Chemotaxis of Mercenaria mercenaria hemocytes to bacteria in vitro.

Hemocytes of the hard clam Mercenaria mercenaria migrate toward secreted bacterial products in vitro by chemotaxis (i.e., by detection of an increasing chemical gradient of attractant). The attractants produced by Escherichia coli are peptides or small proteins. Clam hemocytes also migrate toward formyl-methionyl-leucyl-phenylalanine (fMLF), a mammalian neutrophil chemoattractant produced by bacteria, but not toward the related compound formyl-methionyl-valine. Migration of hemocytes to fMLF was blocked with the neutrophil fMLF receptor antagonist, t-Boc-MLF, suggesting that the hemocytes possess this receptor and that the response is receptor-mediated. However, fMLF is not the major bacterial chemoattractant for clam hemocytes, as t-Boc-MLF did not block migration of these cells to secreted bacterial chemoattractants.

Phagocytosis by hemocytes of the hard clam, Mercenaria mercenaria.

Large granular hemocytes of Mercenaria mercenaria avidly phagocytose a variety of biological particles (red blood cells of six species, yeast, and gram-positive and gram-negative bacteria) as well as polystyrene spheres. Clam hemolymph is not necessary for phagocytosis but may have some opsonic effect in certain circumstances (e.g., low temperature and low particle density). Formaldehyde treatment of red blood cells enhances susceptibility to phagocytosis. Phagocytosis by Mercenaria hemocytes in vitro appears to be a nonspecific process.

Agglutinins in the hemolymph of the hard clam, Mercenaria mercenaria.

Lectins in the serum of the clam Mercenaria mercenaria agglutinate some red blood cells, bacteria, and yeast. The interaction of these substances with particles is affected by sugars, ions, temperature, and alteration of particle surfaces. Lectins are not needed for phagocytosis of foreign particles in vitro. In M. mercenaria these recognition molecules do not enhance defense mechanisms.

Synchronous neoplasms in patients with diminutive colorectal adenomas.

The distribution of synchronous neoplasms was retrospectively analyzed in 220 patients undergoing initial colonoscopic evaluation for colorectal neoplasms. In 159 of the 220 patients, an index neoplasm was present in the rectosigmoid region. Of these 159 patients, 32 had an index rectosigmoid adenoma less than 5 mm in diameter (diminutive), 105 had an index rectosigmoid adenoma greater than or equal to 5 mm in diameter and 22 had an index rectosigmoid adenocarcinoma. Among these patients with different index neoplasms the frequency of synchronous neoplasms was 34%, 53%, and 73%, respectively. The synchronous neoplasm was an adenoma greater than or equal to 5 mm in diameter in 13%, 40%, and 64%, respectively. The synchronous neoplasm was a carcinoma in 0%, 7%, and 5%, respectively. Two or more synchronous neoplasms occurred in 9%, 34%, and 41% of the index neoplasm groups, respectively. Finally, symptoms providing an indication for colonoscopy were present in 31%, 75%, and 86%, respectively. It is concluded that patients with diminutive index adenomas had fewer and smaller synchronous neoplasms (P less than 0.025) than patients with larger adenomas or invasive carcinoma as the index lesion. Thus, total colonoscopy does not appear to be necessary in asymptomatic patients with only diminutive adenomas found at flexible sigmoidoscopy.

Colorectal neoplasms and Barrett's esophagus.

Prospective colonoscopic study of 36 patients with Barrett's esophagus found colorectal adenomas in 33% of patients. Of patients aged less than 60, four of 17 (24%) had adenomas, while patients aged 60 or more had adenomas in eight of 19 (42%) cases. All adenomas were less than or equal to 10 mm diameter. No colorectal malignancies were found in these patients. This prevalence of neoplasms is consistent with results of autopsy studies. It is concluded that no increased risk of colorectal neoplasms was found in this group of patients with Barrett's esophagus.

Influence of route of administration on the humoral response of channel catfish (Ictalurus punctatus) to Yersinia ruckeri.

Channel catfish were inoculated intraperitoneally, intramuscularly, or intraesophageally with Yersinia ruckeri. Three antigen doses were administered by each route of injection. Four fish from each treatment were sacrificed at 5-day intervals for 40 days. Serum from each individual was tested for antibody activity against Y. ruckeri by indirect enzyme-linked immunosorbent assay (ELISA). High titers of anti-Y. ruckeri antibody were elicited by all doses (10(5) to 10(9) cells/g of fish) regardless of the route of administration. Mean titers for saline injected fish ranged up to 1:64 for each route of inoculation while mean titers for bacteria injected fish ranged up to 1:4096. Mean titers of 1:128 or greater were observed by day 15 post injection; titers peaked about day 30 and diminished thereafter. Channel catfish were most responsive to the antigen (10(7) to 10(9) cells/g of fish) when administered intramuscularly although lower doses (10(5) to 10(6) cells/g of fish) administered intraperitoneally elicited a substantial response. There was little evidence of dose-dependent responses for any of the routes of immunization. The rapid onset of relatively high serum titers suggests that the fish were mounting a secondary response to Yersinia ruckeri.

Recurrent stomal variceal bleeding. Successful treatment using injection sclerotherapy.

Stomal varices may develop in patients with gastrointestinal stomas and portal hypertension. Bleeding often is recurrent and may be fetal. A 48-year-old woman had six major stomal variceal bleeds requiring 20 U of blood in the four months before beginning stomal sclerotherapy. "Paravariceal" injections using various combinations of sodium tetradecyl sulfate, ethanol, and saline resulted in a decrease in blood transfusions to 3 U during a 20-month follow-up. Injection sclerotherapy deserves consideration in patients with recurrent stomal variceal bleeding.

Changes in regional myocardial blood flow and variable development of hypertrophy after aortic banding in puppies.

Supravalvar aortic banding was performed in 6 to 12 week puppies. Sixteen animals were studied 7.3 (3.5 to 10) months later, closed-chested under morphine-chloralose, catheters being positioned in the great vessels and heart, including the left atrium for microsphere injection. Compared with 11 controls, eight dogs developed biventricular hypertrophy, four isolated left ventricular hypertrophy and four had no hypertrophy. The left ventricular systolic pressure was similar (P greater than 0.05) in these 3 banded groups (mean, 30 +/- 2 [SEM] kPa, [222 +/- 16 mmHg], n = 16). The left ventricle was divided into three coronal slices with approximately 59 samples being taken from subendocardial, midwall, and subepicardial layers and additional samples from the atria and right ventricle for regional myocardial flow measurement. As left ventricular hypertrophy increased, the subendocardial/subepicardial flow ratio decreased (r = -0.8). Heterogeneity of left ventricular regional myocardial flow, including a base-to-apex decrease in flow, present in controls, was markedly reduced in the banded dogs. Analysis of variance was found to be the most sensitive test for detecting left ventricular perfusion abnormalities since in banded dogs without hypertrophy, total and regional subendocardial/subepicardial flow ratios were not significantly different from control values, whereas the subendocardial circumferential flow pattern determined by analysis of variance was significantly different from control in these dogs (P less than 0.05).

Recent developments in the measurement of cardiac output and regional blood flow using indocyanine green and microspheres.

Densitometric studies show that the large flow measurement errors and inability to obtain reproducible densitometer calibrations reported with indocyanine green (ICG) in nearly isotonic saline may have arisen from two sources: (a) slowed optical stabilization, and (b) sedimentation of dye aggregates formed in the salt "solutions" of ICG, both of which are avoidable by preparing the dye in water. The assumptions of the widely used regional blood flow measurement technique using radionuclide-labeled microspheres are described. Simultaneous injection of 8mu and 15mu microspheres in turkeys and in dogs demonstrated the existence of at least 8 mu arteriovenous communications (AVCs) in the stomach and intestine, not previously described by this technique, which, in addition to their physiologic functions, may play a role in production of acute gastric mucosal ischemia and erosions. Similar AVCs, producing a lesser degree of "shunting," were also found in the heart. Loss of 8 mu relative to 15 mu microspheres continued with time in the gastrointestinal circulation.

Simultaneous regional myocardial blood flows by tritiated water and microspheres.

Regional myocardial blood flow (RMF) was measured simultaneously by use of labeled 8-mum microspheres and the constant-rate infusion of 3H2O in 22 open-chest dogs (Na pentobarbital anesthesia) under markedly different hemodynamic conditions. Following cardiac excision, three adjacent 80-mg tissue samples were taken from the subendocardial, mid-wall, and subepicardial layers of quadrantal left ventricular (LV) segments of the basal and midventricular cardiac slices, and from one segment of the apical slice, totaling 81 samples per LV. RMF was calculated by the microsphere reference-flow technique and by two 3H2O tissue-uptake models. Good agreement between techniques (r=0.9-0.96) was found in comparing flows to the myocardial layers. Using Kety's "single-mixer" model of 3H2O tissue uptake, fairly good agreement was found between techniques in the 80-mg tissue samples; the cofficient of variation from regression was 18.5% which improved markedly to 12.3% when the flow values for each technique were averaged in the three adjacent samples. Analysis of variance showed that flow to the various LV subdivisions (layer, segment, slice) of control animals was heterogeneous.

Effect of nitroglycerin with and without systemic hypotension on canine regional myocardial tritiated water deposition.

A marked alteration in the transmural distribution of left ventricular blood flow, with a relative increase in subendocardial and mid-wall flows, but with no change in the distribution of the relative blood flow to the two ventricles occurred when nitroglycerin was administered and the systemic arterial blood pressure in the upper body maintained near control levels in anaesthetized, open-chested dogs. The relative increase in subendocardial and mid-wall flows may have resulted from a direct action of nitroglycerin on the coronary vasculature. On the other hand, the intravenous administration of nitroglycerin, when followed by the hypotension which it produces, did not alter the transmural distribution of blood flow in the left ventricle of the dog. Blood flow to the right ventricle relative to flow to the left ventricle increased in this situation.

Characterization of the factors responsible for death of fish infected with Vibrio anguillarum.

Vibrio anguillarum produced substances toxic for goldfish (Crassius auretus) that are released from living bacteria and associated with heat-killed bacteria. Heating (100 degrees C) enhances the potency of the extracellular toxin.