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Biomedical subjects

F Garcia

Publications and source records attributed to F Garcia.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Mediastinoscopy in the case of recurrent uveitis].

INTRODUCTION: The authors report the case of a patient who presented for 4 years recurrent anterior uveitis accompanied by asymptomatic tuberculous mediastinal lymphadenitis. EXEGESIS: CT scan of the chest showed the existence of mediastinal lymphadenopathy (< 1 cm). Mediastinoscopy with biopsy of the right laterotracheal lymph node was performed. The culture was positive for Mycobacterium tuberculosis, thus permitting the diagnosis of tuberculosis. CONCLUSION: This case report stresses the advantage of extensive etiological assessment when faced with unexplained uveitis; particularly it emphasizes the importance of investigating potential tuberculosis. The existence of granulomatous uveitis, a positive skin test, the ethnic origin, and mostly results of chest CT scan, were the rationale for the use of mediastinoscopy with lymph node biopsy to help guide diagnosis.

Adult↗
PubMed1999

A new statistical method for transfer coefficient calculations in the framework of the general multiple-compartment model of transport for radionuclides in biological systems.

A new and simple statistical procedure (STATFLUX) for the calculation of transfer coefficients of radionuclide transport to animals and plants is proposed. The method is based on the general multiple-compartment model, which uses a system of linear equations involving geometrical volume considerations. By using experimentally available curves of radionuclide concentrations versus time, for each animal compartment (organs), flow parameters were estimated by employing a least-squares procedure, whose consistency is tested. Some numerical results are presented in order to compare the STATFLUX transfer coefficients with those from other works and experimental data.

Animals↗
PubMed1999

Analysis of charges and complications of permanent pacemaker implantation in the cardiac catheterization laboratory versus the operating room.

During the last two decades, an increasing number of permanent pacemakers have been implanted outside of the operating room (OR) by nonsurgeons. Previous investigators have demonstrated that pacemakers can be safely implanted in the cardiac catheterization laboratory with no increase in complications or infections. This is the first study of its kind to simultaneously evaluate cost, length of hospitalization, and complications between pacemakers implanted in the OR by surgeons with those implanted in the catheterization laboratory by an electrophysiologist. A total of 254 consecutive pacemaker implants were analyzed over a 2-year period. The OR group consisted of 122 patients with a mean age of 64 +/- 21 years versus 132 patients in the catheterization laboratory group with a mean age of 65 +/- 17 years. The indication and type of pacemaker implanted were similar among both groups with 78% of OR patients and 73% of catheterization laboratory patients receiving dual chamber devices. The average cost for pacemaker implantation in our study was significantly higher in the OR group $5,464 +/- $1,670 versus $2,682 +/- $8 for the catheterization laboratory group (P < 0.001). There was a reduction in preimplant days in the catheterization laboratory group 3.16 +/- 12.40 days versus 5.65 +/- 9.54 days in the OR group (P < 0.05). Complications were minimal and there were no significant differences between the two groups. This study confirms that pacemakers can be safely implanted in the catheterization laboratory by nonsurgeons with no increase in complications and a significant reduction in hospital costs.

Aged↗
PubMed1999

Daily injections of fluoxetine induce dose-dependent desensitization of hypothalamic 5-HT1A receptors: reductions in neuroendocrine responses to 8-OH-DPAT and in levels of Gz and Gi proteins.

The present studies examined the dose-response relationship of fluoxetine-induced desensitization of hypothalamic postsynaptic 5-HT1A receptors, as measured from the reduced neuroendocrine responses to a 5-HT1A agonist. Because hypothalamic Gz proteins mediate the ACTH and oxytocin responses to 5-HT1A receptor activation, we also determined the effect of fluoxetine on the levels of Gz proteins in the hypothalamus. Rats were injected daily for 14 days with saline or with fluoxetine doses of 0.3, 1, 3, 5, 7. 5, or 10 mg/kg/day. Fluoxetine produced a dose-dependent reduction in the oxytocin, ACTH, and corticosterone responses to the 5-HT1A agonist 8-hydroxy-2-(dipropylamino)tetralin (8-OH-DPAT, 50 micrograms/kg, s.c.). The lowest fluoxetine dose that significantly, although incompletely, reduced the neuroendocrine responses to 8-OH-DPAT was 5 mg/kg/day. The 10 mg/kg/day dose of fluoxetine maximally inhibited all neuroendocrine responses to 8-OH-DPAT. Hypothalamic levels of Gz protein were reduced by both the 7.5 and 10 mg/kg/day doses of fluoxetine, whereas Gi1 protein levels were reduced only after the highest dose (10 mg/kg/day) of fluoxetine. Gi2, Gi3, and Go levels were not reduced by any fluoxetine dose. Cytosolic levels of Gi1 and Gz proteins were unaltered, indicating that reductions in Gz and Gi1 proteins are not caused by a redistribution of the proteins from the membrane into the cytosol. The results from the present study indicate that fluoxetine-induced desensitization of hypothalamic postsynaptic 5-HT1A receptor systems is dose-dependent and may be caused in part by reductions in the hypothalamic levels of Gz proteins.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1999

Sustained desensitization of hypothalamic 5-Hydroxytryptamine1A receptors after discontinuation of fluoxetine: inhibited neuroendocrine responses to 8-hydroxy-2-(Dipropylamino)Tetralin in the absence of changes in Gi/o/z proteins.

Long-term exposure to fluoxetine produces a desensitization of hypothalamic postsynaptic 5-hydroxytryptamine (5-HT)1A receptors, indicated by a substantial inhibition of the 5-HT1A receptor-mediated stimulation of oxytocin and adrenocorticotropic hormone (ACTH) secretion. The present study investigated the time course and mechanism of this desensitization after discontinuation of fluoxetine administration. Male rats were injected with saline or fluoxetine (10 mg/kg/day, i.p.) for 14 days and were challenged with a 5-HT1A agonist, [8-hydroxy-2-(dipropylamino)tetralin (8-OH-DPAT) 50 microg/kg, s.c.] 2, 4, 7, 14, 28, or 60 days post-treatment. In control animals, 8-OH-DPAT significantly increased (approximately 15-fold) plasma levels of oxytocin and ACTH. At 2 days post-treatment, oxytocin and ACTH responses to 8-OH-DPAT were reduced by 74% and 68%, respectively. During further withdrawal from fluoxetine, there was a gradual increase in the oxytocin response toward control levels. However, even 60 days after discontinuation of fluoxetine, the oxytocin response was still significantly reduced by 26% compared with controls. In contrast, the suppressed ACTH response to 8-OH-DPAT (a less-sensitive indicator of desensitization) gradually returned to control levels by day 14 of withdrawal from fluoxetine. Interestingly, the sustained reductions in the hormone responses occurred in the absence of reductions in Gz or Gi protein levels in the hypothalamus. Furthermore, this desensitization was sustained in the absence of detectable levels of fluoxetine and norfluoxetine in plasma and brain tissue. These findings suggest that the sustained desensitization of hypothalamic 5-HT1A receptor systems, observed during fluoxetine withdrawal, may be due to altered interactions among the protein components of the 5-HT1A receptor system, rather than their absolute levels.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1998

Interaction between CO2-mass transfer, light availability, and hydrodynamic stress in the growth of phaeodactylum tricornutum in a concentric tube airlift photobioreactor

The microalga Phaeodactylum tricornutum was grown in a concentric tube airlift photobioreactor. A maximum specific growth rate of 0. 023 h-1 was obtained using a superficial gas velocity around 0.055 m/s. Lower or higher gas flow rates limited the culture performance. To establish if the observed limitation was due to CO2 or to the photosynthetically active irradiance, characteristic times for mixing, mass transfer and CO2 consumption, and the photon flux absorbed by the culture were analyzed. The CO2-gradients in the culture were shown to be responsible for the limitation during the exponential growth phase, and both CO2 and light irradiance were limiting in the linear growth phase. The decrease in specific growth rate relative to the maximum was found to be related to the specific gas-liquid interfacial area, the length scale of the microeddies and the shear rate. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗
PubMed1998

Cytotoxic T cell response against the chimeric ETV6-AML1 protein in childhood acute lymphoblastic leukemia.

Cytotoxic T lymphocytes (CTL) are potent effector cells that could provide long term antitumor immunity if induced by appropriate vaccines. CTL recognize 8-14 amino acid-long peptides processed intracellularly and presented by MHC class I molecules. A well-characterized example of a potential tumor antigen in childhood pre-B Acute Lymphoblastic Leukemia (ALL) results from the chromosomal translocation 12;21 leading to the fusion of the ETV6 and AML1 genes. This translocation is observed in > 25% of ALL-patients. In this study, we have examined whether the chimeric ETV6-AML1 protein could serve as a tumor specific antigen for CTL in HLA-A2.1 individuals. We have identified a nonapeptide (RIAECILGM), encoded by the fusion region of the ETV6-AML1 protein, that binds to HLA-A2.1 molecules and induces specific primary CTL in peripheral blood lymphocytes from healthy donors. These CTL specifically lysed HLA-A2.1 tumor cells endogeneously expressing the ETV6-AML fusion protein. CTL with similar functional capacities were found with high frequencies and cloned from one patient's bone marrow indicating that ETV6-AML1-specific anti-ALL CTL are, at least in some patients, spontaneously stimulated and might participate to host antileukemia defense.

Amino Acid Sequence↗
PubMed1998

Minimum CAG repeat in the human calmodulin-1 gene 5' untranslated region is required for full expression.

The human calmodulin-1 gene (hCALM1) contains a (CAG)7 repeat in its 5'-untranslated region (5'-UTR). We found this repeat to be stable and nonpolymorphic in the human population. To determine whether the repeat region affects hCALM1 expression and whether repeat expansions to numbers known to be associated with disease in other genes may alter expression, we tested luciferase reporter genes driven by the hCALM1 promoter and 5'-UTR containing 0, 7 (wild-type), 20, and 45 CAG repeats in human NT2/D1 teratoma cells. Interestingly, the repeat deletion, (CAG)0, decreased expression by 45%, while repeat expansions to (CAG)20 and (CAG)45, or the insertion of a scrambled (C,A,G)7 sequence did not alter gene expression. These data indicate (1) that the endogenous repeat element is required for full expression of hCALM1, and (2) that some triplet repeat expansions in the 5'-UTR of protein-coding genes may be well tolerated and even optimize gene expression.

Animals↗
PubMed1998

Gastrointestinal autonomic nerve tumors (plexosarcomas). is A radiological diagnosis possible?

The gastrointestinal autonomic nerve (GAN) tumor, or plexosarcoma, is a very uncommon stromal tumor of the gastrointestinal tract and retroperitoneum. Distinction of GAN tumors from other stromal tumors is not possible based on imaging studies, and needs specific ultrastructural and inmunohistochemical techniques. There are some morphologic characteristics that the radiologist should know, so as to include these rare tumors in the differential diagnosis of an abdominal mass. We report two new cases: small bowel (jejunum-ileum) and stomach GAN tumors.

Aged↗
PubMed1998

Recurrent embolism caused by floating thrombus in the thoracic aorta.

A case of embolic recurrent episodes resulting in acute lower-limb ischemia from an unusual source is reported. This occurred in a patient on steroids for rheumatoid arthritis. Femoropopliteal thromboembolectomy successfully restored arterial flow. Diagnostic evaluation for identifying the source of embolism revealed a large, pedunculated and mobile thrombus arising from a nonaneurysmatic and nonatherosclerotic descending thoracic aorta. The thrombus was identified by transesophageal echocardiography and was successfully removed by aortic thromboendarterectomy. We emphasize the importance of transesophageal echocardiography as a reliable method for the diagnosis of thoracic aorta diseases and for identification of aortic thrombi. An aggressive surgical approach is recommended in the low-risk patient to prevent further embolic episodes.

Anti-Inflammatory Agents↗
PubMed1998

Characterization of the human CALM2 calmodulin gene and comparison of the transcriptional activity of CALM1, CALM2 and CALM3.

Human calmodulin is encoded by three genes CALM1, CALM2 and CALM3 located on different chromosomes. To complete the characterization of this family, the exon-intron structure of CALM2 was solved by a combination of genomic DNA library screening and genomic PCR amplification. Intron interruptions were found at identical positions in human CALM2 as in CALM1 and CALM3; however, the overall size of CALM2 (16 kb) was almost twice that of the other two human CALM genes. Over 1 kb of the 5' flanking sequence of human CALM2 were determined, revealing the presence of a TATA-like sequence 27 nucleotides upstream of the transcriptional start site and several conserved sequence elements possibly involved in the regulation of this gene. To determine if differential transcriptional activity plays a major role in regulating cellular calmodulin levels, we directly measured and compared the mRNA abundance and transcriptional activity of the three CALM genes in proliferating human teratoma cells. CALM3 was at least 5-fold more actively transcribed than CALM1 or CALM2. CALM transcriptional activity agreed well with the mRNA abundance profile in the teratoma cells. In transient transfections using luciferase reporter genes driven by 1 kb of the 5' flanking DNA of the three CALM genes, the promoter activity correlated with the endogenous CALM transcriptional activity, but only when the 5' untranslated regions were included in the constructs. We conclude that the CALM gene family is differentially active at the transcriptional level in teratoma cells and that the 5' untranslated regions are necessary to recover full promoter activation.

Amino Acid Sequence↗
PubMed1998

A practical method for simultaneous multiple intracerebral implantations for microdialysis in rats.

Many experimental designs require the chronic implantation of different elements destined to act as channels that facilitate the information conveyance between the brain and some external devices or vice versa. Electrodes for electrophysiological or electrochemical recording or brain stimulation, and guide shafts for drug administration or chemical monitoring of the extracellular space are the most common examples of channels serving those purposes. The stereotaxic implantation of one or more of those experimental tools in the same antero-posterior plane is relatively easy, but surgery is nonetheless more complicated when two or more elements have to be placed using totally different coordinates. In those cases the current strategy consists in the successive implantation of the elements, waiting for the hardening of the dental acrylic destined to fix one of them in place before dealing with the next. This procedure takes time, is considerably more laborious than surgery for single elements and is particularly difficult when the elements have to be implanted in close proximity. The present report describes a method that simplifies surgery for multiple intracerebral implantation and allows the simultaneous and exact placement of as many electrodes or guide shafts as is practical in any experimental design. The method requires the previous construction of a jig or template designed to temporarily hold the elements to be implanted, allowing them to assume and keep the same positional relationship that they should have when definitively in place within the skull. The design may vary according to the type of elements to be implanted and the coordinates required for each particular experiment, but here it is illustrated describing the assembly of a particular jig for the simultaneous implantation of guide shafts for ulterior microdialysis in the prefrontal cortex (PFC), nucleus accumbens (NAC) and striatum (STR). Some rules can be derived from this particular case to make the method a more general one and suitable for any combination of elements and stereotaxic coordinates.

Animals↗
PubMed1998

Differential distribution of dynamin isoforms in mammalian cells.

Dynamins are 100-kDa GTPases that are essential for clathrin-coated vesicle formation during receptor-mediated endocytosis. To date, three different dynamin genes have been identified, with each gene expressing at least four different alternatively spliced forms. Currently, it is unclear whether these different dynamin gene products perform distinct or redundant cellular functions. Therefore, the focus of this study was to identify additional spliced variants of dynamin from rat tissues and to define the distribution of the dynamin family members in a cultured rat epithelial cell model (Clone 9 cells). After long-distance reverse transcription (RT)-PCR of mRNA from different rat tissues, the full-length cDNAs encoding the different dynamin isoforms were sequenced and revealed four additional spliced variants for dynamin I and nine for dynamin III. Thus, in rat tissues there are a total of at least 25 different mRNAs produced from the three dynamin genes. Subsequently, we generated stably transfected Clone 9 cells expressing full-length cDNAs of six different spliced forms tagged with green fluorescent protein. Confocal or fluorescence microscopy of these transfected cells revealed that many of the dynamin proteins associate with distinct membrane compartments, which include clathrin-coated pits at the plasma membrane and the Golgi apparatus, and several undefined vesicle populations. These results indicate that the dynamin family is more extensive than was originally predicted and suggest that the different dynamin proteins are localized to distinct cytoplasmic or membrane compartments.

Amino Acid Sequence↗