls but not with monocytes from type I- or type II-deficient individuals, and thus it is postulated that mCD36 could be structurally different in normal and type II CD36-deficient individuals. CONCLUSION: CD36 deficiency is frequent in sub-Saharan Africans; development of anti-CD36 can lead to serious complications in multiply transfused patients, such as those with sicke cell disease.

Adult↗
PubMed1999

Fish consumption and cancer risk.

BACKGROUND: Although several studies have investigated the relation between fish consumption and the risk of cardiovascular diseases, less attention has been paid to the relation between fish consumption and cancer risk. OBJECTIVE: The relation between frequency of consumption of fish and risk of selected neoplasms was analyzed by using data from an integrated series of case-control studies conducted in northern Italy between 1983 and 1996. DESIGN: The overall data set included the following incident, histologically confirmed neoplasms: oral cavity and pharynx (n = 181), esophagus (n = 316), stomach (n = 745), colon (n = 828), rectum (n = 498), liver (n = 428), gallbladder (n = 60), pancreas (n = 362), larynx (n = 242), breast (n = 3412), endometrium (n = 750), ovary (n = 971), prostate (n = 127), bladder (n = 431), kidney (n = 190), thyroid (n = 208), Hodgkin disease (n = 80), non-Hodgkin lymphomas (n = 200), and multiple myelomas (n = 120). Control subjects were 7990 patients admitted for acute, nonneoplastic conditions unrelated to long-term modifications of diet. Odds ratios (ORs) were computed for subsequent levels of fish consumption compared with no or occasional consumption (<1 serving/wk) by using multiple logistic regression, including terms for several covariates. RESULTS: There was a consistent pattern of protection against the risk of digestive tract cancers with fish consumption: oral cavity and pharynx, OR = 0.5 for the highest compared with the lowest level of consumption; esophagus, OR = 0.6; stomach, OR = 0.7; colon, OR = 0.6; rectum, OR = 0.5; and pancreas, OR = 0.7. There were inverse trends in risk of larynx (OR = 0.7), endometrial (OR = 0.8), and ovarian (OR = 0.7) cancers and multiple myeloma (OR = 0.5). No pattern of cancer risk in relation to fish consumption was observed for cancers of the liver, gallbladder, breast, bladder, kidney, or thyroid or for lymphomas. CONCLUSION: This study suggests that the consumption of even relatively small amounts of fish is a favorable indicator of the risk of several cancers, especially of the digestive tract.

Adult↗
PubMed1999

Gender inequalities in health and health care services use in Catalonia (Spain).

BACKGROUND AND OBJECTIVES: While socio-economically derived differences in health and health services use have long been a subject of study, differences based on gender, considered as the explicative variable, have scarcely been quantified from population-based data. The aim of this investigation was to analyse inequalities in health and health care services utilisation between men and women in Catalonia (Spain). DESIGN, SETTING, PARTICIPANTS, AND MEASURES: Data from the Catalan Health Interview Survey, a cross sectional survey conducted in 1994, were used. A total of 6604 women and 5641 men aged 15 years or over were included for analysis. Health related variables studied were self perceived health, restriction of activity (past two weeks), and presence of chronic conditions; health services use variables analysed were having visited a health professional (past two weeks), an optometrist (12 months), or a dentist (12 months); and hospitalisation (past 12 months). Age standardised proportions were computed according to gender, and prevalence odds ratios (OR) were derived from logistic regression equations. MAIN RESULTS: Women more frequently rated their health as fair or poor than men (29.8% v 21.4%; OR = 1.22; 95% CI: 1.10, 1.34). More women than men reported having restricted activity days (OR = 1.86; 95% CI: 1.59, 2.18) and chronic conditions (OR = 1.74; 95% CI: 1.60, 1.89). The proportion of women visiting a health professional was slightly greater than that for men (OR = 1.20; 95% CI: 1.09, 1.31), as was the proportion of women visiting an optometrist (OR = 1.21; 95% CI: 1.11, 1.33), and a dentist (OR = 1.43; 95% CI: 1.31, 1.55). The proportion of hospitalisation was lower in women (6.6%) than in men (7.7%; OR = 0.73; 95% CI: 0.63, 0.85). When health services use was analysed according to self perceived health, women declaring good health reported a greater probability of consulting a health professional (OR = 1.35; 95% CI: 1.20, 1.52). There were no differences in respect to hospitalisation, visits to the optometrist and to the dentist. CONCLUSIONS: These results indicate a pattern close to the inverse care law, as women, who express a lower level of health and thus would need more health care, are not, however, using health services more frequently than men.

Adolescent↗
PubMed1998

Accessibility of selenomethionine proteins by total chemical synthesis: structural studies of human herpesvirus-8 MIP-II.

The determination of high resolution three-dimensional structures by X-ray crystallography or nuclear magnetic resonance (NMR) is a time-consuming process. Here we describe an approach to circumvent the cloning and expression of a recombinant protein as well as screening for heavy atom derivatives. The selenomethionine-modified chemokine macrophage inflammatory protein-II (MIP-II) from human herpesvirus-8 has been produced by total chemical synthesis, crystallized, and characterized by NMR. The protein has a secondary structure typical of other chemokines and forms a monomer in solution. These results indicate that total chemical synthesis can be used to accelerate the determination of three-dimensional structures of new proteins identified in genome programs.

Amino Acid Sequence↗
PubMed1998

Neurons and fractals: how reliable and useful are calculations of fractal dimensions?

In the past 15 years it has become possible to determine the fractal dimension (Df) of complex objects, including neurons, by automated image analysis methods. However, there are many unresolved issues that need to be addressed. In this paper we discuss how the Df calculated by different methods may vary and how fractal analysis may be of use for retinal ganglion cell characterization. The goal of this work was to acknowledge inherent sources of variation during measurement and evaluate current fractal analysis methods for describing structure. Our results show that different algorithms and even the same algorithm performed by different computer programs and/or experimenters may give different but consistent numerical values. All described methods demonstrated their suitability for classifying cat retinal ganglion cells into distinct groups. Our results reinforce the idea that comparison of measurements of different profiles using the same measurement method may be useful and valid even if an exact numeric value of the dimension is not realised in practice.

Animals↗
PubMed1998

An evolutionary approach to the design of glutathione-linked enzymes.

Studies of protein structure provide information about principles of protein design that have come into play in natural evolution. This information can be exploited in the redesign of enzymes for novel functions. The glutathione-binding domain of glutathione transferases has similarities with structures in other glutathione-linked proteins, such as glutathione peroxidases and thioredoxin (glutaredoxin), suggesting divergent evolution from a common ancestral protein fold. In contrast, the binding site for glutathione in human glyoxalase I is located at the interface between the two identical subunits of the protein. Comparison with the homologous, but monomeric, yeast glyoxalase I suggests that new domains have originated through gene duplications, and that the oligomeric structure of the mammalian glyoxalase I has arisen by 'domain swapping'. Recombinant DNA techniques are being used for the redesign of glutathione-linked proteins in attempts to create binding proteins with novel functions and catalysts with tailored specificities. Enzymes with desired properties are selected from libraries of variant structures by use of phage display and functional assays.

Binding Sites↗
PubMed1998

Comparison of ultrasonography and hysteroscopy in the diagnosis of intrauterine lesions in infertile women.

STUDY OBJECTIVE: To compare the effectiveness of transvaginal ultrasound versus hysteroscopy in the diagnosis of benign intrauterine lesions, with histology as the gold standard. DESIGN: Retrospective study (Canadian Task Force classification II-1). SETTING: Unit of Reproductive Medicine, Department of Obstetrics and Gynecology of Clinica Las Condes, Santiago, Chile. PATIENTS: Infertile women who had undergone complete fertility evaluation. INTERVENTION: Transvaginal ultrasound, hysteroscopy, and histologic evaluation of endometrial samples performed in all 126 women. MEASUREMENTS AND MAIN RESULTS: The most frequent condition was a normal cavity (59.5%), followed by endometrial polyps (34.9%) and fibromyomas (3.9%). Synechiae and bone metaplasia were extremely rare. Sensitivity of transvaginal ultrasound for the diagnosis of endometrial polyps was 95.6% compared with 89.9% for hysteroscopy (NS). Specificity was 97.4% with transvaginal ultrasound versus 93. 3% with hysteroscopy (NS). Positive and negative predictive values were similar for both methods. CONCLUSION: Transvaginal ultrasound is as effective as hysteroscopy in diagnosing benign intrauterine lesions. It could be the first clinical diagnostic test in the investigation of the uterine cavity.

Female↗
PubMed1998

Synthesis of dahllite through a cement setting reaction.

Dahllite is a synthetic carbonated hydroxyapatite with a carbonate ion content similar to bone mineral. The first objective of this study was to investigate the stoichiometric conditions under which dahllite formation occurs in a powder mixture of alpha-Ca3(PO4)2, Ca(H2PO4)2 and CaCO3. The second objective was to identify how these conditions apply to commercially available cement, Skeletal Repair System (SRS), and other alpha-Ca3(PO4)2-based cements currently under investigation. The stoichiometric coefficients were found to be a function of both the percentage of carbonate ions incorporated into the hydroxyapatite structure, and the amount of CO2 released during the reaction. As a consequence, a stability field has been obtained where different initial proportions of the reactants in the powder mixture should give the same reaction product if sufficient CO2 is released into the solution. However, increasing amounts of CaCO3 in the initial mixture have been shown to affect the solution pH in such a way that only partial reaction of the reactants takes place. SRS and other alpha-Ca3(PO4)2-based cements have been located inside the stability field and a comparison between their reported setting and hardening properties has been performed.

Journal Article↗
PubMed1998

Emergency admission for cancer: a matter of survival?

The objective of this study was to compare the pre-hospital health care process, clinical characteristics at admission and survival of patients with a digestive tract cancer first admitted to hospital either electively or via the emergency department. The study involved cross-sectional analysis of information elicited through personal interview and prospective follow-up. The setting was a 450-bed public teaching hospital primarily serving a low-income area of Barcelona, Catalonia, Spain. Two hundred and forty-eight symptomatic patients were studied, who had cancer of the oesophagus (n = 31), stomach (n = 70), colon (n = 82) and rectum (n = 65). The main outcome measures were stage, type and intention of treatment and time elapsed from admission to surgery; the relative risk of death was calculated using Cox's regression. There were 161 (65%) patients admitted via the emergency department and 87 (35%) electively. The type of physician seen at the first pre-hospital visit had more often been a general practitioner in the emergency than in the elective group (89% vs 75%, P < 0.01). Emergency patients had seen a lower number of physicians from symptom onset until admission, but two-thirds had made repeated visits to a primary care physician. Emergency patients were less likely to have a localized tumour and a diagnosis of cancer at admission, and surgery as the initial treatment. Median survival was 30 months for elective patients and 8 months for emergency patients (P < 0.001), and the relative risk of death (RR) was 1.83 (95% confidence interval, CI, 1.32-2.54). After adjustment for strong prognostic factors, emergency patients continued to experience a significant excess risk (RR = 1.58; CI 1.10-2.27). In conclusion, in digestive tract cancers, admission to hospital via the emergency department is a clinically important marker of a poorer prognosis. Emergency departments can only partly counterbalance deficiencies in the effectiveness of and integration among the different levels of the health system.

Adult↗
PubMed1998

Improved exercise performance following lung volume reduction surgery for emphysema.

Lung volume reduction surgery (LVRS) for emphysema has been suggested to improve patient lung function and activity. The short-term impact of LVRS on exercise performance was evaluated using maximal and submaximal steady-state exercise testing in 27 patients with severe hypoxemic chronic obstructive pulmonary disease (COPD), along with measurements of patient function, dyspnea, and quality of life. LVRS significantly improved exercise performance, due to ventilatory improvements associated with increased ventilatory reserve, enhanced tidal volume recruitment, and improved alveolar ventilation. Preoperative measurements of ventilatory reserve and dead space ventilation during exercise testing were closely associated with improved exercise performance. Improvements in patient dyspnea, walk distances, and quality of life also occurred following LVRS and were associated with improvements in exercise performance. Surgical mortality from LVRS was low (4%), but short-term all-cause mortality was increased (19%). Short-term mortality was associated with reduced expiratory muscle strength and markedly elevated dead space ventilation. We conclude that LVRS produces significant improvements in exercise performance, dyspnea, and quality of life in selected patients with COPD. Physiologic prediction of patients most likely to survive for an extended period and have significant benefit following LVRS may also be possible.

Adult↗
PubMed1998

Neurofibromatosis type 2: growth stimulation of mixed acoustic schwannoma by concurrent adjacent meningioma: possible role of growth factors. Case report.

The authors report the case of a young man suffering from neurofibromatosis type 2 (NF2) who harbored bilateral acoustic schwannomas and a parasellar meningioma. Neuroimaging studies performed during a 4-year follow-up period showed that the bilateral schwannomas had grown very little and at similar rates. However, after the meningioma had infiltrated the tentorium and approached the ipsilateral schwannoma at the incisura, both Schwann cell tumors started to grow rapidly, particularly the one adjacent to the meningioma, of which the percentage of annual growth rate increased by approximately a factor of 10(2). At the same time, magnetic resonance imaging showed that this tumor also changed its features. During surgery, the acoustic schwannoma was firmly adherent to both meningioma and tentorium. Histological examination revealed meningotheliomatous cells in the schwannoma adjacent to the meningioma. Antiphosphotyrosine immunoblotting of PC12 cells was compatible with the presence of an epidermal growth factor (EGF)-like molecule in the cerebrospinal fluid (CSF) of the patient. This factor was not detected in the CSF of five other NF2 patients, two of whom bore associated bilateral acoustic schwannomas and meningioma in remote locations. It is hypothesized that the meningotheliomatous cells infiltrating the schwannoma triggered an autocrine/paracrine growth-stimulatory mechanism that involved an EGF-like factor.

Adolescent↗
PubMed1998

Malaria diagnosis by dipstick assay in a Honduran population with coendemic Plasmodium falciparum and Plasmodium vivax.

A Plasmodium lactate dehydrogenase dipstick designed to separately detect P. falciparum and P. vivax malaria was evaluated in two Honduran populations where both species are endemic. The dipstick was compared to thick film microscopy; the polymerase chain reaction (PCR) was used to analyze discordant results. The dipstick had a sensitivity of 100% and a specificity of 95% compared with microscopy in the diagnosis of Plasmodium infections in a hospital population; the mean parasite density was approximately 590/mm3. In a field sample of mostly asymptomatic volunteers, the sensitivity of the dipstick for Plasmodium infection varied with parasite density. Additionally, the sensitivity and specificity of the dipstick was similar to thick film microscopy in the diagnosis of vivax malaria compared with the PCR. The dipstick was unable to detect P. vivax in the presence of P. falciparum because of cross-reactivity in the pan-specific band. Accurate species identification in mixed infections remains a problem in malaria diagnosis.

Clinical Enzyme Tests↗
PubMed1998

Hormone replacement therapy and risk of colon and rectal cancer.

The hypothesis that sex hormones may influence colorectal cancer risk was formulated in the early 1980s, but epidemiological studies on a relationship between colorectal cancer risk and hormone replacement therapy (HRT) have only accumulated over the last few years. To investigate the relationship between HRT and colon and rectal cancer and the role of other covariates that might modify it, we analyzed combined data from two case-control studies conducted in Italy between 1985 and 1996, including 994 women with incident colon cancer, 542 with rectal cancer, and 3110 controls with acute, non-neoplastic, nondigestive, non-hormone-related disorders. Odds ratios (ORs) and 95% confidence intervals (CIs) were derived from unconditional multiple logistic regression equations including terms for age, center/study period, education, family history of colorectal cancer, status and age at menopause, parity, use of oral contraceptives, total energy intake, and body mass index. Ever use of HRT was inversely associated with cancer of the colon (OR = 0.64, 95% CI = 0.46-0.88) and of the rectum (OR = 0.46, 95% CI = 0.29-0.72). Increasing duration of use of HRT was related to decreasing risk for colon and rectal cancers (P for trend < 0.01). No interaction emerged, and the inverse association persisted across separate strata of other risk factors. This study, one of the largest case-control investigations on exogenous female hormones and colorectal cancer thus far, provides further evidence that women who have ever used HRT are at lower risk of colon and rectal cancer. Because colorectal cancer is the second most common neoplasm and cause of death among nonsmoking women in developed countries, these results may have a major public health impact.

Aged↗