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Biomedical subjects

C Lopez

Publications and source records attributed to C Lopez.

At least 55 records · Page 3Linked to original sources
PubMed1999

Comparison of ultrasound and dimercaptosuccinic acid scintigraphy changes in acute pyelonephritis.

The strategy for morphological investigations in children with acute pyelonephritis (APN) remains debatable. We studied 70 children (median age 2.0 years) admitted with a first episode of pyelonephritis using a high-resolution ultrasound technique (RUS) and compared the results with 99m technetium-dimercaptosuccinic acid (DMSA) renal scintigraphy. The DMSA scan was abnormal in 62 children (89%). However, using a high-frequency transducer we found abnormal sonogram changes in 61 children (87%), consisting of an increased kidney volume in 42, and/or a thickening of the wall of the renal pelvis in 42, and/or a focal hyper- or hypoechogenicity in 36, and/or a diffuse hyperechogenicity in 31 children. Micturating cystourethrography was performed in all children, revealing vesicoureteral reflux (VUR) in 22 (31%). Among those children with VUR, 4 had a normal DMSA scan, 2 an abnormal RUS, and 2 a normal DMSA scan and RUS. Our data suggest that B-mode RUS performed with a high-frequency transducer by a trained radiologist is nearly as sensitive as the DMSA scan in diagnosing renal involvement in children with unobstructed APN and in predicting VUR.

Acute Disease↗
PubMed1999

Differential parental communication with adolescents who are disabled and their healthy siblings.

PURPOSE: To examine the levels of parental communication and differential conversational styles with adolescents who are disabled and their healthy siblings, to better understand why the adolescent who is disabled has a higher risk of psychosocial problems during the transition into adulthood. METHODS: Families who had a disabled adolescent and at least one other adolescent who was not disabled were videorecorded during dinner at home. Twenty adolescents (12 girls and 8 boys) and their families participated. Analyses were conducted on the 392 interactions. RESULTS: Not only did the healthy adolescents participate in family interactions at higher frequencies than the adolescents who were disabled F(1, 383) = 14.00, p < .001, but the interactions were also more meaningful with healthy adolescents, F(2, 383) = 5.25, p < .01. Furthermore, healthy siblings had significantly greater conversational control than did their siblings with disabilities, chi2 (1) = 14.36, p < .001. Parents responded more negatively when adolescents who were disabled initiated a topic in comparison with their response to the healthy siblings, F(2, 69) = 5.44, p < .01. Finally, adolescents with disabilities were ignored more often than their healthy siblings, z = -3.75, p < .001, and they did not monopolize the conversation as often as did their healthy siblings, z = -3.91, p < .001. CONCLUSION: These results suggest that adolescents who are disabled may be at a disadvantage when engaged in family interactions in contrast with their healthy siblings.

Adolescent↗
PubMed1999

The extracellular domain of the human erythropoietin receptor: expression as a fusion protein in Escherichia coli, purification, and biological properties.

We developed an efficient production system of the soluble extracellular domain of the human erythropoietin receptor (sEPO-R) and characterized the binding of erythropoietin (EPO) with the purified recombinant protein. The sEPO-R, fused to the maltose binding protein (MBP), was expressed as a soluble protein in the periplasm of Escherichia coli (E. coli) and did not accumulate in inclusion bodies. After lysis of the bacteria by an osmotic shock, the fusion protein was purified by affinity chromatography on amylose followed by size exclusion chromatography (SEC). Specific binding of 125I-labelled EPO to the sEPO-R was demonstrated by competitive and saturation binding assays. A single affinity class (Kd = 0.25 nM) of the binding site was evident by Scatchard analysis. This value is similar to the Kd observed between EPO and the EPO-R of high affinity present on human erythroid progenitors. The complex has a molecular size corresponding to a 1:1 complex of EPO and the fusion protein.

ATP-Binding Cassette Transporters↗
PubMed1999

Toward an ecosocial view of health.

The changing patterns of health in the United States justify both celebration and dismay. We can celebrate declining mortality rates, increased life expectancy, and improvements in diagnostic and therapeutic technologies. But public health was caught by surprise by the return of infectious disease; the gap in health outcomes between rich and poor and between whites and blacks increases; there is a growing discrepancy between what is technically possible and the actual health status; and despite its greater expenditures on health, the United States lags behind the other developed countries in health outcomes. The authors examine four reasons for this: we do not buy more health care, only pay more for it; we receive more health care, but much of it inappropriate, ineffective, or harmful; only some of us get more health care; and we have created a way of life that makes us sick, then spend more to repair the damage. Major failures arise when problems are understood too narrowly. An ecosocial perspective attempts to look at the whole. It rejects as false the dichotomies social/biological, physical/psychological, genetic/environmental, lifestyle/environment, examining their interrelations rather than assigning them relative weights. In addition to looking at average differences among populations, the authors examine patterns of variability in health outcomes.

Adolescent↗
PubMed1999

[Pressure-flow urologic analysis in children: reflections after 20 years of practice].

Pressure-flow analysis in children allows optimal definition of the main urodynamic parameters of micturition and clarifies certain aspects of physiology and functional disorders. This examination has allowed urologists to establish reliable relationships between the findings of the clinical interview and clinical examination and the reality of urodynamic parameters, so that, after being widely used for more than 20 years, its indications have now become exceptional, limited to the detection of detrusor-sphincter pathophysiology and a few rare voiding disorders, poorly defined by clinical findings or imaging.

Child↗
PubMed1999

[Prenatal diagnosis of bilateral polycystic kidney disease in a twin pregnancy].

Polycystic renal dysplasia is a lethal malformation when it is bilateral. The authors report a rare case of polycystic dysplasia observed in both foetuses of a twin pregnancy, one of whom survived despite bilateral polycystic kidney disease. These biamniotic monoplacental twins were delivered prematurely at 33 weeks of amenorrhoea. The diagnosis was made by antenatal ultrasound. The first twin presented bilateral renal lesions: right polycystic kidney, segmental polycystic dysplasia of the superior pole of the left kidney on a completely duplicated system. The second twin presented a right polycystic kidney. In the light of this case report, the authors describe the various antenatal presentations of polycystic kidney and the associated urological malformations. Involvement of both foetuses of a twin pregnancy raises a discussion of the aetiopathogenesis of polycystic renal dysplasia.

Adult↗
PubMed1999

[Role of the ORL anesthetist in foreseen or unforseen difficult intubations].

Difficult intubation (DI) is a daily problem in a ENT unit. The place of the ENT anesthesiologist in the management of a DI is both in his own unit and in the hospital as an expert in DI. An anesthesiologist working in a ENT unit should be an expert in techniques allowing to manage intubation and oxygenation in every situations: i.e. fiberscopic intubation, LMA and intubating LMA and transtracheal ventilation. The ENT anesthesiologist may also play a role in the management of a DI in the hospital as an expert, both helping to cope with a difficult airway and teaching airway skills and the value of having a plan before managing any airway.

Anesthesiology↗
PubMed1998

Heat-shock protein 90 (hsp90) binds in vitro to tubulin dimer and inhibits microtubule formation.

Hsp90 interacts with steroid hormone receptors, protein kinases, and cytoskeletal proteins. The mode of action of hsp90 on microtubules and tubulin has not been investigated. Using isolated purified hsp90 and isolated tubulin, we demonstrated in vitro by difference absorption and fluorescence spectroscopy that hsp90 bound to tubulin with an apparent affinity constant of 5 x 10(5) M-1, assuming an apparent stoichiometry of 1 at 25 degrees C. Using microcalorimetry, we found a delta H of -9.8 +/- 0.8 kJ.mol-1. The binding of hsp90 to tubulin was confirmed by a sedimentation assay. Moreover, we showed that hsp90 inhibited tubulin polymerisation.

Animals↗
PubMed1998

Thermodynamic analysis of calcium and magnesium binding to calmodulin.

To elucidate some aspects still debated concerning the interaction of Ca2+ and Mg2+ with CaM, the thermodynamic binding parameters of Ca2+-CaM and Mg2+-CaM complexes were characterized by flow dialysis and isothermal microcalorimetry under different experimental conditions. In particular, the enthalpy and entropy changes associated with Ca2+ and Mg2+ binding to their sites were determined, allowing a better understanding of the mechanism underlying cation-CaM interactions. Ca2+-CaM interaction follows an enthalpy-entropy compensation relationship, suggesting that CaM explores a subspace of isoenergetical conformations which is modified by Ca2+ binding. This Ca2+-induced change in CaM dynamics is proposed to play a key role in CaM function, i.e. in its interaction with and/or activation of target proteins. Furthermore, data show that Mg2+ does not act as a direct competitor for Ca2+ binding on the four main Ca2+ binding sites, but rather as an allosteric effector. This implies that the four main Mg2+ binding sites are distinct from the EF-hand Ca2+ binding sites. Finally, Ca2+ is shown to interact with auxiliary binding sites on CaM. These weak affinity sites were thermodynamically characterized. The results presented here challenge the current accepted view of CaM ion binding.

Binding Sites↗
PubMed1998

Antiviral activity and toxicity of fialuridine in the woodchuck model of hepatitis B virus infection.

Woodchucks were used to study the antiviral activity and toxicity of fialuridine (FIAU; 1,-2'deoxy-2'fluoro-1-beta-D-arabinofuranosyl-5-iodo-uracil). In an initial experiment, groups of six chronic woodchuck hepatitis virus (WHV) carrier woodchucks received daily doses of FIAU by intraperitoneal injection for 4 weeks. At 0.3 mg/kg/d, the antiviral effect was equivocal, but at 1.5 mg/kg/d, FIAU had significant antiviral activity. No evidence of drug toxicity was observed during the 4-week period of treatment or during posttreatment follow-up. In a second experiment, groups of nine WHV carriers or uninfected woodchucks were given 1.5 mg/kg/d of FIAU orally for 12 weeks, and the results compared with placebo-treated controls. After 4 weeks, the serum WHV-DNA concentration in the FIAU-treated carrier group was two to three logs lower than that in the placebo-treated group. After 12 weeks of FIAU treatment, serum WHV DNA was not detectable by conventional dot-blot analysis, hepatic WHV-DNA replicative intermediates (RI) had decreased 100-fold, and hepatic expression of WHV core antigen was remarkably decreased. No evidence of toxicity was observed after 4 weeks, but, after 6 to 7 weeks, food intake decreased and, after 8 weeks, the mean body weights of woodchucks treated with FIAU were significantly lower than controls. Anorexia, weight loss, muscle wasting, and lethargy became progressively severe, and all FIAU-treated woodchucks died or were euthanized 78 to 111 days after treatment began. Hepatic insufficiency (hyperbilirubinemia, decreased serum fibrinogen, elevated prothrombin time), lactic acidosis, and hepatic steatosis were characteristic findings in the final stages of FIAU toxicity in woodchucks. The syndrome of delayed toxicity in woodchucks was similar to that observed previously in humans treated with FIAU, suggesting that the woodchuck should be valuable in future investigations of the molecular mechanisms of FIAU toxicity in vivo and for preclinical toxicological evaluation of other nucleoside analogs before use in patients.

Animals↗
PubMed1998

Seasonal variation and effects of age, food availability, size, gonadal development, and parasitism on the hemogram of mytilus galloprovincialis

The study of hemogram characteristics in a population of cultured mussels through a period of 18 months revealed that the concentration of circulating Mytilus galloprovincialis hemocytes varied, following a seasonal pattern, being positively correlated with water temperature. Most mussels had between 1 and 5 x 10(6) hemocytes/ml of hemolymph. Differential counts showed that M. galloprovincialis hemolymph contained more granulocytes than hyalinocytes. The hemolymph cell concentration was not associated with size or weight of mussels. Circulating hemocyte concentration did not decrease in mussels with reabsorbing gonad, despite the hemocytic accumulation inside and around gonad follicles. No significant difference in hemolymph cell concentration was found between two groups of mussels of different ages. Nevertheless, older mussels had higher mean values of circulating granulocytes although these differences were only significant in the winter sample. Infestation by the protistan Marteilia refringens caused a significant increase of hemocytes in the hemolymph. In addition, the occurrence of some parasites induced significant changes in the proportion of circulating hemocyte types. Results suggested that a hemocytic response was detected in hemolymph when the foreign organisms are pathogenic and evoke a heavy inflammatory reaction. Mussels with large or numerous granulocytomas had a higher number of circulating granulocytes and hyalinocytes than those without granulocytomas. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

The constitutive heat shock protein-70 is required for optimal expression of myelin basic protein during differentiation of oligodendrocytes.

To further elucidate the role of the constitutive heat shock protein-70 (HSC70) as a chaperone for the synthesis of myelin basic protein (MBP), HSC70 content was decreased in oligodendrocyte precursor cells prior to MBP expression either by transfection with an antisense oligonucleotide specific for HSC70, or by exposure to low levels of quercetin, a bioflavonoid known to decrease synthesis of HSC70. As these cells underwent differentiation in vitro, antisense treatment decreased HSC70 levels to 66% of controls. At the same time, a sharp induction resulted in the stress-inducible heat shock protein-70 (HSP70). Levels of two other stress proteins increased as well, namely, the 25-kDa heat shock protein (HSP25) and the 78-kDa glucose regulated protein (GRP78). MBP synthesis proceeded over a normal time course, but at only 50% of control values. As HSC70 content returned to normal, MBP synthesis was also restored to normal levels. Quercetin reduced the expression of HSC70 to an even greater extent than transfection, and prevented the induction of HSP70. In contrast to antisense-treated cells, MBP synthesis was essentially blocked in quercetin-treated cells even though levels of HSP25 and GRP78 increased. Taken together, these observations (a) indicate that HSP70 partially compensates for decreased chaperoning of nascent MBP by HSC70 (HSC70 and HSP70 are closely related and perform similar functions); (b) preclude the involvement of HSP25 and GRP78 in MBP synthesis; and (c) emphasize the requirement of HSC70 for optimal synthesis of MBP.

Animals↗
PubMed1998

[Varicocele in adolescents. Treatment by sclerotherapy and percutaneous embolization: reflections on the method. Apropos of 23 cases].

OBJECTIVE: The authors report their experience of the treatment of varicocele in adolescents. As a result of progress in interventional radiology and embolization techniques, they have used a technique combining sclerotherapy and percutaneous embolization since 1993. MATERIAL AND METHODS: Since 1993, twenty three adolescents between the ages of 11 and and 17 years (mean = 14.5 years) were treated percutaneously for grade II and II left varicocele. The operation was performed under local anaesthesia and/or neuroleptanalgesia. Phlebography by selective catheterization of the left spermatic vein was performed for anatomical assessment (ostial incontinence, collateral vessels). Embolization was then performed under fluoroscopic control by injection of a sclerosing liquid, sodium tetradecyl sulphate (Trombovar), and systematically completed by insertion of endovascular occlusive metal coils. RESULTS: The follow-up ranged from 6 to 48 months (mean = 30 months). The follow-up clinical and ultrasound examination showed complete disappearance of the varicocele in 22 cases (95% of cases), with a persistent grade I asymptomatic left varicocele in 1 case. No complications were observed. The mean hospital stay was 48 hours. CONCLUSION: This constitutes a rapid method, which is minimally traumatic for the adolescent. Its efficacy is comparable to that of classical surgical techniques with lasting results. Insertion of coils is the endovascular equivalent of surgical ligation of the pathological vein. The liquid embolus is particularly useful as it diffuses and scleroses collateral veins, responsible for recurrence. The advantage of this method resides in a better understanding of the reflux mechanisms, allowing the procedure to be adapted to the venous anatomy. This technique ensures treatment of complex varicoceles, such as postsurgical recurrences.

Administration, Cutaneous↗
PubMed1998

[Lung resections for cancer in the elderly].

BACKGROUND: The purpose of this study is to investigate the value of surgical treatment for lung cancer in the elderly. Results are compared with findings in younger patients operated on during the same period (1985-1990). METHODS: 137 patients 70 years of age or older (range: 70 yrs-87 yrs) (group A) underwent surgical resection [pneumonectomy in 19 (13.8%), lobectomy or bilobectomy in 84 (61.3%), segmentectomy or wedge resection in 22 (16%)]. In group B (younger patients) 561 were treated by pneumonectomy in 156 (27.8%), lobectomy or bilobectomy in 294 (52.4%) and segmentectomy or wedge resection in 64 (11.4%). RESULTS: The overall 2-year survival rate was 64.6% in group A and 61.4% in B. The 5-year survival rate was 36.2% (group A) and 43.2% (group B). CONCLUSIONS: These data suggest that advanced age should not be a contraindication to curative pulmonary resections. More attention must be paid to pre-codiseases of the increasing risk of postoperative complications.

Age Factors↗
PubMed1997

Enzymes Involved in Defense Functions of Hemocytes of Mussel Mytilus galloprovincialis

Mytilus galloprovincialis hemocytes contain phosphatases, esterases, proteases, and glucosidases as revealed by a semiquantitative colorimetric method. The activity levels of some enzymes changed throughout the months of the experiment without a seasonal pattern. No differences in the enzyme levels were found between the two groups of mussels of different age (cultivated 11 and 19 months on ropes hung from the same raft). Light microscopy study of hemocyte enzymes showed that hyalinocytes and granulocytes had reaction of acid phosphatase, beta-glucuronidase, alpha-naphthyl butyrate esterase, naphthol AS-D chloroacetate esterase, and alpha-naphthyl acetate esterase. Phenoloxidase and peroxidase activities were also detected in monolayers of hemocytes. Ultrastructural study revealed that the granules of hemocytes contained acid phosphatase, beta-glucuronidase, nonspecific esterases, peroxidase, and NADH oxidase. Products of beta-glucuronidase and peroxidase reaction were also localized in the plasma membrane. Lysozyme activity level was higher in hemocytes than in serum. Comparison between the two groups of different age showed a higher activity level of lysozyme in younger mussels.

Journal Article↗
PubMed1997

Omeprazole, a specific gastric secretion inhibitor on oxynticopeptic cells, reduces gizzard erosion in broiler chicks fed with toxic fish meals.

The relation between gizzard erosion-black vomit (GE-BV) and gastric secretion is not completely understood. A pharmacological approach to reduce the presence of GE-BV in chicks due to fish meal in diets is also unknown. In this study the use of omeprazole, a H+/K+ ATPase inhibitor, and fish meals of different biotoxicological characteristics, showed that: 1) Omeprazole decreased total gastric acid content, GE scores and severe GE (SGE) cases, in a dose-dependent manner. This reduction was significant at levels higher than 20 mg omeprazole/Kg body weight (BW)/day (p < 0.01). The addition of 50 mg omeprazole/kg BW/day almost completely prevented the incidence of SGE cases and reduced in 50% GE score in chicks (p < 0.01). 2) A significant reduction in specific mortality, near 90%, was also seen with all toxic fish meals when omeprazole (50 mg/Kg BW/day) was added to experimental diets in comparison to control groups. However, no mortality was observed when omeprazole was added to diets containing non-toxic fish meals. 3) In chicks fed with toxic fish meals, addition of different amounts of omeprazole to diets changed the relative weight of proventriculus (p < 0.01) and gizzard (p < 0.05). Maximum effect was obtained with omeprazole concentration higher than 50 mg/Kg BW/day. 4) Omeprazole did not change feed intake in chicks fed with toxic fish meal. However, in some fish meal a reduction on weight gain was observed with the addition of omeprazole.

Administration, Oral↗
PubMed1997

Multiple sclerosis: altered expression of 70- and 27-kDa heat shock proteins in lesions and myelin.

Recent studies have implicated heat shock proteins (HSP) in the pathogenesis of the multiple sclerosis (MS) lesion. Expression of the 73 kDa constitutive HSP (HSC70), the 72 kDa stress-inducible HSP (HSP70), and the 27 kDa small HSP (HSP27) was analyzed in white matter and myelin from central nervous system (CNS) tissue of MS and normal subjects using a combination of immunocytochemistry and quantitative immunoblotting. Plaques of all types were sharply defined by reduced immunostaining for HSC70, and shown by immunoblotting to contain 30 to 50% less HSC70 than surrounding white matter or normal tissue. In contrast, HSP27 was markedly enhanced 2.5- to 4-fold in plaque regions, especially in fibrous astrocytes and in hyperplastic interfascicular oligodendrocytes at the lesion edge. HSP70 was less abundant than HSC70, and no significant differences in HSP70 levels were noted between MS and normal white matter. Myelin isolated from active plaques contained 3- to 4-fold more HSC70 than normal myelin. Pronounced expression of HSP70 and HSP27 was also found in MS myelin, although neither protein was detected in normal myelin. Thus, white matter undergoing immune-mediated destruction in MS was associated with altered distribution and expression of HSC70 and HSP27. These changes may initially serve to protect myelin from further destruction and facilitate repair; however, enhanced expression of HSC70, HSP70, and HSP27 in myelin may subsequently present as additional immune targets involved in the progression of disease.

Astrocytes↗