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Biomedical subjects

J A Sanchez

Publications and source records attributed to J A Sanchez.

At least 19 recordsLinked to original sources
PubMed2002

Sensory, chemical and bacteriological changes during storage of iced squid (Todaropsis eblanae).

AIMS: To relate sensory shelf-life of iced whole and gutted squid to bacterial growth and chemical changes. METHODS AND RESULTS: Cooked mantles from whole and gutted individuals were rejected after 10 and 12 days of storage, respectively, due to ammoniacal off-odours. Rate of production of both ammonia and trimethylamine was highest in the whole lot. Agmatine, which was only present in trace amounts in freshly-caught squid, increased rapidly in both lots. The main microflora at the time of sensory rejection of iced whole squid included Gram-negative, motile and non-fermentative rods, which were psychrophilic and had a requirement for NaCl. 16S rDNA sequence analyses identified the strains as belonging to the genus Pseudoalteromonas. Shewanella putrefaciens, Pseudoalteromonas sp. and Pseudomonas sp. dominated in spoiled gutted squid. Identification of strains from the stomach and digestive gland of recently-captured squid showed that the main flora consisted of Photobacterium phosphoreum. CONCLUSIONS: Spoilage of iced squid is likely to result from a combination of autolytic and bacterial changes. Agmatine seems to be an excellent freshness indicator. Photobacterium phosphoreum may contribute to spoilage through activity in the digestive gland, followed by diffusion of volatile compounds and amines to the mantle. SIGNIFICANCE AND IMPACT OF THE STUDY: Due to the psychrophilic nature of P. phosphoreum and Pseudoalteromonas sp., spread-plating and low temperature incubation are recommended for bacteriological evaluation of iced squid.

Animals↗
PubMed2002

Modelling population dynamics of Orius laevigatus and O. albidipennis (Hemiptera: Anthocoridae) to optimize their use as biological control agents of Frankliniella occidentalis (Thysanoptera: Thripidae).

ORIUS LAEVIGATUS: (Fieber) and O. albidipennis (Reuter) play an important role in the control of Frankliniella occidentalis (Pergande) in crops and natural vegetation in the Mediterranean area. The biological parameters of the two anthocorids were studied and modelled in relation to temperature to optimize their use in thrips control programmes. Development times and reproductive parameters of O. laevigatus and O. albidipennis were determined at 20, 25, 30 and 35 degrees C. Pre-imaginal development times ranged from 34.6 and 37.2 days at 20 degrees C to 12.3 and 10.2 days at 35 degrees C in O. laevigatus and O. albidipennis, respectively. The lower thermal development threshold was significantly higher for O. albidipennis (14.2 +/- 0.9 degrees C) than for O. laevigatus (11.3 +/- 0.7 degrees C). No significant differences in fecundities between the two anthocorids were observed at 20, 25 and 30 degrees C. At 35 degrees C, O. albidipennis had a significantly higher fecundity than O. laevigatus. Non-linear models were used to explain reproduction and female survivorship in relation to temperature. The upper reproductive thresholds were estimated at 40.9 +/- 0.3 and 35.5 +/- 0.1 degrees C for O. albidipennis and O. laevigatus, respectively. The different optimum temperatures may explain, at least in part, the different distributions of the two species in the Palaeartic region and their population dynamics in greenhouses and natural vegetation in the south of Spain. The estimation of rm as a function of temperature showed high variability between years. Three release rates of 0.75-0.25 Orius per plant are recommended from early March to mid May to deal with thrips outbreaks in pepper crops.

Animals↗
PubMed2001

Nonrandom location and orientation of the inactive X chromosome in human neutrophil nuclei.

The nuclei of human neutrophils typically consist of a linear array of three or four lobes joined by DNA-containing filaments. Terminal lobes are connected to internal lobes via a single filament, while internal lobes have two filaments, each to an adjacent lobe. Some lobes also have appendages of various shapes and sizes. In particular, up to 17% of neutrophil nuclei of healthy women exhibit a drumstick-shaped appendage that contains the inactive X chromosome. This report provides a detailed analysis of the relationship between nuclear morphology and the location of the X and Y chromosomes in human neutrophils. Fluorescent in situ hybridization analysis revealed that the X and the Y chromosomes of male neutrophil nuclei are randomly distributed among nuclear lobes. Similarly, in female neutrophil nuclei with a drumstick appendage, the active X chromosome is also randomly distributed among lobes. In contrast, the inactive X chromosome is preferentially located in a terminal lobe in over 90% nuclei with drumsticks. Within the terminal lobe of nuclei with drumsticks, the inactive X chromosome lies distal to the point of filament attachment in 80% of the nuclei. The inactive X chromosome also exhibits a specific orientation within the drumstick appendage, with over 95% of nuclei having the X centromere located toward the tip of the appendage. Female nuclei without a drumstick appendage also have one of the X chromosomes (presumably the inactive chromosome) preferentially situated in a terminal lobe. Nonrandom distribution of the inactive X chromosome is discussed in the context of a model that considers chromosomes as determinants of neutrophil nuclear morphology.

Cell Nucleus↗
PubMed2001

Association of parvovirus B19 with plasma cell-rich myocardial infiltrates after heart transplantation.

In this report we describe the development of plasma cell-rich myocardial infiltrates in association with a parvovirus B19 infection in a heart transplant patient. We hypothesize that the virus, either alone or in association with the cardiac allograft, may polarize the immune response in the direction of T helper 2 (Th2) cells rather than the expected Th1 cells. This favors the development of a humoral immune response and infiltration of the graft with plasma cells.

Biopsy↗
PubMed2000

Leukapheresis components may be cryopreserved at high cell concentrations without additional loss of HPC function.

BACKGROUND: The aim of this study was to assess the feasibility of freezing mobilized peripheral blood progenitor cell (PBPC) components at higher cell concentrations than are classically recommended for bone marrow. This approach might have potential benefits, such as lower cost of processing and storage and less risk of the complications associated with the transfusion of large component volumes and large quantities of DMSO. STUDY DESIGN AND METHODS: In the first phase, small aliquots of 19 apheresis components were cryopreserved at standard and higher cell concentrations (Aliquots A and B, respectively). In the second phase, 21 apheresis components were split into two bags each and frozen at standard (Bag A) and high (Bag B) cell concentrations. The differences in viability, cloning efficiency, and nucleated cell recovery in Bags A and B were examined. Finally, the hematologic recovery of 10 patients who underwent autologous transplantation with PBPC components frozen at high cell concentrations was analyzed. RESULTS: The median cell concentration at freezing was 94 (57-100) x 10(6) per mL and 291 (220-467) x 10(6) per mL for Aliquots A and B, respectively, and 90.9 (45.4-92) x 10(6) per mL and 332 (171-582) x 10(6) per mL for Bags A and B, respectively. The viability was significantly lower in samples frozen at higher cell concentrations: 92 versus 83 percent (p = 0.001) and 87 versus 77 percent (p<0.001) for Aliquots and Bags A and B, respectively. Significant differences were not observed in the recovery of total nucleated cells (102 vs. 101% and 98 vs. 105%) or the cloning efficiency after thawing (13 vs. 16% and 27 vs. 23%) for Aliquots and Bags A and B, respectively. The time to granulocyte engraftment >0.5 x 10(9) per L and platelet engraftment >20 x 10(9) per L was 9 (8-11) and 10.5 (7-21) days, respectively. CONCLUSION: The cryopreservation of PBPC components at standard concentrations and 3.3 (1.8-6.2)-fold cell concentrations has no adverse effect on the function of HPCs after thawing.

Blood Preservation↗
PubMed2000

Real-time PCR using molecular beacons for accurate detection of the Y chromosome in single human blastomeres.

We describe a highly accurate method for determining the sex of human embryos via real-time polymerase chain reaction (PCR) amplification of highly-conserved, moderately-repeated sequences within the TSPY genes on the Y chromosome and the U2 genes on chromosome 17. Individual male lymphocytes, female lymphocytes, and blastomeres from donated cleavage-stage embryos were lysed prior to PCR using an optimized buffer containing proteinase K. Molecular beacons, a new type of fluorescent probe, were used to detect and quantify accumulating amplicons during each cycle of PCR carried out in closed tubes. The present work is part of an ongoing study to construct and implement a new, convenient and reliable system of preimplantation genetic diagnosis (PGD).

Blastomeres↗
PubMed1999

New insights into the mechanisms of nuclear segmentation in human neutrophils.

During human neutrophil differentiation, large portions of the genome condense and associate with the nuclear envelope to form filament-like structures. As a result, the nucleus of the mature neutrophil typically consists of a linear array of three or four lobes joined by thin, DNA-containing filaments. Despite the medical significance of neutrophil nuclear morphology, little is known about the events regulating neutrophil nuclear differentiation and its pathological states. This work presents a new model of the mechanisms governing nuclear filament formation in human neutrophils. This model is based on recent chromosome mapping studies in human neutrophils and on studies of genetic and pathological conditions affecting neutrophil nuclear shape. According to this model, filament assembly is initiated by factors that interact with specific regions of the genome in a hierarchical and dose-dependent manner. In this regard, the strategies governing the molecular interactions responsible for filament formation appear to resemble those involved in transcriptional silencing, a phenomenon that also affects the properties of extended chromosomal regions. According to the silencing paradigm, bound filament control Factors must recruit additional Filament Foehn factors which spread along adjacent DNA to mediate filament formation. A better understanding of the factors that shape the neutrophil nucleus may lead to new clinical tools for the diagnosis and manipulation of abnormal neutrophil differentiation.

Cell Nucleus↗
PubMed1999

Heart preservation for transplantation: principles and strategies.

While transplantation is a proven modality for the treatment of end stage organ disease, an important determinant of outcome is the adequacy of organ preservation. Currently, heart preservation is limited to 4 to 6 hours of cold ischemic storage, and the effectiveness depends to a great extent on the solution and its temperature. The formulation of the solution is based on three basic principles: (a) hypothermic arrest of metabolism, (b) provision of a physical and biochemical environment to maintain viability of the structural components of the tissue during hypothermic metabolic slowing, and (c) minimization of reperfusion injury. This review presents the physiologic principles underlying the use of hypothermia and the chemical components of preservation fluids, specifically pertaining to preservation of the heart for transplantation. New approaches designed to protect the heart from surgical ischemic-reperfusion injury are presented as well. The object is to survey current strategies and generate insight into new and promising solutions designed to optimize donor heart preservation.

Animals↗
PubMed1999

ETS protein-dependent accessibility changes at the immunoglobulin mu heavy chain enhancer.

Directed accessibility mediated by antigen-receptor gene enhancers ensures developmental stage-specific activation of V(D)J recombination. Here, we used a combination of in vitro and in vivo assays to explore the mechanisms that regulate immunoglobulin mu heavy chain gene enhancer-dependent chromatin accessibility. Ets-1 or PU.1 bound to mu enhancer-containing plasmids assembled into chromatin in vitro and increased restriction enzyme access to a proximal site. In complementary analyses, expression of PU.1 in Ets-1-containing 2017 pro-T cells or NIH 3T3 cells induced sterile I mu transcripts at the IgH locus and increased accessibility of the endogenous mu enhancer to restriction endonucleases. These observations suggest that one role of PU.1 is to increase accessibility of the mu locus to initiate heavy chain gene expression.

3T3 Cells↗
PubMed1999

Patterns of relative cerebral blood flow in minor cognitive motor disorder in human immunodeficiency virus infection.

Individuals infected with HIV are at risk to develop cognitive impairment during the course of their disease. Although many patients develop an HIV-associated dementia, others may develop the less severe minor cognitive motor disorder (MCMD). In this study, relative cerebral blood flow was measured with PET imaging in HIV+ MCMD patients, HIV+ control subjects, and HIV- control subjects; analyses were performed by using statistical parametric mapping. Comparing a short-term memory task versus a rest state yielded activation in superior temporal cortex, postcentral gyrus, and cerebellum in all three subject groups. Comparing long- and short-term memory tasks yielded activation throughout the frontal cortex, including BA46. Activation in this area was reduced in the HIV+ control subjects and further reduced in the MCMD+ patients. Thus, brain activation associated with lower-level, automatic processing appears normal in HIV+ MCMD+ subjects, but activation associated with effortful retrieval and organizational processes is abnormal.

Brain↗
PubMed1998

Ribosomal DNA replication in the fission yeast, Schizosaccharomyces pombe.

We have employed genetic and two-dimensional (2D) gel electrophoretic methods to identify replication initiation, pausing, and termination sites in the tandem ribosomal DNA (rDNA) repeats of the fission yeast, Schizosaccharomyces pombe. An autonomously replicating sequence (ARS) element, ars3001, maps to a 2.3-kb restriction fragment spanning the junction between the nontranscribed spacer (NTS) and the external transcribed spacer upstream of the ribosomal RNA genes, and 2D gel analysis shows that replication initiates in the NTS portion of the same fragment. A pause region at the 3' end of the rRNA genes inhibits forks from entering these genes counter to the direction of transcription. Thus, most forks move through the genes in the same direction as transcription. In these respects, fission yeast rDNA replication resembles that in the budding yeast, Saccharomyces cerevisiae, and in multicellular eukaryotic organisms. A feature which, so far, has been detected only in fission yeast is the pausing of replication forks in a broad region near the 5.8S rRNA gene.

DNA Replication↗
PubMed1997

Acute mediastinitis due to Rhodococcus equi in a patient with human immunodeficiency virus infection.

A patient with human immunodeficiency virus infection developed anterior mediastinitis during antibiotic treatment for empyema due to Rhodococcus equi. This is the first reported case of infection with this organism in this setting. Despite an adequate course of therapy and maintenance treatment with antibiotics to which the isolate of Rhodococcus equi was susceptible in vitro, the patient experienced relapse of the infection into the mediastinum. Clinicians should consider this complication when Rhodococcus equi is present in pleural effusions.

AIDS-Related Opportunistic Infections↗
PubMed1996

Reoperative mitral valve surgery via right thoracotomy: decreased blood loss and improved hemodynamics.

BACKGROUND AND AIMS OF THE STUDY: Reoperative mitral surgery via sternotomy can be associated with significant complications, including excessive blood loss and injuries to the heart, great vessels and patent coronary artery grafts. The right antero-lateral thoracotomy offers excellent exposure with less risk from re-entry. MATERIALS AND METHODS: Between 1982 and 1992, 221 patients had repeat mitral valve procedures at our institution. Fifteen of these 221 underwent mitral valve replacement via right thoracotomy. Indications for surgery in each group included bioprosthetic valve failure, paravalvular leak and bacterial endocarditis. Fifteen patients having reoperative mitral valve surgery via right thoracotomy approach were compared with a control group of 33 patient who underwent surgery via repeat sternotomy. All thoracotomy patients underwent mitral replacement or repair with ventricular fibrillation without aortic cross-clamping. Operative time, cardiopulmonary bypass time, requirement for inotropic support, blood loss within the first six postoperative hours, number of blood units transfused, length of ICU stay, days to discharge, and 30-day survival were compared between the two groups. In addition, the preoperative PaO2/FiO2 (P/F) ratio was evaluated as a prognostic indicator. RESULTS: Bypass time (162 +/- 43 min thoracotomy group vs. 131 +/- 34 min sternotomy group), operative time (389 +/- 100 min thoracotomy group vs. 450 +/- 25 min sternotomy group), ICU stay (6 +/- 8 days thoracotomy group vs. 5 +/- 6 days sternotomy group), P/F ratio (352 +/- 142 thoracotomy group vs. 423 +/- 108 sternotomy group), and 30-day survival (93% thoracotomy group vs. 91% sternotomy group) were not found to be significantly different between groups. Of great significance was the reduction in blood loss (277 +/- 152 ml thoracotomy vs. 651 +/- 504 ml sternotomy, p < 0.05) and blood transfused (2.0 +/- 1.7 units thoracotomy vs. 6.5 +/- 3.3 units sternotomy, p < 0.01) with the thoracotomy approach. Also of significance was a reduction in frequency with which significant inotropic support was needed to separate from cardiopulmonary bypass (26% vs. 63%, p < 0.05). Despite decreased access to the heart for de-airing maneuvers, no cerebrovascular events whatsoever were noted with the thoracotomy approach. CONCLUSION: The right thoracotomy approach is recommended for redo mitral valve surgery. Despite these advantages, severe pulmonary dysfunction (as indicated by a P/F ratio less than 300) correlated with a prolonged hospital course in four thoracotomy patients; such patients should have repeat sternotomy.

Blood Loss, Surgical↗
PubMed1995

Developmental regulation of Fos-protein during proliferative growth of the otic vesicle and its relation to differentiation induced by retinoic acid.

This work studies Fos protein expression in the otic vesicle and the developing cochleovestibular ganglion (CVG), focusing on the possible role of Fos in the regulation of cell proliferation and differentiation during otic development. Fos was detected as a product of 56-62 kDa in otic vesicles and CVG lysates. Expression was transient and stage-dependent. Maximal levels occurred at stage 20 in the otic vesicle and at Day 4 in the CVG. Another wave of Fos expression occurred after Day 7 of development, out of the early proliferative period. Fos immunoreactivity was localized in cell nuclei of otic epithelium and CVG. Fos was readily induced by mitogens like serum and bombesin and this induction was inhibited by 25 nM retinoic acid, an inhibitor of cell proliferation in the otic vesicle.c-fos antisense oligonucleotides inhibited growth in the otic vesicle in parallel with a reduction in Fos expression. High levels of Fos protein were not sufficient, however, to sustain growth of isolated otic vesicles in the absence of mitogens. Incubation with retinoic acid (24 hr) induced differentiation of sensory hair-cells in parallel with inhibition of cell proliferation. Contrary to retinoic acid, Fos inhibition by antisense did not induce differentiation. The results suggest that Fos is part of the signaling mechanisms regulating normal development of the inner ear. Regulation of Fos may be required for controlling of the transition between cell proliferation and differentiation.

Animals↗