PubMed Health⌕ Search

Biomedical subjects

J Carrasco

Publications and source records attributed to J Carrasco.

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

Effect of chip size on steam explosion pretreatment of softwood.

Although considerable progress has been made in technology for converting lignocellulosic biomass into ethanol, substantial opportunities still exist to reduce production costs. In biomass pretreatment, reducing milling power is a technological improvement that will substantially lower production costs for ethanol. Improving sugar yield from hemicellulose hydrolysis would also reduce ethanol production costs. Thus, it would be desirable to test innovative pretreatment conditions to improve the economics by reducing electrical power of the milling stage and by optimizing pretreatment recovery of hemicellulose, as well as to enhance cellulose hydrolysis. The objective of this study was to evaluate the effect of chip size (2-5, 5-8, and 8-12 mm) on steam-explosion pretreatment (190 and 210 degrees C, 4 and 8 min) of softwood (Pinus pinaster).

Biomass↗
PubMed1999

CNS wound healing is severely depressed in metallothionein I- and II-deficient mice.

To characterize the physiological role of metallothioneins I and II (MT-I+II) in the brain, we have examined the chronological effects of a freeze injury to the cortex in normal and MT-I+II null mice. In normal mice, microglia/macrophage activation and astrocytosis were observed in the areas surrounding the lesion site, peaking at approximately 1 and 3 d postlesion (dpl), respectively. At 20 dpl, the parenchyma had regenerated. Both brain macrophages and astrocytes surrounding the lesion increased the MT-I+II immunoreactivity, peaking at approximately 3 dpl, and at 20 dpl it was similar to that of unlesioned mice. In situ hybridization analysis indicates that MT-I+II immunoreactivity reflects changes in the messenger levels. In MT-I+II null mice, microglia/macrophages infiltrated the lesion heavily, and at 20 dpl they were still present. Reactive astrocytosis was delayed and persisted at 20 dpl. In contrast to normal mice, at 20 dpl no wound healing had occurred. The rate of apoptosis, as determined by using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling, was drastically increased in neurons of ipsilateral cortex of the MT-I+II null mice. Our results demonstrate that MT-I+II are essential for a normal wound repair in the CNS, and that their deficiency impairs neuronal survival.

Animals↗
PubMed1999

Strongly compromised inflammatory response to brain injury in interleukin-6-deficient mice.

Injury to the central nervous system (CNS) elicits an inflammatory response involving activation of microglia, brain macrophages, and astrocytes, processes likely mediated by the release of proinflammatory cytokines. In order to determine the role of interleukin-6 (IL-6) during the inflammatory response in the brain following disruption of the blood-brain barrier (BBB), we examined the effects of a focal cryo injury to the fronto-parietal cortex in interleukin-6-deficient (IL-6-/-) and normal (IL-6+/+) mice. In IL-6+/+ mice, brain injury resulted in the appearance of brain macrophages and reactive astrocytes surrounding the lesion site. In addition, expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) and metallothionein-I+II (MT-I+II) were increased in these cells, while the brain-specific MT-III was only moderately upregulated. In IL-6-/- mice, however, the response of brain macrophages and reactive astrocytes was markedly depressed and the number of NSE positive neurons was reduced. Brain damage-induced GM-CSF and MT-I+II expression were also markedly depressed compared to IL-6+/+ mice. In contrast, MT-III immunoreactivity was markedly increased in brain macrophages and astrocytes. In situ hybridization analysis indicates that MT-I+II but not MT-III immunoreactivity reflect changes in the messenger levels. The number of cell divisions was similar in IL-6+/+ and IL-6-/- mice. The present results demonstrate that IL-6 is crucial for the recruitment of myelo-monocytes and activation of glial cells following brain injury with disrupted BBB. Furthermore, our results suggest IL-6 is important for neuroprotection and the induction of GM-CSF and MT expression. The opposing effect of IL-6 on MT-I+II and MT-III levels in the damaged brain suggests MT isoform-specific functions.

Animals↗
PubMed1999

Identification of a signal transducer and activator of transcription (STAT) binding site in the mouse metallothionein-I promoter involved in interleukin-6-induced gene expression.

Mechanisms of regulation of mouse metallothionein (MT)-I gene expression in response to bacterial endotoxin-lipopolysaccharide (LPS) were examined. Northern blot analysis of hepatic MT-I mRNA in interleukin (IL)-6 or tumour necrosis factor (TNF)-receptor type I knock-out mice demonstrated that IL-6, not TNF-alpha, is of central importance in mediating hepatic MT-I gene expression in vivo after LPS injection. In vivo genomic footprinting of the MT-I promoter demonstrated a rapid increase, after LPS injection, in the protection of several guanine residues in the -250 to -300 bp region of the MT-I promoter. The protected bases were within sequences which resemble binding sites for the signal transducers and activators of transcription (STAT) transcription factor family. Electrophoretic mobility-shift assays using oligonucleotides from footprinted MT-I promoter regions showed that injection of LPS resulted in a rapid increase in the specific, high-affinity, in vitro binding of STAT1 and STAT3 to a binding site at -297 bp (TTCTCGTAA). Western blotting of hepatic nuclear proteins showed that the time-course for changes of total nuclear STAT1 and STAT3 after LPS injection paralleled the increased complex formation in vitro using this oligonucleotide, and binding was specifically competed for by a functional STAT-binding site from the rat alpha2-macroglobulin promoter. Furthermore, the MT-I promoter -297 bp STAT-binding site conferred IL-6 responsiveness in the context of a minimal promoter in transient transfection assays using HepG2 cells. This study suggests that the effects of LPS on hepatic MT-I gene expression are mediated by IL-6 and involve the activation of STAT-binding to the proximal promoter.

Animals↗
PubMed1999

Metallothionein (MT)-III: generation of polyclonal antibodies, comparison with MT-I+II in the freeze lesioned rat brain and in a bioassay with astrocytes, and analysis of Alzheimer's disease brains.

Metallothionein-III is a low molecular weight, heavy-metal binding protein expressed mainly in the central nervous system. First identified as a growth inhibitory factor (GIF) of rat cortical neurons in vitro, it has subsequently been shown to be a member of the metallothionein (MT) gene family and renamed as MT-III. In this study we have raised polyclonal antibodies in rabbits against recombinant rat MT-III (rMT-III). The sera obtained reacted specifically against recombinant zinc-and cadmium-saturated rMT-III, and did not cross-react with native rat MT-I and MT-II purified from the liver of zinc injected rats. The specificity of the antibody was also demonstrated in immunocytochemical studies by the elimination of the immunostaining by preincubation of the antibody with brain (but not liver) extracts, and by the results obtained in MT-III null mice. The antibody was used to characterize the putative differences between the rat brain MT isoforms, namely MT-I+II and MT-III, in the freeze lesion model of brain damage, and for developing an ELISA for MT-III suitable for brain samples. In the normal rat brain, MT-III was mostly present primarily in astrocytes. However, lectin staining indicated that MT-III immunoreactivity was also present in microglia, monocytes and/or macrophages in the leptomeninges and lying adjacent to major vessels. In freeze lesioned rats, both MT-I+II and MT-III immunoreactivities increased in the ipsilateral cortex. The pattern of MT-III immunoreactivity significantly differed from that of MT-I+II, since the latter was evident in both the vicinity of the lesioned tissue and deeper cortical layers, whereas that of the former was located only in the deeper cortical layers. This suggests different roles for these MT isoforms, and indeed in a new bioassay measuring astrocyte migration in vitro, rMT-III promoted migration to a higher extent than MT-I+II. Thus, MT-III could not only affect neuronal sprouting as previously suggested, but also astrocyte function. Finally, MT-III protein levels of patients with Alzheimer's disease (AD) were, if anything, increased when compared with similarly aged control brains, which was in agreement with the significantly increased MT-III mRNA levels of AD brains.

Alzheimer Disease↗
PubMed1999

Expression of growth inhibitory factor (metallothionein-III) mRNA and protein following excitotoxic immature brain injury.

The balance between trophic factors and inhibitory molecules is likely to determine the outcome of neural tissue damage. The growth inhibitory factor (GIF), a member of the metallothionein family of proteins named metallothionein-III (MT-III), has been suggested to play an important role in tissue repair after adult brain injury. Because no information is available on this factor in relation to immature brain damage, we examined the chronological changes of GIF (MT-III) mRNA and protein following excitotoxic lesions to the postnatal day 9 brain using in situ hybridization and immunocytochemical techniques. We observed a significant decrease of neuronal GIF (MT-III) mRNA and protein levels between 4 and 24 hours postinjury and an increase in glial GIF (MT-III) levels. Double immunocytochemical techniques showed GIF (MT-III) and GFAP positive astrocytes from 2-4 hours postinjury. From 3 days postinjury strongly reactive astrocytes expressed strong levels of both GIF (MT-III) mRNA and protein, which were maintained in the glial scar formed at longer times. These results show the expression of an inhibitory molecule by postnatal reactive astrocytes. Glial GIF (MT-III) expression may play an important role in the tissue reconstruction after immature brain damage.

Age Factors↗
PubMed1998

Interleukin-6 and tumor necrosis factor-alpha type 1 receptor deficient mice reveal a role of IL-6 and TNF-alpha on brain metallothionein-I and -III regulation.

Metallothioneins (MTs) are a family of low molecular weight proteins which in rodents is comprised of several isoforms (MT-I to MT-IV). MT-I and MT-II are widely expressed isoforms, whereas MT-III is mainly expressed in the central nervous system and is the only isoform that inhibits survival and neurite formation of rat cortical neurons in vitro. However, the physiological roles and regulation of these proteins in the brain are poorly characterized. In this report we have studied the putative role of IL-6 and TNF-alpha on the regulation of brain MT-I and MT-III, by using mice carrying a null mutation in the IL-6 or the TNF-alpha type 1 receptor genes or both. In situ hybridization analysis revealed that brain MT-I induction by bacterial lipopolysaccharide (LPS) was significantly lower in IL-6- and TNFR1-deficient mice, and to a greater extent in the double mutant mice, in most brain areas studied. These results suggest that the MT-I isoform could be considered an acute-phase protein in the brain, which is consistent with previous studies in transgenic mice overexpressing IL-6 in astrocytes. In contrast to LPS, brain MT-I induction by restraint stress was not affected significantly by IL-6 or TNFR1 deficiencies, suggesting that these cytokines are not important during the stress response in the brain. In basal conditions, it was also observed that the double mutant mice had diminished MT-I mRNA levels in several brain areas. In contrast to MT-I, MT-III mRNA levels were minimally affected by either LPS or stress. Yet, significant decreasing effects of IL-6 and TNFR1 deficiencies were observed in the Purkinje neuronal layer of the cerebellum (after LPS) and ependymal cells (after LPS and stress). In contrast, significant increasing effects, especially of TNFR1 deficiency, were observed in CA1 hippocampal area, retrosplenial and parietal cortex, and in thalamic nuclei (after LPS). These results demonstrate that IL-6 and TNF-alpha are involved in brain MTs regulation during LPS-elicited inflammatory response but not during the stress response.

Animals↗
PubMed1998

Localization of metallothionein-I and -III expression in the CNS of transgenic mice with astrocyte-targeted expression of interleukin 6.

The effect of interleukin-6 (IL-6) on metallothionein-I (MT-I) and MT-III expression in the brain has been studied in transgenic mice expressing IL-6 under the regulatory control of the glial fibrillary acidic protein gene promoter (GFAP-IL6 mice), which develop chronic progressive neurodegenerative disease. In situ hybridization analysis revealed that GFAP-IL6 (G16-low expressor line, and G36-high expressor line) mice had strongly increased MT-I mRNA levels in the cerebellum (Purkinje and granular layers of the cerebellar cortex and basal nuclei) and, to a lesser degree, in thalamus (only G36 line) and hypothalamus, whereas no significant alterations were observed in other brain areas studied. Microautoradiography and immunocytochemistry studies suggest that the MT-I expression is predominantly localized to astrocytes throughout the cerebrum and especially in Bergman glia in the cerebellum. However, a significant expression was also observed in microglia of the GFAP-IL6 mice. MT-III expression was significantly increased in the Purkinje cell layer and basal nuclei of the cerebellum, which was confirmed by Northern blot analysis of poly(A)+ mRNA and by ELISA of the MT-III protein. In contrast, in the G36 but not G16 mice, transgene expression of IL-6 was associated with significantly decreased MT-III RNA levels in the dentate gyrus and CA3 pyramidal neuron layer of the hippocampus and, in both G36 and G16 mice, in the occipital but not frontal cortex and in ependymal cells. Thus, both the widely expressed MT-I isoform and the CNS specific MT-III isoform are significantly affected in a MT isoform- and CNS area-specific manner in the GFAP-IL6 mice, a chronic model of brain damage.

Animals↗
PubMed1998

Effect of nitric oxide synthesis inhibition on mouse liver and brain metallothionein expression.

The role of nitric oxide (NO) production on metallothionein (MT) regulation in the liver and the brain has been studied in mice by means of the administration of nitric oxide synthase (NOS) inhibitors. Mice injected with either the arginine analog NG-monomethyl-L-arginine (L-NMMA) or the heme binding compound 7-nitro indazole (7-NI) showed consistently increased liver MT-I mRNA and MT-I + II total protein levels, suggesting that NO is involved in the hepatic MT regulation. In agreement with the liver results, in situ hybridization analysis demonstrated a significant upregulation of the brain MT-I isoform in areas such as the cerebrum cortex, neuronal CA1-CA3 layers and dentate gyrus of the hippocampus, and Purkinje cell layer of the cerebellum, in 7-NI treated mice. The same trend was observed for the brain specific isoform, MT-III, but to a much lower extent. The effect of NOS inhibition was also evaluated in a MT-inducing condition, namely during immobilization stress. In both the liver and the brain, stress upregulated the MT-I isoform, and 7-NI significantly reduced or even blunted the MT-I response to stress, suggesting a mediating role of NO on MT-I regulation during stress. Stress also increased the MT-III mRNA levels in some brain areas, an effect blunted by the concomitant administration of 7-NI, which in some areas even decreased MT-III mRNA levels below the saline injected mice. Results in primary culture of neurons and astrocytes demonstrate significant effects of the NOS inhibitors in some experimental conditions. The present results suggest that NO may have some role on MT regulation in both the liver and the brain.

Animals↗
PubMed1998

Behaviour of Lutzomyia longipalpis in an area of southern Honduras endemic for visceral/atypical cutaneous leishmaniasis.

The predominant sandfly in Las Maria de Pavana, Choluteca, Honduras, was found to be Lutzomyia longipalpis, most (69%) of the 791 specimens of this species caught being male. When local Lu. longipalpis were studied over 1 year (1986-1987) using CDC traps, peaks in the size of the adult population were observed in December and July, each after a period of rain. Most [51% (24/47)-67% (97/144)] of the flies caught inside houses were female whereas most [55% (6/11)-56% (37/66)] of those caught outside were male. Far more Lu. longipalpis of both sexes were collected, per h of collection, from cattle and horses than from dogs or pigs, the vast majority (83%-93%) of the flies caught on each type of animal being male. The males may benefit from resting on the mammals because the females with which they mate come to the same animals for blood. The females may benefit by the presence of the males, not only by the increased chance of finding a mate but also because pheremones from the males may attract the females both to the males and to a bloodmeal source. The adult Lu. longipalpis only appeared to be active during the hours of darkness, none alighting in the twilight of dawn (04.00-06.00 hours) or dusk (18.00-20.00 hours) on the large mammals investigated.

Animals↗
PubMed1997

Discriminating between generalized anxiety disorder and anxiety disorder not otherwise specified in a Hispanic population: is it only a matter of worry?

One hundred and two Hispanic persons who presented for treatment at a specialized anxiety disorders clinic were evaluated at intake using the Anxiety Disorders Interview Schedule-Revised (ADIS-R; DiNardo and Barlow [1988] Albany: Center for Stress and Anxiety Disorders, State University of New York at Albany). Results indicated that 14% of these patients suffered from anxiety and/or affective disorders that were not adequately captured by our current diagnostic system. Given that the majority of these cases were characterized by predominantly anxious features, further investigation was undertaken to determine the degree of overlap between these patients (anxiety disorder, not otherwise specified; NOS) and those with generalized anxiety disorder (GAD). The two groups differed only with regard to the number of excessive worries they reported and not in terms of somatic symptomatology, psychosocial stressors, or demographic variables. These data suggest that excessive worry may be a discriminating factor between the GAD and NOS groups, providing support for the notion of GAD as a disorder of chromic worry. Future research is needed to tease apart the relative influences of culture and socioeconomic status on our findings.

Adult↗
PubMed1993

Optimization of the simultaneous saccharification and fermentation process using thermotolerant yeasts.

Different treatments to improve the thermotolerance of fermenting yeasts for simultaneous ethanol saccharification and fermentation process of cellulosic materials have been examined. Yeasts of the genera Saccharomyces and Kluyveromyces were tested for growth and fermentation at progressively higher temperatures in the range of 42-47 degrees C. The best results were obtained with K. marxianus LG, which was then submitted to different treatments in order to achieve thermotolerant clones. A total of 35 new clones were obtained that dramatically improved the SSF of 10% Solka-floc substrate at 45 degrees C when compared to the original strain, some with ethanol concentrations as high as 33 g/L.

Adaptation, Physiological↗
PubMed1991

Selection of thermotolerant yeasts for simultaneous saccharification and fermentation (SSF) of cellulose to ethanol.

A total of 27 yeast strains belonging to the groups Candida, Saccharomyces, and Kluyveromyces were screened for their ability to grow and ferment glucose at temperatures ranging 32-45 degrees C. K. marxianus and K. fragilis were found to be the best ethanol producing organisms at the higher temperature tested and, so, were selected for subsequent simultaneous saccharification and fermentation (SSF) studies. SSF experiments were performed at 42 and 45 degrees C, utilizing Solkafloc (10%) as cellulose substrate and a cellulase loading of 15 FPU/g substrate. Best results were achieved at 42 degrees C with K. marxianus L. G. and K. fragilis L. G., both of which produced close to 38 g/L ethanol and 0.5 ethanol yield, in 78 h.

Candida↗
PubMed1984

CT findings in human fascioliasis.

Three patients with fascioliasis are presented in whom CT demonstrated abscesses and granulomas and permitted control of the disease's evolution after medical treatment.

Adult↗
PubMed1983

Sugar-containing lipids in the classification of representative Actinomadura and Nocardiopsis species.

The major sugar-containing lipids of some Actinomadura and Nocardiopis strains--recognized as an important agent of actinomycetoma -- were analyzed by thin-layer and gas-liquid chromatography. It was demonstrated that Nocardiopsis dassonvillei strains contained two characteristic glycolipids identified as monomannosyl diglyceride and monoacylated glucose. None of them was found in the representatives of Actinomadura madurae and Actinomadura pelletieri strains, which possessed phosphatidylinositol-mannosides as major sugar-containing lipids. The glycolipids of Nocardiopsis dassonvillei seem to be of value in the taxonomy. In connection with this a simple glycolipid patterns of these microorganisms, established by TLC, was presented.

Actinomycetales↗