PubMed Health⌕ Search

Biomedical subjects

A Almeida

Publications and source records attributed to A Almeida.

At least 19 recordsLinked to original sources
PubMed2007

Synergistic induction of apoptosis in primary rat decidual cells by INF-gamma and TNF.

In the rat, in response to blastocyst implantation, stromal cells of the endometrium proliferate and differentiate into decidual cells, forming the decidua. After reaching its maximum development, the decidua undergoes regression. This phenomenon appears to be due to an active process involving apoptosis. As there is sparse knowledge concerning the mechanisms of induction of decidual cell death, the potential role of cytokines present in the uterine environment during pregnancy, such as tumor necrosis factor (TNF) and interferon-gamma (INF-gamma) was explored in primary cultures of rat decidual cells. The effects of these factors upon cellular viability, nuclear morphologic alterations, expression, and enzymatic activities of the effector caspases-3/7 were evaluated. The results obtained demonstrated that in contrast to TNF, which did not induce any alteration, INF-gamma and in association with TNF caused a decrease in cell viability and an increase in the appearance of apoptotic bodies in a time-dependent manner that was augmented in the co-presence of TNF. An increase in caspase-3/7 activities after 12 hr of TNF/INF-gamma treatment was also observed. These findings suggest that INF-gamma expressed in the uterine environment may play an important role in regulating apoptosis through potential synergistic mechanisms with TNF and thereby modulate decidual stability and regression during pregnancy.

Animals↗
PubMed2006

Brain projections from the medullary dorsal reticular nucleus: an anterograde and retrograde tracing study in the rat.

In the last 15 years a role has been ascribed for the medullary dorsal reticular nucleus as a supraspinal pain modulating area. The medullary dorsal reticular nucleus is reciprocally connected with the spinal dorsal horn, is populated mainly by nociceptive neurons and regulates spinal nociceptive processing. Here we analyze the distribution of brain projections from the medullary dorsal reticular nucleus using the iontophoretic administration of the anterograde tracer biotinylated-dextran amine and the retrograde tracer cholera toxin subunit B. Fibers and terminal boutons labeled from the medullary dorsal reticular nucleus were located predominately in the brainstem, although extending also to the forebrain. In the medulla oblongata, anterograde labeling was observed in the orofacial motor nuclei, inferior olive, caudal ventrolateral medulla, rostral ventromedial medulla, nucleus tractus solitarius and most of the reticular formation. Labeling at the pons-cerebellum level was present in the locus coeruleus, A5 and A7 noradrenergic cell groups, parabrachial and deep cerebellar nuclei, whereas in the mesencephalon it was located in the periaqueductal gray matter, deep mesencephalic, oculomotor and anterior pretectal nuclei, and substantia nigra. In the diencephalon, fibers and terminal boutons were found mainly in the parafascicular, ventromedial, and posterior thalamic nuclei and in the arcuate, lateral, posterior, peri- and paraventricular hypothalamic areas. Telencephalic labeling was consistent but less intense and concentrated in the septal nuclei, globus pallidus and amygdala. The well-known role of the medullary dorsal reticular nucleus in nociception and its pattern of brain projections in rats suggests that the nucleus is possibly implicated in the modulation of: (i) the ascending nociceptive transmission involved in the motivational-affective dimension of pain; (ii) the endogenous supraspinal pain control system centered in the periaqueductal gray matter-rostral ventromedial medulla-spinal cord circuitry; (iii) the motor reactions associated with pain.

Animals↗
PubMed2005

[Stereotactic radiosurgery in the intracranial benign neoplasms and malignant tumors of the brain].

Stereotactic Radiosurgery has proven to be during the last years the therapy of choice in more and more patients with benign and malignant brain tumors. The potential advantages comparatively to surgery and conventional radiotherapy made this technique a very important tool in the therapeutic armamentarium of neurooncology. This series presents the experience of treating more than 100 intracranial lesions with linear accelerator-based radiosurgery at Hospital de Santa Maria in Lisbon with special emphasis on the indications and results. It also provides a review of the concepts and procedures of this modality as well as a general overview of the main published results in series of patients with brain tumors treated with stereotactic radiosurgery.

Adult↗
PubMed2005

ANCA: serology in Wegener's granulomatosis.

BACKGROUND AND OBJECTIVES: Wegener's granulomatosis (WG) is being increasingly diagnosed in India, which exists in two forms, the 'limited Wegener's granulomatosis' (LWG) having upper respiratory tract (URT) and lower respiratory tract (LRT) involvement and the 'classical Wegener's granulomatosis' (CWG), with the triad of URT, LRT involvement along with kidney involvement. Cytoplasmic ANCA (C-ANCA) or anti-Proteinase3 (anti-PR3), which is highly diagnostic for WG, rarely perinuclear ANCA (P-ANCA) may exist. AIMS: To detect anti-neutrophil cytoplasmic antibodies (ANCA) and correlate it with serological, hematological parameters, and the Birmingham Vasculitis Activity Score (BVAS). SETTINGS AND DESIGN: Twenty-three clinically and histopathologically proven WG (16 CWG, 7 LWG) were studied. MATERIAL AND METHODS: C-ANCA and P-ANCA patterns were identified by immunofluorescence and specificities were confirmed by 'alpha granule' enzyme linked immunosorbent assay (ELISA), anti-PR3, anti-MPO (myeloperoxidase) and anti-Lactoferrin (anti-LF) by ELISA. RESULTS: LRT involvement was seen in 91.3%, URT in 78.3%, and renal manifestations in 69.6% cases. The BVAS in CWG was significantly higher than BVAS in the LWG. Decreased hemoglobin, increased WBC counts, ESR, CRP and Creatinine were seen in CWG as compared to LWG. The C-ANCA was present in 65.2% patients and P-ANCA in 13% cases. Anti-PR3 was seen in 69.6% patients and anti-LF in 17.4% cases. Severity of disease and ANCA was higher in CWG than in LWG. CONCLUSIONS: Vasculitis syndromes are known to overlap and many go undetected; therefore ANCA testing, along with the clinical and histopathological observations may be helpful in early detection and management of WG cases.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed2004

Impact of donor and recipient cytokine genotypes on renal allograft outcome.

Allelic differences in gene promoter or codifying regions have been described to affect regulation of gene expression, consequently increasing or decreasing cytokine production and signal transduction responses to a given stimulus. This observation has been reported for interleukin (IL)-10 (-1082 A/G; -819/-592 CT/CA), transforming growth factor (TGF)-beta (codon 10 C/T, codon 25 G/C), tumor necrosis factor (TNF)-alpha (-308 G/A), TNF-beta (+252 A/G), interferon (IFN)-gamma (+874 T/A), IL-6 (-174 G/C), and IL-4R alpha (+1902 G/A). To evaluate the influence of these cytokine genotypes on the development of acute or chronic rejection, we correlated the genotypes of both kidney graft recipients and cadaver donors with the clinical outcome. Kidney recipients had 5 years follow-up, at least 2 HLA-DRB compatibilities, and a maximum of 25% anti-HLA pretransplantation sensitization. The clinical outcomes were grouped as follows: stable functioning graft (NR, n = 35); acute rejection episodes (AR, n = 31); and chronic rejection (CR, n = 31). The cytokine genotype polymorphisms were defined using PCR-SSP typing. A statistical analysis showed a significant prevalence of recipient IL-10 -819/-592 genotype among CR individuals; whereas among donors, the TGF-beta codon 10 CT genotype was significantly associated with the AR cohort and the IL-6 -174 CC genotype with CR. Other albeit not significant observations included a strong predisposition of recipient TGF-beta codon 10 CT genotype with CR, and TNF-beta 252 AA with AR. A low frequency of TNF-alpha -308 AA genotype also was observed among recipients and donors who showed poor allograft outcomes.

Cytokines↗
PubMed2004

Automated computer result reporting for haemoglobinopathy screening.

The anticipated introduction of universal antenatal screening can be expected to increase the workload of haemoglobinopathy laboratories throughout the country. We have devised a rule-based system to process those results that does not require skilled interpretation, thereby freeing staff time for more specialized work. The system relies on a calculated test to create a total haemoglobin peak value, which incorporates the values for HbA, HbA2 and HbF, the MCV and MCH from the full blood count. Each parameter has a series of defined ranges which, when subjected to an interpretation process within the laboratory computer system, generates an automated result text for the sample. During a 6-month verification period, the automated result interpretation system in conjunction with laboratory information systems (LIS) validation reduced the number of samples requiring manual review by 60%. The system was found to be 100% sensitive and 61.8% specific. We feel that the current specificity is acceptable in order to maintain a safe system. The ability to concentrate on potentially abnormal results will allow laboratories and health care workers more time to develop appropriate and timely frameworks to deal with abnormal results.

Clinical Laboratory Information Systems↗
PubMed2003

Brain afferents to the lateral caudal ventrolateral medulla: a retrograde and anterograde tracing study in the rat.

The ventrolateral medulla (VLM) modulates autonomic functions, motor reactions and pain responses. The lateralmost part of the caudal VLM (VLMlat) was recently shown to be the VLM area responsible for pain modulation. In the present study, the brain sources of VLMlat afferent fibers were determined by tract-tracing techniques. Following injection of cholera toxin subunit B into the VLMlat, retrogradely labeled neurons in the forebrain occurred at the somatosensory, insular, motor, limbic and infralimbic cortices, and at the central amygdaloid nucleus. Retrogradely labeled neurons in diencephalic regions were observed in the lateral hypothalamus, posterior hypothalamus and paraventricular nucleus. In the brainstem, retrograde labeling occurred at the periaqueductal gray, red nucleus, parabrachial area, nucleus raphe magnus, nucleus tractus solitarii, lateral reticular nucleus and dorsal and ventral medullary reticular formation. In the cerebellum, retrogradely labeled neurons occurred at the lateral nucleus. Following injections of the anterograde tracer biotinylated dextran amine (BDA) into the lateral hypothalamus or paraventricular nucleus, anterogradely labeled fibers were mainly observed in the VLMlat. Injections of BDA into the periaqueductal gray, red nucleus or lateral nucleus of the cerebellum resulted in anterograde labeling in the VLMlat and lateral reticular nucleus. The present study gives an account of the brain regions putatively involved in triggering the modulatory actions elicited from the VLMlat. These include areas committed to somatosensory processing, autonomic control, somatic and visceral motor activity and affective reactions. The findings suggest that the VLMlat may play a major homeostatic role in the integration of nociception with other brain functions.

Adjuvants, Immunologic↗
PubMed2002

Induction of micronuclei by alkaloids extracted from Senecio brasiliensis and stored for 23 years.

In the present study, we report the results of an investigation on pyrrolizidine alkaloids extracted from Senecio brasiliensis (Sprengel) Less., which were stored for more than 23 years under variable conditions of temperature and humidity and exposed to light. Both the crude alkaloid (integerrimine+retrorsine+impurities) and pure integerrimine conserved the ability to induce acute toxicity in mice, leading to the death of the animals in less than 24h. The alkaloids also conserved the potential to induce significant increases in micronucleus frequencies in polychromatic erythrocytes of mouse bone marrow compared to the negative control. The administration of alkaloids to lymphocyte cultures blocked with cytochalasin-B showed no significant increase in micronucleus frequency in binucleated cells, probably due to the lack of a metabolic activation mechanism. However, an antimitotic effect was observed.

Adult↗
PubMed2002

Unusual presentation of factor XIII deficiency.

Factor XIII deficiency is a rare inherited bleeding disorder that is often difficult to diagnose. The standard screening tests are normal in these patients and their bleeding phenotype may be variable. We report the case of a 3-year-old girl who presented with an intracranial haemorrhage. Several confounding factors, such as the suspicion of an arteriovenous malformation and the development of a deep venous thrombosis, led to a delay in the diagnosis of factor XIII deficiency. Subsequently, her brother was also found to have severe factor XIII deficiency. This case highlights the importance of a detailed history and of screening families in which index cases have been identified. It should also remind physicians that bleeding disorders may have unusual presentations and should be sought when investigating unexplained bleeding.

Consanguinity↗
PubMed2001

Different responses of astrocytes and neurons to nitric oxide: the role of glycolytically generated ATP in astrocyte protection.

It was recently proposed that in Jurkat cells, after inhibition of respiration by NO, glycolytically generated ATP plays a critical role in preventing the collapse of mitochondrial membrane potential (Deltapsi(m)) and thus apoptotic cell death. We have investigated this observation further in primary cultures of rat cortical neurons and astrocytes-cell types that differ greatly in their glycolytic capacity. Continuous and significant ( approximately 85%) inhibition of respiration by NO (1.4 microM at 175 microM O(2)) generated by [(z)-1-[2-aminoethyl]-N-[2-ammonioethyl]amino]diazen-1-ium-1,2 diolate (DETA-NO) initially (10 min) depleted ATP concentrations by approximately 25% in both cell types and increased the rate of glycolysis in astrocytes but not in neurons. Activation of glycolysis in astrocytes, as judged by lactate production, prevented further ATP depletion, whereas in neurons, which do not invoke this mechanism, there was a progressive decrease in ATP concentrations over the next 60 min. During this time, there was a persistent mitochondrial hyperpolarization and absence of apoptotic cell death in astrocytes, whereas in the neurons there was a progressive fall in Deltapsi(m) and increased apoptosis. After glucose deprivation or treatment with inhibitors of the F(1)F(0)-ATPase and adenine nucleotide translocase, astrocytes responded to NO with a fall in Deltapsi(m) and apoptotic cell death similar to the response in neurons. Finally, although treatment of astrocytes with NO partially prevented staurosporin-induced collapse in Deltapsi(m) and cell death, NO and staurosporin synergized in decreasing Deltapsi(m) and inducing apoptosis in neurons. These results demonstrate that although inhibition of cellular respiration by NO leads to neurotoxicity, it may also result in initial neuroprotection, depending on the glycolytic capacity of the particular cell.

Adenosine Triphosphate↗
PubMed2001

Projection sites of superficial and deep spinal dorsal horn cells in the nucleus tractus solitarii of the rat.

By using anterograde transport of biotin dextran amine injected into the cervical spinal dorsal horn, we have shown that fibres from superficial and deep dorsal horn project to the nucleus tractus solitarii via two distinct pathways. Afferent fibres from the superficial lamina (I-III) were found to course in the dorsal funiculus and terminate bilaterally in the caudal zone of the nucleus tractus solitarii (NTS), mainly within the commissural subnucleus. In contrast, afferents from the deeper dorsal horn laminae (IV-V) were found to course in the dorsolateral fasciculus and terminate ipsilaterally, mostly in the lateral areas of the caudal nucleus tractus solitarii. Similar, but more extensive patterns of labelled fibres were produced by injections into the white matter of the dorsal funiculus and dorsolateral fasciculus, respectively. These observations suggest that the caudal NTS not only serves as a location of visceral afferent convergence and integration, but may also be a receptive area for monosynaptic projections from dorsal horn neurons receiving sensory afferent inputs. Such projections may represent pathways through which NTS neurons are influenced by nociceptive and non-nociceptive information from the dorsal horn and thereby can co-ordinate the appropriate autonomic response, including adjustments in cardiorespiratory reflex output.

Afferent Pathways↗
PubMed2001

Induction of micronuclei in mouse polychromatic erythrocytes by the administration of non-radioactive CsCl by the oral and intraperitoneal route.

In the present study, we describe the effects of the concentration and route of administration of non-radioactive cesium chloride (CsCl) in inducing micronuclei in mouse bone marrow polychromatic erythrocytes (PCEs). When the dose of 500mg/kg body weight was administered perorally (p.o.), no significant incidence of micronuclei was detected. However, when the same dose was administered intraperitoneally (i.p.), a significant induction of micronuclei in PCEs was observed compared to control. At the dose of 1000mg/kg, both routes were efficient, with no significant difference in micronucleus frequencies. We conclude that both the p.o. and i.p. routes are efficient in inducing micronuclei, with the i.p. route being more efficient when lower CsCl doses are used.

Administration, Oral↗
PubMed2001

Structure of the X-phase of 38% brominated betaine calcium chloride dihydrate.

The structures of the high- and low-temperature phases of 38% brominated BCCD [betaine (trimethylammonioacetate) calcium chloride dihydrate], the latter being known as the X-phase, have been determined by single-crystal neutron diffraction at 295 and 20 K, respectively. The symmetry of the X-phase is described by the P2(1)2(1)2(1) space group. The distortion with respect to the high-temperature Pnma phase is characterized by anti-symmetric displacements of the betaine molecules as well as of the Ca octahedra. On the basis of a symmetry-mode analysis, we propose an interpretation of the direct phase transition that occurs around 80 K between these two phases.

Journal Article↗
PubMed2001

Olanzapine reduces urge to drink after drinking cues and a priming dose of alcohol.

RATIONALE: Haloperidol, a D2 antagonist, has been shown to moderate the effects of alcohol consumption on craving. OBJECTIVE: The present study was designed to determine whether a single 5-mg dose of olanzapine (a D2/5-HT2 antagonist) would influence responses to alcohol cues or an alcohol challenge. It was hypothesized that olanzapine would attenuate cue-elicited urge to drink, attenuate the effects of alcohol consumption on urge to drink, and reduce the rewarding effects of alcohol. METHODS: To test these hypotheses, 26 heavy social drinkers were randomized to receive either 5 mg olanzapine or placebo approximately 8 h before each of two experimental sessions. Participants consumed a moderate dose of alcohol in one experimental session and a non-alcohol control beverage in another session. RESULTS: Results indicated that mere exposure to alcohol cues and consumption of alcohol increased urge to drink and that olanzapine attenuated these effects. Results also indicated that alcohol increased subjective stimulation and high while olanzapine did not moderate these effects. CONCLUSIONS: These results suggest that olanzapine did not influence the rewarding effects of alcohol but did attenuate the effects of alcohol cues and an alcohol challenge on urge to drink.

Adult↗
PubMed2001

Fludarabine-based stem cell transplantation protocol for Fanconi's anaemia in myelodysplastic transformation.

Allogeneic stem cell transplantation (SCT) represents the treatment of choice for severe bone marrow (BM) failure in patients with Fanconi's anaemia (FA). However, for FA patients developing leukaemic or myelodysplastic transformation, the results of SCT are much less encouraging. We present a 17-year-old girl with myelodysplastic transformation of FA (refractory anaemia with excess blasts) and oculocutaneous albinism, who was treated by sibling SCT using conditioning with fludarabine, cyclophosphamide (CY) and anti-lymphocyte globulin (ALG). She had rapid engraftment with no toxicity and no graft-versus-host disease (GVHD). Twenty-two months after SCT, she had 100% donor chimaerism on Southern blot analysis.

Adolescent↗
PubMed2001

Depletion of glutathione up-regulates mitochondrial complex I expression in glial cells.

Glutathione deficiency is commonly associated with mitochondrial complex I dysfunction and loss of viability in neurones, but not in glia. In order to address the possible mechanism responsible for this cellular difference, the regulation of mitochondrial complex I expression by glutathione depletion was investigated in glial cells. Incubation of rat-cultured astrocytes and C6 glioma cells with the specific gamma-glutamylcysteine synthetase inhibitor L-buthionine-(S:,R:)-sulfoximine (L-BSO; 0.1-1 mM) decreased the total specific content of glutathione in a dose- and time-dependent fashion. Northern blot analyses revealed that glutathione deficiency caused by L-BSO (0.1 mM) was associated with a twofold enhancement in complex I regulatory subunit ND6 (mitochondrially encoded) mRNA expression after 24-72 h. This effect was accompanied by a twofold increase in complex-I activity at 72 h in L-BSO-treated cells, as compared with control cells, but complex II-III, complex IV and citrate synthase activities were unaltered. It is suggested that the oxidative stress caused by glutathione depletion in glial cells would up-regulate complex-I activity by enhancing the expression of the mitochondrially encoded regulatory subunit. These results could offer further insight into the different degree of cellular susceptibility observed in glial vs. neuronal cells against oxidative stress.

Animals↗
PubMed2001

A transient inhibition of mitochondrial ATP synthesis by nitric oxide synthase activation triggered apoptosis in primary cortical neurons.

In order to investigate the relationship between nitric oxide-mediated regulation of mitochondrial function and excitotoxicity, the role of mitochondrial ATP synthesis and intracellular redox status on the mode of neuronal cell death was studied. Brief (5 min) glutamate (100 microM) receptor stimulation in primary cortical neurons collapsed the mitochondrial membrane potential (psi(m)) and transiently (30 min) inhibited mitochondrial ATP synthesis, causing early (1 h) necrosis or delayed (24 h) apoptosis. The transient inhibition of ATP synthesis was paralleled to a loss of NADH, which was fully recovered shortly after the insult. In contrast, NADPH and the GSH/GSSG ratio were maintained, but progressively decreased thereafter. Twenty-four hours after glutamate treatment, ATP was depleted, a phenomenon associated with a persistent inhibition of mitochondrial succinate-cytochrome c reductase activity and delayed necrosis. Blockade of either nitric oxide synthase (NOS) activity or the mitochondrial permeability transition (MPT) pore prevented psi(m) collapse, the transient inhibition of mitochondrial ATP synthesis, early necrosis and delayed apoptosis. However, blockade of NOS activity, but not the MPT pore, prevented the inhibition of succinate-cytochrome c reductase activity and delayed ATP depletion and necrosis. From these results, we suggest that glutamate receptor-mediated NOS activation would trigger MPT pore opening and transient inhibition of ATP synthesis leading to apoptosis in a neuronal subpopulation, whereas other groups of neurons would undergo oxidative stress and persistent inhibition of ATP synthesis leading to necrosis.

2-Amino-5-phosphonovalerate↗