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Biomedical subjects

A Carrasco

Publications and source records attributed to A Carrasco.

At least 19 recordsLinked to original sources
PubMed2005

A prospective study of a series of 356 patients with supratentorial spontaneous intracerebral haematomas treated in a Neurosurgical Department.

BACKGROUND: Spontaneous supratentorial intracerebral haemorrhages (SSIH) carry high morbidity and mortality rates. At present, the proper role of surgery is not clear and data from the International STICH trial have not clarified this challenging question. On the other hand, few prospective studies have measured long term survival regardless of the treatment and clinical condition of the patient. PATIENTS AND METHODS: We prospectively collected data from all SSIH patients (n = 356) admitted at a tertiary reference hospital over a 40-month time period regardless of their clinical condition and treatment received. Among data investigated were preclinical neurological state, GCS on admission, history of systemic hypertension and treatment (surgical or conservative). Clinical factors influencing mortality at 1-year follow-up were analysed statistically by univariable and multivariable methods. FINDINGS: We found that patients in the eighth decade were the most frequent. Hypertension was present in 47% of patients. Based on the prehospitalisation modified Rankin Scale, 305 (86%) patients were independent for activities of daily living (ADL). At 12-months follow-up, 91 (46% of alive patients) remained independent for ADL. The surgical rate was 22%. Although it was not a randomised study, we did not find a significantly different mortality rate according to whether the patient was treated surgically or conservatively. Overall, the mortality rate was 44% (157 patients) with a 79% of deaths taking place in the first 30 days after admission. CONCLUSIONS: This study underscores the high mortality rate of SSIH, especially so in the first month after admission. Among the subgroup of patients clinically independent before the haemorrhagic stroke, only 29.8% remained independent one year after the event. We did not find any statistically significant difference in mortality according to treatment modality received (surgical vs conservative) although treatment assignment was not randomised. Among other clinical factors, pre-ictal functional status, age, level of consciousness on admission and volume of haemorrhage strongly influence mortality as determined at the 1-year follow-up.

Activities of Daily Living↗
PubMed2005

Cytotoxicity assessment of some carbon nanotubes and related carbon nanoparticle aggregates and the implications for anthropogenic carbon nanotube aggregates in the environment.

Nanotechnology and nanomaterials have become the new frontier world-wide over the past few years and prospects for the production and novel uses of large quantities of carbon nanotubes in particular are becoming an increasing reality. Correspondingly, the potential health risks for these and other nanoparticulate materials have been of considerable concern. Toxicological studies, while sparse, have been concerned with virtually uncharacterized, single wall carbon nanotubes, and the conclusions have been conflicting and uncertain. In this research we performed viability assays on a murine lung macrophage cell line to assess the comparative cytotoxicity of commercial, single wall carbon nanotubes (ropes) and two different multiwall carbon nanotube samples; utilizing chrysotile asbestos nanotubes and black carbon nanoaggregates as toxicity standards. These nanotube materials were completely characterized by transmission electron microscopy and observed to be aggregates ranging from 1 to 2 microm in mean diameter, with closed ends. The cytotoxicity data indicated a strong concentration relationship and toxicity for all the carbon nanotube materials relative to the asbestos nanotubes and black carbon. A commercial multiwall carbon nanotube aggregate exhibiting this significant cell response was observed to be identical in structure to multiwall carbon nanotube aggregates demonstrated to be ubiquitous in the environment, and especially in indoor environments, where natural gas or propane cooking stoves exist. Correspondingly, preliminary epidemiological data, although sparse, indicate a correlation between asthma incidence or classification, and exposure to gas stoves. These results suggest a number of novel epidemiological and etiological avenues for asthma triggers and related respiratory or other environmental health effects, especially since indoor number concentrations for multiwall carbon nanotube aggregates is at least 10 times the outdoor concentration, and virtually all gas combustion processes are variously effective sources. These results also raise concerns for manufactured carbon nanotube aggregates, and related fullerene nanoparticles.

Adolescent↗
PubMed2004

High affinity recognition of a Phytophthora protein by Arabidopsis via an RGD motif.

The RGD tripeptide sequence, a cell adhesion motif present in several extracellular matrix proteins of mammalians, is involved in numerous plant processes. In plant-pathogen interactions, the RGD motif is believed to reduce plant defence responses by disrupting adhesions between the cell wall and plasma membrane. Photoaffinity cross-linking of [125I]-azido-RGD heptapeptide in the presence of purified plasma membrane vesicles of Arabidopsis thaliana led to label incorporation into a single protein with an apparent molecular mass of 80 kDa. Incorporation could be prevented by excess RGD peptides, but also by the IPI-O protein, an RGD-containing protein secreted by the oomycete plant pathogen Phytophthora infestans. Hydrophobic cluster analysis revealed that the RGD motif of IPI-O (positions 53-56) is readily accessible for interactions. Single amino acid mutations in the RGD motif in IPI-O (of Asp56 into Glu or Ala) resulted in the loss of protection of the 80-kDa protein from labelling. Thus, the interaction between the two proteins is mediated through RGD recognition and the 80-kDa RGD-binding protein has the characteristics of a receptor for IPI-O. The IPI-O protein also disrupted cell wall-plasma membrane adhesions in plasmolysed A. thaliana cells, whereas IPI-O proteins mutated in the RGD motif (D56A and D56E) did not.

Amino Acid Motifs↗
PubMed2004

[Tentorial meningiomas. Report of our series].

PURPOSE: The main objectives of this report are to describe the clinical and radiological features, surgical management, complications, and final outcome of patients with a tentorial meningioma. METHODS: This is a retrospective study of 25 patients operated on for tentorial meningiomas at our department since december 1975 to may 2002. All the patients, except the first, were diagnosed by computed tomography; in 13 of them a magnetic resonance imaging was performed too; in 14 patients, diagnosis was completed with cerebral arteriography. The preoperative clinical condition, the interval between the first symptoms and the date of the operation, the postoperative morbidity and the recurrence are analysed. RESULTS: There were 20 women and 5 men of ages ranging from 35 to 79 years (average of 54.6). Surgical removal was considered radical (Simpson I-II) in 22 patients. Of them one had a recurrence 25 years after the operation, another had three recurrences, in two years, that were reoperated, and a third one had recurrence at five years who did not require surgery. The postoperative mortality was 8%. The mean follow-up period was of 5.3 years. The final outcome was good recovery in 19 patients, moderate disability in 1 and death in 4. CONCLUSIONS: Despite the advances in Neuroradiology and Microsurgery, these tumors represent a challenge for the neurosurgeon, due in some cases to a large tumor size and extension to critical areas. A removal as complete as possible allows minimizing the recurrence risk.

Adult↗
PubMed2000

Effect of vaccination with Brucella abortus strain RB51 on heifers and pregnant cattle.

Thirteen cows, which had been vaccinated as calves with strain 19, were revaccinated twice or three times as adults with I x 109 cfu of B. abortus strain RB51. Their serological responses following adult vaccination remained negative to conventional brucellosis surveillance tests. Vaccination with strain RB51 during the eighth month of pregnancy did not induce abortion, although strain RB51 was recovered from milk for up to 69 days after vaccination. In a parallel study, thirteen 8- to 10-month-old heifers were vaccinated as calves with 109 cfu of strain RB51. The heifers remained seronegative to conventional brucellosis surveillance tests but antibody responses to RB51 could be demonstrated using an indirect ELISA. This study showed that multiple vaccination with strain RB51 did not induce seroconversion to brucellosis surveillance tests. In addition, this study suggests that 109 cfu of strain RB51 is safe for use in pregnant cattle.

Animals↗
PubMed1998

Free-flow electrophoresis for fractionation of Arabidopsis thaliana membranes.

Highly purified tonoplast and plasma membrane vesicles were isolated from microsomes of Arabidopsis thaliana by preparative free-flow electrophoresis. The most electronegative fractions were identified as tonoplast using nitrate-inhibited Mg2+-ATPase as enzyme marker. The least electronegative fractions were identified as plasma membrane using glucan-synthase II, UDPG: sterol-glucosyl-transferase, and vanadate-inhibited Mg2+-ATPase as enzyme markers. Other membrane markers, latent inosine-5'-diphosphatase (Golgi), NADPH-cytochrome-c reductase (endoplasmic reticulum) and cytochrome-c oxidase (mitochondria) were recovered in the fractions intermediate between tonoplast and plasma membrane. Immunoblot analysis of membrane fractions by antibodies directed against tonoplast and plasma membrane proteins confirmed the nature and the purity of the isolated membranes. The cytoskeletal protein actin, which was also identified by immunoblotting, was found to be specifically attached to the plasma membrane vesicles. The structural and functional integrity of the isolated membranes from Arabidopsis thaliana is discussed in the light of results obtained for the location of receptors and enzymes, or for the determination of ligand binding activity.

Antigen-Antibody Reactions↗
PubMed1998

High affinity RGD-binding sites at the plasma membrane of Arabidopsis thaliana links the cell wall.

The heptapeptide Tyr-Gly-Arg-Gly-Asp-Ser-Pro containing the sequence Arg-Gly-Asp (RGD--the essential structure recognised by animal cells in substrate adhesion molecules) was tested on epidermal cells of onion and cultured cells of Arabidopsis upon plasmolysis. Dramatic changes were observed on both types of cells following treatment: on onion cells, Hechtian strands linking the cell wall to the membrane were lost, while Arabidopsis cells changed from concave to convex plasmolysis. A control heptapeptide Tyr-Gly-Asp-Gly-Arg-Ser-Pro had no effect on the shape of plasmolysed cells. Protoplasts isolated from Arabidopsis cells agglutinate in the presence of ProNectinF, a genetically engineered protein of 72 kDa containing 13 RGD sequences: several protoplasts may adhere to a single molecule of ProNectinF. The addition of the RGD-heptapeptide disrupted the adhesion between the protoplasts. Purified plasma membrane from Arabidopsis cells exhibits specific binding sites for the iodinated RGD-heptapeptide. The binding is saturable, reversible, and two types of high affinity sites (Kd1 approximately 1 nM, and Kd2 approximately 40 nM) can be discerned. Competitive inhibition by several structurally related peptides and proteins noted the specific requirement for the RGD sequence. Thus, the RGD-binding activity of Arabidopsis fulfils the adhesion features of integrins, i.e. peptide specificity, subcellular location, and involvement in plasma membrane-cell wall attachments.

Arabidopsis↗
PubMed1997

Expression of the ubiquitin genes in brain of normal and Fe/Dextran injected rats.

Using in situ hybridization techniques with an RNA probe coding for approximately 3.5 repeats of ubiquitin, corresponding to the polyubiquitin genes, we were able to demonstrate that under normal conditions the expression of the ubiquitin genes predominates specially in regions CA1, CA2 and CA3 of the hippocampus, in the dentate gyrus and in Purkinje cells of the cerebellum, being less prominent in neuronal cell bodies of the cerebral cortex. When the animals were submitted to an acute oxidative stress by injection of Fe/Dextran, the hybridization signal was apparently increased in the above mentioned regions of the hippocampus and in the cerebral cortex. On the other hand, the animals chronically injected with Fe/Dextran showed a highly intense gene expression in the cerebral cortex and in the cerebellum, particularly in the granular cell layer of this structure. The hybridization signal of the transcripts was absent in the Purkinje cells. The results suggest that the expression of the ubiquitin genes by CNS neurons depends on the anatomical location of the cells and that it increases as a consequence of the oxidative stress conditions to which they are submitted.

Animals↗
PubMed1992

Ion channels from the Bacillus subtilis plasma membrane incorporated into planar lipid bilayers.

Fusion of Bacillus subtilis plasma membrane vesicles with planar lipid bilayers induced the appearance of discrete current fluctuations characteristic of ion channels. These channels showed a wide range of conductances and kinetic behaviors. In 300 mM KCl, their conductances ranged from a few hundreds of pS to more than 1 nS, and most of them exhibited several sub-states. The channels poorly discriminated between small univalent anions and cations. Some of them showed voltage dependence and most of them presented a complex gating kinetics. The results are consistent with the hypothesis of the presence in the B. subtilis plasma membrane of pores composed of subunits that function cooperatively.

Bacillus subtilis↗
PubMed1990

Indicators of biotin status: a study of patients on prolonged total parenteral nutrition.

Plasma biotin concentration and lymphocyte propionyl CoA carboxylase (PCC) and its activation index (the ratio of enzyme activity in cells incubated with biotin to activity in cells incubated without the vitamin) were compared as markers of biotin status in patients on biotin-free prolonged total parenteral nutrition (TPN). Five patients had been on biotin-free TPN for over 1 month when the study was started, and had already developed clinical signs that may be caused by this vitamin deficiency. They had markedly reduced levels of both biotin and carboxylase levels, which increased to near normal levels 4 months after biotin was added to the TPN. They initially presented subnormal plasma zinc concentrations which were normal at the end of the study. Another 4 patients also received biotin-free TPN. After 1 month propionyl CoA carboxylase, which was already below normal in 3 of them at admission, further decreased and became undetectable in 1 of them, who presented clinical deficiency manifestations. The enzyme activation index increased more than twice, although plasma biotin remained normal. When the vitamin was added to the TPN solution, PCC activity increased and its activation index decreased to normal. Plasma zinc concentrations remained normal throughout in this other group of patients indicating that changes of biotin markers are not likely to be related to zinc status variation. Plasma biotinidase, a key enzyme in biotin endogenous recycling, was already subnormal at admission and had become normal at the end of the study, but was not associated with the biotin status.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Parathyroid hormone: perinatal aspects].

Authors have measured parathormone levels in 28 mothers at delivery and their respective newborns at 40-50 hours after birth. They also quantified these levels in umbilical vessels. Control groups was formed by 48 healthy non pregnant women. PTH levels in pregnant women were similar to controls. In umbilical artery these values were higher than in umbilical vein and in both, lower than other groups. Newborns at 40-50 hours after birth showed higher PTH levels than controls and pregnant women at delivery. A positive correlation between the PTH levels of the mother and those of the umbilical vessels is found. PTH levels of the neonate at 40-50 hours after birth correlated with levels of umbilical artery and umbilical vein. They do not observe a hyperparathyroidism at the delivery, although there is a slight decrease in Ca levels. Newborns at 40-50 hours after birth did show an increase in their PTH levels in parallel with hypocalcemia correlation found between PTH levels of the mother and those of the umbilical vessels could suggest a placental transfer for this hormone.

Calcium↗
PubMed1986

Rapid Degradation of Abnormal Proteins in Vacuoles from Acer pseudoplatanus L. Cells.

In Acer pseudoplatanus cells, the proteins synthesized in the presence of an amino acid analog ([(14)C]p-fluorophenylalanine), were degraded more rapidly than normal ones ([(14)C]phenylalanine as precursor). The degradation of an important part of these abnormal proteins occurred inside the vacuoles. The degradation process was not apparently associated to a specific proteolytic system but was related to a preferential transfer of these aberrant proteins from the cytoplasm to the vacuole.

Journal Article↗
PubMed1986

Ionic calcium levels during pregnancy, at delivery and in the first hours of life.

Free calcium ion concentration (mmol/l) and pH were determined in whole blood using a semiautomatic electrode system (ICA-1 Radiometer, Copenhagen, Denmark) in 37 normal women, 90 pregnant women (30 from each trimester of gestation), 28 mothers at delivery and their respective newborns. The blood samples from normal controls, pregnant women, umbilical cord and 40-50-hour-old infants were collected anaerobically in vacuum tubes. Duplicate samples drawn from newborns shortly after birth by heel puncture were collected in special heparinized capillary tubes. We observed that Ca2+ concentrations in the second (1.20 +/- 0.04) and third (1.20 +/- 0.05) trimesters of pregnancy, and at delivery (1.18 +/- 0.05), were lower than in the control group (1.23 +/- 0.04). The [Ca2+] in samples from the umbilical vein (1.44 +/- 0.11) and artery (1.45 +/- 0.08) and from newborns 2-5 min after birth (1.34 +/- 0.12) was greater than in control samples. The [Ca2+] in newborns 40-50 hours after birth was lower (1.16 +/- 0.14) than in the control group.

Adult↗
PubMed1981

Genetic and biochemical characterization of D-arabinose dehydrogenase from Neurospora crassa.

D-Arabinose dehydrogenase has been purified to homogeneity from wild-type Neurospora crassa 74-A (FGSC 262) and from two colonial mutants, col-15a (FGSC 1391) and col-16a (FGSC 1349), found to contain more of the enzyme. The enzymes were characterized by measurement of several kinetic and physicochemical parameters. The enzymes were the same in all characteristics studied thus far. Immunological studied performed with enzyme preparations from the three strains showed antigenic identity and indicated that those colonial strains contain more normal enzyme, rather than the usual amount of an altered "improved" enzyme. Quantitation of the enzyme in crude extracts, performed by single radial immunodiffusion, showed that the colonial strains have twice the level of enzyme as the wild-type strain. Genetic characterization, performed by analysis of meiotic products, heterokaryosis, and reversions, indicated that the difference in D-arabinose dehydrogenase activity detected among the three strains is probably determined by one gene. The genetic control, structural or regulatory of this enzyme activity is different from that determining the morphological alterations exhibited by mutant strains carrying the col-15 or col-16 gene.

Arabinose↗
PubMed1981

Cytoplasmic membrane fraction that promotes septation in an Escherichia coli lon mutant.

A particulate fraction derived from bacterial cells stimulates septation in irradiated Escherichia coli lon mutants when added to postirradiation plating media. It was established that the particles are derived from the cytoplasmic membrane and that they have been partially purified by sucrose density gradient centrifugation. These particles also contain the cytochrome-based respiratory activity of the cell. A variety of experiments established a correlation between the septation-promoting activity of the particles and their ability to remove oxygen from the postirradiation plating medium. It was suggested that the efficient removal of oxygen from the medium allowed the lon cells to repair radiation-induced damage to the septation mechanism.

Cell Division↗
PubMed1981

Zinc and copper abnormalities in fasting patients undergoing total parenteral nutrition.

Low serum levels of zinc and copper have recently been reported in association with TPN and the fasting state. A prospective study during May 1977 through November 1978 was performed in 28 patients undergoing TPN. Serum and urinary Zn and Cu levels were detected; the patient population was divided in septic and non septic groups and each was subdivided according to plasma administration. In both groups low serum Zn and Cu levels were detected. The urinary losses were greater in the group with sepsis. Three patients had clinical manifestations of Zn deficiency, in two it was reversible with the administration of diet or oral Zn. The third one died of sepsis. The low serum levels found in our patients suggested that plasma administration might be insufficient to cover the daily requirements of such elements. This requirement is augmented by the increased urinary losses seen in septic postoperative stages.

Bacterial Infections↗