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Biomedical subjects

I Costa

Publications and source records attributed to I Costa.

At least 19 recordsLinked to original sources
PubMed2006

Ultrastructure and germination of Vitis vinifera cv. Loureiro pollen.

The cultivar Loureiro of Vitis vinifera is one of the most economically important, recommended in almost the totality of the Região Demarcada dos Vinhos Verdes. In vineyards, the grape productivity of this cultivar is normal while in others it is extremely low. The aim of this work was to study the morphology and germination of Vitis vinifera cv. Loureiro pollen with high and low productivity. The pollen grain was examined under light, transmission and scanning electron microscopy. Typically V. vinifera pollen present three furrows but in the cultivar Loureiro we found tricolporated and acolporated (without furrows or pores) pollen grains. Both pollen types present generative and vegetative cells with the usual aspect and a dense cytoplasm rich in organelles. In the acolporated pollen a continuous exine layer and an irregular intine layer were observed. Differences were found in the starch accumulation, since only in tricolporated pollen abundant plastids filled with numerous starch granules were observed. To determine the causes of the low productivity of this cultivar we tested pollen viability by the fluorochromatic reaction and pollen germinability by in vitro assays. We observed that the acolporated pollen grain is viable, but no germination was recorded.

Cell Survival↗
PubMed2006

Are the olive oil and other dietary lipids related to cancer? Experimental evidence.

There is a wealth of evidence supporting the relationship between dietary lipids and cancer, particularly those of the breast, colon and rectum and prostate. The main support comes from the international correlational studies and, especially, from experimental ones. The evidence from human analytical studies is less consistent because of several conflicting findings, probably due to methodological issues. Experimentally, it has been clearly demonstrated that quantity and type of dietary lipids as well as the particular critical phases of the carcinogenesis in which they act, are the essential factors in this relationship. Thus, whereas high dietary intake of n-6 polyunsaturated fatty acids (PUFA), primarily LA, and saturated fat has tumor-enhancing effects, long chain n-3 PUFA, CLA and GLA have inhibitory effects. Monounsaturated fatty acids (MUFA), mainly OA, present in high quantities in olive oil, seem to be protective although some inconsistent results have been reported. Bioactive compounds of virgin olive oil may also account for the protective effect of this oil, which is the main source of fat in the Mediterranean diet. Experimental studies have also provided evidence of several putative mechanisms of action of dietary lipids on cancer. Lipids can influence the hormonal status, modify cell membranes structure and function, cell signalling transduction pathways and gene expression, and modulate the function of the immune system. Although further studies are needed to evaluate and verify these mechanisms in humans, based on the multiple ways dietary lipids can act, they may have an important influence on tumorigenesis.

Animals↗
PubMed2005

A comparative study of the in vitro corrosion behavior and cytotoxicity of a superferritic stainless steel, a Ti-13Nb-13Zr alloy, and an austenitic stainless steel in Hank's solution.

In this study, the in vitro corrosion resistance of a superferritic stainless steel in naturally aerated Hank's solution at 37 degrees C has been determined to evaluate the steel for use as a biomaterial. The potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS) were used to determine the corrosion resistance. The polarization results showed very low current densities at the corrosion potential and electrochemical behavior typical of passive metals. At potentials above 0.75 V (SCE), and up to that of the oxygen evolution reaction, the superferritic steel exhibited transpassive behavior followed by secondary passivation. The superferritic stainless steel exhibited high pitting resistance in Hank's solution. This steel did not reveal pits even after polarization to 3000 mV (SCE). The EIS results indicated high impedance values at low frequencies, supporting the results obtained from the polarization measurements. The results obtained for the superferritic steel have been compared with those of the Ti-13Nb-13Zr alloy and an austenitic stainless steel, as Ti alloys are well known for their high corrosion resistance and biocompatibility, and the austenitic stainless steel is widely used as an implant material. The cytotoxicity tests indicated that the superferritic steel, the austenitic steel, and the Ti-13Nb-13Zr alloy were not toxic. Based on corrosion resistance and cytotoxicity results, the superferritic stainless steel can be considered as a potential biomaterial.

Alloys↗
PubMed2004

Electrochemical impedance spectroscopy characterization of passive film formed on implant Ti-6Al-7Nb alloy in Hank's solution.

The influence of potential on electrochemical behavior of Ti-6Al-7Nb alloy under simulated physiological conditions was investigated by electrochemical impedance spectroscopy (EIS). The experimental results were compared with those obtained by potentiodynamic polarization curves. All measurements were carried out in Hank's aerated solution at 25 degrees C, at pH 7.8 and at different potentials (corrosion potential, 0 mV(SCE), 1000 mV(SCE), and 2000 mV(SCE)). The EIS spectra exhibited a two-step or a two-time constant system, suggesting the formation of a two-layer oxide film on the metal surface. The high corrosion resistance, displayed by this alloy in electrochemical polarization tests, is due to the dense inner layer, while its osseointegration ability can be ascribed to the presence of the outer porous layer.

Alloys↗
PubMed2002

The electrochemical behavior of Ti-6Al-7Nb alloy with and without plasma-sprayed hydroxyapatite coating in Hank's solution.

The electrochemical behavior of Ti-6Al-7Nb alloy with and without plasma-sprayed hydroxyapatite (HA) coating was investigated in Hank's balanced salt solution at 37 degrees C. This behavior was evaluated by analyzing both corrosion potential variation with time curves and potentiodynamic polarization curves. The polarization curves were determined both in aerated and deaerated solutions. It was found that the corrosion potential of uncoated sample is always more noble than that of coated one. In aerated solutions the polarization curve of a coating-free alloy presents a typical passive/transpassive behavior, which is absent in the HA-coated alloy and in deaerated solution for both coated and uncoated conditions. In the latter polarization curves, the current density continuously increases with the increase of the potential. The corrosion rate determined from polarization curves is higher for HA-coated alloys, but it still can be considered negligible (less than 1 microA/cm(2)).

Alloys↗
PubMed2000

Cytotoxicity due to corrosion of ear piercing studs.

It is well known that allergic and/or inflammatory reactions can be elicited from the use of gold-coated studs, particularly the type used for piercing ears, since they are left in contact with body fluids until the puncture heals. Inasmuch as gold is known as a non-toxic element, other elements of the substrate material may be responsible for some allergies. Therefore, characteristics of the coating, such as defects that expose the substrate to the human skin or body fluids, play an important role in the development of skin sensitization. In this study, the cytotoxicity of commercial studs used for ear piercing and laboratory-made studs was determined in a culture of mammalian cells. The corrosion performance of the studs was investigated by means of weight loss measurements and electrochemical impedance spectroscopy. The elements that leached out into the medium were also analysed by instrumental neutron activation analysis. Further, the surfaces of the studs were examined by scanning electron microscopy and analysed by energy dispersive spectroscopy to identify defects and reaction products on the surface, both before and after their exposure to the culture medium. The stud which showed lower corrosion performance resulted in higher cytotoxicity. Ti showed no cytotoxicity and high corrosion resistance, proving to be a potential material for the manufacture of ear piercing studs.

Alloys↗
PubMed2000

Assessment of genetic relatedness of vaginal isolates of Candida albicans from different geographical origins.

PCR fingerprinting with single non-specific primers was used to type vaginal isolates of C. albicans from Portugal, Angola, Madagascar, and two regions of Germany (Berlin and Munich). In addition to analysing isolates that exhibited the normal biotype of C. albicans, the study included atypical strains that failed to assimilate glucosamine and N-acetylglucosamine, which were isolated from women in Angola and Madagascar. A total of 212 strains of C. albicans were studied, representing 87 different multi-locus genotypes. The genotypes of strains from each geographical population were highly similar but not identical. There was one exception: a strain from Portugal grouped with the typical strains from Angola. The typical and especially the atypical populations from Africa displayed less genotype variation than the populations from Europe. The Portuguese samples exhibited the greatest genotypic heterogeneity. Distance analysis (UPGMA) revealed a statistically weak correlation between genotype and geographical origin of the C. albicans isolates.

Adolescent↗
PubMed2000

Oral conditions in children from birth to 5 years: the findings of a children's dental program.

The study aimed to assess oral conditions other than caries and gingival inflammation present in the mouth of children from birth to 5 years old attending a Community Dental Program. Data were collected through the examination of all dental records, who attended the clinic from November 1997 until November 1999. A total of 1042 records were examined. The results showed that 97.7% of the patients had no lesions present in the mouth during the visits to the clinic, while 2.3% who presented did have lesions. The conditions most frequently found were: Bohn's nodules, candidiasis and benign migratory glossitis.

Brazil↗
PubMed1999

Short-term intensive consolidation therapy after all-trans retinoic acid in acute promyelocytic leukemia.

Complete remission induced by all-trans retinoic acid (ATRA) in acute promyelocytic leukemia is short lived, and several consolidation chemotherapy courses usually are given to reduce the relapse rate. To assess the value of short-term intensive consolidation, 38 patients with newly diagnosed acute promyelocytic leukemia entered a prospective study in which induction therapy with ATRA immediately was followed by a single course of mitoxantrone plus high-dose cytarabine (3 g/m2 every 12 hours, days 1-4), with no further treatment. Complete remission was achieved in 31 patients (81.6%) after a median time of 49 days of ATRA (to which chemotherapy was added at entry in 10 patients with leukocytosis). Thirty patients received the planned consolidation course. After a median follow-up of 36 months, four of these patients have relapsed and 24 are still in first complete remission, for an estimated disease-free survival of 75% at 60 months. The authors conclude that this single course consolidation of ATRA-induced remission provides excellent long-term control of acute promyelocytic leukemia.

Adult↗
PubMed1999

Immunophenotyping by flow cytometry of fine needle aspirates in the diagnosis of lymphoproliferative disorders: A retrospective study.

In order to determine the value of flow cytometric (FCM) immunophenotyping of fine-needle aspirates (FNA) in the diagnosis and classification of lymphoproliferative diseases, 61 tissue samples were studied and compared with the cytologic/histological results. In vivo and ex vivo FNA biopsy yielded the material for FCM, which comprised an extensive number of lymphoid cell markers. In all but three cases sufficient cells were collected. Overall, malignancy was diagnosed in 33 cases from a total of 47 (70.2%), and in the remaining cases malignancy was not detected. Eleven cases were correctly diagnosed as reactive processes (11/11). There were no false positive cases of malignancy, as diagnosed by FCM-FNA. The best accuracy was achieved in the low-grade B-cell lymphomas and lymphoblastic lymphoma/leukemia. We conclude that in a significant number of cases, FCM-FNA permits the separation between lymphoid malignancies and reactive processes without false positive results. It was found to be particularly useful in the differential diagnosis of mantle-cell and small-lymphocytic lymphoma and in the identification of lymphoblastic lymphoma/leukemia.

Antibodies, Monoclonal↗
PubMed1998

K-ras mutations in nonmucinous ovarian epithelial tumors: a molecular analysis and clinicopathologic study of 144 patients.

BACKGROUND: To assess the putative prognostic value of K-ras mutations in nonmucinous ovarian tumors, the authors looked for K-ras point mutations at codons 12 and 13 in 144 nonmucinous ovarian tumors. METHODS: A series of 144 consecutive, unselected, archival, nonmucinous ovarian tumors (35 benign, 12 borderline, and 97 malignant) were studied. K-ras mutations at codons 12 and 13 were determined by polymerase chain reaction using the restriction fragment length polymorphism method with mismatched nested primers. Extensive clinicopathologic and follow-up data on all patients were evaluated. RESULTS: The overall prevalence of K-ras mutations at codons 12 and 13 was 30.5% (44/144). In benign tumors, it was 20% (7/35); in borderline tumors, 25% (3/12); and in carcinomas, 35% (34/97). The presence of K-ras point mutations did not correlate with survival. Among the benign tumors, K-ras mutations were detected in three Brenner tumors with a mucinous component. CONCLUSIONS: These results indicate that K-ras mutations are not initial events in the pathogenesis of nonmucinous ovarian tumors and do not appear to be related to survival.

Adult↗
PubMed1998

Intracystic (encysted) papillary carcinoma of the breast: a clinical, pathological, and immunohistochemical study.

Intracystic papillary carcinoma (IPC) of the breast is a rare tumor with predilection for elderly women and distinctive pathological features that must be distinguished from ductal carcinoma in situ (DCIS) of papillary type and from invasive papillary carcinoma. The clinical, radiological, and pathological features of 29 cases of IPC are reported. The cases were divided into three groups (IPC alone, associated with DCIS, or associated with invasive carcinoma) and studied in terms of their size, predominant architectural pattern, nuclear grade, and presence of necrosis. Immunohistochemical studies were performed to evaluate the c-erbB2 oncoprotein, estrogen receptors, and ki-67 antigen expression. The median age of the patients was 75 years. Microscopically, nine tumors (31.0%) were IPC alone, nine (31.0%) had IPC associated with DCIS, and 11 (38.0%) were IPC associated with invasive carcinoma. Most of the IPC cases had low or intermediate nuclear grade, no necrosis, strongly expressed estrogen receptor, and was negative for c-erbB-2. Nuclear grade 3 and necrosis were found only in cases of IPC associated with invasive carcinoma. The median Ki-67 antigen expression was 10.6%. One patient with IPC alone had a recurrence 5 years later. Lymph node metastases were found in one patient who had the tumor with the biggest invasive area. IPC is a low-grade carcinoma with overall good prognosis. However, there is a high frequency of DCIS or invasive carcinoma associated with it, and the prognosis of these cases is related to the type, grade, and size of the associated lesions.

Aged↗
PubMed1998

Parasuicide and mental disorders.

This study aims to provide a better follow-up of parasuicidal subjects, focusing on their diagnostic profile with regard to whether the parasuicide intention was death or not. A total of 235 parasuicidal out-patients (PS) and a comparison group of 235 non-parasuicidal out-patients (CG) were surveyed. A structured interview was applied to both groups. Parasuicide intention was appraised by means of the Suicide Intent Scale of Beck. The PS patients were divided into two groups, depending on whether their intention was death (PSD) or not (OPS), and they were matched with their CG counterparts. The diagnostic profile of each group was analysed and differences in diagnosis distribution were found. The rates of major depression, alcohol dependence and schizophrenia were higher among PSD than in OPS patients. The same was true for comorbidity of major depression and alcohol dependence. On Axis II, borderline personality ranks first among PSD patients. The diagnostic profile of PSD approaches that of completed suicide as shown in retrospective and prospective studies. The methodology employed here could therefore be recommended for estimating parasuicide intention. As well as the diagnosis, a detailed profile could also be obtained in the light of that intention. Bearing in mind such a profile among PSD patients could contribute to a drop in the suicide rate among these subjects.

Adjustment Disorders↗
PubMed1998

Granulocyte-macrophage colony-stimulating factor in post-remission therapy of acute myeloid leukemia.

The impact on occult leukemia of GM-CSF as a sensitizing agent has not been studied. We treated 41 adult patients with de novo acute myeloid leukemia, 25 of whom achieved complete remission and were given 1 to 3 post-remission courses, each course including GM-CSF begun 4 days prior to chemotherapy and given until day 3. After a median follow-up of 32 months, the probability of remaining in continuous complete remission was 17% at 46 months. GM-CSF in this setting was not associated with an improved outcome, arguing against a priming effect.

Acute Disease↗
PubMed1997

ACTH-producing carcinoma of the pituitary with haematogenic metastases.

The case report is presented of a 47-year-old white woman with Cushing's disease treated by bilateral adrenalectomy in June 1981. A first computed tomography (CT) scan in September 1984 showed a voluminous pituitary adenoma with invasion of the sphenoid sinus and left parasellar extension. The tumour increased progressively in size, a suprasellar extension developed and the optic chiasm was eventually affected. In March 1988 and June 1989 the patient underwent two surgeries for the pituitary tumour, the second followed by radiotherapy. During this period, the ACTH values varied between 100 pmol/l and 403 pmol/l (normal: < 13 pmol/l). After radiotherapy, a progressive shrinking of the tumour was observed and the ACTH concentrations decreased to a lowest value of 27.5 pmol/l. The patient was clinically well until September 1993 when, suddenly, the plasma ACTH concentration increased to very high levels (greater than 965 pmol/l). There was no evidence of tumour growth on the sellar CT scan. In January 1995, an ACTH-producing pituitary carcinoma was diagnosed, based on the presence of bone metastases. The patient died in May 1995.

Adrenocorticotropic Hormone↗
PubMed1997

Masson's intravascular papillary endothelial hyperplasia mimicking Stewart-Treves syndrome: report of a case.

Masson's intravascular papillary endothelial hyperplasia, also called Masson's pseudoangiosarcoma, represents a benign vascular proliferation, presently considered as a peculiar histopathologic reaction pattern of the endothelium to diverse stimuli. Differentiation from angiosarcoma represents the main diagnostic concern. We report a case of Masson's intravascular papillary endothelial hyperplasia presenting in a 55-year-old woman with ipsilateral lymphedema secondary to surgery and radiation therapy for breast carcinoma. The diagnosis was intravascular papillary endothelial hyperplasia. This is the first description of Masson's pseudoangiosarcoma in this clinical context, to our knowledge. We believe it represents a peculiar morphologic pattern of endothelium proliferation secondary to venous stasis and thrombosis due to lymphedema.

Arm↗
PubMed1997

[Intestinal obstruction in cancer patients. Palliative treatment].

The treatment of intestinal obstruction (IO) in patients with advanced or terminal cancer represents an open and widely discussed topic in clinical oncology practice. As surgical palliation is a complex issue, the decision to advance with surgery should be made in consultation with the patients and family members. The prognostic factors, mainly the survival time and the surgical risks can be considered guideline indicators. If there is any possibility that surgery will be of benefit, the patient should be treated with intravenous fluids and nasogastric suction while appropriate radiological investigations are performed. When surgical intervention is contraindicated, symptomatic medical treatment should be started through continuous subcutaneous administration of analgesic and antiemetic drugs. Minor episodes of vomiting may occur, which do not trouble patients since the most distressing symptom, nausea, can be controlled. Dehydration may be avoided with a liquid diet in small quantities. In this way, it is possible to manage patients with IO for several weeks without the need of nasogastric suction or intravenous fluids. Percutaneous gastrostomy, nasogastric tube, or hypodermoclysis may be necessary for a small number of patients, principally with high obstruction, who have refractory symptoms.

Diagnosis, Differential↗