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Biomedical subjects

A Robert

Publications and source records attributed to A Robert.

At least 397 records · Page 22Linked to original sources
PubMed1979

Cytoprotection by prostaglandins in rats. Prevention of gastric necrosis produced by alcohol, HCl, NaOH, hypertonic NaCl, and thermal injury.

Oral administration to fasted rats of either absolute ethanol, 0.6 N hydrochloric acid, 0.2 N sodium hydroxide, 25% sodium chloride, or boiling water produced extensive necrosis of the gastric mucosa. Pretreatment with several prostaglandins of the A, E, or F type, either orally or subcutaneously, prevented such necrosis, and the effect was dose-dependent. This property of prostaglandins is called "cytoprotection." The protective effect against oral administration of absolute ethanol was already maximal 1 min after PGE2 given orally, and 15-30 min after PGE2 given subcutaneously. Cytoprotection by prostaglandins is unrelated to the inhibition of gastric acid secretion since, (a) it is maximal at doses that have no effect on gastric secretion, and (b) anti-secretory compounds (cimetidine, methscopolamine bromide) and antacids are not cytoprotective. Although the mechanism of gastric cytoprotection is unknown, prostaglandins appear to increase the resistance of gastric mucosal cells to the necrotizing effect of strong irritants. These results suggest that certain prostaglandins, by a mechanism other than the inhibition of gastric acid secretion, maintain the cellular integrity of the gastric mucosa, and might be beneficial in the treatment of a variety of diseases in which gastric mucosal injury is present.

Animals↗
PubMed1978

[Determination of mean platelet volume in pediatric hematology. Practical value (author's transl)].

Some particle counters give a routine determination of mean platelet volume. 272 determinations of this new parameter were performed on 107 hospitalized children in the hematology field. Giant platelets are a frequent sign in peripheral thrombocytopenia, and they are never observed in central thrombocytopenia. The determination of the mean platelet volume is of value in an emergency examination for thrombocytopenia, while awaiting the results of a myelogram, and in monitoring primary thrombocytopenic purpura. In this later condition, the persistance of an increased mean platelet volume in spite of an improvement in the number of platelets should lead to a suspicion of a relapse.

Acute Disease↗
PubMed1978

Peripheral metabolism of testosterone during puberty in the male guinea-pig.

Variations in the metabolic clearance rate and the production rate of testosterone during puberty in the male guinea-pig were established by single injection and constant infusion methods. Similar results were obtained; MCR (1/24h) increases from Day 20 to Day 70 and then stabilizes between Days 70 and 90 to levels comparable to those of a 6-month-old adult. MCR as 1/24 h/100 g decreases steadily between Days 20 and 60. The evolution of the testosterone production rate (PR: ng/24 h) is characterized by a marked rise between Days 20 and 70, and then a decrease up to Day 90, continuing until 6 months. PR as ng/24 h/100 g increases between Days 20 and 40, remains stable until Day 70, then decreases. Testosterone half-life is stable throughout the pubertal period. The rate of conversion of testosterone to androstenedione remains stable except for a rise between Days 50 and 60. We conclude that the increase in testosterone concentrations during puberty is due to a rise in the production rate and not to a decrease of clearance rate.

Animals↗
PubMed1978

[Development of seminiferous tubules in guinea pigs during puberty].

The study of development of the seminiferous tubules of the guinea-pig along the puberty is based on diameter, length and volume relate to testicular weight and age. During this period the development is linear. A correlation exist between testicular testosterone concentration and growth of seminiferous tubules in diameter and in length from day 16 to 60, stage of puberty in which the first spermatozoa appear.

Aging↗
PubMed1978

Intraoperative autotransfusion in elective and emergency vascular surgery.

Intraoperative autotransfusion was studied in 62 patients undergoing elective or emergency thoracic or abdominal vascular surgery systemic heparinization. The results in 58 patients who received a mean autotransfusion volume of 1.8 liters were compared with a group of four patients in whom 9 liters of blood was autotransfused. The quality of the autotransfused blood also was studied and was shown to have a normal platelet count (mean, 144,000/cu mm) and normal fibrinogen value (mean, 212 mg%). No significant differences in the hematological or coagulation parameters measured were detected in the groups given moderate or massive autotransfusion. The mean homologous blood requirement during the hospital admission in the "moderate" group was 300 ml and in the "massive" group 1,000 ml. With careful technique excessive hemolysis or pulmonary microaggregate embolism does not occur; 75% of patients required no homologous blood throughout their hospital admission. No complications which would be attributed to autotransfusion were seen in either group. It is concluded that intraoperative autotransfusion is safe and effective and deserves wider application.

Abdomen↗
PubMed1978

Antisecretory and antiulcer properties of prostaglandins.

Certain prostaglandins inhibit gastric secretion and exert an antiulcer activity. These properties, first discovered in animals, were confirmed in humans and are likely to be useful in the treatment of peptic ulcer. On the other hand, several prostaglandins given at high doses favor the passage of water and electrolytes into the intestinal lumen. This accumulation of fluid seems to be the cause of the diarrhea observed on occasion after prostaglandins are given.

Animals↗
PubMed1977

Resistance of germfree rats to indomethacin-induced intestinal lesions.

Indomethacin given orally to conventional rats produced in three days a syndrome, often fatal, of intestinal lesions characterized by multiple ulcers and peritonitis. Male germfree rats were found to be resistant to this effect of indomethacin, while female germfree rats developed very mild lesions. Germfree rats became sensitive again to such lesions when monocontaminated with E. coli. In such animals, however, the lesions were less severe than in conventional animals, presumably because more than one microorganism is necessary for the full syndrome to develop. These results suggest that microorganisms are necessary for the development of indomethacin-induced intestinal lesions. Secondary bile acids, absent in germfree animals, may also be necessary. The prostaglandin deficiency caused by indomethacin appears to weaken the resistance of the intestinal mucosa to microorganisms and/or their toxins. The latter may then penetrate the mucosa, damage the cells and produce ulcers and perforations. Since several prostaglandins also protect against indomethacin-induced lesions, the hypothesis is advanced that certain prostaglandins may protect the mucosa ("cytoprotection") by preventing the spread of microorganisms and/or their toxin through the intestinal wall.

Animals↗
PubMed1977

[Total frequency of dental caries in the Canton of Vaud after the transition from fluoride tablets to fluoridation of table salt].

This report shows results of a survey on dental caries in the canton of Vaud in the years 1970 and 1974. In this canton fluoridation was carried out by means of fluoride tablets distributed at school until 1969/70 and in subsequent years by adding 250 mg F/kg fluoride to domestic salt. For comparison, results from adjoining and other cantons are also presented. In 1970 the 3 communities in the canton of Vaud (Moudon, Grandson and Vevey) showed a remarkably low overall caries level due to the distribution of fluoride tablets, supplemented in Grandson with regular brushings with fluoride solutions. When the fluoride tablets were discontinued in 1968/70 and fluoridated domestic salt containing 250 mg F/kg NaCl was introduced, caries incidence reached an even lower level. In these 3 communities caries prevalence fell to the lowest level reached, so far, by means preventive measures in Bettlach (canton of Solothurn, toothbrushing with fluoride solutions 6 times per year combined with information, fluoride tablets on every school day, and in addition consumption of table salt fluoridated at a suboptimal level of 90 ppm). The children in the control communities Romont (canton of Fribourg), St-Aubin (canton of Neuchâtel) and Châtel-St-Denis (canton of Fribourg) also showed decreases of caries levels from 1970 to 1974. This decrease is attributed to the distribution of fluoride tablets started at the schools of this community in the late sixties. Caries incidence in the age spans 8 to 12 and 10 to 14 years was estimated. Children from the canton of Vaud where fluoridated table salt was practically the only preventive measure showed a smaller DMF increase than those from the cantons of Fribourg and Neuchâtel. By means of a method combining DMF means of various age groups it was possible to obtain sufficiently large numbers of children for a study of the caries prevalence in each community. All communities showed a decrease of caries levels. In the canton of Vaud this reduction started in 1970 at an already low level and in 1974 reached consistently lower values than those of the control communities of the cantons of Fribourg and Neuchâtel.

Administration, Oral↗