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Biomedical subjects

R Segura

Publications and source records attributed to R Segura.

At least 73 records · Page 4Linked to original sources

Fatty acids of plasma and red blood cell lipids in a normal population.

A detailed study of the fatty acid composition of each of the lipids present in plasma and red blood cells of 62 healthy subjects of our area (Barcelona and surrounding counties), by coupling thin-layer and gas chromatography techniques has been made. The results are presented as normative data for comparison with those found in pathological situations. No significant sex differences were found. With increasing age, there was a tendency for the proportion of linoleic acid to decrease. Correlation analyses between the fatty acid composition of different lipids suggested that the interchange of fatty acids between plasma and cells mainly affects the phosphatidylcholine of the latter.

Adolescent↗

Correlation of thyroxine and thyroid-stimulating hormone with personality measurements: a study in psychosomatic patients and healthy subjects.

A comparative study performed in psychosomatic patients and healthy subjects reveals different profiles of thyroxine (T4) and thyroid-stimulating hormone (TSH) correlations with personality measurements (Minnesota Multiphasic Personality Inventory (MMPI); Sensation-Seeking Scale (SSS), and Susceptibility to Punishment Scale (SP). Three distinct sets of results may be enumerated, namely: (1) a negative correlation between sensation-seeking and TSH; (2) a positive correlation between the most indicative scales predisposing to depression-anxiety (hypochondriasis, depression, social introversion, susceptibility to punishment) and T4, and (3) the Hypomania Scale (Ma) showed a significant negative correlation with T4 in the patient group and a positive but nonsignificant relationship in the healthy group.

Adolescent↗

Risk of myocardium adjacent to infarcted myocardium: electrocardiographic, metabolic and scintigraphic evidence within the first week of acute myocardial infarction.

Atrial pacing was carried out within 5 days of an uncomplicated acute myocardial infarction (AMI) in 28 patients to detect the existence of a menaced area. A positive pacing response (at least 1.0 mm of ST-segment shift) was observed in 23 patients (82%, group I), whereas pacing results were negative in 5 (18%, group II). Pacing-induced electrocardiographic changes involved the leads affected by AMI in patients with transmural necrosis. A well-defined thallium-201 redistribution, mostly localized near or within the AMI site, was present in 10 patients from group I (43%), in 1 from group II (20%), and in 1 of 12 comparable patients (8%) in whom pacing was not performed. During pacing, abnormal lactate metabolism was observed in 11 of 17 patients from group I (65%) and in 0 of 5 from group II (0%). A 90% or greater coronary stenosis of at least 1 artery was found in 19 of 23 patients from group I (83%) and in 1 of 5 from group II (20%); 2- to 3-vessel disease (more than 70% diameter stenosis) was present in 14 patients from group I (61%) and 1 from group II (20%). During a 15-month follow-up (range 9 to 25), effort angina developed in 9 patients from group I (39%) and in none from group II. No deaths or reinfarctions occurred in either group. Thus, very early after a first AMI, most patients have a jeopardized periinfarction area that is usually associated with a critical coronary stenosis and that heralds effort angina in a significant proportion of them.

Adult↗

Prolonged angina pectoris and persistent negative T waves in the precordial leads: response to atrial pacing and to methoxamine-induced hypertension.

In 18 consecutive patients without a history of myocardial infarction (MI), prolonged angina pectoris with persistent negative T waves in the precordial leads was associated with a high frequency of in-hospital spontaneous angina (14 of 18, 78%), usually accompanied by S-T segment elevation, and occasionally in-hospital MI (4 of 18, 22%). Angina and MI always involved the electrocardiographic leads with negative T waves. Coronary arteriography, performed in 16 patients, revealed greater than or equal to 90% proximal diameter reduction of the left anterior descending (LAD) coronary artery in 14 patients. No patient had severe narrowing of all 3 major coronary arteries, but the 3 who had 100% LAD occlusion lacked collateral circulation. The ejection fraction was greater than or equal to 50% in 13 patients. Atrial pacing performed in 11 patients at an average rate of 142 beats/min produced a 1.0 mm S-T segment change in only 5 patients (45%), 3 of whom had an associated lactate production. Arterial systemic hypertension induced by methoxamine in 14 patients caused reversal of negative T waves without significant S-T segment shifts or chest pain and failed to elicit lactate extraction abnormalities in each of the 5 patients in whom it was determined. Thus, prolonged angina with persistent negative T waves in the precordial leads is almost invariably associated with a critical and proximal LAD obstruction, severe narrowing of 1 or 2 coronary arteries, and poor or absent collateral vessels. The relatively preserved coronary reserve in 55% of our patients suggests that negative T waves do not represent active myocardial ischemia. The study also suggests that transient "positivization" of the negative T waves may not necessarily relate to myocardial ischemia when associated with acute systemic hypertension.

Adult↗

Reduced hepatic insulin extraction in obesity: relationship with plasma insulin levels.

To elucidate if there are alterations in insulin metabolic clearance in obesity under basal conditions, plasma insulin and C-peptide were measured in 22 obese patients and 8 normal subjects, and the plasma C-peptide to insulin molar ratio was used as an index of hepatic insulin extraction. In obese patients, the C-peptide to insulin molar ratio correlated indirectly with basal plasma insulin levels (r = 0.71; P less than 0.001), being low in the obese patients with higher insulin levels and within the normal range in obese patients in which insulin levels were similar to those of control subjects. It is suggested that hepatic insulin extraction is decreased in obesity, even under basal conditions, but this alteration is only manifested when plasma insulin levels are high.

Adult↗

A serological and bacteriological survey of canine brucellosis in Mexico.

Using agglutination procedures, 203 human and 500 dog sera collected in Mexico City were tested for canine brucellosis. Blood samples from the 500 dogs also were cultured for Brucella canis (B. canis). Positive agglutination titers (1:100 or greater) were found in 27 (13.3%) of the human and 140 (28.0%) of the dog sera tested. B. canis was isolated from the blood of eight dogs. The disease was experimentally produced in susceptible dogs by inoculation with one of the isolated strains.

Animals↗

Contrasting effects on plasma lipoproteins of intravenous versus oral administration of a triglyceride-phospholipid emulsion.

The effect of fat on plasma lipoproteins was compared when administered by the oral and intravenous routes to healthy control subjects on a low fat diet for 5-6 weeks. During this time each subject underwent two 5 day periods of fat supplementation with a soya bean triglyceride-egg yolk phospholipid emulsion (Intralipid), once via intragastric tube, once intravenously. Changes in plasma lipoproteins were assessed by measurement of their lipid and protein content. Intragastric fat administration significantly decreased the level of very low density lipoprotein (VLDL), whereas intravenous fat administration caused a significant rise in low density lipoprotein (LDL). Morphological evidence of persistence of exogenous phospholipid in plasma following intravenous fat administration was confirmed by alterations in the fatty acid composition of lecithin in the d 1.006-1.063 fraction of plasma. In vitro studies showed that exchange readily occurred between Intralipid and LDL lecithin, causing the latter to assume a more saturated pattern. It is concluded that the occurrence of similar changes in vivo could explain the rise in low density lipoprotein following intravenous fat, possibly by influencing the catabolic rate of the apoprotein. Hydrolysis of ingested phospholipids during absorption presumably explains why none of these changes occurred after oral fat supplementation, and would seem to be an important regulatory function of the small intestine in relation to plasma lipoprotein metabolism.

Administration, Oral↗