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Biomedical subjects

A Motta

Publications and source records attributed to A Motta.

At least 127 records · Page 7Linked to original sources
PubMed1987

Nuclear Overhauser effects in linear peptides. A low-temperature 500 MHz study of Met-enkephalin.

Met5-enkephalin was studied in 1 mM solutions in 2H2O at room temperature and in a cryoprotective mixture (DMSOd6/2H2O, mole fraction of DMSO 0.49) in the temperature range 265-298 K. Small positive effects were observed between the ortho and meta protons of Tyr in aqueous solution at room temperature. Intraresidue effects can be made strong and negative by increasing the viscosity of the medium with a combination of cryoprotective mixtures and low temperatures. The use of mixtures with properties very close to water is very promising for conformational studies of enkephalins and of other small linear peptides.

Cold Temperature↗
PubMed1987

Anti-delta antibody in various HBsAg positive Argentine populations.

One thousand five hundred and seventeen HBsAg carriers from different cities of Argentina were studied for the presence of anti-Delta antibody (anti-HDV) in their sera. One thousand one hundred and sixty-eight were volunteer blood donors and 349 were patients with liver disease. Different liver diseases were diagnosed by clinical, biochemical, and histological parameters. Among blood donors, 16 (1.4%) were positive for the antibody and none was Delta-antigen positive. In 130 patients with acute hepatitis, one (0.77%) was positive for anti-HDV, as well as three (2.22%) out of 135 patients with chronic active hepatitis (CAH), and three (5.77%) out of 52 patients with cirrhosis (C). No anti-HDV positive was found among seven fulminant hepatitis (FH) cases. The presence of HBeAg and anti-HBe was studied in anti-HDV positive sera; eleven (69%) volunteer blood donors were anti-HBe positive, and five (31%) were HBeAg positive. HBeAg was positive in the three CAH cases, and in one out of three C Cases with anti-HDV positive. Hepatitis Delta antigen was also positive in the hepatocytic nuclei in the three patients with C and two of the three CAH cases. The present results show that Delta infection is rare among blood donors in Argentina. A small variation without statistical significance could be found within different geographical areas. Among patients with HBsAg related liver disease, the presence of HDV markers was also low.

Adolescent↗
PubMed1987

Plasma fibronectin and microvascular damage in essential mixed cryoglobulinaemia.

Plasma fibronectin (FN) was measured in 17 patients with essential mixed cryoglobulinaemia (EMC) and in 17 normal subjects by single radial immunodiffusion (RID) and enzyme-linked immunosorbent assay (ELISA). In 9 patients the presence of FN in the cryoprecipitates was also assessed by immunoblotting. In the EMC group, plasma FN levels were significantly lower than in control subjects, using both methods, and FN was constantly demonstrated in EMC cryoprecipitates. Capillaroscopic observation of the capillary bed in skin and bulbar conjunctiva, performed in all cases, showed severe alterations of microcirculation in EMC patients. A negative correlation between plasma FN and capillaroscopic abnormalities of skin capillaries was observed. These data support the hypothesis that plasma fibronectin plays a role in the pathogenesis of systemic vasculitis in EMC.

Adult↗
PubMed1987

Two-dimensional echocardiography in the diagnosis of intracardiac masses: a prospective study with anatomic validation.

The accuracy of two-dimensional echocardiography in the detection of intracardiac masses was verified in 334 patients who underwent cardiac catheterization in our laboratory over 21 consecutive months. A complete two-dimensional echocardiographic (2DE) examination was performed a day before catheterization. The presence or absence of a mass was verified at surgery in 77 patients who successively underwent mitral or aortic valve replacement (51), left ventricular aneurysmectomy with or without myocardial revascularization (25), and resection of atrial myxoma (2). In 32 patients 2DE revealed the presence of a mass-left or right atrial thrombi in 12, left atrial myxoma in 2, left ventricular thrombi in 16, and endocardial vegetations in 2. The other 45 patients were free of intracardiac masses on 2DE. Anatomic verification at surgery revealed the presence of an intracardiac mass in 34 patients. In 30 (true positives) of these, 2DE revealed the mass as well, and in 4 (false negatives) the presence of a mass had not been identified by 2DE. In 2 patients (false positives) the predicted mass was not found at surgery. Absence of a mass was correctly predicted by 2DE in 41 patients (true negatives). Thus 2DE detected intracardiac masses with sensitivity of 88.2% and a specificity of 95.3%. We recommend that 2DE be performed in all patients prior to hemodynamic study and/or cardiac surgery to enable safer management of patients with intracardiac masses during cardiac catheterization and/or cardiac surgery.

Adult↗
PubMed1986

Characterization of the low-field proton magnetic resonance spectrum of plasminogen kringle 4 via selective Overhauser experiments in 1H2O.

The low-field 1H NMR spectrum of the kringle 4 domain of human plasminogen has been investigated at 300 and 600 MHz for the protein dissolved in 1H2O. The spectrum exhibits six well-resolved resonances, spanning the 9.8 approximately less than delta approximately less than 13 ppm chemical shift range, which arise from exchange-labile H atoms. The acid-base response of the six resonances was monitored in order to characterize the signals in terms of their pH titration profiles. The sensitivity of the low-field resonances to kringle binding the antifibrinolytic ligands N alpha-acetyl-L-lysine and p-benzylaminesulfonic acid was also investigated. The lowest field resonance, at 12.6 ppm, is a doublet of J approximately 7.9 Hz, a splitting that is unprecedented for His or Trp ring NH signals. Selective Overhauser experiments centered on the exchangeable proton transitions identify four of the other resonances as stemming from the His31, His33, Trp I, and Trp II side-chain NH groups, where the latter two are, as yet, not definitely assigned to the specific residues, Trp25 and Trp62. The relative narrowness of the His imidazole NH signals indicates that the two rings are sterically shielded from direct water accessibility. In particular, the His33 NH site appears to be the most protected. The Overhauser evidence conclusively shows that the two identified exchangeable His ring proton signals arise from imidazole NH3 sites rather than from the NH1 tautomers. Similarly, these experiments lead to an unambigous characterization of the corresponding Trp aromatic CH spin systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1986

Proton magnetic resonance study of kringle 1 from human plasminogen. Insights into the domain structure.

The aromatic H NMR spectrum of the kringle 1 domain from human plasminogen has been investigated by proton Overhauser experiments, acid-base titration, and two-dimensional chemical shift correlated spectroscopy. Spin-echo and pH response experiments lead to the identification of the N-terminal Tyr-3 phenol ring signals. The connectivities among the tryptophanyl aromatic protons have been established and sets of singlet-doublet-triplet resonances stemming from each of the two indole groups sorted according to their common side chain origin. Similarly, the four histidyl singlets have been identified and paired per imidazole group. From their pH responses, it is indicated that a histidyl (His31) and a tryptophanyl (Trp-II) residue are placed in the neighborhood of carboxyl groups. The high-field chemical shifts observed for proton resonances of the ligand epsilon-aminocaproic acid upon binding to kringle 1 indicate that the ligand-binding site is rich in aromatic components. Overhauser experiments reveal that Leu46 is surrounded by a cluster of interacting aromatic side chains, which includes Trp25, Phe36, His41, Trp62, and Tyr64, and define a hydrophobic region contiguous to the kringle lysine-binding site. Relative internuclear distances have been estimated for aromatic H-atoms in the vicinity of Leu46 by reference to one of the latter's CH3 sigma, sigma' groups. Some of the connectives have previously been found for Leu46 in kringle 4 which further supports the idea of a common structure for the homologous domains.

Amino Acid Sequence↗
PubMed1985

Plasma levels and myocardial content of verapamil, norverapamil and two N-dealkyl-metabolites in man.

The plasma levels and myocardial content of verapamil and its metabolites norverapamil, N-dealkylverapamil and N-dealkylnorverapamil were determined in 15 patients with valvular [3] or ischaemic [12] heart disease. The mean myocardial plasma concentration ratio (M/P) was 7.05 for verapamil, 11.45 for norverapamil, 8.93 for N-dealkylverapamil, and 11.33 for N-dealkylnorverapamil, with great interpatient variability. The highest M/P ratios of verapamil were generally found in patients with the lowest plasma levels, suggesting that saturable tissue uptake may occur.

Adult↗
PubMed1985

Macro- and micro-stabilities of the kringle 4 domain from plasminogen. The effect of ligand binding.

1H-NMR spectra of kringle 4 from human plasminogen have been recorded over wide pH* and temperature ranges, both in the presence and in the absence of p-benzylaminesulfonic acid (BASA). Several resonances exhibit chemical shift differences between kringle folded and unfolded forms which are sufficiently well resolved to allow for a determination of equilibrium Van't Hoff enthalpies and entropies for unfolding. The interaction with BASA shifts the kringle unfolding temperature from approximately 335 degrees K to approximately 343 degrees K. The pH* range of stability is also wider for the complex than for the free kringle: in the acidic range the pH* of half-unfolding, pHu*, is decreased from 2.8 for the unligated polypeptide to approximately 2.0 in the presence of BASA, while in the basic range pHu*, shifts from approximately 10.8 to 11.5. However, in contrast with what is observed at acidic pH*, unfolding at basic pH* leads to irreversible denaturation and exhibits a sharp, order-disorder transition both in the presence and in the absence of ligand. The structural stabilization conferred by the ligand is accompanied by a drastic reduction of the average rate of 1H-2H exchange in 2H2O under conditions that preclude a major cooperative unfolding. Thus, macro- and micro-stabilities of kringle domains appear to be highly correlated.

Benzylamines↗
PubMed1985

[Sudden and fatal malfunction of a Björk-Shiley prosthesis in mitral position due to rupture of the ventricular bracket and disk embolization].

Mechanical complications of prosthetic valves are increasing. The following report describes a case of fracture of a Björk-Shiley mitral prosthetic strut with dislogment of the valve occluder into the thoracic aorta. At the reoperation a new prosthesis was implanted but the patient died of acute heart failure. The diagnosis of valve disfunction must be made non invasively, because the time required for cardiac catherization usually constitutes a lethal delay. The only hope for survival is prompt surgical treatment.

Adult↗
PubMed1985

[Cardiac failure due to isolated pulmonary sequestration. Description of a clinical case in the neonatal period].

Pulmonary Sequestration is a congenital anomaly rarely seen in the pediatric age. Clinical manifestations commonly appear with a respiratory symptomatology and less frequently with cardiac signs especially in the case of an associated congenital heart disease. In the presented case, isolated Pulmonary Sequestration manifested itself as a congestive heart failure, and a diastolic overloading of the left ventricle. After surgical removal of the Sequestration was demonstrated a normalization of both clinical and haemodynamic findings.

Bronchopulmonary Sequestration↗
PubMed1984

Particle size and surface area distributions of pharmaceutical powders by microcomputerized mercury porosimetry.

The Mayer-Stowe theory was applied to derive the particle size distribution of powders of pharmaceutical interest using mercury porosimetry. Particle size data obtained by this approach are fairly comparable with data derived by other, more popular, techniques such as the electrical sensing zone or the air jet sieving methods provided that the experimental value of the mercury-powder contact angle and the state of aggregation of the powder are carefully studied. Furthermore, by applying the Rootare-Prenzlow method a surface area distribution can also be derived from the same porosimetry data used to obtain the particle size distribution. All experiments were carried out with a microcomputerized mercury porosimeter, which allows storage of data during the analysis and a subsequent fast elaboration at the end of the run, with fully printed data on pore size, pore volume, surface area, and particle size of the powder sample.

Chemistry, Pharmaceutical↗
PubMed1983

Influence of the ionic environment on the conformation of aspartic acid and possible relevance to its neurotransmitter action.

The conformational changes of aspartic acid, a possible neurotransmitter, induced by increasing ionic strength were investigated by means of NMR spectroscopy. The effects of Li, Na, K, and Cs chlorides in basic and neutral conditions were characterized. The effects of the presence of both Ca2+ and Na+ or K+ were also examined. The results always showed a relative stabilization of the two conformers with gauche carboxylates at the expense of the anticonformer. The significant quantitative difference found between Na+ and K+ in basic solutions, as well as between calcium-free and calcium-containing solutions, may bear some relevance for the role of aspartate as a CNS neurotransmitter.

Aspartic Acid↗
PubMed1983

Intravenous maprotiline in severe and resistant primary depression: a double-blind comparison with clomipramine.

A double-blind, randomized trial is described which was designed to compare the clinical effect of 100 mg daily of maprotiline (Ludiomil) and of clomipramine (Anafranil) given by the intravenous route in forty hospitalized female patients with severe and resistant primary depression. Physicians' assessment of patients' progress was made following 5, 9 and 21 days of treatment. The response rates to maprotiline and clomipramine were not significantly different even if a greater number of patients responded to clomipramine. None of the demographic and clinical variables considered could be identified as factor predicting the response to maprotiline and to clomipramine, even if a trend for a preferential responsiveness to clomipramine in the older patients was observed.

Adolescent↗
PubMed1983

[Surgical treatment of isthmic coarctation of the aorta by left subclavian artery post-isthmic aortic by-pass].

Between May 1978 and July 1981 at the Department of Cardiovascular Surgery, Padua University Medical School in Verona, 10 patients with coarctation of the aorta underwent surgical treatment with a by-pass between the left subclavian artery and the descending aorta. A synthetic fibre graft was employed. The patient's age varied between 20 and 46 years and all were hypertensive: 160-220 mmHg systolic, 90-110 diastolic pressure. No hospital deaths occurred. Blood pressure decreased significantly in all patients as well as their electrocardiographic signs of left ventricular hypertrophy.

Adult↗
PubMed1982

[Right atrial-right ventricular anastomosis for correction of tricuspid atresia].

Primary correction of type 1 b tricuspid atresia with a right atrial-right ventricular anastomosis has been performed on a 23-month-old baby with excellent clinical and hemodynamic results. This type of operation, which has been described for the first time by Björk et al. in 3 patients aged 8, 9 and 12 years respectively, does not require any conduit or prosthesis since it employs the right atrial appendage and a patch of autologous pericardium. The authors review the surgical anatomy of tricuspid atresia, the various operative techniques so far employed for its correction, as well as other congenital heart diseases which could benefit from this surgical procedure. Moreover they underline the advantage of the latter technique which avoids the employment of any foreign material, can be performed in early infancy, and can be considered definitive since it obviates the need for initial palliative procedures.

Heart Atria↗