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Biomedical subjects

A Kohn

Publications and source records attributed to A Kohn.

At least 73 records · Page 4Linked to original sources
PubMed1985

Use of chicken and rabbit antibodies in a solid phase protein A radioimmunossay for virus detection.

A new rapid indirect solid phase radioimmunoassay was developed for the detection of Sindbis virus. Chicken antibodies were adsorbed onto wells in microplates to serve as 'capture antibodies' and rabbit antibodies were used as the second antibody. 125I-labelled protein A that does not bind to chicken antibodies, but binds firmly to rabbit antibodies was used as the tracer. All the steps necessary for the development of the assay are described. The minimal amount of Sindbis virus detectable was around 3 x 10(5) PFU/ml and the interassay reproducibility was about +/- 30%.

Animals↗
PubMed1985

Gastric acid and pancreatic polypeptide responses to modified sham feeding: indication of an increased basal vagal tone in a subgroup of duodenal ulcer patients.

The effect of sham feeding upon gastric acid secretion and pancreatic polypeptide release was investigated in 28 patients with duodenal ulcer in order to evaluate whether high basal vagal activity is the cause of basal acid hypersecretion in patients with duodenal ulcer and basal secretion higher than 30% of their peak acid output. The patients were divided into two groups based on the ratio of basal/pentagastrin stimulated peak acid output (BAO/PAO) was higher or lower than 0.30: group A n = 19 (BAO/PAO less than or equal to 0.30) and group B n = 9 (BAO/PAO greater than 0.30). Gastric acid response to sham feeding (SAO) was significantly higher than basal level in group A (SAO: 11.4 mEq/h (2.5-20.1) vs BAO: 5.2 mEq/h (0.8-22.9), p less than 0.01, median (range)) while in group B the acid secretion did not increase with sham feeding (SAO: 9.6 mEq/h (4.5-13.6) vs BAO: 8.8 mEq/h (6.3-13.8) ns, median (range)). A negative correlation (r= -0.6118226, p less than 0.01) was found between acid increase expressed as basal subtracted sham feeding response (SAO-BAO) and BAO/PAO ratio of the entire group of duodenal ulcer patients (n = 28) suggesting that the greater is basal acid secretory capacity the smaller is acid increase in response to residual vagal activation. Pancreatic polypeptide response to sham feeding was higher in group A than in group B but no correlation (r = 0.20, n = 28) nor individual covariation was found between acid and pancreatic polypeptide secretions during vagal stimulation. sham feeding did not change serum gastrin. It is concluded that an increased vagal stimulation seems to be the cause of basal hypersecretion in a subgroup of patients with duodenal ulcer. The lact of correlation between the pancreatic polypeptide and acid responses to vagal stimulation interferes with the reliability of pancreatic polypeptide as indicator of vagal tone on gastric parietal cells.

Adult↗
PubMed1984

First record of Aspiculuris tetraptera (Nitzsch, 1821) (Nematoda : Oxyuroidea) and Dollfusentis chandleri (Golvan, 1969) (Acanthocephala : Illiosentidae) in Haemulon sciurus (Shaw 1803) (Pisces : Pomadasyidae).

Forty specimens of Haemulon sciurus were examined for endoparasites and this paper refers to the recovered Nematodes and Acanthocephalans. Aspiculuris tetraptera is for the first time referred in fish and Dollfusentis chandleri is recorded in Brazil and in a new host.

Acanthocephala↗
PubMed1983

Effects of bombesin on gastrin and gastric acid secretion in patients with duodenal ulcer.

The effect of bombesin, a possible neurotransmitter of gastrin release, upon gastrin and gastric acid secretion was investigated in 25 patients with duodenal ulcer and in 16 normal subjects. In patients with duodenal ulcer bombesin (10 ng/kg/min) produced an increase in plasma gastrin output (median 22.4 (range 7.5-75.8) pmol/l/min) similar to that obtained in normal subjects (median 24.4 (range 5.8-56.5) pmol/l/min), whereas gastrin stimulated by a meal was significantly higher in the group of patients with duodenal ulcer (median 20.7 (range 9.2-42.9) vs 16.2 (range 3.4-22.2) p<0.05). Peak acid output induced by bombesin was significantly higher in patients with duodenal ulcer than in normal subjects (median 24.4 (range 9.0-63.8) vs 14.0 (range 3.0-24.8) mmol/h, p<0.05) despite identical gastrin outputs. The ratio (%) obtained by dividing the acid secretory response to bombesin by the response to pentagastrin, however, was similar in both normal subjects and patients with duodenal ulcer (median 55 (range 20-116) vs 58 (range 31-95) respectively). The difference between the gastrin response to food and bombesin could be explained by the fact that bombesin releases gastrin directly, whereas a protein meal involves several mechanisms (neural, peptidergic, paracrine, endocrine), either stimulatory or inhibitory. The above results indicate that a higher concentration in antral and/or duodenal gastrin is unlikely to be present in patients with duodenal ulcer. An increased parietal cell mass could explain the higher gastric acid response after bombesin infusion in our group of patients with duodenal ulcer.

Adult↗
PubMed1982

Neoapocreadium chabaudi sp. n. (Apocreadiidae) and Schikhobalotrema acuta (Linton, 1910) (Haplosplanchnidae) trematodes parasites of marine fishes in Brazil.

Neoapocreadium chabaudi sp. n. (Digenea, Apocreadiidae) is described from the intestine of a marine fish Stephanolepis hispidus from Brazil, and the genus Schikhobalotrema Skrjabin & Guschanskaja, 1955 represented by its type species S. acuta (Linton, 1910) Skrjabin and Guschanskaja, 1955, is for the first time reported from the intestine of Strongylura marina in Brazil. N. chabaudi sp. n. is more closely related to N. angustum (Sogandares-Bernal, 1959) from which differs mainly in the size of the eggs, by the presence of intercecal vitelline follicles in the region between the testes and acetabulum, and by the large genital atrium.

Animals↗
PubMed1982

Transmission and scanning electron microscopical studies in the tegument of male Schistosoma mansoni after oxamniquine treatment.

Schistosoma mansoni recovered from experimentally infected mice orally treated with oxamniquine were studied by transmission and scanning electron microscopy. The worms were examined 24 hours, 3, 7 and 10 days after a single dose of 100 mg/Kg of the drug. After oxamniquine treatment significant structural alterations were observed in tegumental, muscular and parenchymal levels. The initial alterations were confined to basal vacuolation in the tegument and to structural disorganization both in tegumental and non tegumental cells. Ten days after treatment, intercellular oedema became more prominent originating "bubble-like" lesions with varied dimensions. The intercellular oedema leading to the "bubble" formation seems to be the most striking feature caused by oxamniquine treatment.

Animals↗
PubMed1982

Effect of bombesin on lower esophageal sphincter pressure in humans.

Intravenous infusion of bombesin in humans results in increased serum gastrin levels and increased lower esophageal sphincter pressure. To differentiate a gastrin- from a nongastrin-mediated mechanism, the effect of intravenous bombesin infusion on lower esophageal sphincter pressure was studied in 5 healthy subjects and in 5 antrectomized patients. Lower esophageal sphincter pressure was recorded by three continuously perfused catheters with side-openings located 5 mm apart. Blood samples were taken at regular intervals during the study periods to assay gastrin and pancreatic polypeptide. Manometric tracings and blood samples were coded and evaluated blindly. Lower esophageal sphincter pressure increased during bombesin infusion both in normal and antrectomized subjects. The increase had a delayed onset and persisted after discontinuation of bombesin. No correlation was found between lower esophageal sphincter pressure and serum gastrin or pancreatic polypeptide values. These data indicate that the effect of bombesin on lower esophageal sphincter pressure is not gastrin or pancreatic polypeptide mediated.

Adult↗