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Biomedical subjects

A Robert

Publications and source records attributed to A Robert.

At least 343 records · Page 19Linked to original sources
PubMed1984

Computer interpretation of pediatric orthogonal electrocardiograms: statistical and deterministic classification methods.

Statistical multivariate and conventional deterministic methods of computerized interpretation of the electrocardiogram (ECG) were compared in the analysis of 1711 pediatric orthogonal ECGs validated by nonelectrocardiographic criteria on the basis of clinical and anatomic diagnoses. Among 642 children catheterized for the evaluation of congenital heart disease, there were 140 patients with left ventricular hypertrophy, 299 with right ventricular hypertrophy, and 203 with biventricular hypertrophy. A group of 1069 obviously healthy school children was studied as a control. The overall accuracy of multigroup ECG diagnosis was 85% and 79% for the statistical and deterministic methods, respectively. The diagnostic performances of both methods expressed in terms of sensitivity and predictive value were the highest for normal children and those with right ventricular hypertrophy and lowest for children with biventricular hypertrophy. The statistical method was more sensitive in the diagnosis of left ventricular hypertrophy (74% vs 64%), right ventricular hypertrophy (86% vs 83%), and biventricular hypertrophy (62% vs 50%). Mutual agreement for a correct diagnosis by the two methods was 83% for normal children and 82% for those with right ventricular hypertrophy but only 61% for children with left ventricular hypertrophy and 39% for those with biventricular hypertrophy. In conclusion, better classification results are obtained with statistical multivariate techniques as compared with conventional deterministic analysis, but both methods of ECG interpretation are complementary and their combination in the same electrocardiographic computer program can improve diagnostic accuracy.

Adolescent↗
PubMed1984

The insulin receptor of a human monocyte-like cell line: characterization and function.

Most clinical studies of the insulin receptor in man have been carried out in circulating cells, mainly monocytes. It is important to establish whether the function of the insulin receptor in blood cells reflects that of the major target tissues. Since peripheral monocytes do not divide, they cannot be studied under continuous cell culture conditions. We, therefore, studied the insulin receptor of a monocyte-like human cell line (U-937) to determine whether it could serve as a model for further investigation of the function of the insulin receptor. We found that the U-937 cells bind [125I]insulin specifically and in a time-, temperature-, concentration-, and pH-dependent fashion, similar to circulating monocytes. In addition, they internalize the hormone-receptor complex rapidly and extensively at 37 C in a fashion analogous to that of blood monocytes and hepatocytes. U-937 cells show a similar affinity for insulin as monocytes. Unlike hepatocytes, these cells do not appear to release extensive insulin-degrading activity and do not degrade cell surface-associated ligand during initial incubations. [125I] Insulin extracted or dissociated spontaneously from the cell surface shows full rebindability to fresh cells. The insulin receptor of the U-937 cells can be down-regulated as in the major target cells. As in cultured human lymphocytes, preincubation of U-937 cells with prednisolone results in significantly increased insulin binding. Incubation with a phorbol ester tumor promoter, in contrast, inhibits the extent of specific [125I]insulin binding to U-937 cells by altering the receptor affinity. The insulin receptor of the U-937 monocyte-like cell line mirrors the insulin receptor of blood monocytes and target cells; it is a useful tool for further in vitro studies of the insulin receptor.

Cell Line↗
PubMed1984

Normal limits of pediatric Frank lead electrocardiograms. Differences in data obtained in 4th or 5th intercostal spaces.

Frank lead electrocardiograms (VCGs) were recorded from 970 young subjects in order to establish normal limits for pediatric VCGs. In 245 children and 231 adolescents, the thoracic electrodes were located at the levels of the 4th and of the 5th intercostal space with subjects in supine position. Pairwise comparisons of 211 linear and angular parameters were made, using the 4th interspace as the reference. In children, there were 155 parameters with statistically significant differences and 56 parameters without significant differences between levels 4 and 5. In adolescents, corresponding figures were 158 parameters with significant differences and 53 without. Results for selected measurements showed an increase of the amplitude of Q and R waves in leads X and Y, a decrease of Q and R waves in lead Z and an increase of maximal spatial and planar QRS vectors, with the QRS loop being more anteriorly oriented by shifting the electrodes from level 4 to level 5. The mean differences in amplitude and orientation were generally small and of little practical value. However, the percentile distribution of the differences indicated that substantial changes in either direction can occur in some subjects. Thus, quantitative analysis of the pediatric Frank VCGs can be critically affected by modification of electrode placement. It is suggested that normal limits should be determined for each recording level and that criteria for analysis should be applied only to VCGs recorded at the same specified level.

Adolescent↗
PubMed1984

Prostaglandins: effects on the gastrointestinal tract.

Several prostaglandins have been shown to exert five major gastrointestinal actions. Inhibition of gastric acid secretion, orally and parenterally. Antiulcer activity (they prevent gastric and duodenal ulcers produced experimentally in animals, and they accelerate the rate of healing of duodenal ulcers in humans). Cytoprotection for the stomach, the small and the large intestine. Cytoprotection is defined as the property of many prostaglandins to protect the mucosa of the stomach and intestine from becoming inflamed and necrotic when this mucosa is exposed to noxious agents. Cytoprotection is separate from, and unrelated to, inhibition of gastric secretion. In humans, certain prostaglandins of the E type given at very low doses prevent gastric bleeding produced by aspirin and indomethacin. Stimulation of intestinal secretion, through increase of cyclic AMP formation. Stimulation of smooth muscle contraction. Certain prostaglandins are likely to be beneficial in the treatment of gastric ulcers, stress ulcers, duodenal ulcers, and perhaps gastritis and certain forms of inflammatory bowel disease.

Animals↗
PubMed1984

Lack of correlation between mucus gel thickness and gastric cytoprotection in rats.

The effect of various cytoprotective agents on the thickness of gastric mucus gel layer in rats was studied. It was hypothesized that an increase in the mucus gel layer might be involved in cytoprotection. The results show that this is not the case. Neither prostaglandin E2, 16,16-dimethyl prostaglandin E2, nor mild irritants (20% ethanol, 0.35 M HCl, 20% glucose, 20% mannitol), all given orally, altered the thickness of the mucus gel layer, although these agents were found to be cytoprotective, i.e., inhibiting the formation of gastric mucosal necrotic lesions caused by oral administration of absolute ethanol. The only agents that significantly increased the thickness of the mucus gel layer were a hypertonic solution (4% NaCl) and sodium salicylate. We conclude that if mucus plays a role in cytoprotection, it is not by virtue of an increase in thickness of the gel layer adherent to the gastric mucosa.

Animals↗
PubMed1984

Distinction between antiulcer effect and cytoprotection.

Gastric ulcerations were produced in rats by oral administration of aspirin (ASA) suspended in a vehicle consisting of either water or increasing concentrations of HCl (0.005 M to 0.35 M). The lesions were prevented by antisecretory doses of a histamine H2 blocker (cimetidine) and by an anticholinergic agent (pro-banthine), but only when the acidity of the vehicle was low (0.05 M to 0.15 M), not at higher (0.35 M). On the other hand, 16,16-dimethyl PGE2 prevented ulcer formation even when ASA was suspended in all HCl concentrations, including 0.35 M HCl. In other studies, gastric mucosal necrosis was produced by oral administration of absolute ethanol. These lesions were not affected by cimetidine or two anticholinergic agents, pro-banthine and methscopolamine bromide, nor by alkalinization of the gastric lumen with NaHCO3 or pH 7 buffer; however, these ethanol-induced lesions were completely prevented by 16,16-dimethyl PGE2. We conclude that antisecretory agents, by blocking endogenous formation of acid, are antiulcer as long as no acid or only small amounts of acid (1 ml of 0.15 M or less) are given together with ASA. When higher concentrations are used (e.g. 0.35 M HCl), the antisecretory effect of the inhibitors is overcome by the exogenous acid, and ulcers still form. Under these conditions, only "true" cytoprotective agents, such as 16,16-dimethyl PGE2, prevent ASA-induced ulcers, even in the presence of high acidity. Although cimetidine and pro-banthine were shown earlier to reduce ASA-induced ulcers at nonantisecretory doses, these agents may still decrease acid formation within the gastric glands.(ABSTRACT TRUNCATED AT 250 WORDS)

16,16-Dimethylprostaglandin E2↗
PubMed1984

Factors influencing postoperative survival in aortic regurgitation. Analysis by Cox regression model.

From 1965 to 1981, 114 patients underwent aortic valve replacement for severe aortic regurgitation in our institution. Catheterization was performed preoperatively in 103 patients. Follow-up was possible in 98% of the survivors. Long-term survival was significantly different between patients in preoperative Functional Class I-II and those in Class III-IV (p less than 0.03); those with a preoperative cardiothoracic ratio less than 0.64 versus greater than or equal to 0.64 (p less than 0.001); and those with a preoperative ejection fraction greater than 0.50 versus less than or equal to 0.50 (p less than 0.03). A multifactorial analysis was used to identify the dominant preoperative prognostic variables affecting survival. Three of the 13 parameters examined simultaneously were found to independently influence survival rates: cardiothoracic ratio (p = 0.001), strain pattern on the electrocardiogram (p = 0.072), and left ventricular end-systolic pressure (p = 0.127). After stratification of the population into two groups according to preoperative functional class, the predictive variables were cardiothoracic ratio (p = 0.014), strain pattern (p = 0.050), and acute/chronic form of aortic regurgitation (p = 0.034). This statistical analysis enabled us to derive a mathematical equation for predicting an individual patient's probability of survival. We found a close fit between the survival rate predicted by the mathematical model and the observed survival rate.

Adolescent↗
PubMed1983

[Immunoallergic complication induced by rifampicin with disseminated intravascular coagulation].

In a 48-years old woman, intermittent rifampicin treatment induced an immunoallergic reaction with digestive disorders, haemolysis, acute renal failure and prolonged prothrombin time. The reintroduction of rifampicin, 17 days later, resulted in a similar, though more severe, reaction associated with diffuse haemorrhages from disseminated intravascular coagulation, this association being exceptional. The responsibility of rifampicin was demonstrated by the chronological relationship between clinical symptoms and administration of the drug, and by the presence in the patient's serum of anti-rifampicin antibodies. The antigen-antibody reaction with complement activation and haemolysis probably explains the disseminated intravascular coagulation.

Acute Kidney Injury↗
PubMed1983

Protein-stimulated enrichment of human platelet membranes in linoleylphosphatidylcholines. Effect upon adenylate cyclase and fluidity.

In order to study the effect of linoleyl enrichment of platelet membranes upon adenylate cyclase activity and membrane fluidity, manipulations of platelet phospholipids are carried out with phosphatidylcholine-loaded high-density lipoproteins (HDL) or phospholipid-exchange protein and phospholipid-cholesterol mixed vesicles. Incubation with HDL does not appear to be valuable for this purpose. On the other hand, phospholipid-exchange protein and mixed vesicles can be used successfully. Phospholipid-exchange protein stimulated 3-fold the spontaneous exchange of 2-linoleylphosphatidylcholine between the vesicles and the platelets. Linoleyl enrichment of platelets by dilinoleylphosphatidylcholine is about 25% and by 2-linoleylphosphatidylcholine is about 45-50%. The unsaturation index remains constant when the enrichment is performed using dilinoleylphosphatidylcholine but it increases with 2-linoleylphosphatidylcholine. Basal and prostaglandin E1-stimulated adenylate cyclase activities are not modified by dilinoleylphosphatidylcholine, while they increase significantly in the case of 2-linoleylphosphatidylcholine. There is no significant variation in diphenyl hexatriene fluorescence polarization parameters, either with dilinoleylphosphatidylcholine or with 2-linoleylphosphatidylcholine.

Adenylyl Cyclases↗
PubMed1983

Computer interpretation of pediatric Frank vectorcardiograms in the evaluation of congenital heart disease.

The evaluation of a new computer program for analysis and interpretation of pediatric Frank vectorcardiograms is reported. The program includes extensive age- and sex-dependent criteria based on tables of limits for numerous vectorcardiographic parameters. In 728 catheterized patients, the diagnostic performance for type A statements was tested against independent and objective evidence obtained from hemodynamic and angiographic data. The overall diagnostic accuracy ranged from 75 to 89% without difference between children less than 2 years of age and those greater than or equal to 2 years of age. Sensitivities and specificities of the various diagnoses did not differ much between the 2 age groups. In the younger children, the accuracy of a positive diagnosis of left ventricular hypertrophy, right ventricular hypertrophy, and biventricular hypertrophy was 20, 15, and 32% higher, respectively, than in the older children. The accuracy of the diagnosis "normal" was 28% lower in the younger children. These differences were explained by the higher proportion of pathologic findings in the younger children: 93% versus 74% in the older children. Given the strict methods of the evaluation, the diagnostic accuracy of this pediatric program was considered clinically satisfactory. Program performance appears to be dependent not on patient age but on prevalence of abnormalities in the population analyzed. Further improvement can be expected by making the criteria more adaptable to the composition of the population.

Adolescent↗
PubMed1983

Mild irritants prevent gastric necrosis through "adaptive cytoprotection" mediated by prostaglandins.

Several prostaglandins (PG) were found earlier to be cytoprotective for the stomach and the intestine. We now report that mild irritants, given intragastrically, are also cytoprotective by stimulating the release of PG by the stomach. Several "mild irritants," 10-20% ethanol, 0.2-0.35 M HCl, 0.05-0.075 M NaOH, 2-4% NaCl, and water at 70 degrees C, were given orally to fasted rats. Fifteen minutes later, one of the following necrotizing agents was administered orally: 100% ethanol, 0.6 M HCl, 0.2 M NaOH, 25% NaCl solution, and boiling water. One hour later, the stomachs were removed and necrotic lesions graded. The mild irritants inhibited the necrotic lesions dose dependently. After a single treatment, protection lasted 1 h; repeated administrations maintained cytoprotection for as long as the mild irritants were being given. Indomethacin, an inhibitor of PG synthesis, abolished cytoprotection by mild irritants. After oral administration of NaOH at cytoprotective concentrations (0.01-0.1 M), the amounts of PGE2, PGF2 alpha, and thromboxane B2 formed by the gastric mucosa increased steadily up to threefold. The protection elicited by mild irritants is called "adaptive cytoprotection." The increased synthesis of PG may represent a physiological, natural defense mechanism that may be necessary to maintain cellular integrity of the gastrointestinal mucosa, in spite of the hostile environment caused by luminal contents.

Acclimatization↗
PubMed1983

[Fetal and neonatal transmission of type-b anti-haemophilus influenzae antibodies protecting the newborn rat].

Haemophilus influenzae type b is the most common cause of bacterial meningitis in children. Intranasal or intraperitoneal inoculation of infant rats with Haemophilus influenzae type b results in bacteremia and meningitis and has been proved to be a reproductible model of the human disease. For these reasons, it was of interest to use rats as experimental model for the study of anti-Haemophilus influenzae type b vaccine. Immune serum against Haemophilus influenzae type b cell surface extracts was prepared on rabbit. In a first experiment, pregnant rats were passively immunized with either immune rabbit serum or normal rabbit serum or saline. In a second experiment, suckling rat mothers were passively immunized with either immune rabbit serum or normal rabbit serum or saline. All infant rats were inoculated intraperitoneally at 6 days of age with Haemophilus influenzae type b. Bacteremia was determined in all infected rats 24 h after challenge. Only infant rats from immune serum-treated mothers were protected. This protection may be transferred from mother to young rat either before of after the birth.

Animals↗
PubMed1983

Factor VIII related antigen, coagulation tests and acute renal failure.

Coagulation factors were measured in 50 patients presenting with acute renal failure on the day of their admission (D1) and seven days later (D7). A number of changes were observed, particularly in those patients with a poor prognosis (decreased platelet counts and plasminogen concentrations and increased factor VIII related antigen concentrations). In the majority of cases it would appear that disseminated intravascular coagulation remains sub-clinical.

Acute Kidney Injury↗