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E Rodriguez

Publications and source records attributed to E Rodriguez.

At least 55 records · Page 3Linked to original sources
PubMed2000

A quantitative study of gamma-band activity in human intracranial recordings triggered by visual stimuli.

This paper studies gamma-band responses from two implanted epileptic patients during a simple visual discrimination task. Our main aim was to ascertain, in a reliable manner, whether evoked (stimulus-locked) and induced (triggered by, but not locked to, stimuli) responses are present in intracranial recordings. For this purpose, we introduce new methods adapted to detect the presence of gamma responses at this level of recording, intermediary between EEG-scalp and unicellular responses. The analysis relies on a trial-by-trial time-frequency analysis and on the use of surrogate data for statistical testing. We report that visual stimulation reliably elicits evoked and induced responses in human intracranial recordings. Induced intracranial gamma activity is significantly present in short oscillatory bursts (a few cycles) following visual stimulation. These responses are highly variable from trial to trial, beginning after 200 ms and lasting up to 500 ms. In contrast, intracranial-evoked gamma responses concentrate around 100 ms latencies corresponding to evoked responses observed on the scalp. We discuss our results in relation to scalp gamma response in a similar protocol [Tallon-Baudry et al. (1996) J. Neurosci., 16, 4240-4249] and draw some conclusions for bridging the gap between gamma oscillations observed on the scalp surface and their possible cortical sources.

Adolescent↗
PubMed2000

Basket catheter localization of the origin of atrial tachycardia with atypical morphology after atrial flutter ablation.

Atrial activation from a site in the low lateral right atrium will typically proceed in a superior direction. We present a case of a low lateral right atrial tachycardia with a surface electrocardiographic P wave morphology that appeared to have an inferiorly directed axis. The tachycardia occurred 2 years after successful atrial flutter ablation. The use of a multipolar basket catheter allowed confirmation of the focal origin of the tachycardia, permitted its rapid localization, facilitated catheter ablation, and provided clues to atrial activation that helped describe the appearance of the P wave.

Cardiac Catheterization↗
PubMed2000

Stimulation of glucose transport by thyroid hormone in 3T3-L1 adipocytes: increased abundance of GLUT1 and GLUT4 glucose transporter proteins.

In 3T3-L1 adipocytes we have examined the effect of tri-iodothyronine (T(3)) on glucose transport, total protein content and subcellular distribution of GLUT1 and GLUT4 glucose transporters. Cells incubated in T(3)-depleted serum were used as controls. Cells treated with T(3) (50 nM) for three days had a 3.6-fold increase in glucose uptake (P<0.05), and also presented a higher insulin sensitivity, without changes in insulin binding. The two glucose carriers, GLUT1 and GLUT4, increased by 87% (P<0.05) and 90% (P<0. 05), respectively, in cells treated with T(3). Under non-insulin-stimulated conditions, plasma membrane fractions obtained from cells exposed to T(3) were enriched with both GLUT1 (3. 29+/-0.69 vs 1.20+/-0.29 arbitrary units (A.U.)/5 microg protein, P<0.05) and GLUT4 (3.50+/-1.16 vs 0.82+/-0.28 A.U./5 microg protein, P<0.03). The incubation of cells with insulin produced the translocation of both glucose transporters to plasma membranes, and again cells treated with T(3) presented a higher amount of GLUT1 and GLUT4 in the plasma membrane fractions (P<0.05 and P<0.03 respectively). These data indicate that T(3) has a direct stimulatory effect on glucose transport in 3T3-L1 adipocytes due to an increase in GLUT1 and GLUT4, and by favouring their partitioning to plasma membranes. The effect of T(3) on glucose uptake induced by insulin can also be explained by the high expression of both glucose transporters.

3T3 Cells↗
PubMed2000

Clinical and programmatic mismanagement rather than community outbreak as the cause of chronic, drug-resistant tuberculosis in Buenaventura, Colombia, 1998.

SETTING: Buenaventura, Colombia. OBJECTIVE: To assess whether antituberculosis drug resistance was generated by poor management or community transmission. DESIGN: Treatment-failure and new tuberculosis (TB) patients identified between May 1997 and June 1998 were interviewed and their treatment histories reviewed. Bacteriologic testing, including drug susceptibility profiles (DSP) and DNA fingerprinting by restriction fragment length polymorphism (RFLP), was performed and human immunodeficiency virus (HIV) testing was offered. RESULTS: DSP and RFLP fingerprints were obtained for isolates from 34 of 64 treatment-failure patients; 25 (74%) were resistant to > or = one drug. Fifteen of the 25 patients consented to HIV testing; none were positive. An average of 2.8 major treatment errors per patient was identified. RFLP from the treatment-failure patients revealed 20 unique isolates and six clusters (isolates with identical RFLP); 4/6 clusters contained isolates with different DSP. Analysis of the RFLP from both treatment-failure and new patients revealed that 44/111 (40%) isolates formed 18 clusters. Four of 47 (9%) new patients had multidrug-resistant TB (MDR-TB). Eleven isolates belonged to the Beijing family, related to the MDR strain W. CONCLUSION: Drug resistance in Buenaventura results from both poor management and community transmission. Dependence on DSP to identify TB transmission is inadequate when programmatic mismanagement is common.

AIDS-Related Opportunistic Infections↗
PubMed1999

A defect in interleukin 12-induced activation and interferon gamma secretion of peripheral natural killer T cells in nonobese diabetic mice suggests new pathogenic mechanisms for insulin-dependent diabetes mellitus.

The function of natural killer T (NKT) cells in the immune system has yet to be determined. There is some evidence that their defect is associated with autoimmunity, but it is still unclear how they play a role in regulating the pathogenesis of T cell-mediated autoimmune diseases. It was originally proposed that NKT cells could control autoimmunity by shifting the cytokine profile of autoimmune T cells toward a protective T helper 2 cell (Th2) type. However, it is now clear that the major function of NKT cells in the immune system is not related to their interleukin (IL)-4 secretion. In fact, NKT cells mainly secrete interferon (IFN)-gamma and, activated in the presence of IL-12, acquire a strong inflammatory phenotype and cytotoxic function.

Animals↗
PubMed1999

Preimplantation genetic diagnosis for spinal muscular atrophy type I.

OBJECTIVE: Couples with children who have spinal muscular atrophy type I (SMA) face a 25% risk of having affected offspring with spontaneous conception. Preimplantation genetic testing (PGT) is possible for the deletions in the survival motor neuron (SMN) gene that have been identified in 98% of SMA type I cases. PGT would provide new reproductive options for families at risk for SMA. METHODS: Three couples with previously affected children confirmed by DNA testing each underwent in vitro fertilization (IVF) and PGT of the resulting embryos. One or two blastomeres were biopsied from each embryo and analyzed for deletions in exons 7 and 8 of the SMN gene. RESULTS: Nine embryos were predicted to be unaffected, three to be affected, and one embryo could not be interpreted. One of three patients receiving transfer of unaffected embryos became pregnant with twins. CONCLUSIONS: Preimplantation genetic testing provides a means for couples at risk for spinal muscular atrophy type I to reduce their chance of initiating an affected pregnancy.

Adult↗
PubMed1999

Von Willebrand disease as cause of unanticipated bleeding following adeno-tonsillectomy.

Von Willebrand disease (vWD) is a frequent autosomal bleeding disorder. We report two unsuspected patients over 6 years of age with this disease operated by tonsillectomy and adenoidectomy (T&A) at our Department. Preoperative hematologic work-up (with activated partial thromboplastic time, prothrombin time, fibrinogen, and platelet count) was normal. Both patients had undergone previous adenoidectomy without complications. In both cases, profuse bleeding was noted in the immediate postoperative period. The therapeutic measures in these situations are discussed and a review of the current literature concerning preoperative hematologic evaluation of T&A is included.

Adenoidectomy↗
PubMed1999

Different sensitivity of recombinant Aspergillus niger phytase (r-PhyA) and Escherichia coli pH 2.5 acid phosphatase (r-AppA) to trypsin and pepsin in vitro.

Proteolysis of two purified recombinant enzymes, namely, the Aspergillus niger phytase (r-PhyA) and the Escherichia coli pH 2.5 acid phosphatase (r-AppA), by pepsin and trypsin was investigated in this study. After r-PhyA and r-AppA were incubated with different concentrations of pepsin or trypsin, their residual phytase activities and amounts of inorganic phosphorus released from soybean meal were determined. Both enzymes retained more than 85% of their original activities at the trypsin/phytase ratios (w/w) 0.001 and 0. 005, while r-AppA and r-PhyA lost 60 and 20% of the original activity at the ratio of 0.01 or 0.025, respectively. In contrast, there was a 30% increase in phytase activity after r-AppA was incubated with pepsin at the ratios of 0.005 or 0.01. Meanwhile, r-PhyA lost 58 to 77% of its original activity under the same conditions. Trypsin and pepsin affected the hydrolysis of phytate phosphorus from soybean meal by r-AppA and r-PhyA in a similar way to their residual phytase activities. All of these in vitro proteolyses were confirmed by SDS-PAGE analysis. Our results demonstrate different sensitivities of r-AppA and r-PhyA to trypsin and pepsin, suggesting active trypsin resistant r-PhyA and pepsin resistant r-AppA polypeptides.

6-Phytase↗
PubMed1999

Cloning, sequencing, and expression of an Escherichia coli acid phosphatase/phytase gene (appA2) isolated from pig colon.

Bacterial strains were isolated from the pig colon to screen for phytase and acid phosphatase activities. Among 93 colonies, Colony 88 had the highest activities for both enzymes and was identified as an Escherichia coli strain. Using primers derived from the E. coli pH 2.5 acid phosphatase appA sequence (Dassa et al. (1990), J. Bacteriol. 172, 5497-5500), we cloned a 1482 bp DNA fragment from the isolate. In spite of 95% homology between the sequenced gene and the appA, 7 amino acids were different in their deduced polypeptides. To characterize the properties and functions of the encoded protein, we expressed the coding region of the isolated DNA fragment and appA in Pichia pastoris, respectively, as r-appA2 and r-appA. The recombinant protein r-appA2, like r-appA and the r-phyA phytase expressed in Aspergillus niger, was able to hydrolyze phosphorus from sodium phytate and p-nitrophenyl phosphate. However, there were distinct differences in their pH profiles, Km and Vmax for the substrates, specific activities of the purified enzymes, and abilities to release phytate phosphorus in soybean meal. In conclusion, the DNA fragment isolated from E. coli in pig colon seems to encode for a new acid phosphatase/phytase and is designated as E. coli appA2.

6-Phytase↗
PubMed1999

Perception's shadow: long-distance synchronization of human brain activity.

Transient periods of synchronization of oscillating neuronal discharges in the frequency range 30-80 Hz (gamma oscillations) have been proposed to act as an integrative mechanism that may bring a widely distributed set of neurons together into a coherent ensemble that underlies a cognitive act. Results of several experiments in animals provide support for this idea. In humans, gamma oscillations have been described both on the scalp (measured by electroencephalography and magnetoencephalography) and in intracortical recordings, but no direct participation of synchrony in a cognitive task has been demonstrated so far. Here we record electrical brain activity from subjects who are viewing ambiguous visual stimuli (perceived either as faces or as meaningless shapes). We show for the first time, to our knowledge, that only face perception induces a long-distance pattern of synchronization, corresponding to the moment of perception itself and to the ensuing motor response. A period of strong desynchronization marks the transition between the moment of perception and the motor response. We suggest that this desynchronization reflects a process of active uncoupling of the underlying neural ensembles that is necessary to proceed from one cognitive state to another.

Adult↗
PubMed1999

Obstetric and newborn outcomes in a cohort of HIV-infected pregnant women: a report of the women and infants transmission study.

OBJECTIVE: To determine obstetric and neonatal outcomes in a cohort of HIV-infected pregnant women and to assess whether HIV-related immunosuppression increases the risk of adverse outcomes of pregnancy. METHODS: Between 1989 and 1994, interview, physical examination, laboratory, and medical record data were prospectively collected from HIV-infected pregnant women and on their newborns. Factors associated with adverse pregnancy outcome and HIV disease status were correlated with pregnancy outcome using logistic regression analysis. RESULTS: 634 women delivered after 24 weeks of gestation. Preterm birth, low birth weight, and small-for-gestational-age neonates occurred in 20.5%, 18.9%, and 24.0% of pregnancies, respectively. Factors associated with low birth weight were CD4 percentage <14%, history of adverse pregnancy outcome, pediatric HIV infection, bleeding during pregnancy, and Trichomonas infection. Preterm birth was associated with CD4 percentage <14%, a history of adverse pregnancy outcome, and bleeding during pregnancy. Being small for gestational age was associated with maternal hard drug use during pregnancy, Trichomonas infection, history of adverse pregnancy outcome, and hypertension. CONCLUSIONS: Adverse pregnancy outcomes are common for HIV-infected women and are associated with low maternal CD4 percentage and pediatric HIV infection. Preterm birth, low birth weight, and small-for-gestational-age ranking, however, are also associated with previously recognized sociodemographic and obstetric factors that are not unique to HIV infection.

Adult↗
PubMed1999

Measuring phase synchrony in brain signals.

This article presents, for the first time, a practical method for the direct quantification of frequency-specific synchronization (i.e., transient phase-locking) between two neuroelectric signals. The motivation for its development is to be able to examine the role of neural synchronies as a putative mechanism for long-range neural integration during cognitive tasks. The method, called phase-locking statistics (PLS), measures the significance of the phase covariance between two signals with a reasonable time-resolution (<100 ms). Unlike the more traditional method of spectral coherence, PLS separates the phase and amplitude components and can be directly interpreted in the framework of neural integration. To validate synchrony values against background fluctuations, PLS uses surrogate data and thus makes no a priori assumptions on the nature of the experimental data. We also apply PLS to investigate intracortical recordings from an epileptic patient performing a visual discrimination task. We find large-scale synchronies in the gamma band (45 Hz), e.g., between hippocampus and frontal gyrus, and local synchronies, within a limbic region, a few cm apart. We argue that whereas long-scale effects do reflect cognitive processing, short-scale synchronies are likely to be due to volume conduction. We discuss ways to separate such conduction effects from true signal synchrony.

Brain↗
PubMed1999

Histochemical localization of reverse transcriptase in polytene chromosomes of chironomids.

The localization of a reverse transcriptase-related protein in salivary gland polytene chromosomes was investigated by immunohistochemistry in two species of Chironomus. The antibodies used were raised against a recombinant protein containing phylogenetically conserved motifs of reverse transcriptases and derived from an abundant non-LTR element previously identified in Chironomus. Immunoreactive protein was found in some telomeres, in a centromeric region, in a few interstitial bands and in Balbiani ring 3. The telomeric signal was probably dependent on transcription and increased dramatically when telomeric heat shock puffs were induced. A correlation with transcription was also seen in Balbiani ring 3, the immunobinding of which disappeared after inhibition of transcription with actinomycin D.

Animals↗
PubMed1999

The effect of arthrocentesis of the temporomandibular joint in patients with rheumatoid arthritis.

PURPOSE: This study evaluated the objective and subjective changes in a group of rheumatoid arthritic (RA) patients with temporomandibular joint (TMJ) complaints who were subjected to joint lysis and lavage. PATIENTS AND METHODS: Twelve females with previous documented RA underwent baseline assessment with erythrocyte sedimentation rate, physical examination of TMJ function, and a visual analog pain scale (VAPS). The VAPS and jaw function changes were recorded at 2-week intervals for 6 weeks after lysis and lavage under local anesthesia in an ambulatory setting. RESULTS: All patients showed statistically significant post-treatment improvement in their pain, and function was enhanced. CONCLUSION: TMJ arthrocentisis is a useful adjunct in the short-term management of the symptoms of rheumatoid arthritis.

Adult↗
PubMed1999

Complete primary structure of the chicken alpha1(V) collagen chain.

Chicken alpha1(V) collagen cDNAs have been cloned by a variety of methods and positively identified. We present here the entire translated sequence of the chick polypeptide and compare selected regions to other collagen chains in the type V/XI family.

Amino Acid Sequence↗
PubMed1999

Platelet function during cardiac surgery and cardiopulmonary bypass with low-dose aprotinin.

OBJECTIVE: To determine whether two low-dose regimens of aprotinin influence platelet function. DESIGN: Prospective, randomized, single-blinded trial. SETTING: University teaching hospital performing 600 cardiac operations per year. PARTICIPANTS: Fifty-nine patients scheduled for cardiac surgery undergoing cardiopulmonary bypass (CPB) of expected duration of 60 minutes or more. INTERVENTIONS: Patients were randomized into three groups. Group C (control) included 21 patients who did not receive aprotinin. In group A2, 17 patients received 14,286 kallikrein inhibitor units (KIU)/kg (2 mg/kg) of aprotinin before surgery, followed by a continuous infusion of 7,143 KIU/kg/h (1 mg/kg/h) until the end of surgery. In group A4, 19 patients received 28,572 KIU/kg (4 mg/kg) of aprotinin before surgery, followed by the same infusion. MEASUREMENTS AND MAIN RESULTS: Postoperative bleeding and transfusion requirements were significantly less in group A4. Changes in platelet number and function were similar in the three groups. Platelet aggregation was assessed in four periods: before CPB (T1), post-CPB (T2), and 2 hours (T3) and 4 hours (T4) after CPB. Platelet aggregation induced by adenosine diphosphate, 1 and 2 micromol/L; ristocetin, 1 mg/mL; and arachadonic acid (AA), 1.4 mmol/L, decreased at T2 (p < 0.001) in all groups, and for the ristocetin and AA groups, remained at less than baseline values at T3 and T4. In five patients from each group, platelet receptors for glycoprotein IIb-IIIa (GPIIb-IIIa) and expression of platelet activation markers, guanosine monophosphate 140 (GMP-140) and lysosomal protein, were measured by flow cytometry before and after CPB. Modifications in the expression of GPIIb-IIIa were always modest and without statistical significance. Platelet activation markers, GMP-140 or lysosomal protein, nearly doubled from baseline to post-CPB only in the A4 group, whereas they remained stable in both other groups (statistically not significant). CONCLUSION: The two regimens of aprotinin, both considered low dosage, did not exert a protective effect on platelet function. Neither dose produced changes in platelet GPIIb-IIIa or platelet activation markers. However, bleeding and transfusion needs were decreased.

Adenosine Diphosphate↗
PubMed1999

Hepatitis C virus-related fibrosing cholestatic hepatitis after cardiac transplantation: is azathioprine a contributory factor?

We report a patient who acquired hepatitis C virus (HCV) infection at cardiac transplantation, developing fibrosing cholestatic hepatitis (FCH) with early liver failure and a fatal outcome. FCH is a recently described clinicopathological entity characterized by a cholestatic pattern of serum liver enzyme abnormalities, a progressive course leading to liver failure, and a pathological picture defined by periportal fibrosis, neutrophilic infiltrates and signs of histological cholestasis. Although it was initially described secondary to hepatitis B virus infection, it has also been recently related to HCV infection. Some histopathological features consistent with azathioprine hepatotoxicity like cholestasis, perisinusoidal fibrosis, veno-subocclusive lesions and nodular regenerative hyperplasia were also observed in this case. Therefore, a direct cytopathic effect of HCV and the concurrent pathogenic role of azathioprine hepatotoxicity may be involved in the development of this complication of transplantation.

Azathioprine↗