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Biomedical subjects

R M Santos

Publications and source records attributed to R M Santos.

46 records · Page 3Linked to original sources
PubMed1986

Direct identification of electrophysiologically monitored cells within intact mouse islets of Langerhans.

Cells found to be electrically active within microdissected mouse islets of Langerhans perifused with high (greater than or equal to 11.1 mM) glucose concentrations were labeled by injecting Lucifer yellow through the recording electrode. After fixation, these cells were located by fluorescence microscopy on sections serially cut throughout the islets and were subsequently identified by immunofluororescence staining with specific anti-islet hormone sera. Electrophysiologic control confirmed that the electrode tip had remained within the same cell throughout the experiment and showed that Lucifer yellow labeling did not affect the electrical activity of the impaled cell. Upon individual impalements, Lucifer yellow labeled either the impaled cell alone or this cell and some of its neighbors to which it was dye coupled. Immunofluorescence staining of the Lucifer yellow-labeled cells revealed that glucose-induced electrical activity was recorded from individual B-cells or groups of dye-coupled B-cells as well as from A-cells coupled to B-cells.

Action Potentials↗
PubMed1979

Renal papillary adenocarcinoma.

Papillary adenocarcinoma of the kidney is an uncommon variant of renal tubular carcinoma, which on radiographic and ultrasonographic evaluation presents characteristically as a predominantly solid hypovascular or avascular mass. Surgery is required to distinguish this lesion from other solid renal lesions, which differs from the more common form of renal tubular carcinoma in several important respects.

Adenocarcinoma, Papillary↗
PubMed1978

Effect of scorpion toxin (tityustoxin, TsTx) on the salivary gland of the rat, in vivo and in vitro.

Intravenous injection of purified scorpion toxin (tityustoxin, TsTX) brings about the appearance of salivary flow and of kallikrein and amylase secretion in the saliva of rats. In experiments performed in vitro, using slices of parotid gland, a dose-response curve correlating tityustoxin concentration with kallikrein and amylase activities was obtained. The secretion of kallikrein is slower and smaller than that of amylase after up to 60 min of incubation. Experiments in which propranolol, phenoxybenzamine or atropine were injected into rats or added to parotid gland slices showed that the release of kallikrein is more dependent on cholinergic mechanisms, whereas the release of amylase is mainly related to adrenergic effects. Pre-treatment of the animals with reserpine confirms these results. The actions of tityustoxin on the kallikrein and amylase secretions, per min, are more effective than those by pilocarpine and isoproterenol, respectively.

Amylases↗
PubMedDate not supplied

Immobilization of luciferase from a firefly lantern extract on glass strips as an alternative strategy for luminescent detection of ATP.

The bioluminescent reaction catalysed by firefly luciferase has become widely established as an outstanding analytical system for assay of ATP. When used in solution, luciferase is unstable and cannot be re-used, a problem that can be partially circumvented by immobilizing the enzyme on solid substrates. Transparent glass is especially advantageous over alternative immobilizing matrices, since it allows most of the emitted photons to be detected. We report a new method for luciferase immobilization on glass which does not require prior silanization and glutaraldehyde activation, thus saving preparation time and minimizing enzyme inactivation. Our method is based on the co-immobilization by adsorption of luciferase (from a firefly lantern extract) and poly-L-lysine (PL) on non-porous glass strips. Luciferase immobilized in this way exhibits minimal variations in intersample activity, high sensitivity for ATP detection (linear luminescence responses down to 50 nmol/L) and good stability (full activity for at least 60 days when stored at -80 degrees C). PL-mediated immobilization of luciferase on glass strips provides an attractive strategy for the design of specific ATP biosensors, with potential in industry, environmental screening, medicine and biological research.

Adenosine Triphosphate↗
PubMedDate not supplied

Effect of orally administered misoprostol and cimetidine on the steady state pharmacokinetics of diazepam and nordiazepam in human volunteers.

The effects of misoprostol and cimetidine on diazepam pharmacokinetics were evaluated in order to determine whether the kinetic variables for diazepam and nordiazepam alone differ with the repeated oral administration of misoprostol and cimetidine to healthy adult volunteers. The trial was conducted as an open crossover study in 12 normal subjects, divided into two groups with all subjects receiving both regimens. Total study duration was 5 weeks. An initial clinical assessment, including blood biochemistry and assessment of subject oxidation status was carried out on study day 1. On this day, subjects began taking diazepam (10 mg) orally for one week, with pharmacokinetic studies performed at day 8, when steady state levels of diazepam were reached. This was followed by one week with active drug, misoprostol to Group I and cimetidine to Group II, with pharmacokinetic studies performed at the end of a 1-week treatment. After a 2-week wash-out period, both groups took for one week, the alternate drug, i.e. cimetidine plus diazepam to Group I and misoprostol plus diazepam to Group II. On days 8, 15 and 36, subjects were admitted to the hospital for 12 h, during which time a clinical examination was carried out and blood samples were taken at time zero and at 4, 8, 12, 24, and 36 h post-dosing for the measurement of serum diazepam and nordiazepam. The main parameters measured and evaluated were diazepam and nordiazepam pharmacokinetics at steady state (days 8, 15 and 36). These were areas under the curve in the dose intervals (AUC0-24h), maximum plasma concentrations (Cmax), time to peak concentrations (Tmax), elimination half-life (t1/2), elimination constant (Kel), distribution volume (Vd), total body clearance (ClB) and clearance after oral administration (Cloral). The results demonstrated that plasma diazepam and nordiazepam concentrations had a significant increase after steady states have been reached with the simultaneous administration of 800 mg of cimetidine daily for one week. The simultaneous administration of 800 micrograms of misoprostol did not cause any significant change in diazepam and nordiazepam plasma levels after steady states had been reached. Comparing the pharmacokinetic parameters of Groups A and B as well as within groups on days 8, 15 and 36, a significant increase in plasma diazepam and nordiazepam levels was detected. This was due to a cimetidine-induced impairment in microsomal oxidation of diazepam and nordiazepam, which caused a decrease in total metabolic clearance and increased mean steady state plasma concentrations. A more prolonged half-life was observed for both groups taking cimetidine as well as an increase of mean maximum plasma concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Oral↗
PubMedDate not supplied

[Heart failure at an internal medicine department: a retrospective study].

The files of 222 patients (112 men) admitted to a Medical Department (Medicina 1) of the Hospital de Santa Maria (Lisbon) between 1/1/87 and 21/6/88 with the diagnosis of congestive heart failure (CHF) were studied retrospectively. The next parameters were considered: sex, age, cause of cardiac disease, duration of CHF, presence of diabetes, predispondent factors of CHF episodes, cardiac rhythm and blood pressure on admission, presence of rales, ascitis and edema, echocardiographic findings and evolution. Ischemic heart disease (IHD) (50%) and hypertensive heart disease (HHD) (31%) were the most frequent causes of CHF in this study. The mean age was 70 years, being higher in women (74 versus 66 years). Men were predominant in the younger groups. The rheumatic heart disease (RHD) group had the lowest mean age (54) while the cardiac diseases of unknown origin had the highest mean age (79). Patients with RHD were those with longer CHF (16 years) while patients with IHD, idiopathic cardiomyopathy and cor pulmonale had a shorter duration of CHF (less than 5 years). The respiratory infection was the most frequent predisponent factor (40%). In a high number of cases (31%) it was not possible to find the presumable cause of the CHF episode. Atrial fibrillation was the predominant disarrhythmia (44%) on admission, specially in patients with RHD. Patients with HHD isolated or associated to other causes were those with higher initial blood pressure. Echocardiographic studies were suggestive that HHD can be associated with CHF without a significant increase in left atrium and ventricle dimensions nor impairment of left ventricle systolic function. Echocardiographic analysis of larger numbers of patients and the study of left ventricular diastolic function and Doppler flow patterns will eventually contribute to a better understanding of CHF physiopathology.

Adult↗
PubMedDate not supplied

[Rheumatic fever--exacerbation or decline? Analysis of patients admitted to a medical service within a period of 20 years].

The authors revised 116 clinical files of patients admitted to a Medicine ward with Rheumatic Fever in the years 1959-63 and 1979-83, in order to detect a possible recrudescence of the disease. The following parameters were analysed: age, sex, length of hospital stay, clinical manifestations, ancillary exams, therapeutics and evolution. It was found an impressive decline in the incidence of the disease (90 cases vs 26) and also a very significant decrease of the period of hospitalization in the recent group of patients (p less than 0.0005); Carditis and relapses of Rheumatic Fever were more frequent in the old group of patients.

Adolescent↗