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Biomedical subjects

A M Pinto

Publications and source records attributed to A M Pinto.

15 recordsLinked to original sources
PubMed2001

Chlorophyll-a determination via continuous measurement of plankton fluorescence: methodology development.

A methodology is presented for the continuous measurement of chlorophyll-a concentration due to plankton, in surface water environments. A Turner 10-AU fluorometer equipped with the F4T5.B2/BP lamp (blue lamp), a Cs 5-60 equivalent excitation path filter, and a 680 nm emission filter, has been used. This configuration allows the in vivo, in situ determination of chlorophyll-a by measuring the fluorescence due to the pigments. In field work the fluorometer, data logging and positioning equipment were placed aboard a manageable boat which navigated following a scheme of regularly spaced crossings. Some water samples were collected during the measurement for laboratory chlorophyll-a measurements by the spectrophotometric method, thus providing for calibration and comparison. Spatial chlorophyll-a concentration distributions can be easily defined in large volumes, such as reservoirs, etc. Two distinct environments have been monitored: in the Vargem das Flores reservoir chlorophyll-a concentrations varied between 0.7 and 2.6 mg/m3, whereas in the Lagoa Santa lake these values lied in the 12 to 18 mg/m3 range. The simplicity, versatility and economy of the method, added to the large amount of data that can be gathered in a single run, clearly justify its use in field environmental studies.

Calibration↗
PubMed2000

Iron mobilization by succinylacetone methyl ester in rats. A model study for hereditary tyrosinemia and porphyrias characterized by 5-aminolevulinic acid overload.

Accumulation of 5-aminolevulinic acid (ALA) is an event characteristic of porphyrias that may contribute to their pathological manifestations. To investigate effects of ALA independent of porphyrin accumulation we treated rats with the methyl ester of succinylacetone, an inhibitor of 5-aminolevulinic acid dehydratase that accumulates in the porphyric-like syndrome hereditary tyrosinemia. Acute 2-day treatment of fasted rats with succinylacetone methyl ester (SAME) promoted a 27% increase in plasma ALA. This increase in plasma ALA was accompanied by augmentation of the level of total nonheme iron in liver (37%) and brain (20%). Mobilization of iron was also indicated by 49% increase in plasma iron and a 77% increase in plasma transferrin saturation. Liver responded with a mild (12%) increase in ferritin. Under these acute conditions, some indications of oxidative stress were evident: a 15% increase in liver reactive protein carbonyls, and a 42% increase in brain subcellular membrane TBARS. Brain also showed a 44% increase in CuZnSOD activity, consistent with observations in treatment with ALA. Overall, the data indicate that SAME promotes ALA-driven changes in iron metabolism that could lead to increased production of free radicals. The findings support other evidence that accumulation of ALA in porphyrias and hereditary tyrosinemia may induce iron-dependent biological damage that contributes to neuropathy and hepatoma.

Aminolevulinic Acid↗
PubMed1999

Tc-99m sestamibi scintigraphy in multiple myeloma.

Tc-99m sestamibi imaging was performed in two patients with multiple myeloma. Focal areas of increased uptake in one patient and diffuse skeletal uptake in the second patient were found. Tc-99m sestamibi appears to identify bone marrow and osteolytic involvement in multiple myeloma.

Adult↗
PubMed1999

Detection of focal myeloma lesions by technetium-99m-sestaMIBI scintigraphy.

BACKGROUND AND OBJECTIVE: The tracer tachnetium-99m-2-methoxy-isobutyl-isonitrile (Tc99m-sestaMIBI) has recently been shown to concentrate in some neoplastic tissues, including myeloma. We investigated the diagnostic capacity and limits of this procedure in tracing focal myeloma lesions, and compared them with those of conventional radiological procedures (Xr). DESIGN AND METHODS: We studied 55 patients suffering from multiple myeloma (MM) or solitary plasmacytoma in different stages and clinical conditions, or from monoclonal gammopathy of undefined significance (MGUS), by whole body scans obtained 10 minutes after injection of 555 MBq of Tc99m-sestaMIBI. Scans were defined as normal (physiological uptake only), diffuse (presence of bone marrow uptake), or focal (localized areas of uptake), and were compared to conventional skeletal Xr. RESULTS: Thirty patients showed no focal areas of Tc99m-sestaMIBI uptake; this group consisted of 5 patients with MGUS, 6 with MM in stage IA and 2 in stage IIA, 11 patients studied after effective chemotherapy and 6 in early relapse. Twenty-five patients showed one or more spots of focal uptake: all of them had active disease (untreated, resistant or relapsing MM). In the setting of tracing focal lesions, Tc99m-sestaMIBI scans were concordant with the radiological examination in 38 patients and discordant in 17. Among the latter, in 4 cases Tc99m-sestaMIBI revealed focal lesions not detected by Xr, and in 13 cases lytic areas detected by Xr did not show Tc99m-sestaMIBI uptake. INTERPRETATION AND CONCLUSIONS: In untreated patients, the number of lesions revealed by Tc99m-sestaMIBI was comparable to that shown by Xr, while in pretreated patients Tc99m-sestaMIBI traced a number of lesions lower than that detected by Xr. The reason for this discrepancy is that Tc99m-sestaMIBI traces only active lesions. Tc99m-sestaMIBI limitations in identifying focal lesions may derive from the dimension of the smallest traceable lesion (about one centimeter), and from the possibility that focal plasma cell localizations in collapsed bone may not be visualized due to inadequate vascularization. Tc99m-sestaMIBI scintigraphy is an interesting tool for diagnosing, staging and following up focal myeloma lesions, in the bone as well as in soft tissues. It is more specific than conventional Xr in identifying sites of active disease.

Adult↗
PubMed1998

Expression of adhesion molecules in chronic B-cell lymphoproliferative disorders.

BACKGROUND AND OBJECTIVE: Abnormalities in the expression of cell adhesion molecules (CAM) are thought to influence the patterns of intranodal growth and hematogeneous spread of malignant cells in chronic lymphoproliferative disorders (LPD). Therefore, the characterization of CAM phenotypic profiles of the neoplastic clones in LPD may help to identify distinct subtypes with prognostic implications. In this work we sought to investigate whether the expression of CAM by circulating malignant cells in patients with B-cell LPD differed from that of normal peripheral blood B-lymphocytes (PBL) and whether the observed phenotypic patterns could be correlated to other biological and clinical parameters of known clinical relevance. DESIGN AND METHODS: Peripheral blood mononuclear cells were obtained from 148 patients with B-cell chronic lymphocytic leukemia (B-CLL), 52 with B-cell non-Hodgkin lymphomas (NHL) and 10 with hairy cell leukemia (HCL). The expression of CAM was analyzed by flow cytometry using monoclonal antibodies against CD49d, CD29, CD11a, CD11b, CD11c, CD18, CD62L, CD54 and CD44. RESULTS: All CAM were detected in normal peripheral blood B-lymphocytes, except CD11c and CD54, which were present in only a minority of cells. Fluorescence mean channel values (FMC) showed that all molecules, with the exception of CD44, were expressed with dim intensity. Emerging patterns of CAM expression, as assessed by FMC values, were observed in different LPD: thus, B-CLL is characterized by a very low expression of CD49d/CD29 and beta 2 integrins. In this disorder, CD49d/CD29, CD11a, and CD54 increase with tumor burden; NHL show high expression of CD29 and CD54; strong expression of all molecules (except CD11a) was found in HCL, particularly CD11c (FMC values 60 times higher than normal). CD62L was faintly expressed in all diagnostic groups, whereas CD11c showed consistently high FMC values. INTERPRETATION AND CONCLUSIONS: The data shows that the phenotypic characterization of LPD can be further refined by the analysis of their patterns of CAM expression which may help to identify distinct subsets within each nosological group.

Adult↗
PubMed1997

Correlation between plasma 5-aminolevulinic acid concentrations and indicators of oxidative stress in lead-exposed workers.

5-Aminolevulinic acid (ALA), a heme precursor accumulated in acute intermittent porphyria and lead poisoning, undergoes metal-catalyzed aerobic oxidation at physiological pH to yield reactive free radical species (O2., HO., and ALA.). We analyzed the relationships between plasma ALA concentrations, blood concentrations of lead, protoporphyrin IX (PP-IX), superoxide dismutase (SOD), and methemoglobin (metHb), and urine chemiluminescence (CL) in samples collected from lead-exposed workers. All variables measured were substantially (P < 0.01) higher (2-8-fold) in the lead-exposed workers (n = 60). Plasma ALA concentrations were, on average, 6-fold higher in lead-exposed workers. We observed positive linear relationships between ALA and lead (r = 0.992), ALA and PP-IX (r = 0.891), ALA and metHb (r = 0.984), lead and SOD (r = 0.948), ALA and urine CL (r = 0.987), and lead and PP-IX (r = 0.993). These data are consistent with our free radical hypothesis for lead poisoning, where ALA distribution to and accumulation in several organs may trigger oxidative stress responses.

Adolescent↗
PubMed1994

Hemagglutinating and sialidase activities of subpopulations of influenza A viruses.

The present study was conducted to investigate the characteristics of two samples of influenza A/England/42/72 (H3N2) virus, one of them selected by an adsorption-elution technique, to determine the possible existence of virus variants or subpopulations. Based on specificity of virulence-related cell receptor-binding and sialidase activities, this selection technique using human O group erythrocytes revealed the presence of variants within a standard virus sample with diversity for their hemagglutinating and sialidase activities. The standard-like (E1) sample exhibited titers of 4 and 32 HAU (hemagglutinating units in 25 microliters) with human O group and chicken erythrocytes, respectively, while the sample obtained by the adsorption-elution process (E2) exhibited titers of 32 and 4 HAU, respectively, with these same types of erythrocytes. The E2 sample showed higher sialidase activity at pH values between 5.4 and 6.6 with human erythrocytes (128-256 HAU), but the E1 sample did not exhibit significant sialidase activity with either human or chicken erythrocytes. The different pH optima for hemolysis (5.2) and sialidase (5.4-6.6) activities and the higher hemolysis indexes present in samples with sialidase activity inhibited by heating (at 56 degrees C for 30 min) or by treatment with EDTA (dilution in buffer containing 2 mM EDTA, a chelating agent on calcium-dependent sialidase activity) demonstrate the independence of these activities in the selected sample: native E2 (absorbance = 0.18), EDTA-treated native E2 (absorbance = 0.28), heated E2 (absorbance = 0.26), EDTA-treated heated E2 (absorbance = 0.41).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Mitral valve replacement with porcine bioprosthesis in children. Evaluation of 29 patients during 12 years].

PURPOSE: To analyze the clinical result of the mitral valve substitution for the porcine bioprostheses, the incidence of dysfunction caused by calcification and its importance related to the durability of bioprostheses and also the patients' survival. METHODS: Twenty-nine children of about seven to sixteen years old were operated on from November 1977 to August 1982 and all of them received porcine bioprostheses of low profile. RESULTS: There were three (10.34%) hospital deaths and nine other late mortalities. The follow-up period varied from 4 to 128 months with average of 58.17 months and with the loss of nine patients. An actuarial survival rate of 46.08% has been observed at 11 years after surgery. Calcification of 21 bioprostheses occurred in 14 out of 17 follow-up patients; 47.6% of them happened until the third year of pos-operative and 85.7% until the fifth year. Eleven patients were reoperated on with 9.09% of hospital mortality. There were no cases of thromboembolism. CONCLUSION: Porcine bioprostheses works well with an evident clinical improvement of patients, with no thromboembolic accidents. However, its durability has been affected by the high incidence of calcification, which is responsible for an increase in late morbidity and mortality. Mitral valve disease treatment in children must be conservative, in an attempt to solve the problem with the different available plastic technics and leave the valve substitution to be a last option. In that case, the preference is given to the homologous bioprostheses.

Actuarial Analysis↗
PubMedDate not supplied

Retinal complications after bungee jumping.

Bungee jumping is becoming a popular sport in the Western world with some cases of ophthalmic complications being reported in recent literature. The authors reported a case of a 23-year-old healthy female who presented retinal complications following a bungee jumping. Her fundi showed superficial retinal hemorrhages in the right eye and a sub-internal limiting membrane hemorrhage affecting the left eye. A general examination, including a full neurological examination, was normal and laboratorial investigations were all within normal values. More studies are necessary to identify risk factors and the true incidence of related ocular lesions, but until then, we think this sport activity should be desencouraged, especially to those that are not psychological and physically fit.

Adult↗
PubMedDate not supplied

Comparative evaluation of a simple and sensitive assay for detection of orthomyxo and paramyxoviruses.

Studies were done to evaluate comparatively the traditional HA assay and a more recently introduced lectin-neuraminidase (LN) methodology in search of a simple and sensitive assay for virus detection during laboratorial diagnosis. The results proved the value of LN assay as a sensitive methodology for detection of virus particles, presenting results at least equal to those obtained by HA (hemagglutination) assay, with significant values of accumulated frequencies for LN/HA factors (ratios between LN and HA titers) higher than two. The accumulated values of frequencies for LN/HA factors as high as four were very significant, 72.7% for influenzavirus and 60.7% for Newcastle disease virus (NDV), moreover accumulated frequencies for LN/HA factors even as high as 32 were due to influenzavirus (45.4%) and NDV (7.2%) samples. After the storage period, most of those concentraded samples that even did not present HA titers could be detected through LN assay, demonstrating a lower threshold for virus detection.

Animals↗