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Biomedical subjects

R Ramírez

Publications and source records attributed to R Ramírez.

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

Cluster analysis of antinuclear autoantibodies in the prognosis of SLE nephropathy: are anti-extractable nuclear antibodies protective?

To investigate the possible role of anti-ENA autoantibodies in the pathogenesis of SLE nephropathy, we performed a cross sectional clustering study of 91 SLE patients using 75 clinical and laboratory variables examining the presence of anti-dsDNA and ENA autoantibodies by ELISA and Western blot. We applied principal component, hierarchical cluster, multiple correspondence and logistical regression analysis. Two polar forms of SLE nephropathy and five clinical groups were identified: group 1 without overt nephropathy (n = 37), group 2 with nephropathy and only proteinuria (n = 19), group 3 nephropathy and only hematuria (n = 11), group 4 with hematuria and proteinuria (n = 14) and group 5 on renal failure (n = 10). When analyzed individually, levels of anti-dsDNA and single anti-ENA antibodies did not allow us to differentiate between renal and non-renal groups. However, when the anti-ENA autoantibodies were analyzed as a cluster, a high predictive value for clinical nephropathy was obtained. Thus, the absence of ENA antibodies (ENA ve or Venezuelan cluster) increased eleven-fold the odds ratio to develop SLE nephropathy. We suggested that the ENA ve cluster may predict development of the most severe forms of renal lupus while the ENA Sm/RNP and the ENA Ro/La/Sm/RNP clusters could be associated with the absence and the most benign form of SLE nephropathy. It must be interesting to apply similar cluster methodology in an SLE population with different ethnic background.

Adolescent↗
PubMed2000

[Thyroid lymphoma. A case report].

Thyroid lymphoma represents less than 1% of malignant thyroid tumors and its diagnosis is difficult. We report a 25 years old woman, admitted with the diagnosis of diffuse euthyroid goiter and thyroid cancer. She was subjected to a subtotal thyroidectomy and the pathological study of the surgical piece showed a Hodgkin lymphoma, subtype nodular sclerosis. The patient was treated with three cycles of chemotherapy, using cyclophosphamide, vincristine, procarbazine, prednisone, doxorubicin, blemycin, vinblastin and radiotherapy. She refused to continue treatment after the third cycle and after 3 years and 5 months of follow up, is well and free of disease.

Adult↗
PubMed2000

[Congenital malformations in the offspring of diabetic mothers].

The offspring of diabetic mothers have a 10 times higher frequency of congenital malformations and 5 times higher frequency of spontaneous abortions. Since the discovery of insulin, the prognosis of pregnancies has improved, both for the mother and the offspring. However, the prevalence of congenital malformations at birth has not decreased significantly. The embryological process that leads to anomalies in the offspring of diabetic mothers probably occurs between 6 and 8 weeks of gestation. According to animal experiments, hyperglycemia, ketones and free radicals may be involved in the genesis of malformations, but different strains of rats respond differently to these potential teratogenic agents. Possibly, a higher genetic susceptibility towards congenital malformations also plays a role in diabetic women. Therefore, although the intimate mechanism producing malformations in the offspring of diabetic women is not known, several strategies to decrease the prevalence of malformations in these women, such as the use of antioxidants, are being tested.

Abnormalities, Drug-Induced↗
PubMed1999

The humoral immune response to the kinetoplastid membrane protein-11 in patients with American leishmaniasis and Chagas disease: prevalence of IgG subclasses and mapping of epitopes.

The kinetoplastid membrane protein-11 (KMP-11) is a major target of the humoral immune response during Leishmania-infections. The majority of sera from visceral leishmaniasis, mucocutaneous leishmaniasis and even some cutaneous leishmaniasis patients contain detectable IgG antibodies against KMP-11. We also provide evidence that this protein may act as a potent antigen in T. cruzi infections, since most Chagas sera show immunological cross-reactivity. Therefore, KMP-11 cannot be used as a specific diagnostical tool for the serodiagnosis of leishmaniasis in those regions where both, Leishmania and T. cruzi infections overlap geographically. When analyzing the subclass specificity of the antibody response to KMP-11 we observed the following order of reactivity: IgG1 > > IgG3 > IgG2 > IgG4, which is similiar to that seen in crude parasite extract. The mapping of antigenic determinants by using synthetic 20-mer peptides revealed the existence of predominantly conformational epitopes in leishmaniasis, while 50% of sera from Chagas patients reacted with a particular KMP-11 peptide. These results therefore suggest the presence of disease-specific B-cell epitopes.

Amino Acid Sequence↗
PubMed1999

NO induces a cGMP-independent release of cytochrome c from mitochondria which precedes caspase 3 activation in insulin producing RINm5F cells.

Exposure of RINm5F cells to interleukin-1beta and to several chemical NO donors such as sodium nitroprusside (SNP), SIN-1 and SNAP induce apoptotic events such as the release of cytochrome c from mitochondria, caspase 3 activation, Bcl-2 downregulation and DNA fragmentation. SNP exposure led to transient activation of soluble guanylate cyclase (sGC) and prolonged protein kinase G (PKG) activation but apoptotic events were not attenuated by inhibition of the sGC/PKG pathway. Prolonged activation of the cGMP pathway by exposing cells to the dibutyryl analogue of cGMP for 12 h induced both apoptosis and necrosis, a response that was abolished by the PKG inhibitor KT5823. These results suggest that NO-induced apoptosis in the pancreatic beta-cell line is independent of acute activation of the cGMP pathway.

Animals↗
PubMed1999

Clinical and urodynamic evaluation after ureterocystoplasty with different amounts of tissue.

PURPOSE: Ureter is one of the best tissues for bladder augmentation. The amount of ureteral segment available is extremely variable among patients. We compared results in patients who underwent ureterocystoplasty with 2 ureters, 1 complete ureter or a distal segment only after transureteroureterostomy. MATERIALS AND METHODS: During a 6-year period we performed 32 ureterocystoplasties at 2 pediatric centers in Argentina (16) and Chile (16). Median patient age at surgery was 9 years (range 4 months to 20 years). Clinical presentation included urinary infection, hydronephrosis, incontinence and undiversion. The diagnosis was neurogenic bladder in 20 cases, infravesical obstruction in 7, massive reflux in 3 and ureterocele in 2. All patients had poor bladder compliance and vesicoureteral reflux. We used different options to augment the bladder, including 2 ureters in 5 patients, bilateral nephrectomy in 3, a complete duplex system in 1 and a bilateral partial ureter in 1 (group 1); a complete ureter in 14 (group 2), and a distal segment of ureter with transureteroureterostomy in 13 (group 3). When transureteroureterostomy was performed, a suprapubic tube remained indwelling for 2 weeks and a Double-J stent was placed for 1 month. Median followup was 16 months (range 4 months to 6 years). Clinical and radiological evaluations, including ultrasound, cystography, urodynamics, renal scan and renal function measurement, were done 4 months postoperatively and twice yearly thereafter as needed. RESULTS: We noted no significant difference in bladder capacity when 1 or 2 ureters were used. Median increase in bladder capacity in groups 1 and 2 was 375% (range 80 to 800). All patients who received a complete segment of ureter had clinical improvement, decreased hydronephrosis and resolution of reflux with improved bladder compliance. When a partial segment of ureter was used median capacity increased 230% (range 40 to 400) with clinical improvement in 12 patients (92.3%). Compliance improved, which led to longer intervals between clean intermittent catheterizations. No patient has needed repeat augmentation to date. CONCLUSIONS: There is a difference in median increased bladder capacity when a segment of distal ureter is used to augment the bladder versus 1 or 2 whole ureters. However, the use of distal ureter still represents a safe alternative for augmenting the bladder and simultaneously resolving massive reflux. Ureterocystoplasty is an excellent choice for increasing bladder capacity and improving bladder compliance despite the different amounts of tissue available.

Adolescent↗
PubMed1999

Allergens induce apoptosis in lymphocytes from atopic patients.

Repeated stimulation of immune cells may induce an "activation-induced cell death" (AICD) program. Allergy is characterized by the cyclic activation of allergen-reactive immune cells. To study the effects of allergen stimulation in cell proliferation and apoptosis in atopic subjects, peripheral blood mononuclear cells (PBL) from 40 atopic patients with positive reactivity to the allergens Olea Europaea (OE) and Lollium Perenne (LP) (20 without immunotherapy and 20 with specific immunotherapy) and 10 normal subjects were cultured with the allergens OE and LP. PBL from atopic patients proliferate more vigorously than cells from normal subjects after culture in vitro with both allergens, although PBL from atopic subjects without immunotherapy proliferate more than PBL from atopic subjects with immunotherapy. The study of cell proliferation shows that in atopic patients PBL mainly exhibit the CD4/CD45RO phenotype. This preferential proliferation is more evident in PBL from atopic patients treated without immunotherapy. Cell culture with specific allergens induces apoptosis in PBL from atopic patients. The percentage of apoptosis increased when atopic patients had been previously treated with immunotherapy. In addition to the observed increase in cell proliferation, apoptosis mainly occurs in the CD45RO cells that support the involvement of these cells in allergy. Furthermore, results obtained in cells from immunized patients suggest that an AICD process may partly at least explain the mechanism of action of allergen immunotherapy.

Allergens↗
PubMed1999

Screening for fibrinolytic activity in eight Viperid venoms.

Snake venoms contain direct-acting fibrinolytic metalloproteinases (MMP) that could have important applications in medicine. Fibrinolytic enzymes isolated from venom can induce in vitro clot lysis by directly acting on a fibrin clot. The most ideal fibrinolytic enzyme would have high affinity for clots, dissolve clots directly without causing hemorrhage, and would not be neutralized in vivo by endogenous metalloproteinase inhibitors. The purpose of this study was to compare DEAE/HPLC venom profiles from Viperid snakes and identify fractions that contain fibrinolytic activity with no hemorrhagic activity and are not neutralized by animal sera. The sera selected were from four (Virginia opossum, Gray woodrat, Mexican ground squirrel, and Hispid cottonrat) animals known to neutralize hemorrhagic activity in snake venoms. Nineteen fractions from the Viperid venoms had fibrinolytic activity. Agkistrodon venom fractions contained the highest specific fibrinolytic activities. A. piscivorus leucostoma fraction 4 contained a high specific fibrinolytic activity, no hemorrhagic activity, and the fibrinolytic activity was not neutralized by the proteinase inhibitors of the four animal sera. A. contortrix laticinctus fraction 1 also had a high specific fibrinolytic activity and no hemorrhagic activity. However, the fibrinolytic activity was neutralized by Didelphis virginiana (Virginia opossum) serum.

Animals↗
PubMed1999

Coefficient of restitution of colliding viscoelastic spheres.

We perform a dimension analysis for colliding viscoelastic spheres to show that the coefficient of normal restitution epsilon depends on the impact velocity g as epsilon=1-gamma(1)g(1/5)+gamma(2)g(2/5)-/+..., in accordance with recent findings. We develop a simple theory to find explicit expressions for coefficients gamma(1) and gamma(2). Using these and few next expansion coefficients for epsilon(g) we construct a Padé approximation for this function which may be used for a wide range of impact velocities where the concept of the viscoelastic collision is valid. The obtained expression reproduces quite accurately the existing experimental dependence epsilon(g) for ice particles.

Journal Article↗
PubMed1999

Acidic fibroblast growth factor induces an antifibrogenic phenotype in human lung fibroblasts.

Acidic fibroblast growth factor (FGF-1), a prototype member of the heparin-binding growth factor family, influences proliferation, differentiation, and protein synthesis in different cell types. However, its possible role on lung extracellular matrix (ECM) metabolism has not been evaluated. In this study we examined the effects of FGF-1 and FGF-1 plus heparin on type I collagen, collagen-binding stress protein HSP47, interstitial collagenase (matrix metalloproteinase [MMP]-1), gelatinase A, and tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 expression by normal human lung fibroblasts. Heparin was used because it enhances the biologic activities of FGF-1. Fibroblasts were exposed either to 20 ng/ml FGF-1 plus 100 micrograms/ml heparin for 48 h or to FGF-1 or heparin alone. Messenger RNA (mRNA) expression was analyzed by Northern blot. Collagen synthesis was evaluated by digestion of [3H]collagen with bacterial collagenase, MMP-1 by Western blot, and gelatinolytic activities by zymography. Our results show that FGF-1 induced collagenase mRNA expression, which was strongly enhanced when FGF-1 was used with heparin. Likewise, both FGF-1 and FGF-1 plus heparin reduced by 70 to 80% the expression of type I collagen transcript, in part through effect on pro-alpha1(I) collagen mRNA stability. A downregulation of HSP47 gene expression was also observed. Synthesis of collagen and collagenase proteins paralleled gene expression results. FGF-1 activities were abolished with genistein, a tyrosine kinase inhibitor. Neither FGF-1 nor FGF-1 plus heparin affected the expression of TIMP-1, TIMP-2, and gelatinase A. These findings demonstrate that FGF-1, mostly in the presence of heparin, upregulates collagenase and downregulates type I collagen expression that might have a protective role in avoiding collagen accumulation during lung ECM remodeling.

Collagen↗
PubMed1999

The Spanish Alcohol Use Disorder and Associated Disabilities Interview Schedule (AUDADIS): reliability and concordance with clinical diagnoses in a Hispanic population.

OBJECTIVE: The study reports the process of translation into Spanish and adaptation to the Hispanic culture of the Alcohol Use Disorder and Associated Disabilities Schedule (AUDADIS). This instrument is a structured diagnostic interview schedule specifically developed for the assessment of substance-related disorders and their comorbid disorders and disabilities. METHOD: A random sample (N = 169) of adults from a primary health care clinic in Puerto Rico was selected. The test-retest reliability of the instrument was examined across time and across interviewers, and the validity was assessed by comparing computer-derived diagnoses obtained through the administration of lay interviewers with best estimate diagnoses given by board-certified psychiatrists. RESULTS: For most diagnoses and symptoms studied, as well as for most of the alcohol consumption measures, the test-retest reliability of the Spanish AUDADIS was consistent with results reported in other national and international studies using this instrument. Good to excellent test-retest reliability was obtained for the diagnoses of alcohol dependence and major depression. Similarly, good to excellent agreement was obtained between the lay administered AUDADIS and best estimate diagnoses for most diagnostic categories, with the exception of dysthymia. As in other studies, the reliability and validity of the substance abuse category was poor. When agreement for this category was estimated independent of lifetime dependence, both the reliability and validity coefficients were considerably improved. CONCLUSIONS: The Spanish AUDADIS generally demonstrates good to excellent levels of reliability and validity that are comparable to findings reported for this instrument in other national and international studies.

Adult↗
PubMed1999

[Dual photon absorptiometry in full-term newborns].

BACKGROUND: There is scanty information about bone mineral density in newborns. Normal values are needed to assess the effects of diseases and drugs used during the neonatal period. AIM: To assess bone mineral density in normal newborns. PATIENTS AND METHODS: Total body bone mineral density was measured in 16 newborns with 39 +/- 1.2 weeks of gestational age, using a Norland dual photon densitometer. RESULTS: The mean weight of newborns was 3.366 +/- 325 g. Bone mineral content was 58.3 +/- 10.8 g and bone mineral density was 0.369 +/- 9.6 g/cm2. RESULTS: The availability of normal bone mineral content values in newborns will be useful for the assessment of conditions that affect bone mineralisation.

Absorptiometry, Photon↗
PubMed1998

[Seroepidemiologic study of cytomegalovirus in childbearing age women in the community of Madrid].

BACKGROUND: The determination of seroprevalence against cytomegalovirus in women from the Autonomous Region of Madrid (Spain), and the study of risk factors associated with the infection. MATERIAL AND METHOD: Cytomegalovirus specific IgG was studied in serum samples from the women included in the 2nd Serosurvey of the Autonomous Region of Madrid. RESULTS: Seroprevalence was 75.6%, ranging from 60.6% (age group 15-24 yr) to 94.6% (36-45), being significantly higher in mothers and in those living in stacking conditions, and significantly lower in women with university studies. CONCLUSIONS: Cytomegalovirus infection is frequent in childbearing women from Madrid, more than 30% of them could be infected.

Adolescent↗
PubMed1998

The effect of early dexamethasone administration on bronchopulmonary dysplasia in preterm infants with respiratory distress syndrome.

OBJECTIVES: This study was carried to evaluate the effect of early administration of dexamethasone on the incidence of bronchopulmonary dysplasia (BPD) and/or death in surfactant-treated preterm infants with respiratory distress syndrome (RDS). STUDY DESIGN: In a multicenter, double-blind, placebo-controlled trial, 109 preterm infants with RDS and birth weights between 700 and 1600 gm, who were treated with mechanical ventilation and surfactant, were randomly assigned before 36 hours of life to receive dexamethasone (n = 55) or placebo (n = 54) for 12 days. RESULTS: There were no differences in the incidence of BPD and/or death between groups. However, fewer patients in the dexamethasone group were oxygen-dependent at 36 weeks after conception (8% vs 33%, p < 0.05). The dexamethasone group had a lower incidence of necrotizing enterocolitis (0% vs 9%, p < 0.05). The incidence of arterial hypertension, hyperglycemia, and sepsis was not affected by the treatment. Basal and poststimulation serum cortisol levels did not differ between groups. CONCLUSION: The administration of dexamethasone early in the course of RDS does not decrease the incidence of BPD and/or death in preterm infants. However, dexamethasone may reduce oxygen dependency at 36 weeks after conception.

Anti-Inflammatory Agents↗